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Ma L, Kuhn J, Chang YT, Elnatan D, Luxton GWG, Starr DA. FLN-2 functions in parallel to linker of nucleoskeleton and cytoskeleton complexes and CDC-42/actin pathways during P-cell nuclear migration through constricted spaces in Caenorhabditis elegans. Genetics 2024:iyae071. [PMID: 38797871 DOI: 10.1093/genetics/iyae071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 04/24/2024] [Indexed: 05/29/2024] Open
Abstract
Nuclear migration through narrow constrictions is important for development, metastasis, and proinflammatory responses. Studies performed in tissue culture cells have implicated linker of nucleoskeleton and cytoskeleton (LINC) complexes, microtubule motors, the actin cytoskeleton, and nuclear envelope repair machinery as important mediators of nuclear movements through constricted spaces. However, little is understood about how these mechanisms operate to move nuclei in vivo. In Caenorhabditis elegans larvae, six pairs of hypodermal P cells migrate from lateral to ventral positions through a constricted space between the body wall muscles and the cuticle. P-cell nuclear migration is mediated in part by LINC complexes using a microtubule-based pathway and by an independent CDC-42/actin-based pathway. However, when both LINC complex and actin-based pathways are knocked out, many nuclei still migrate, suggesting the existence of additional pathways. Here, we show that FLN-2 functions in a third pathway to mediate P-cell nuclear migration. The predicted N-terminal actin-binding domain in FLN-2 that is found in canonical filamins is dispensable for FLN-2 function; this and structural predictions suggest that FLN-2 does not function as a filamin. The immunoglobulin-like repeats 4-8 of FLN-2 were necessary for P-cell nuclear migration. Furthermore, in the absence of the LINC complex component unc-84, fln-2 mutants had an increase in P-cell nuclear rupture. We conclude that FLN-2 functions to maintain the integrity of the nuclear envelope in parallel with the LINC complex and CDC-42/actin-based pathways to move P-cell nuclei through constricted spaces.
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Affiliation(s)
- Linda Ma
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Jonathan Kuhn
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Yu-Tai Chang
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Daniel Elnatan
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - G W Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
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2
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Gregory EF, Luxton GWG, Starr DA. Anchorage of H3K9-methylated heterochromatin to the nuclear periphery helps mediate P-cell nuclear migration though constricted spaces in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595380. [PMID: 38826247 PMCID: PMC11142143 DOI: 10.1101/2024.05.22.595380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Nuclei adjust their deformability while migrating through constrictions to enable structural changes and maintain nuclear integrity. The effect of heterochromatin anchored at the nucleoplasmic face of the inner nuclear membrane on nuclear morphology and deformability during in vivo nuclear migration through constricted spaces remains unclear. Here, we show that abolishing peripheral heterochromatin anchorage by eliminating CEC-4, a chromodomain protein that tethers H3K9-methylated chromatin to the nuclear periphery, disrupts constrained P-cell nuclear migration in Caenorhabditis elegans larvae in the absence of the established LINC complex-dependent pathway. CEC-4 acts in parallel to an actin and CDC-42-based pathway. We also demonstrate the necessity for the chromatin methyltransferases MET-2 and JMJD-1.2 during P-cell nuclear migration in the absence of functional LINC complexes. We conclude that H3K9-nethylated chromatin needs to be anchored to the nucleoplasmic face of the inner nuclear membrane to help facilitate nuclear migration through constricted spaces in vivo.
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Affiliation(s)
- Ellen F Gregory
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616 USA
| | - G W Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616 USA
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616 USA
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3
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Ho J, Guerrero LA, Libuda DE, Luxton GWG, Starr DA. Actin and CDC-42 contribute to nuclear migration through constricted spaces in C. elegans. Development 2023; 150:dev202115. [PMID: 37756590 PMCID: PMC10617605 DOI: 10.1242/dev.202115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023]
Abstract
Successful nuclear migration through constricted spaces between cells or in the extracellular matrix relies on the ability of the nucleus to deform. Little is known about how this takes place in vivo. We have studied confined nuclear migration in Caenorhabditis elegans larval P cells, which is mediated by the LINC complex to pull nuclei towards the minus ends of microtubules. Null mutations of the LINC component unc-84 lead to a temperature-dependent phenotype, suggesting a parallel pathway for P-cell nuclear migration. A forward genetic screen for enhancers of unc-84 identified cgef-1 (CDC-42 guanine nucleotide exchange factor). Knockdown of CDC-42 in the absence of the LINC complex led to a P-cell nuclear migration defect. Expression of constitutively active CDC-42 partially rescued nuclear migration in cgef-1; unc-84 double mutants, suggesting that CDC-42 functions downstream of CGEF-1. The Arp2/3 complex and non-muscle myosin II (NMY-2) were also found to function parallel to the LINC pathway. In our model, CGEF-1 activates CDC-42, which induces actin polymerization through the Arp2/3 complex to deform the nucleus during nuclear migration, and NMY-2 helps to push the nucleus through confined spaces.
