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United States

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Cell Biology Professor | Quantitative Imaging Expert | Virology, Nuclear Mechanics & Aging Research

Profile Summary

Associate Adjunct Professor at UC Davis with expertise spanning virology, quantitative imaging, and cellular mechanics. I develop advanced microscopy techniques to measure biophysical properties in living cells, with applications from viral infection mechanisms to aging research. My virology background includes studying herpesvirus capsid transport and viral-host interactions, while my current work focuses on quantitative analysis of cellular mechanics during aging using nanorheology and single-cell measurements. Published in Science Advances and other top journals, I bridge quantitative biophysics with cell biology across multiple biological systems. I have extensive experience in image analysis software development, statistical modeling of cellular data, C. elegans genetics, and viral pathogenesis. My interdisciplinary approach combines cutting-edge imaging technologies with rigorous quantitative analysis to understand complex biological processes from molecular to organismal levels.

Subject Matter Expertise

• ☆ Molecular Engineering
• ☆ Microbiology
• ☆ Virology
• ☆ Molecular Virology
• ☆ Biostatistics
• ☆ Molecular Biology
• ☆ Biomarkers
• ☆ Genetics
• ☆ Chromatin
• ☆ Epigenetics
• ☆ PCR
• ☆ Molecular Cloning
• ☆ Next Generation Sequencing (NGS)
• ☆ DNA Sequencing
• ☆ Microinjection
• ☆ Mutagenesis
• ☆ Exome Sequencing
• ☆ Recombinant DNA
• ☆ Plasmid DNA
• ☆ DNA Damage & Repair
• ☆ Kinases
• ☆ Cell Biology
• ☆ Cell-Based Assays
• ☆ Cytochemistry
• ☆ Cytogenetics
• ☆ Cell Signaling Pathways
• ☆ Membrane Biology
• ☆ Biophysics
• ☆ Biotechnology & Bioengineering
• ☆ Biomedical Engineering
• ☆ Microscopy
• ☆ Light Microscopy
• ☆ Electron Microscopy
• ☆ Fluorescence Microscopy
• ☆ Data Analysis
• ☆ Image Processing
• ☆ Statistics
• ☆ Applied Statistics
• ☆ Applied Mechanics
• ☆ Statistical Mechanics
• ☆ Cell Culture
• ☆ Primary Cells
• ☆ Cell Line Engineering
• ☆ Large Scale Cell Culture
• ☆ Biomolecular Engineering
• ☆ Genetic Engineering
• ☆ Gene Editing/CRISPR
• ☆ Protein/Enzyme Engineering
• ☆ Antibody Engineering
• ☆ Gene Delivery
• ☆ Blotting
• ☆ Immunohistochemistry
• ☆ Cytometry
• ☆ Cell Aging
• ☆ Drug Development
• ☆ Gene Therapy

Services

• Writing
• Data & AI

Writing Technical Writing

Data & AI Statistical Analysis, Image Processing, Image Analysis, Data Visualization

Work Experience

Associate Professional Researcher

University of California-Davis

June 2020 - Present

Medical School Affiliates, Assistant Professor

University of Minnesota

April 2015 - September 2020

Faculty, Assistant Professor

University of Minnesota

August 2011 - June 2020

Education

Analytical and Quantitative Light Microscopy

Marine Biological Laboratory

May 2012 - May 2012

Postdoc (Pathology and Cell Biology)

Columbia University Medical Center

2006 - 2011

Ph.D. (Immunology and Microbial Pathogenesis)

Northwestern University Feinberg School of Medicine

2001 - 2005

B.A. (Biology)

Grinnell College

1997 - 2001

Certifications

• Certification details not provided.

Publications

JOURNAL ARTICLE

Ching-Ming Lin, Jay-How Yang, Hwei-Jen Lee, Yu-Pang Lin, Li-Ping Tsai, Chih-Sin Hsu, GW Gant Luxton, Chih-Fen Hu (2021). Whole Exome Sequencing Identifies a Novel Homozygous Missense Mutation in the CSB Protein-Encoding <i>ERCC6</i> Gene in a Taiwanese Boy with Cockayne Syndrome . Life.

(2020). Differentiating Luminal and Membrane-Associated Nuclear Envelope Proteins . Biophysical journal.

Julia E. H&#246;lper, Barbara G. Klupp, GW Gant Luxton, Kati Franzke, Thomas C. Mettenleiter (2020). Function of Torsin AAA+ ATPases in Pseudorabies Virus Nuclear Egress . Cells.

Identifying Heteroprotein Complexes in the Nuclear Envelope @article{f521b870721e434888a91010f0109a9e, title = "Identifying Heteroprotein Complexes in the Nuclear Envelope", abstract = "The nucleus is delineated by the nuclear envelope (NE), which is a double membrane barrier composed of the inner and outer nuclear membranes as well as a ∼40-nm wide lumen. In addition to its barrier function, the NE acts as a critical signaling node for a variety of cellular processes, which are mediated by protein complexes within this subcellular compartment. Although fluorescence fluctuation spectroscopy is a powerful tool for characterizing protein complexes in living cells, it was recently demonstrated that conventional fluorescence fluctuation spectroscopy methods are not suitable for applications in the NE because of the presence of slow nuclear membrane undulations. We previously addressed this challenge by developing time-shifted mean-segmented Q (tsMSQ) analysis and applied it to successfully characterize protein homo-oligomerization in the NE. However, many NE complexes, such as the linker of the nucleoskeleton and cytoskeleton complex, are formed by heterotypic interactions, which single-color tsMSQ is unable to characterize. Here, we describe the development of dual-color (DC) tsMSQ to analyze NE heteroprotein complexes built from proteins that carry two spectrally distinct fluorescent labels. Experiments performed on model systems demonstrate that DC tsMSQ properly identifies heteroprotein complexes and their stoichiometry in the NE by accounting for spectral cross talk and local volume fluctuations. Finally, we applied DC tsMSQ to study the assembly of the linker of the nucleoskeleton and cytoskeleton complex, a heteroprotein complex composed of Klarsicht/ANC-1/SYNE homology and Sad1/UNC-84 (SUN) proteins, in the NE of living cells. Using DC tsMSQ, we demonstrate the ability of the SUN protein SUN2 and the Klarsicht/ANC-1/SYNE homology protein nesprin-2 to form a heterocomplex in vivo. Our results are consistent with previously published in vitro studies and demonstrate the utility of the DC tsMSQ technique for characterizing NE heteroprotein complexes.", author = "Jared Hennen and Hur, {Kwang Ho} and John Kohler and {Reddy Karuka}, Siddarth and Isaac Angert and Luxton, {G. W.Gant} and Mueller, {Joachim D.}", note = "Publisher Copyright: {\textcopyright} 2019 Biophysical Society", year = "2020", month = jan, day = "7", doi = "10.1016/j.bpj.2019.11.020", language = "English (US)", volume = "118", pages = "26--35", journal = "Biophysical journal", issn = "0006-3495", publisher = "Elsevier B.V.", number = "1", } . Biophysical journal.

(2019). Identifying Heteroprotein Complexes in the Nuclear Envelope . Biophysical journal.

