title: Linker of nucleoskeleton and cytoskeleton (LINC) complex-mediated actin-dependent nuclear positioning orients centrosomes in migrating myoblasts.
abstract: Myoblast migration is essential for muscle development and repair; however, the factors that contribute to the polarity of migrating myoblasts are relatively unknown. We find that randomly migrating C2C12 myoblasts orient their centrosomes in the direction of migration. Using wounded monolayers, we further show that centrosome orientation is stimulated by the serum factor lysophosphatidic acid (LPA) and involves the rearward movement of the nucleus while the centrosome is maintained at the cell centroid. The rate of nuclear movement correlated with that of actin retrograde flow and both cytochalasin D and blebbistatin prevented nuclear movement and centrosome orientation. Actin-dependent rearward nuclear movement in fibroblasts is mediated by assembly of nuclear membrane nesprin-2G and SUN2 LINC complexes into transmembrane actin-associated nuclear (TAN) lines anchored by A-type lamins and emerin. In C2C12 myoblasts, depletion of nesprin-2G, SUN2 or lamin A/C prevented nuclear movement and endogenous nesprin-2G and a chimeric GFP-mini-nesprin-2G formed TAN lines during nuclear movement. Depleting nesprin-2G strongly interfered with directed cell migration and reduced the efficiency of myoblast fusion into multinucleated myotubes. Our results show that nuclear movement contributes to centrosome orientation and polarity for efficient migration and fusion of myoblasts. Given that mutations in the genes encoding A-type lamins, nesprin-2 and SUN2 cause Emery-Dreifuss muscular dystrophy and related myopathies, our results have implications for understanding the mechanism of disease pathogenesis.
authors.affiliation: a Department of Pathology and Cell Biology ; College of Physicians and Surgeons; Columbia University ; New York , NY USA.
authors.forename: Wakam
authors.initials: W
authors.lastname: Chang
authors.forename: Susumu
authors.initials: S
authors.lastname: Antoku
authors.forename: Cecilia
authors.initials: C
authors.lastname: Östlund
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Worman
authors.forename: Gregg G
authors.initials: GG
authors.lastname: Gundersen
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D018385:Centrosome / Q000187:drug effects / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000378:metabolism; D034904:Lamin Type A / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D008565:Membrane Proteins / Q000172:deficiency / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000172:deficiency / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000378:metabolism; D009687:Nuclear Proteins / Q000172:deficiency / Q000378:metabolism*
chemical_list: D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; D034904:Lamin Type A; D008246:Lysophospholipids; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C413025:SUN2 protein, human; C485904:SYNE2 protein, human; C440308:lamin C; C032881:lysophosphatidic acid
keywords: CH, calponin homology; EDMD, Emery-Dreifuss muscular dystrophy; GFP, green fluorescent protein; GFP-mN2G, GFP-mini-nesprin-2G; LINC complex; LINC, linker of nucleoskeleton and cytoskeleton; LPA, lysophosphatidic acid; TAN lines, transmembrane actin-associated nuclear lines; cell migration; centrosome orientation; muscle differentiation, TAN lines; nuclear positioning