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Affiliation(s)
- Jamie Ho
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Leslie A. Guerrero
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Diana E. Libuda
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - G. W. Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Daniel A. Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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4
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Ma L, Kuhn J, Chang YT, Elnatan D, Luxton GWG, Starr DA. FLN-2 functions in parallel to LINC complexes and Cdc42/actin pathways during P-cell nuclear migration through constricted spaces in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552041. [PMID: 37577634 PMCID: PMC10418278 DOI: 10.1101/2023.08.04.552041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Nuclear migration through narrow constrictions is important for development, metastasis, and pro-inflammatory responses. Studies performed in tissue culture cells have implicated LINC (linker of nucleoskeleton and cytoskeleton) complexes, microtubule motors, the actin cytoskeleton, and nuclear envelope repair machinery as important mediators of nuclear movements through constricted spaces. However, little is understood about how these mechanisms operate to move nuclei in vivo. In C. elegans larvae, 6 pairs of hypodermal P cells migrate from lateral to ventral positions through a constricted space between the body wall muscles and the cuticle. P-cell nuclear migration is mediated in part by LINC complexes using a microtubule-based pathway and by an independent CDC-42/actin-based pathway. However, when both LINC complex and actin-based pathways are knocked out, many nuclei still migrate, suggesting the existence of additional pathways. Here we show that FLN-2 functions in a third pathway to mediate P-cell nuclear migration. The predicted N-terminal actin binding domain in FLN-2 that is found in canonical filamins is dispensable for FLN-2 function, this and structural predictions suggest that FLN-2 is not a divergent filamin. The immunoglobulin (Ig)-like repeats 4-8 of FLN-2 were necessary for P-cell nuclear migration. Furthermore, in the absence of the LINC complex component unc-84, fln-2 mutants had an increase in P-cell nuclear rupture. We conclude that FLN-2 functions to maintain the integrity of the nuclear envelope in parallel with the LINC complex and CDC-42/actin-based pathways to move P-cell nuclei through constricted spaces.
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Affiliation(s)
- Linda Ma
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Jonathan Kuhn
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Yu-Tai Chang
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Daniel Elnatan
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - G W Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
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5
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Gregory EF, Kalra S, Brock T, Bonne G, Luxton GWG, Hopkins C, Starr DA. Caenorhabditis elegans models for striated muscle disorders caused by missense variants of human LMNA. PLoS Genet 2023; 19:e1010895. [PMID: 37624850 PMCID: PMC10484454 DOI: 10.1371/journal.pgen.1010895] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 09/07/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
Striated muscle laminopathies caused by missense mutations in the nuclear lamin gene LMNA are characterized by cardiac dysfunction and often skeletal muscle defects. Attempts to predict which LMNA variants are pathogenic and to understand their physiological effects lag behind variant discovery. We created Caenorhabditis elegans models for striated muscle laminopathies by introducing pathogenic human LMNA variants and variants of unknown significance at conserved residues within the lmn-1 gene. Severe missense variants reduced fertility and/or motility in C. elegans. Nuclear morphology defects were evident in the hypodermal nuclei of many lamin variant strains, indicating a loss of nuclear envelope integrity. Phenotypic severity varied within the two classes of missense mutations involved in striated muscle disease, but overall, variants associated with both skeletal and cardiac muscle defects in humans lead to more severe phenotypes in our model than variants predicted to disrupt cardiac function alone. We also identified a separation of function allele, lmn-1(R204W), that exhibited normal viability and swimming behavior but had a severe nuclear migration defect. Thus, we established C. elegans avatars for striated muscle laminopathies and identified LMNA variants that offer insight into lamin mechanisms during normal development.