Contractile acto-myosin network on nuclear envelope remnants positions human chromosomes for mitosis @article{9c8e2d1a2feb4b9cad129065ebf0d855, title = "Contractile acto-myosin network on nuclear envelope remnants positions human chromosomes for mitosis", abstract = "To ensure proper segregation during mitosis, chromosomes must be efficiently captured by spindle microtubules and subsequently aligned on the mitotic spindle. The efficacy of chromosome interaction with the spindle can be influenced by how widely chromosomes are scattered in space. Here, we quantify chromosome-scattering volume (CSV) and find that it is reduced soon after nuclear envelope breakdown (NEBD) in human cells. The CSV reduction occurs primarily independently of microtubules and is therefore not an outcome of interactions between chromosomes and the spindle. We find that, prior to NEBD, an acto-myosin network is assembled in a LINC complex-dependent manner on the cytoplasmic surface of the nuclear envelope. This acto-myosin network remains on nuclear envelope remnants soon after NEBD, and its myosin-II- mediated contraction reduces CSV and facilitates timely chromosome congression and correct segregation. Thus, we find a novel mechanism that positions chromosomes in early mitosis to ensure efficient and correct chromosome–spindle interactions.", author = "Booth, {Alexander J.R.} and Zuojun Yue and Eykelenboom, {John K.} and Tom Stiff and Luxton, {G. W.Gant} and Helfrid Hochegger and Tanaka, {Tomoyuki U.}", note = "Funding Information: Wellcome 096535/Z/11/Z Tomoyuki Tanaka Wellcome 097945/Z/11/Z Tomoyuki Tanaka Wellcome 208401/Z/17/Z Tomoyuki Tanaka Cancer Research UK C28206/A114499 Helfrid Hochegger Medical Research Council MR/K015869/1 Tomoyuki Tanaka The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. Funding Information: We thank Tanaka lab members, A Ciulli, A Testa, J Januschke and M Gierlinski for discussion; G Ball for help with image analysis; L Clayton for editing the manuscript;, T Fukagawa, J Swedlow, S Mega-son, R Adelstein, M Davidson, and RY Tsien for reagents; S Swift, and P Appleton for microscope maintenance. This work was supported by the Wellcome Trust (096535/Z/11/Z, 097945/Z/11/Z, 208401/Z/17/Z), Cancer Research UK (C28206/A114499) and Medical Research Council (MR/ K015869/1). TUT is a Wellcome Trust Principal Research Fellow. The authors declare no competing financial interests. Publisher Copyright: {\textcopyright} Booth et al.", year = "2019", month = jul, doi = "10.7554/eLife.46902", language = "English (US)", volume = "8", journal = "eLife", issn = "2050-084X", publisher = "eLife Sciences Publications Ltd", } . eLife.

Protein oligomerization and mobility within the nuclear envelope evaluated by the time-shifted mean-segmented Q factor @article{08efe79ffc2649c8acbe55e684173479, title = "Protein oligomerization and mobility within the nuclear envelope evaluated by the time-shifted mean-segmented Q factor", abstract = "Analysis of fluorescence fluctuation experiments by the mean-segmented Q (MSQ) method was recently used to successfully characterize the oligomeric state and mobility of proteins within the nuclear envelope (NE) of living cells. However, two significant shortcomings of MSQ were recognized. Non-ideal detector behavior due to dead-time and afterpulsing as well as the lack of error analysis currently limit the potential of MSQ. This paper presents time-shifted MSQ (tsMSQ), a new formulation of MSQ that is robust with respect to dead-time and afterpulsing. In addition, a protocol for performing error analysis on tsMSQ data is introduced to assess the quality of fit models and estimate the uncertainties of fit parameters. Together, these developments significantly simplify and improve the analysis of fluorescence fluctuation data taken within the NE. To demonstrate these new developments, tsMSQ was used to characterize the oligomeric state and mobility of the luminal domains of two inner nuclear membrane SUN proteins. The results for the luminal domain of SUN2 obtained through tsMSQ without correction for non-ideal detector effects agree with a recent study that was conducted using the original MSQ formulation. Finally, tsMSQ was applied to characterize the oligomeric state and mobility of the luminal domain of the germline-restricted SUN3.", author = "Jared Hennen and Hur, {Kwang Ho} and Karuka, {Siddarth Reddy} and Luxton, {G. W.Gant} and Mueller, {Joachim D.}", note = "Funding Information: We thank Ang Li and Patrick Willey for excellent technical assistance. This work was supported by the National Institutes of Health ( R01 GM064589 ). Publisher Copyright: {\textcopyright} 2018 Elsevier Inc.", year = "2019", month = mar, day = "15", doi = "10.1016/j.ymeth.2018.09.008", language = "English (US)", volume = "157", pages = "28--41", journal = "Methods", issn = "1046-2023", } . Methods.

Imbalanced nucleocytoskeletal connections create common polarity defects in progeria and physiological aging @article{b3ce5b74196a40aa8863cb7eeb2e436a, title = "Imbalanced nucleocytoskeletal connections create common polarity defects in progeria and physiological aging", abstract = "Studies of the accelerated aging disorder Hutchinson–Gilford progeria syndrome (HGPS) can potentially reveal cellular defects associated with physiological aging. HGPS results from expression and abnormal nuclear envelope association of a farnesylated, truncated variant of prelamin A called “progerin.” We surveyed the diffusional mobilities of nuclear membrane proteins to identify proximal effects of progerin expression. The mobilities of three proteins—SUN2, nesprin-2G, and emerin—were reduced in fibroblasts from children with HGPS compared with those in normal fibroblasts. These proteins function together in nuclear movement and centrosome orientation in fibroblasts polarizing for migration. Both processes were impaired in fibroblasts from children with HGPS and in NIH 3T3 fibroblasts expressing progerin, but were restored by inhibiting protein farnesylation. Progerin affected both the coupling of the nucleus to actin cables and the oriented flow of the cables necessary for nuclear movement and centrosome orientation. Progerin overexpression increased levels of SUN1, which couples the nucleus to microtubules through nesprin-2G and dynein, and microtubule association with the nucleus. Reducing microtubule-nuclear connections through SUN1 depletion or dynein inhibition rescued the polarity defects. Nuclear movement and centrosome orientation were also defective in fibroblasts from normal individuals over 60 y, and both defects were rescued by reducing the increased level of SUN1 in these cells or inhibiting dynein. Our results identify imbalanced nuclear engagement of the cytoskeleton (microtubules: high; actin filaments: low) as the basis for intrinsic cell polarity defects in HGPS and physiological aging and suggest that rebalancing the connections can ameliorate the defects.", keywords = "Centrosome orientation, Hutchinson–Gilford progeria syndrome, LINC complex, Nuclear movement, SUN proteins", author = "Wakam Chang and Yuexia Wang and {Gant Luxton}, {G. W.} and Cecilia {\"O}stlund and Worman, {Howard J.} and Gundersen, {Gregg G.}", note = "Funding Information: This research was supported by NIH Grants GM099481 (to G.G.G.) and AR068636 (to G.G.G. and H.J.W.). Publisher Copyright: {\textcopyright} 2019 National Academy of Sciences. All Rights Reserved.", year = "2019", month = feb, day = "26", doi = "10.1073/pnas.1809683116", language = "English (US)", volume = "116", pages = "3578--3583", journal = "Proceedings of the National Academy of Sciences of the United States of America", issn = "0027-8424", publisher = "National Academy of Sciences", number = "9", } . Proceedings of the National Academy of Sciences of the United States of America.

A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly @article{14b11bbdfbf64fcb9895c4ba46b04765, title = "A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly", abstract = "The linker of nucleoskeleton and cytoskeleton (LINC) is a conserved nuclear envelope-spanning molecular bridge that is responsible for the mechanical integration of the nucleus with the cytoskeleton. LINC complexes are formed by a transluminal interaction between the outer and inner nuclear membrane KASH and SUN proteins, respectively. Despite recent structural insights, our mechanistic understanding of LINC complex assembly remains limited by the lack of an experimental system for its in vitro reconstitution and manipulation. Here, we describe artificial nuclear membranes (ANMs) as a synthetic biology platform based on mammalian cell-free expression for the rapid reconstitution of SUN proteins in supported lipid bilayers. We demonstrate that SUN1 and SUN2 are oriented in ANMs with solvent-exposed C-terminal KASH-binding SUN domains. We also find that SUN2 possesses a single transmembrane domain, while SUN1 possesses three. Finally, SUN protein-containing ANMs bind synthetic KASH peptides, thereby reconstituting the LINC complex core. This work represents the first in vitro reconstitution of KASH-binding SUN proteins in supported lipid bilayers using cell-free expression, which will be invaluable for testing proposed models of LINC complex assembly and its regulation.", keywords = "Cell-free expression, Cytoskeleton complex, KASH, Linker of nucleoskeleton, Nuclear membrane, Reconstitution, SUN", author = "Sagardip Majumder and Willey, {Patrick T.} and DeNies, {Maxwell S.} and Liu, {Allen P.} and Luxton, {G. W.Gant}", note = "Funding Information: This work was financially supported in part by the Dystonia Medical Research Foundation (G.W.G.L.) and the National Science Foundation (NSF) (MCB-1612917 to A.P.L.). M.S.D. was supported by the NSF Graduate Research Fellowship Program. Publisher Copyright: {\textcopyright} 2018. Published by The Company of Biologists Ltd", year = "2019", month = feb, day = "1", doi = "10.1242/jcs.219451", language = "English (US)", volume = "132", journal = "Journal of cell science", issn = "0021-9533", publisher = "Company of Biologists Ltd", number = "4", } . Journal of cell science.

