Syncoilin isoform organization and differential expression in murine striated muscle.
Syncoilin is a 64kDa intermediate filament (IF) protein expressed in myocytes at the sarcolemma, perinucleus, myotendenous and neuromuscular junctions. Here we present a revised domain projection and structural analysis for the original isoform (sync-1) and introduce two novel syncoilin isoforms (sync-2 and sync-3) generated by exon splicing. On the basis of consensus identity we propose that syncoilin be reclassified as a type III IF protein. All three syncoilin isoforms lack a L1 domain, a significant departure from standard IF rod domain projections that is likely to impact significantly on their biological function. Our analyses indicate that syncoilin is unlikely to form classical intermediate filament structures by itself, and that the significant difference in C-terminal structure between the three isoforms indicates that they may play divergent roles in myocytes. We show that despite lacking an apparent structural role in striated muscle, syncoilin isoforms are differentially and strongly upregulated in response to cardiotoxin induced regeneration and denervation induced atrophy in the C57BL/6 mouse, possibly suggesting an atypical role for syncoilin in muscle.
Kemp
Matthew W
MW
MRC Functional Genomics Unit, Department of Anatomy, Physiology and Genetics, University of Oxford, South Parks Road, Oxford OX13QX, UK.
Edwards
Ben
B
Burgess
Matthew
M
Clarke
W Thomas
WT
Nicholson
George
G
Parry
David A D
DA
Davies
Kay E
KE
D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism; D003893:Desmin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology; D054792:Muscle, Striated / Q000378:metabolism*; D009133:Muscular Atrophy / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012038:Regeneration / Q000502:physiology; D016415:Sequence Alignment; D014162:Transfection
D003893:Desmin; D007381:Intermediate Filament Proteins; D009124:Muscle Proteins; D020033:Protein Isoforms; C503782:Sync protein, mouse