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Affiliation(s)
- Ellen F. Gregory
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
| | - Shilpi Kalra
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
| | - Trisha Brock
- InVivo Biosystems, Eugene, Oregon, United States of America
| | - Gisèle Bonne
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - G. W. Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
| | | | - Daniel A. Starr
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
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6
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Gümüşderelioğlu S, Resch L, Brock T, Luxton GWG, Cope H, Tan QKG, Hopkins C, Starr DA. A humanized Caenorhabditis elegans model of hereditary spastic paraplegia-associated variants in KLC4. Dis Model Mech 2023; 16:dmm050076. [PMID: 37565267 PMCID: PMC10481945 DOI: 10.1242/dmm.050076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 07/31/2023] [Indexed: 08/12/2023] Open
Abstract
Hereditary spastic paraplegia (HSP) is a group of degenerative neurological disorders. We identified a variant in human kinesin light chain 4 (KLC4) that is suspected to be associated with autosomal-dominant HSP. How this and other variants relate to pathologies is unknown. We created a humanized Caenorhabditis elegans model in which klc-2 was replaced by human KLC4 (referred to as hKLC4) and assessed the extent to which hKLC4 retained function in the worm. We observed a slight decrease in motility but no nuclear migration defects in the humanized worms, suggesting that hKLC4 retains much of the function of klc-2. Five hKLC4 variants were introduced into the humanized model. The clinical variant led to early lethality, with significant defects in nuclear migration when homozygous and a weak nuclear migration defect when heterozygous, possibly correlating with the clinical finding of late-onset HSP when the proband was heterozygous. Thus, we were able to establish humanized C. elegans as an animal model for HSP and to use it to test the significance of five variants of uncertain significance in the human gene KLC4.
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Affiliation(s)
- Selin Gümüşderelioğlu
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | | | | | | | - G. W. Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Heidi Cope
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
| | - Queenie K.-G. Tan
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
| | | | - Daniel A. Starr
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
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7
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Gümüşderelioğlu S, Resch L, Brock T, Luxton GWG, Tan QKG, Hopkins C, Starr DA. A humanized Caenorhabditis elegans model of Hereditary Spastic Paraplegia-associated variants in kinesin light chain KLC4. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.07.523106. [PMID: 36789438 PMCID: PMC9928042 DOI: 10.1101/2023.01.07.523106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Hereditary spastic paraplegia (HSP) is a group of degenerative neurological disorders. We identified a variant in human kinesin light chain KLC4 that is suspected to be associated with autosomal dominant HSP. How this and other variants relate to pathologies is unknown. We created a humanized C. elegans model where klc- 2 was replaced with human KLC4 and assessed the extent to which hKLC4 retained function in the worm. We observed a slight decrease in motility but no nuclear migration defects in the humanized worms, suggesting that hKLC4 retains much of the function of klc-2 . Five hKLC4 variants were introduced into the humanized model. The clinical variant led to early lethality with significant defects in nuclear migration when homozygous, and a weak nuclear migration defect when heterozygous, possibly correlating with the clinical finding of late onset HSP when the proband was heterozygous. Thus, we were able to establish humanized C. elegans as an animal model for HSP and use it to test the significance of five variants of uncertain significance in the human gene KLC4 . Summary Statement We identified a variant in KLC4 associated with Hereditary Spastic Paraplegia. The variant had physiological relevance in a humanized C. elegans model where we replaced klc-2 with human KLC4 .