Navjot Kaur Gill, Chau Ly, Paul H. Kim, Cosmo A. Saunders, Loren G. Fong, Stephen G. Young, GW Gant Luxton, Amy C. Rowat(2019). DYT1 dystonia patient-derived fibroblasts have increased deformability and susceptibility to damage by mechanical forces . Frontiers in Cell and Developmental Biology. 7. (JUN). Frontiers Media SA

Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning @article{51f2d6e8809646f2b61411db13407659, title = "Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning", abstract = "Many nuclear positioning events involve linker of nucleoskeleton and cytoskeleton (LINC) complexes, which transmit forces generated by the cytoskeleton across the nuclear envelope. LINC complexes are formed by trans-luminal interactions between inner nuclear membrane SUN proteins and outer nuclear membrane KASH proteins, but how these interactions are regulated is poorly understood. We combine in vivo C. elegans genetics, in vitro wounded fibroblast polarization, and in silico molecular dynamics simulations to elucidate mechanisms of LINC complexes. The extension of the KASH domain by a single alanine residue or the mutation of the conserved tyrosine at −7 completely blocked the nuclear migration function of C. elegans UNC-83. Analogous mutations at −7 of mouse nesprin-2 disrupted rearward nuclear movements in NIH 3T3 cells, but did not disrupt ANC-1 in nuclear anchorage. Furthermore, conserved cysteines predicted to form a disulfide bond between SUN and KASH proteins are important for the function of certain LINC complexes, and might promote a developmental switch between nuclear migration and nuclear anchorage. Mutations of conserved cysteines in SUN or KASH disrupted ANC-1-dependent nuclear anchorage in C. elegans and Nesprin-2G-dependent nuclear movements in polarizing fibroblasts. However, the SUN cysteine mutation did not disrupt nuclear migration. Moreover, molecular dynamics simulations showed that a disulfide bond is necessary for the maximal transmission of cytoskeleton-generated forces by LINC complexes in silico. Thus, we have demonstrated functions for SUN-KASH binding interfaces, including a predicted intermolecular disulfide bond, as mechanistic determinants of nuclear positioning that may represent targets for regulation. Cain et al. test the function of mutant SUN and KASH proteins in C. elegans nuclear positioning, NIH 3T3 fibroblast polarization, and simulations of LINC complexes under mechanical strain to gain mechanistic insights into how SUN-KASH interactions might be regulated to transfer forces from the cytoskeleton to the nucleus.", keywords = "KASH proteins, LINC complex, Nesprin, SUN proteins, nuclear envelope, nuclear positioning", author = "Cain, {Natalie E.} and Zeinab Jahed and Amy Schoenhofen and Valdez, {Venecia A.} and Baila Elkin and Hongyan Hao and Harris, {Nathan J.} and Herrera, {Leslie A.} and Woolums, {Brian M.} and Mofrad, {Mohammad R.K.} and Luxton, {G. W.Gant} and Starr, {Daniel A.}", note = "Funding Information: We thank Thomas Schwartz, Ulrike Kutay, and members of the Starr, Mofrad, and Luxton laboratories for helpful discussions. This work was supported by the NIH ( R01GM073874 to D.A.S.; R21NS095109 to G.W.G.L.; and AR007612 to N.J.H.), National Science Foundation (CAREER award CBET-0955291 to M.R.K.M.), Natural Sciences and Engineering Research Council of Canada (to Z.J.), Dystonia Medical Research Foundation (to G.W.G.L.), and American Cancer Society Illinois Division ( PF-13-094-01-CGC to N.E.C.). Funding Information: Caenorhabditis elegans were cultured on nematode growth medium plates spotted with OP50 bacteria and maintained at 15°C or room temperature (approximately 22°C). N2 was used as the wild-type control strain [ 49 ]. Some strains were provided by the Caenorhabditis Genetics Center, funded by the National Institutes of Health Office of Research Infrastructure Programs (P40 OD010440). Only healthy animals that were not used in previous procedures and were naive to testing were used. See the Key Resources Table for strain list. Funding Information: We thank Thomas Schwartz, Ulrike Kutay, and members of the Starr, Mofrad, and Luxton laboratories for helpful discussions. This work was supported by the NIH (R01GM073874 to D.A.S.; R21NS095109 to G.W.G.L.; and AR007612 to N.J.H.), National Science Foundation (CAREER award CBET-0955291 to M.R.K.M.), Natural Sciences and Engineering Research Council of Canada (to Z.J.), Dystonia Medical Research Foundation (to G.W.G.L.), and American Cancer Society Illinois Division (PF-13-094-01-CGC to N.E.C.). Publisher Copyright: {\textcopyright} 2018 Elsevier Ltd", year = "2018", month = oct, day = "8", doi = "10.1016/j.cub.2018.08.001", language = "English (US)", volume = "28", pages = "3086--3097.e4", journal = "Current Biology", issn = "0960-9822", publisher = "Cell Press", number = "19", } . Current Biology.

Fluorescence fluctuation spectroscopy reveals differential SUN protein oligomerization in living cells @article{da150f09664a4deba354e18d6efacd03, title = "Fluorescence fluctuation spectroscopy reveals differential SUN protein oligomerization in living cells", abstract = "Linker-of-nucleoskeleton-and-cytoskeleton (LINC) complexes are conserved molecular bridges within the nuclear envelope that mediate mechanical force transmission into the nucleoplasm. The core of a LINC complex is formed by a transluminal interaction between the outer and inner nuclear membrane KASH and SUN proteins, respectively. Mammals encode six KASH proteins and five SUN proteins. Recently, KASH proteins were shown to bind to the domain interfaces of trimeric SUN2 proteins in vitro. However, neither the existence of SUN2 trimers in living cells nor the extent to which other SUN proteins conform to this assembly state have been tested experimentally. Here we extend the application of fluorescence fluctuation spectroscopy to quantify SUN protein oligomerization in the nuclear envelopes of living cells. Using this approach, we demonstrate for the first time that SUN2 trimerizes in vivo and we demonstrate that the in vivo oligomerization of SUN1 is not limited to a trimer. In addition, we provide evidence to support the existence of potential regulators of SUN protein oligomerization in the nuclear envelope. The differential SUN protein oligomerization illustrated here suggests that SUN proteins may have evolved to form different assembly states in order to participate in diverse mechanotransduction events.", author = "Jared Hennen and Saunders, {Cosmo A.} and Mueller, {Joachim D.} and Luxton, {G. W.Gant}", note = "Publisher Copyright: {\textcopyright} 2018 Hennen, Saunders, et al.", year = "2018", month = may, day = "1", doi = "10.1091/mbc.E17-04-0233", language = "English (US)", volume = "29", pages = "1003--1011", journal = "Molecular biology of the cell", issn = "1059-1524", publisher = "American Society for Cell Biology", number = "9", } . Molecular biology of the cell.

Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope @article{838b58851d074373ab566693acda8b47, title = "Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope", abstract = "The LINC complex is found in a wide variety of organisms and is formed by the transluminal interaction between outer- and inner-nuclear-membrane KASH and SUN proteins, respectively. Most extensively studied are SUN1 and SUN2 proteins, which are widely expressed in mammals. Although SUN1 and SUN2 play functionally redundant roles in several cellular processes, more recent studies have revealed diverse and distinct functions for SUN1. While several recent in vitro structural studies have revealed the molecular details of various fragments of SUN2, no such structural information is available for SUN1. Herein, we conduct a systematic analysis of the molecular relationships between SUN1 and SUN2, highlighting key similarities and differences that could lead to clues into their distinct functions. We use a wide range of computational tools, including multiple sequence alignments, homology modeling, molecular docking, and molecular dynamic simulations, to predict structural differences between SUN1 and SUN2, with the goal of understanding the molecular mechanisms underlying SUN1 oligomerization in the nuclear envelope. Our simulations suggest that the structural model of SUN1 is stable in a trimeric state and that SUN1 trimers can associate through their SUN domains to form lateral complexes. We also ask whether SUN1 could adopt an inactive monomeric conformation as seen in SUN2. Our results imply that the KASH binding domain of SUN1 is also inhibited in monomeric SUN1 but through weaker interactions than in monomeric SUN2.", author = "Zeinab Jahed and Darya Fadavi and Vu, {Uyen T.} and Ehsaneddin Asgari and Luxton, {G. W.Gant} and Mofrad, {Mohammad R.K.}", note = "Funding Information: This work was supported by the National Science Foundation through grant CBET-0955291 . In addition, this research used resources of the National Energy Research Scientific Computing Center , a Department of Energy Office of Science user facility supported by the Office of Science of the U.S. Department of Energy under contract No. DE-AC02-05CH11231 . Publisher Copyright: {\textcopyright} 2018 Biophysical Society", year = "2018", month = mar, day = "13", doi = "10.1016/j.bpj.2018.01.015", language = "English (US)", volume = "114", pages = "1190--1203", journal = "Biophysical journal", issn = "0006-3495", publisher = "Elsevier B.V.", number = "5", } . Biophysical journal.

