Synemin interacts with the LIM domain protein zyxin and is essential for cell adhesion and migration.
Synemin is a unique cytoplasmic intermediate filament protein for which there is limited understanding of its exact cellular functions. The single human synemin gene encodes at least two splice variants named alpha-synemin and beta-synemin, with the larger alpha-synemin containing an additional 312 amino acid insert within the C-terminal tail domain. We report herein that, by using the entire tail domain of the smaller beta-synemin as the bait in a yeast two-hybrid screen of a human skeletal muscle cDNA library, the LIM domain protein zyxin was identified as an interaction partner for human synemin. The synemin binding site in human zyxin was subsequently mapped to the C-terminal three tandem LIM-domain repeats, whereas the binding site for zyxin within beta-synemin is within the C-terminal 332 amino acid region (SNbetaTII) at the end of the long tail domain. Transient expression of SNbetaTII within mammalian cells markedly reduced zyxin protein level, blocked localization of zyxin at focal adhesion sites and resulted in decreased cell adhesion and increased motility. Knockdown of synemin expression with siRNAs within mammalian cells resulted in significantly compromised cell adhesion and cell motility. Our results suggest that synemin participates in focal adhesion dynamics and is essential for cell adhesion and migration.
Muscle Biology Group, Department of Biochemistry, Biophysics and Molecular Biology and of Animal Science, Iowa State University, Ames, 3110 Molecular Biology Bldg, IA 50011-3260, USA.
Ning
N
Sun
Ted W
TW
Huiatt
Denise
D
Paulin
Zhenlin
Z
Li
Richard M
RM
Robson
D000818:Animals; D001665:Binding Sites; D002448:Cell Adhesion; D002465:Cell Movement; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D034622:RNA Interference; D020349:Surface Plasmon Resonance; D014162:Transfection; D020798:Two-Hybrid System Techniques; D060589:Zyxin
D003598:Cytoskeletal Proteins; D006023:Glycoproteins; D007381:Intermediate Filament Proteins; C092842:ZYX protein, human; D060589:Zyxin; C430456:desmuslin