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Affiliation(s)
- Selin Gümüşderelioğlu
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | | | | | - G W Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - Queenie K-G Tan
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | | | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
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8
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Taiber S, Gozlan O, Cohen R, Andrade LR, Gregory EF, Starr DA, Moran Y, Hipp R, Kelley MW, Manor U, Sprinzak D, Avraham KB. A Nesprin-4/kinesin-1 cargo model for nuclear positioning in cochlear outer hair cells. Front Cell Dev Biol 2022; 10:974168. [PMID: 36211453 PMCID: PMC9537699 DOI: 10.3389/fcell.2022.974168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 09/07/2022] [Indexed: 11/14/2022] Open
Abstract
Nuclear positioning is important for the functionality of many cell types and is mediated by interactions of cytoskeletal elements and nucleoskeleton proteins. Nesprin proteins, part of the linker of nucleoskeleton and cytoskeleton (LINC) complex, have been shown to participate in nuclear positioning in multiple cell types. Outer hair cells (OHCs) in the inner ear are specialized sensory epithelial cells that utilize somatic electromotility to amplify auditory signals in the cochlea. Recently, Nesprin-4 (encoded by Syne4) was shown to play a crucial role in nuclear positioning in OHCs. Syne4 deficiency in humans and mice leads to mislocalization of the OHC nuclei and cell death resulting in deafness. However, it is unknown how Nesprin-4 mediates the position of the nucleus, and which other molecular components are involved in this process. Here, we show that the interaction of Nesprin-4 and the microtubule motor kinesin-1 is mediated by a conserved 4 amino-acid motif. Using in vivo AAV gene delivery, we show that this interaction is critical for nuclear positioning and hearing in mice. Nuclear mislocalization and cell death of OHCs coincide with the onset of hearing and electromotility and are solely restricted to outer, but not inner, hair cells. Likewise, the C. elegans functional homolog of Nesprin-4, UNC-83, uses a similar motif to mediate interactions between migrating nuclei and kinesin-1. Overall, our results suggest that OHCs require unique cellular machinery for proper nuclear positioning at the onset of electromotility. This machinery relies on the interaction between Nesprin-4 and kinesin-1 motors supporting a microtubule cargo model for nuclear positioning.
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Affiliation(s)
- Shahar Taiber
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel,School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Oren Gozlan
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Roie Cohen
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Leonardo R. Andrade
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Ellen F. Gregory
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Daniel A. Starr
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rebecca Hipp
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, United States
| | - Matthew W. Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, United States
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - David Sprinzak
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel,*Correspondence: David Sprinzak, ; Karen B. Avraham,
| | - Karen B. Avraham
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel,*Correspondence: David Sprinzak, ; Karen B. Avraham,
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9
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Hao H, Kalra S, Jameson LE, Guerrero LA, Cain NE, Bolivar J, Starr DA. The Nesprin-1/-2 ortholog ANC-1 regulates organelle positioning in C. elegans independently from its KASH or actin-binding domains. eLife 2021; 10:e61069. [PMID: 33860766 PMCID: PMC8139857 DOI: 10.7554/elife.61069] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 04/11/2021] [Indexed: 12/15/2022] Open
Abstract
KASH proteins in the outer nuclear membrane comprise the cytoplasmic half of linker of nucleoskeleton and cytoskeleton (LINC) complexes that connect nuclei to the cytoskeleton. Caenorhabditis elegans ANC-1, an ortholog of Nesprin-1/2, contains actin-binding and KASH domains at opposite ends of a long spectrin-like region. Deletion of either the KASH or calponin homology (CH) domains does not completely disrupt nuclear positioning, suggesting neither KASH nor CH domains are essential. Deletions in the spectrin-like region of ANC-1 led to significant defects, but only recapitulated the null phenotype in combination with mutations in the transmembrane (TM) span. In anc-1 mutants, the endoplasmic reticulum ER, mitochondria, and lipid droplets were unanchored, moving throughout the cytoplasm. The data presented here support a cytoplasmic integrity model where ANC-1 localizes to the ER membrane and extends into the cytoplasm to position nuclei, ER, mitochondria, and other organelles in place.
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Affiliation(s)
- Hongyan Hao
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Shilpi Kalra
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Laura E Jameson
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Leslie A Guerrero
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Natalie E Cain
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Jessica Bolivar
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
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10
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Abstract
LINC complexes (Linker of Nucleoskeleton and Cytoskeleton), consisting of inner nuclear membrane SUN (Sad1, UNC-84) proteins and outer nuclear membrane KASH (Klarsicht, ANC-1, and Syne Homology) proteins, are essential for nuclear positioning, cell migration and chromosome dynamics. To test the in vivo functions of conserved interfaces revealed by crystal structures, Cain et al used a combination of Caenorhabditis elegans genetics, imaging in cultured NIH 3T3 fibroblasts, and Molecular Dynamic simulations, to study SUN-KASH interactions. Conserved aromatic residues at the -7 position of the C-termini of KASH proteins and conserved disulfide bonds in LINC complexes play important roles in force transmission across the nuclear envelope. Other properties of LINC complexes, such as the helices preceding the SUN domain, the longer coiled-coils spanning the perinuclear space and higher-order organization may also function to transmit mechanical forces generated by the cytoskeleton across the nuclear envelope.