Jahed Z, Fadavi D, Vu UT, Asgari E, Luxton GWG, Mofrad MRK(2018). Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope . Biophysical journal.

Hennen J, Saunders CA, Mueller JD, Luxton GWG(2018). Fluorescence Fluctuation Spectroscopy Reveals Differential SUN Protein Oligomerization In Living Cells . Molecular biology of the cell.

(2018). A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly . Journal of cell science.

Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning @article{PMID:30245107, Title= {Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning}, Author= {Cain, Natalie E and Jahed, Zeinab and Schoenhofen, Amy and Valdez, Venecia A and Elkin, Baila and Hao, Hongyan and Harris, Nathan J and Herrera, Leslie A and Woolums, Brian M and Mofrad, Mohammad R K and Luxton, G W Gant and Starr, Daniel A}, DOI= {10.1016/j.cub.2018.08.001}, Number= {19}, Volume= {28}, Month= {October}, Year= {2018}, Journal= {Current biology : CB}, ISSN= {0960-9822}, Pages= {3086—3097.e4}, URL= {https://doi.org/10.1016/j.cub.2018.08.001}} . Current biology : CB.

Investigating LINC Complex Protein Homo-oligomerization in the Nuclear Envelopes of Living Cells Using Fluorescence Fluctuation Spectroscopy @article{PMID:30141043, Title= {Investigating LINC Complex Protein Homo-oligomerization in the Nuclear Envelopes of Living Cells Using Fluorescence Fluctuation Spectroscopy}, Author= {Hennen, Jared and Angert, Isaac and Hur, Kwang-Ho and Gant Luxton, GW and Mueller, Joachim D}, DOI= {10.1007/978-1-4939-8691-0_11}, Volume= {1840}, Year= {2018}, Journal= {Methods in molecular biology (Clifton, N.J.)}, ISSN= {1064-3745}, Pages= {121—135}, URL= {https://doi.org/10.1007/978-1-4939-8691-0_11}} . Methods in molecular biology (Clifton, N.J.).

(2018). Protein oligomerization and mobility within the nuclear envelope evaluated by the time-shifted mean-segmented Q factor . Methods (San Diego, Calif.).

(2017). A pUL25 dimer interfaces the pseudorabies virus capsid and tegument . The Journal of general virology.

A pUL25 dimer interfaces the pseudorabies virus capsid and tegument @article{4e16a07fe51542759bb415f77788b21c, title = "A pUL25 dimer interfaces the pseudorabies virus capsid and tegument", abstract = "Inside the virions of α-herpesviruses, tegument protein pUL25 anchors the tegument to capsid vertices through direct interactions with tegument proteins pUL17 and pUL36. In addition to promoting virion assembly, both pUL25 and pUL36 are critical for intracellular microtubule-dependent capsid transport. Despite these essential roles during infection, the stoichiometry and precise organization of pUL25 and pUL36 on the capsid surface remain controversial due to the insufficient resolution of existing reconstructions from cryo-electron microscopy (cryoEM). Here, we report a threedimensional (3D) icosahedral reconstruction of pseudorabies virus (PRV), a varicellovirus of the α-herpesvirinae subfamily, obtained by electron-counting cryoEM at 4.9 {\AA} resolution. Our reconstruction resolves a dimer of pUL25 forming a capsidassociated tegument complex with pUL36 and pUL17 through a coiled coil helix bundle, thus correcting previous misinterpretations. A comparison between reconstructions of PRV and the γ-herpesvirus Kaposi{\textquoteright}s sarcoma-associated herpesvirus (KSHV) reinforces their similar architectures and establishes important subfamily differences in the capsid-tegument interface.", keywords = "CryoEM, PUL17, PUL25 dimer, PUL36 (VP1/2), Pseudorabies virus, Tegument proteins", author = "Liu, {Yun Tao} and Jiansen Jiang and Bohannon, {Kevin Patrick} and Xinghong Dai and {Gant Luxton}, {G. W.} and Hui, {Wong Hoi} and Bi, {Guo Qiang} and Smith, {Gregory Allan} and Zhou, {Z. Hong}", note = "Funding Information: This research was supported in part by grants from the US National Institutes of Health (R01 AI056346 to G. A. S.), the NSFC (313290002 to Z. H. Z.) and the CAS (XDB02050000 to G. Q. B.). We acknowledge the use of instruments at the Electron Imaging Center for Nanoma-chines supported by UCLA and by instrumentation grants from NIH (1S10RR23057) and NSF (DBI-1338135). The cryoEM density map has been deposited in the EM Data Bank under the accession codes EMD-8760. Publisher Copyright: {\textcopyright} 2017 The Authors.", year = "2017", month = nov, doi = "10.1099/jgv.0.000903", language = "English (US)", volume = "98", pages = "2837--2849", journal = "Journal of General Virology", issn = "0022-1317", publisher = "Microbiology Society", number = "11", } . Journal of General Virology.

Quantitative Brightness Analysis of Protein Oligomerization in the Nuclear Envelope @article{6e0c2c4f83ac460b83899d9036559d77, title = "Quantitative Brightness Analysis of Protein Oligomerization in the Nuclear Envelope", abstract = "Brightness analysis of fluorescence fluctuation experiments has been used to successfully measure the oligomeric state of proteins at the plasma membrane, in the nucleoplasm, and in the cytoplasm of living cells. Here we extend brightness analysis to the nuclear envelope (NE), a double membrane barrier separating the cytoplasm from the nucleoplasm. Results obtained by applying conventional brightness analysis to fluorescently tagged proteins within the NE exhibited an unusual concentration dependence. Similarly, the autocorrelation function of the fluorescence fluctuations exhibited unexpected changes with protein concentration. These observations motivated the application of mean-segmented Q analysis, which identified the existence of a fluctuation process distinct from molecular diffusion in the NE. We propose that small changes in the separation of the inner and outer nuclear membrane are responsible for the additional fluctuation process, as suggested by results obtained for luminal and nuclear membrane-associated EGFP-tagged proteins. Finally, we applied these insights to study the oligomerization of the luminal domains of two nuclear membrane proteins, nesprin-2 and SUN2, which interact transluminally to form a nuclear envelope-spanning linker molecular bridge known as the linker of the nucleoskeleton and cytoskeleton complex.", author = "Jared Hennen and Hur, {Kwang Ho} and Saunders, {Cosmo A.} and Luxton, {G. W.Gant} and Mueller, {Joachim D.}", note = "Publisher Copyright: {\textcopyright} 2017 Biophysical Society", year = "2017", month = jul, day = "11", doi = "10.1016/j.bpj.2017.05.044", language = "English (US)", volume = "113", pages = "138--147", journal = "Biophysical journal", issn = "0006-3495", publisher = "Elsevier B.V.", number = "1", } . Biophysical journal.

