Nesprins, but not sun proteins, switch isoforms at the nuclear envelope during muscle development.
Nesprins are a family of nuclear transmembrane proteins anchored via Sun proteins to the nuclear membrane. Analysis of nesprins during human muscle development revealed an increase in nesprin-1-giant during early myogenesis in vitro. During the transition from immature to mature muscle fibres in vivo, nesprin-2 partly replaced nesprin-1 at the nuclear envelope and short nesprin isoforms became dominant. Sun1 and Sun2 proteins remained unchanged during this fibre maturation. In emerin-negative skin fibroblasts, nesprin-2-giant was relocated from the nuclear envelope to the cytoplasm, not to the endoplasmic reticulum, while nesprin-1 remained at the nuclear envelope. In emerin-negative keratinocytes lacking nesprin-1, nesprin-2 remained at the nuclear envelope. HeLa cell nuclear envelopes lacked nesprin-1, which was the dominant form in myoblasts, while a novel 130-kD nesprin-2 isoform dominated Ntera-2 cells. The results suggest the possibility of isoform-specific and tissue-specific roles for nesprins in nuclear positioning.
Randles
K Natalie
KN
Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, United Kingdom.
Lam
Le Thanh
le T
Sewry
Caroline A
CA
Puckelwartz
Megan
M
Furling
Denis
D
Wehnert
Manfred
M
McNally
Elizabeth M
EM
Morris
Glenn E
GE
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D002467:Cell Nucleus / Q000378:metabolism; D003598:Cytoskeletal Proteins; D005347:Fibroblasts / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009132:Muscles / Q000196:embryology*; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D020033:Protein Isoforms; D034501:Telomere-Binding Proteins / Q000378:metabolism
D000911:Antibodies, Monoclonal; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; C506117:SUN1 protein, human; C464932:SUN1 protein, mouse; C413025:SUN2 protein, human; C415465:SYNE1 protein, human; C485904:SYNE2 protein, human; C520338:Sun2 protein, mouse; C485901:Syne1 protein, mouse; C485903:Syne2 protein, mouse; D034501:Telomere-Binding Proteins