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Affiliation(s)
- Hongyan Hao
- a Department of Molecular and Cellular Biology , University of California , Davis , CA USA
| | - Daniel A Starr
- a Department of Molecular and Cellular Biology , University of California , Davis , CA USA
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11
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Gregory EF, Starr DA. tmem-258 is dispensable for both nuclear anchorage and migration in C. elegans. MICROPUBLICATION BIOLOGY 2020; 2020:10.17912/micropub.biology.000208. [PMID: 32550492 PMCID: PMC7252297 DOI: 10.17912/micropub.biology.000208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Daniel Aaron Starr
- University of California, Davis,
Correspondence to: Daniel Aaron Starr ()
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12
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Starr DA. A network of nuclear envelope proteins and cytoskeletal force generators mediates movements of and within nuclei throughout Caenorhabditis elegans development. Exp Biol Med (Maywood) 2019; 244:1323-1332. [PMID: 31495194 PMCID: PMC6880151 DOI: 10.1177/1535370219871965] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nuclear migration and anchorage, together referred to as nuclear positioning, are central to many cellular and developmental events. Nuclear positioning is mediated by a conserved network of nuclear envelope proteins that interacts with force generators in the cytoskeleton. At the heart of this network are li nker of n ucleoskeleton and c ytoskeleton (LINC) complexes made of S ad1 and UN C-84 (SUN) proteins at the inner nuclear membrane and K larsicht, A NC-1, and S yne homology (KASH) proteins in the outer nuclear membrane. LINC complexes span the nuclear envelope, maintain nuclear envelope architecture, designate the surface of nuclei distinctly from the contiguous endoplasmic reticulum, and were instrumental in the early evolution of eukaryotes. LINC complexes interact with lamins in the nucleus and with various cytoplasmic KASH effectors from the surface of nuclei. These effectors regulate the cytoskeleton, leading to a variety of cellular outputs including pronuclear migration, nuclear migration through constricted spaces, nuclear anchorage, centrosome attachment to nuclei, meiotic chromosome movements, and DNA damage repair. How LINC complexes are regulated and how they function are reviewed here. The focus is on recent studies elucidating the best-understood network of LINC complexes, those used throughout Caenorhabditis elegans development.
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Affiliation(s)
- Daniel A Starr
- Department of Molecular and Cellular Biology,
University of California, Davis, CA 95616, USA
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13
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Jahed Z, Hao H, Thakkar V, Vu UT, Valdez VA, Rathish A, Tolentino C, Kim SCJ, Fadavi D, Starr DA, Mofrad MRK. Role of KASH domain lengths in the regulation of LINC complexes. Mol Biol Cell 2019; 30:2076-2086. [PMID: 30995155 PMCID: PMC6727767 DOI: 10.1091/mbc.e19-02-0079] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The linker of the nucleoskeleton and cytoskeleton (LINC) complex is formed by the conserved interactions between Sad-1 and UNC-84 (SUN) and Klarsicht, ANC-1, SYNE homology (KASH) domain proteins, providing a physical coupling between the nucleoskeleton and cytoskeleton that mediates the transfer of physical forces across the nuclear envelope. The LINC complex can perform distinct cellular functions by pairing various KASH domain proteins with the same SUN domain protein. For example, in Caenorhabditis elegans, SUN protein UNC-84 binds to two KASH proteins UNC-83 and ANC-1 to mediate nuclear migration and anchorage, respectively. In addition to distinct cytoplasmic domains, the luminal KASH domain also varies among KASH domain proteins of distinct functions. In this study, we combined in vivo C. elegans genetics and in silico molecular dynamics simulations to understand the relation between the length and amino acid composition of the luminal KASH domain, and the function of the SUN–KASH complex. We show that longer KASH domains can withstand and transfer higher forces and interact with the membrane through a conserved membrane proximal EEDY domain that is unique to longer KASH domains. In agreement with our models, our in vivo results show that swapping the KASH domains of ANC-1 and UNC-83, or shortening the KASH domain of ANC-1, both result in a nuclear anchorage defect in C. elegans.
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Affiliation(s)
- Zeinab Jahed
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Hongyan Hao
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Vyom Thakkar
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Uyen T Vu
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Venecia A Valdez
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Akshay Rathish
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Chris Tolentino
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Samuel C J Kim
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Darya Fadavi
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720.,Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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