Cellular Microbiaxial Stretching to Measure a Single-Cell Strain Energy Density Function @article{21071eba5ee6419fb9d9566bc647698f, title = "Cellular Microbiaxial Stretching to Measure a Single-Cell Strain Energy Density Function", abstract = "The stress in a cell due to extracellular mechanical stimulus is determined by its mechanical properties, and the structural organization of many adherent cells suggests that their properties are anisotropic. This anisotropy may significantly influence the cells' mechanotransductive response to complex loads, and has important implications for development of accurate models of tissue biomechanics. Standard methods for measuring cellular mechanics report linear moduli that cannot capture large-deformation anisotropic properties, which in a continuum mechanics framework are best described by a strain energy density function (SED). In tissues, the SED is most robustly measured using biaxial testing. Here, we describe a cellular microbiaxial stretching (ClBS) method that modifies this tissue-scale approach to measure the anisotropic elastic behavior of individual vascular smooth muscle cells (VSMCs) with nativelike cytoarchitecture. Using ClBS, we reveal that VSMCs are highly anisotropic under large deformations. We then characterize a Holzapfel-Gasser-Ogden type SED for individual VSMCs and find that architecture-dependent properties of the cells can be robustly described using a formulation solely based on the organization of their actin cytoskeleton. These results suggest that cellular anisotropy should be considered when developing biomechanical models, and could play an important role in cellular mechano-adaptation.", author = "Zaw Win and Buksa, {Justin M.} and Steucke, {Kerianne E.} and {Gant Luxton}, {G. W.} and Barocas, {Victor H.} and Alford, {Patrick W.}", note = "Publisher Copyright: Copyright {\textcopyright} 2017 by ASME.", year = "2017", month = jul, day = "1", doi = "10.1115/1.4036440", language = "English (US)", volume = "139", journal = "Journal of biomechanical engineering", issn = "0148-0731", publisher = "The American Society of Mechanical Engineers(ASME)", number = "7", } . Journal of biomechanical engineering.

(2017). Cellular Microbiaxial Stretching to Measure a Single-Cell Strain Energy Density Function . Journal of Biomechanical Engineering.

TorsinA controls TAN line assembly and the retrograde flow of dorsal perinuclear actin cables during rearward nuclear movement @article{6c2742f1b6b345aebe34c402f8f17bb3, title = "TorsinA controls TAN line assembly and the retrograde flow of dorsal perinuclear actin cables during rearward nuclear movement", abstract = "The nucleus is positioned toward the rear of most migratory cells. In fibroblasts and myoblasts polarizing for migration, retrograde actin flow moves the nucleus rearward, resulting in the orientation of the centrosome in the direction of migration. In this study, we report that the nuclear envelope-localized AAA+ (ATPase associated with various cellular activities) torsinA (TA) and its activator, the inner nuclear membrane protein lamina-associated polypeptide 1 (LAP1), are required for rearward nuclear movement during centrosome orientation in migrating fibroblasts. Both TA and LAP1 contributed to the assembly of transmembrane actin-associated nuclear (TAN) lines, which couple the nucleus to dorsal perinuclear actin cables undergoing retrograde flow. In addition, TA localized to TAN lines and was necessary for the proper mobility of EGFP-mini-nesprin-2G, a functional TAN line reporter construct, within the nuclear envelope. Furthermore, TA and LAP1 were indispensable for the retrograde flow of dorsal perinuclear actin cables, supporting the recently proposed function for the nucleus in spatially organizing actin flow and cytoplasmic polarity. Collectively, these results identify TA as a key regulator of actin-dependent rearward nuclear movement during centrosome orientation.", author = "Saunders, {Cosmo A.} and Harris, {Nathan J.} and Willey, {Patrick T.} and Woolums, {Brian M.} and Yuexia Wang and McQuown, {Alex J.} and Amy Schoenhofen and Worman, {Howard J.} and Dauer, {William T.} and Gundersen, {Gregg G.} and Luxton, {G. W.Gant}", note = "Publisher Copyright: {\textcopyright} 2017 Saunders et al.", year = "2017", month = mar, day = "6", doi = "10.1083/jcb.201507113", language = "English (US)", volume = "216", pages = "657--674", journal = "The Journal of cell biology", issn = "0021-9525", publisher = "Rockefeller University Press", number = "3", } . The Journal of cell biology.

et al.(2017). TorsinA controls TAN line assembly and the retrograde flow of dorsal perinuclear actin cables during rearward nuclear movement . The Journal of Cell Biology.

MyTH4-FERM myosins have an ancient and conserved role in filopod formation @article{d857c7d61a6d4a9e8e852d781d4d715a, title = "MyTH4-FERM myosins have an ancient and conserved role in filopod formation", abstract = "The formation of filopodia in Metazoa and Amoebozoa requires the activity of myosin 10 (Myo10) in mammalian cells and of Dictyostelium unconventional myosin 7 (DdMyo7) in the social amoeba Dictyoste-lium. However, the exact roles of these MyTH4-FERM myosins (myosin tail homology 4-band 4.1, ezrin, radixin, moesin; MF) in the initiation and elongation of filopodia are not well defined and may reflect conserved functions among phylogenetically diverse MF myosins. Phylogenetic analysis of MF myosin domains suggests that a single ancestral MF myosin existed with a structure similar to DdMyo7, which has two MF domains, and that subsequent duplications in the metazoan lineage produced its functional homolog Myo10. The essential functional features of the DdMyo7 myosin were identified using quantitative live-cell imaging to characterize the ability of various mutants to rescue filopod formation in myo7-null cells. The two MF domains were found to function redundantly in filopod formation with the C-terminal FERM domain regulating both the number of filopodia and their elongation velocity. DdMyo7 mutants consisting solely of the motor plus a single MyTH4 domain were found to be capable of rescuing the formation of filopodia, establishing the minimal elements necessary for the function of this myosin. Interestingly, a chimeric myosin with the Myo10 MF domain fused to the DdMyo7 motor also was capable of rescuing filopod formation in the myo7-null mutant, supporting fundamental functional conservation between these two distant myosins. Together, these findings reveal that MF myosins have an ancient and conserved role in filopod formation.", keywords = "Actin, Cell motility, Filopodia, MyTH4-FERM, Myosin", author = "Petersen, {Karl J.} and Goodson, {Holly V.} and Arthur, {Ashley L.} and Luxton, {G. W Gant} and Anne Houdusse and Titus, {Margaret A.} and Devreotes, {Peter N.}", note = "Funding Information: We thank Hilary Bauer, Zo? Henrot, and Alex McQuown and Drs. Guillermo Marqu?s and Mark Sanders (University of Minnesota Imaging Centers) for expert technical assistance; Drs. Naomi Courtemanche, Melissa Gardner, Sivaraj Sivaramakrishnan, and Gaku Ashiba for many valuable discussions; Dr. Martin Kollmar for developing and maintaining CyMoBase (cymobase.org); Dr. Tandy Warnow (University of Illinois) for introducing us to SAT?; and the Minnesota Supercomputing Institute for providing excellent computational resources. K.J.P. was supported by NIH Training Program in Muscle Research Grant AR007612 and a University of Minnesota Doctoral Dissertation Fellowship; H.V.G. was supported by National Science Foundation (NSF) Award MCB-1244593; G.W.G.L. was supported by NIH Awards R42DA037622 and R21NS095109-01; A.H. was supported by grants from the ANR-13-BSV8-0019-01, Ligue Nationale Contre le Cancer, and Association pour la Recherche sur le Cancer Subvention Fixe; and M.A.T. was supported by NSF Grant MCB-124423.", year = "2016", month = dec, day = "13", doi = "10.1073/pnas.1615392113", language = "English (US)", volume = "113", pages = "E8059--E8068", journal = "Proceedings of the National Academy of Sciences of the United States of America", issn = "0027-8424", publisher = "National Academy of Sciences", number = "50", } . Proceedings of the National Academy of Sciences of the United States of America.

Mechanism of microtubule lumen entry for the α-tubulin acetyltransferase enzyme αTAT1 @article{3f21e1b4da064e1886e463b6ff9ef6d2, title = "Mechanism of microtubule lumen entry for the α-tubulin acetyltransferase enzyme αTAT1", abstract = "Microtubules are structural polymers inside of cells that are subject to posttranslational modifications. These posttranslational modifications create functionally distinct subsets of microtubule networks in the cell, and acetylation is the only modification that takes place in the hollow lumen of the microtubule. Although it is known that the α-tubulin acetyltransferase (αTAT1) is the primary enzyme responsible for microtubule acetylation, the mechanism for how αTAT1 enters the microtubule lumen to access its acetylation sites is not well understood. By performing biochemical assays, fluorescence and electron microscopy experiments, and computational simulations, we found that αTAT1 enters the microtubule lumen through the microtubule ends, and through bends or breaks in the lattice. Thus, microtubule structure is an important determinant in the acetylation process. In addition, once αTAT1 enters the microtubule lumen, the mobility of αTAT1 within the lumen is controlled by the affinity of αTAT1 for its acetylation sites, due to the rapid rebinding of αTAT1 onto highly concentrated α-tubulin acetylation sites. These results have important implications for how acetylation could gradually accumulate on stable subsets of microtubules inside of the cell.", keywords = "Acetylation, Biophysics, Microscopy, Microtubule, Modeling", author = "Courtney Coombes and Ami Yamamoto and Mark McClellan and Reid, {Taylor A.} and Melissa Plooster and Luxton, {G. W.Gant} and Joshua Alper and Jonathon Howard and Gardner, {Melissa K.}", note = "Funding Information: We thank Brandon Coombes for statistical analysis assistance. This work was funded by an American Heart Association Predoctoral Fellowship (to C.C.). This work was supported by the Pew Charitable Trusts through the Pew Scholars Program in the Biomedical Sciences (M.K.G.) and by NIH National Institute of General Medical Sciences Grant GM-103833 (to M.K.G.). Parts of this work were carried out in the Characterization Facility, University of Minnesota, a member of the National Science Foundation-funded Materials Research Facilities Network (www.mrfn.org/) via the Materials Research Science and Engineering Centers program. Publisher Copyright: {\textcopyright} 2016, National Academy of Sciences. All rights reserved.", year = "2016", month = nov, day = "15", doi = "10.1073/pnas.1605397113", language = "English (US)", volume = "113", pages = "E7176--E7184", journal = "Proceedings of the National Academy of Sciences of the United States of America", issn = "0027-8424", publisher = "National Academy of Sciences", number = "46", } . Proceedings of the National Academy of Sciences of the United States of America.

