Talin phosphorylation by Cdk5 regulates Smurf1-mediated talin head ubiquitylation and cell migration.
Cell migration is a dynamic process that requires temporal and spatial regulation of integrin activation and focal adhesion assembly/disassembly. Talin, an actin and beta-integrin tail-binding protein, is essential for integrin activation and focal adhesion formation. Calpain-mediated cleavage of talin has a key role in focal adhesion turnover; however, the talin head domain, one of the two cleavage products, stimulates integrin activation, localizes to focal adhesions and maintains cell edge protrusions, suggesting that other steps, downstream of talin proteolysis, are required for focal adhesion disassembly. Here we show that talin head binds Smurf1, an E3 ubiquitin ligase involved in cell polarity and migration, more tightly than full-length talin does and that this interaction leads to talin head ubiquitylation and degradation. We found that talin head is a substrate for Cdk5, a cyclin-dependent protein kinase that is essential for cell migration, synaptic transmission and cancer metastasis. Cdk5 phosphorylated talin head at Ser 425, inhibiting its binding to Smurf1, thus preventing talin head ubiquitylation and degradation. Expression of the mutant tal(S425A), which resists Cdk5 phosphorylation thereby increasing its susceptibility to Smurf1-mediated ubiqitylation, resulted in extensive focal adhesion turnover and inhibited cell migration. Thus, talin head produced by calpain-induced cleavage of talin is degraded through Smurf1-mediated ubiquitylation; moreover, phosphorylation by Cdk5 regulates the binding of Smurf1 to talin head, controlling talin head turnover, adhesion stability and ultimately, cell migration.
Huang
Cai
C
Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
Rajfur
Zenon
Z
Yousefi
Nima
N
Chen
Zaozao
Z
Jacobson
Ken
K
Ginsberg
Mark H
MH
D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D051379:Mice; D016716:PC12 Cells; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011485:Protein Binding / Q000502:physiology; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D011554:Pseudopodia / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D000077546:Roscovitine; D012694:Serine / Q000378:metabolism; D016608:Talin / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
D007976:Leupeptins; D061988:Proteasome Inhibitors; D011687:Purines; D011994:Recombinant Proteins; D016608:Talin; C496077:Tln1 protein, mouse; D000077546:Roscovitine; D012694:Serine; C498342:SMURF1 protein, human; C492381:Smurf1 protein, mouse; D044767:Ubiquitin-Protein Ligases; D051360:Cyclin-Dependent Kinase 5; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde