Synemin interacts with the LIM domain protein zyxin and is essential for cell adhesion and migration

• Published in: Experimental cell research Vol. 316; no. 3; pp. 491 - 505
• Main Authors: Sun, Ning, Huiatt, Ted W., Paulin, Denise, Li, Zhenlin, Robson, Richard M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2010; Elsevier BV
• Subjects: Amino acids; Animals; Binding Sites; Cell Adhesion; Cell adhesion & migration; Cell Movement; Cellular biology; Cytoskeletal Proteins - chemistry; Cytoskeletal Proteins - metabolism; Cytoskeleton; Focal adhesions; Gene Knockdown Techniques; Glycoproteins - chemistry; Glycoproteins - metabolism; HeLa Cells; Humans; Intermediate filament; Intermediate Filament Proteins - chemistry; Intermediate Filament Proteins - metabolism; Mice; NIH 3T3 Cells; Protein Binding; Protein Interaction Mapping; Protein Structure, Tertiary; Protein Transport; Proteins; RNA Interference; Surface Plasmon Resonance; Synemin; Transfection; Two-Hybrid System Techniques; Zyxin; AD; IF(s); Synemin; GST; FACS; Intermediate filament; mAb; pAb; BSA; Zyxin; SNT; SNαT; Cytoskeleton; SNβT; Focal adhesions; FA(s); DB
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2009.10.015

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 α-synemin and β-synemin, with the larger α-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 β-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 β-synemin is within the C-terminal 332 amino acid region (SNβTII) at the end of the long tail domain. Transient expression of SNβTII 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.