LINCing Defective Nuclear-Cytoskeletal Coupling and DYT1 Dystonia @article{0205ee5fe64141cc9a736a7e20904432, title = "LINCing Defective Nuclear-Cytoskeletal Coupling and DYT1 Dystonia", abstract = "Mechanical forces generated by nuclear-cytoskeletal coupling through the linker of nucleoskeleton and cytoskeleton (LINC) complex, an evolutionarily conserved molecular bridge in the nuclear envelope (NE), are critical for the execution of wholesale nuclear positioning events in migrating and dividing cells, chromosome dynamics during meiosis, and mechanotransduction. LINC complexes consist of outer Klarsicht, ANC-1, and Syne homology (KASH) and inner Sad1, UNC-84 (SUN) nuclear membrane proteins. KASH proteins interact with the cytoskeleton in the cytoplasm and SUN proteins in the perinuclear space of the NE. In the nucleoplasm, SUN proteins interact with A-type nuclear lamins and chromatin-binding proteins. Recent structural insights into the KASH-SUN interaction have generated several questions regarding how LINC complex assembly and function might be regulated within the perinuclear space. Here we discuss potential LINC regulatory mechanisms and focus on the potential role of the ATPases associated with various cellular activities (AAA+) protein, torsinA, as a LINC complex regulator within the NE. We also examine how defects in LINC complex regulation by torsinA may contribute to the pathogenesis of the human neurological movement disorder, DYT1 dystonia.", keywords = "AAA+ protein, Cytoskeleton, LAP1, LINC complex, LULL1, Mechanotransduction, Nuclear envelope, TorsinA", author = "Saunders, {Cosmo A.} and Luxton, {G. W.Gant}", note = "Funding Information: We thank Drs. Melissa Gardner, David Greenstein, Joachim Mueller, and Meg Titus for helpful discussions. The authors apologize to those whose work we were unable to cite and cover in proper depth due to the limitations of length for this review. Studies in the Luxton Lab are supported by start up funding from the University of Minnesota, a P30 Pilot and Feasibility Grant from the Paul and Sheila Wellstone Muscular Dystrophy Center, and funding from the NIH (R21 NS095109-01, 1R41DA037622, and AR57220). C.A.S. is supported by an NIH training grant (NIH 5T32AR007612-14). Publisher Copyright: {\textcopyright} 2016, Biomedical Engineering Society.", year = "2016", month = jun, day = "1", doi = "10.1007/s12195-016-0432-0", language = "English (US)", volume = "9", pages = "207--216", journal = "Cellular and Molecular Bioengineering", issn = "1865-5025", publisher = "Springer", number = "2", } . Cellular and Molecular Bioengineering.

(2016). LINCing defective nuclear-cytoskeletal coupling and DYT1 dystonia . Cellular and molecular bioengineering.

FHOD1 interaction with nesprin-2G mediates TAN line formation and nuclear movement @article{a448a9c9c2804e7b8845155f5b1b8164, title = "FHOD1 interaction with nesprin-2G mediates TAN line formation and nuclear movement", abstract = "Active positioning of the nucleus is integral to division, migration and differentiation of mammalian cells. Fibroblasts polarizing for migration orient their centrosomes by actin-dependent nuclear movement. This nuclear movement depends on nesprin-2 giant (N2G), a large, actin-binding outer nuclear membrane component of transmembrane actin-associated (TAN) lines that couple nuclei to moving actin cables. Here, we identify the diaphanous formin FHOD1 as an interaction partner of N2G. Silencing FHOD1 expression or expression of fragments containing binding sites for N2G or FHOD1 disrupted nuclear movement and centrosome orientation in polarizing fibroblasts. Unexpectedly, silencing of FHOD1 expression did not affect the formation or rearward flow of dorsal actin cables required for nuclear positioning. Rather, N2G-FHOD1 interaction provided a second connection to actin cables essential for TAN line formation and thus nuclear movement. These results reveal a unique function for a formin in coupling an organelle to actin filaments for translocation, and suggest that TAN lines require multi-point attachments to actin cables to resist the large forces necessary to move the nucleus.", author = "Stefan Kutscheidt and Ruijun Zhu and Susumu Antoku and Luxton, {G. W.Gant} and Igor Stagljar and Fackler, {Oliver T.} and Gundersen, {Gregg G.}", note = "Funding Information: We thank D. Discher and M. Geyer for helpful discussion. This work was financially supported in part by the Deutsche Forschungsgemeinschaft (GRK1188 to S.K., grant FA 378/6-2 to O.T.F.) and NIH (grant GM099481 to G.G.G.). O.T.F. is a member of the CellNetworks Cluster of Excellence EXC81.", year = "2014", month = jul, doi = "10.1038/ncb2981", language = "English (US)", volume = "16", pages = "708--715", journal = "Nature Cell Biology", issn = "1465-7392", publisher = "Nature Research", number = "7", } . Nature Cell Biology.

KASHing up with the nucleus @article{7f395eec0c894ee7a96a710418c0eaad, title = "KASHing up with the nucleus: Novel functional roles of KASH proteins at the cytoplasmic surface of the nucleus", abstract = "Nuclear-cytoskeletal connections are central to fundamental cellular processes, including nuclear positioning and chromosome movements in meiosis. The cytoskeleton is coupled to the nucleoskeleton through conserved KASH-SUN bridges, or LINC complexes, that span the nuclear envelope. KASH proteins localize to the outer nuclear membrane where they connect the nucleus to the cytoskeleton. New findings have expanded the functional diversity of KASH proteins, showing that they interact with microtubule motors, actin, intermediate filaments, a nonconventional myosin, RanGAP, and each other. The role of KASH proteins in cellular mechanics is discussed. Genetic mutations in KASH proteins are associated with autism, hearing loss, cancer, muscular dystrophy and other diseases.", author = "Luxton, {GW Gant} and Starr, {Daniel A.}", note = "Funding Information: DAS thanks David Fay for hosting him at the University of Wyoming, Laramie while on sabbatical. Studies in the Starr lab are supported by grant R01 GM073874 from the National Institutes of Health NIGMS. GWGL thanks the members of his laboratory, Meg Titus, and Melissa Gardner for insightful discussions. Studies in the Luxton lab are supported by start up funding from the University of Minnesota and P30 Pilot and Feasibility Grant from the Paul and Sheila Wellstone Muscular Dystrophy Center.", year = "2014", month = jun, doi = "10.1016/j.ceb.2014.03.002", language = "English (US)", volume = "28", pages = "69--75", journal = "Current Opinion in Cell Biology", issn = "0955-0674", publisher = "Elsevier Ltd", number = "1", } . Current Opinion in Cell Biology.

Building bridges toward invasion @article{0eae9ffc71144523911ae647515efbe2, title = "Building bridges toward invasion: Tumor promoter treatment induces a novel protein kinase C-dependent phenotype in MCF10A mammary cell acini", abstract = "The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) alters many cellular processes through activation of its receptor protein kinase C (PKC), including gene expression, cell cycle, and the regulation of cell morphology, raising an important question for developing targeted methods to prevent cancer: which effects of TPA are crucial for carcinogenesis? To address this question, we studied TPA action in the 3-dimensional (3D) MCF10A human breast epithelial cell system, which models important features of in vivo epithelial tissue including growth constraints, structural organization of cells, and establishment of a basement membrane. MCF10A cells, which are immortalized but nontumorigenic, form hollow, spheroid structures in 3D culture referred to as acini. The development of normal acini requires the tight spatiotemporal regulation of cellular proliferation, polarization, apoptosis, and growth arrest. Treatment of MCF10A acini with TPA caused the appearance of multi-acinar structures. Surprisingly, this phenotype did not involve an increase in cell number or major changes in cell death, and polarization. Instead, live cell and confocal microscopy revealed that TPA stimulates MCF10A acini to aggregate. TPA induces the PKC-dependent production of actin-based protrusions, which leads to the formation of cellular bridges between acini, the clustering of acini, and allows cells to move into adjacent acini. During this process, the integrity of the laminin V basement membrane is disrupted, while E-cadherin-based cell-cell contacts remain intact. Altogether, our results show that under the biochemical and structural constraints of epithelial tissue, as modeled by the 3D MCF10A system, TPA induces a novel PKC-dependent phenotype that resembles local invasion. Of the many effects caused by TPA, these studies highlight the aggressive production of actin-based cellular protrusions as a potentially important event along the pathway to carcinogenesis.", author = "Klos, {Kristine S.} and Warmka, {Janel K.} and Drachenberg, {Disa M.} and Liang Chang and Luxton, {G.W. Gant} and Leung, {Cheuk T} and Kaylee Schwertfeger and Wattenberg, {Elizabeth V}", year = "2014", month = mar, day = "5", doi = "10.1371/journal.pone.0090722", language = "English (US)", volume = "9", journal = "PloS one", issn = "1932-6203", publisher = "Public Library of Science", number = "3", } . PloS one.

Luxton GW, Gundersen GG(2011). Orientation and function of the nuclear-centrosomal axis during cell migration . Current opinion in cell biology.

Orientation and function of the nuclear-centrosomal axis during cell migration @article{efc2734747784fd58e101e8ec8a89b13, title = "Orientation and function of the nuclear-centrosomal axis during cell migration", abstract = "A hallmark of polarity in most migrating cells is the orientation of the nuclear centrosomal (NC) axis relative to the front-back cellular axis. Here, we review 'effector functions' associated with the NC axis during cell migration. We highlight recent research that has demonstrated that the orientation of the NC axis depends upon the coordinated, but separate positioning of the nucleus and the centrosome. We stress the importance of environmental factors such as cell-cell contacts and substrate topology for NC axis orientation. Finally, we summarize tests of the significance of this axis for cell migration and disease.", author = "Luxton, {G. W Gant} and Gundersen, {Gregg G.}", note = "Funding Information: This work is supported by National Institutes of Health grants to G.G.G. and a Dystonia Medical Research Foundation fellowship to G.W.G.L. The authors apologize for not being able to discuss all relevant and important data in this review owing to space limitations. ", year = "2011", month = oct, doi = "10.1016/j.ceb.2011.08.001", language = "English (US)", volume = "23", pages = "579--588", journal = "Current Opinion in Cell Biology", issn = "0955-0674", publisher = "Elsevier Ltd", number = "5", } . Current Opinion in Cell Biology.

Lamin A variants that cause striated muscle disease are defective in anchoring transmembrane actin-associated nuclear lines for nuclear movement @article{880dec5e39154950a79173d221b2c13e, title = "Lamin A variants that cause striated muscle disease are defective in anchoring transmembrane actin-associated nuclear lines for nuclear movement", abstract = "Mutations in LMNA, which encodes A-type lamins, result in disparate diseases, known collectively as laminopathies, that affect distinct tissues, including striated muscle and adipose tissue. Lamins provide structural support for the nucleus and sites of attachment for chromatin, and defects in these functions may contribute to disease pathogenesis. Recent studies suggest that A-type lamins may facilitate connections between the nucleus and the cytoskeleton mediated by nuclear envelope nesprin and SUN proteins. In mammalian cells, however, interfering with A-type lamins does not affect the localization of these proteins. Here, we used centrosome orientation in fibroblasts, which requires separate nuclear and centrosome positioning pathways, as a model system to understand how LMNA mutations affect nucleus-cytoskeletal connections. We find that LMNA mutations causing striated muscle diseases block actin-dependent nuclear movement, whereas most that affect adipose tissue inhibit microtubule-dependent centrosome positioning. Genetic deletion or transient depletion of A-type lamins also blocked nuclear movement, showing that mutations affecting muscle exhibit the null phenotype. Lack of A-type lamins, or expression of variants that cause striated muscle disease, did not affect assembly of nesprin-2G and SUN2 into transmembrane actin-associated nuclear (TAN) lines that attach the nucleus to retrogradely moving actin cables. Nesprin-2G TAN lines were less stable, however, and slipped over the nucleus rather than moving with it, indicating that they were not anchored. Nesprin-2G TAN lines also slipped in SUN2-depleted cells. Our results establish A-type lamins as anchors for nesprin-2G-SUN2 TAN lines to allow productive movement and proper positioning of the nucleus by actin.", keywords = "Linker of nucleoskeleton and cytoskeleton complex, Muscular dystrophy, Nesprin SUN", author = "Folker, {Eric S.} and Cecilia {\"O}stlund and Luxton, {G. W.Gant} and Worman, {Howard J.} and Gundersen, {Gregg G.}", year = "2011", month = jan, day = "4", doi = "10.1073/pnas.1000824108", language = "English (US)", volume = "108", pages = "131--136", journal = "Proceedings of the National Academy of Sciences of the United States of America", issn = "0027-8424", publisher = "National Academy of Sciences", number = "1", } . Proceedings of the National Academy of Sciences of the United States of America.

GW Gant Luxton, Edgar R. Gomes, Eric S. Folker, Howard J. Worman, Gregg G. Gundersen(2011). TAN lines . Nucleus. 2. (3). p. 173--181. Landes Bioscience

Linear arrays of nuclear envelope proteins harness retrograde actin flow for nuclear movement @article{a0474c8052f242e785b3fb7c71d3152a, title = "Linear arrays of nuclear envelope proteins harness retrograde actin flow for nuclear movement", abstract = "Nuclei move to specific locations to polarize migrating and differentiating cells. Many nuclear movements are microtubule-dependent. However, nuclear movement to reorient the centrosome in migrating fibroblasts occurs through an unknown actin-dependent mechanism. We found that linear arrays of outer (nesprin2G) and inner (SUN2) nuclear membrane proteins assembled on and moved with retrogradely moving dorsal actin cables during nuclear movement in polarizing fibroblasts. Inhibition of nesprin2G, SUN2, or actin prevented nuclear movement and centrosome reorientation. The coupling of actin cables to the nuclear membrane for nuclear movement via specific membrane proteins indicates that, like plasma membrane integrins, nuclear membrane proteins assemble into actin-dependent arrays for force transduction.", author = "Luxton, {G. W.Gant} and Gomes, {Edgar R.} and Folker, {Eric S.} and Erin Vintinner and Gundersen, {Gregg G.}", year = "2010", month = aug, day = "20", doi = "10.1126/science.1189072", language = "English (US)", volume = "329", pages = "956--959", journal = "Science", issn = "0036-8075", publisher = "American Association for the Advancement of Science", number = "5994", } . Science.

HDAC6-Pack @article{dfb326bf4ec744ddb5a50b9bba9667b2, title = "HDAC6-Pack: Cortactin Acetylation Joins the Brew", abstract = "The reversible acetylation of lysine residues is an important posttranslational modification for the regulation of histones, transcription factors, chaperones, and microtubules. In a recent article in Molecular Cell, Zhang et al. (2007) describe a new target of reversible acetylation, the actin binding protein cortactin.", author = "Luxton, {G. W.Gant} and Gundersen, {Gregg G.}", year = "2007", month = aug, day = "7", doi = "10.1016/j.devcel.2007.07.014", language = "English (US)", volume = "13", pages = "161--162", journal = "Developmental Cell", issn = "1534-5807", publisher = "Cell Press", number = "2", } . Developmental Cell.

Luxton GW, Gundersen GG(2007). HDAC6-pack: cortactin acetylation joins the brew . Developmental cell.

Identification of an essential domain in the herpesvirus VP1/2 tegument protein @article{ef8e9d248a7542129c192da8460ad862, title = "Identification of an essential domain in the herpesvirus VP1/2 tegument protein: The carboxy terminus directs incorporation into capsid assemblons", abstract = "The herpesvirus tegument is a layer of viral and cellular proteins located between the capsid and envelope of the virion. The VP1/2 tegument protein is critical for the propagation of all herpesviruses examined. Using an infectious clone of the alphaherpesvirus pseudorabies virus, we have made a collection of truncation and in-frame deletion mutations within the VP1/2 gene (UL36) and examined the resulting viruses for spread between cells. We found that the majority of ihe VP1/2 protein either was essential for virus propagation or did not tolerate large deletions. A recently described amino-terminal deubiquitinase-encoding domain was dispensable for alphaherpesvirus propagation, but the rate of propagation in an epithelial cell line and the frequency of transport in axons of primary sensory neurons were both reduced. We mapped one essential domain to a conserved sequence at the VP1/2 carboxy terminus and demonstrated that this domain sufficient to redirect the green fluorescent protein to capsid assemblons in nuclei of infected cells.", author = "Lee, {Joy I Hsuan} and Luxton, {G. W Gant} and Smith, {Gregory Allan}", year = "2006", month = dec, doi = "10.1128/JVI.01184-06", language = "English (US)", volume = "80", pages = "12086--12094", journal = "Journal of virology", issn = "0022-538X", publisher = "American Society for Microbiology", number = "24", } . Journal of virology.

The pseudorabies virus VP1/2 tegument protein is required for intracellular capsid transport @article{0dc491344c304528835f60772a31e01e, title = "The pseudorabies virus VP1/2 tegument protein is required for intracellular capsid transport", abstract = "Transport of capsids in cells is critical to alphaherpesvirus infection and pathogenesis; however, viral factors required for transport have yet to be identified. Here we provide a detailed examination of capsid dynamics during the egress phase of infection in Vero cells infected with pseudorabies virus. We demonstrate that the VP1/2 tegument protein is required for processive microtubule-based transport of capsids in the cytoplasm. A second tegument protein that binds to VP1/2, UL37, was necessary for wild-type transport but was not essential for this process. Both proteins were also required for efficient nuclear egress of capsids to the cytoplasm.", author = "Luxton, {G. W.Gant} and Lee, {Joy I.Hsuan} and Sarah Haverlock-Moyns and Schober, {Joseph Martin} and Smith, {Gregory Allan}", year = "2006", month = jan, doi = "10.1128/JVI.80.1.201-209.2006", language = "English (US)", volume = "80", pages = "201--209", journal = "Journal of virology", issn = "0022-538X", publisher = "American Society for Microbiology", number = "1", } . Journal of virology.

Responsive microtubule dynamics promote cell invasion by Trypanosoma cruzi @article{a3465152f89a49e58f98ad643305ab4f, title = "Responsive microtubule dynamics promote cell invasion by Trypanosoma cruzi", abstract = "The American trypanosome, Trypanosoma cruzi, can invade non-phagocytic cell types by a G-protein-mediated, calcium-dependent mechanism, in which the cell's natural puncture repair mechanism is usurped in order to recruit lysosomes to the parasite/host cell junction or 'parasite synapse.' The fusion of lysosomes necessary for construction of the nascent parasitophorous vacuole is achieved by directed trafficking along microtubules. We demonstrate altered host cell microtubule dynamics during the initial stages of the entry process involving de novo microtubule polymerization from the cytoplasmic face of the parasite synapse which appears to serve as a secondary microtubule organizing centre. The net result of these dynamic changes to the host cell's microtubule cytoskeleton is the development of the necessary infrastructure for transport of lysosomes to the parasite synapse.", author = "Tyler, {Kevin M.} and Luxton, {George W G} and Applewhite, {Derek A.} and Murphy, {Sean C.} and Engman, {David M.}", year = "2005", month = nov, doi = "10.1111/j.1462-5822.2005.00576.x", language = "English (US)", volume = "7", pages = "1579--1591", journal = "Cellular Microbiology", issn = "1462-5814", publisher = "John Wiley and Sons Ltd", number = "11", } . Cellular Microbiology.

Targeting of herpesvirus capsid transport in axons is coupled to association with specific sets of tegument proteins @article{0cadb1e9ca8d464dad1d9005c27fe4c5, title = "Targeting of herpesvirus capsid transport in axons is coupled to association with specific sets of tegument proteins", abstract = "The capsids of neurotropic herpesviruses have the remarkable ability to move in specific directions within axons. By modulating bidirectional capsid transport to favor either retrograde (minus-end) or anterograde (plus-end) motion, these viruses travel to sensory ganglia or peripheral tissue at specific stages of infection. By using correlative motion analysis to simultaneously monitor the trafficking of distinct viral proteins in living neurons, we demonstrate that viral {"}tegument{"} proteins are complexed to capsids moving in axons. The removal of a subset of tegument proteins from capsids invariably preceded retrograde transport to the cell body in sensory ganglia, whereas addition of these proteins was coupled to anterograde transport of progeny capsids to the distal axon. Although capsid transport never occurred without associated tegument proteins, anterograde-specific tegument proteins were competent to travel to the distal axon independent of capsids. These findings are compatible with a model of viral bidirectional transport in which tegument proteins direct capsid traffic to specific intracellular locations during the infectious cycle.", keywords = "Neuron, Virus", author = "Luxton, {G. W.Gant} and Sarah Haverlock and Coller, {Kelly Elizabeth} and Antinone, {Sarah Elizabeth} and Andrew Pincetic and Smith, {Gregory Allan}", year = "2005", month = apr, day = "19", doi = "10.1073/pnas.0500803102", language = "English (US)", volume = "102", pages = "5832--5837", journal = "Proceedings of the National Academy of Sciences of the United States of America", issn = "0027-8424", publisher = "National Academy of Sciences", number = "16", } . Proceedings of the National Academy of Sciences of the United States of America.

Ziying Yan, Roman Zak, GW Gant Luxton, Teresa C. Ritchie, Ursula Bantel-Schaal, John F. Engelhardt(2002). Ubiquitination of both adeno-associated virus type 2 and 5 capsid proteins affects the transduction efficiency of recombinant vectors . Journal of virology. 76. (5). p. 2043--2053. American Society for Microbiology

OTHER

Correction @article{23f0787ac246495ca61b64fa81ba5889, title = "Correction: A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly (doi:10.1242/jcs.219451) (J. Cell Sci. (2019) 132 (jcs219451) DOI:10.1242/jcs.219451)", abstract = "The labels for the N-terminus and C-terminus in Fig. 3A were incorrectly swapped, and Fig. 5 had labels stating that the constructs were from SUN1 when in fact they were from SUN2. The online full-text and PDF versions of the paper have been updated. (Figure presented.)", author = "Sagardip Majumder and Willey, {Patrick T.} and DeNies, {Maxwell S.} and Liu, {Allen P.} and {Gant Luxton}, {G. W.}", note = "Publisher Copyright: {\textcopyright} 2019. Published by The Company of Biologists Ltd.", year = "2019", month = may, day = "1", doi = "10.1242/jcs.234153", language = "English (US)", volume = "132", journal = "Journal of cell science", issn = "0021-9533", publisher = "Company of Biologists Ltd", number = "10", } . Journal of cell science.

A Special Topic on Nuclear Mechanobiology @article{3205e5c2e585412791939d9e4231938a, title = "A Special Topic on Nuclear Mechanobiology", author = "Dahl, {Kris Noel} and Luxton, {G. W.Gant}", note = "Copyright: Copyright 2017 Elsevier B.V., All rights reserved.", year = "2016", month = jun, day = "1", doi = "10.1007/s12195-016-0442-y", language = "English (US)", volume = "9", pages = "203--206", journal = "Cellular and Molecular Bioengineering", issn = "1865-5025", publisher = "Springer", number = "2", } . Cellular and Molecular Bioengineering.

BOOK CHAPTER

Jared Hennen, Isaac Angert, Kwang Ho Hur, GW Gant Luxton, Joachim Mueller(2018). Investigating LINC Complex Protein Homo-oligomerization in the Nuclear Envelopes of Living Cells Using Fluorescence Fluctuation Spectroscopy . Methods in Molecular Biology. p. 121--135. Humana Press Inc.