Abstract
Scaffold proteins are multidomain proteins without enzymatic function that play a central role in coordinating signaling processes. The scaffold protein CNK1 interacts with pathway-specific signaling proteins and thereby regulates these respective pathways. Here, we revealed tyrosine phosphorylation as a critical regulation mechanism to control the function of CNK1. We identified Tyr 26 as a PDGF-induced and, additionally, Tyr 519 and Tyr 665 as SRC-induced tyrosine phosphorylation sites. Phosphomimetic mutants indicate that phosphorylation of Tyr 519 recruits CNK1 to the nucleus and additional phosphorylation of Tyr 26 enables CNK1 to promote SRE-dependent gene expression. Contrary, mutants preventing tyrosine phosphorylation promote matrix metalloproteinase MMP14 promoter activity. CNK1-driven cell proliferation partially depends on its tyrosine phosphorylation. Upon PDGF stimulation, CNK1 is recruited to the plasma membrane mediated by SRC. Knock down of CNK1 prevents PDGF-induced SRE-dependent gene expression, MMP14 promoter activity and cell proliferation. Thus, tyrosine phosphorylation is an important mechanism to control the subcellular localization of CNK1 and its distinct biological functions.
- 14/*biosynthesis/genetics,mutation,phosphorylation/physiology,platelet-derived
- and
- cell
- cells,hela
- cells,humans,intracellular
- enzymologic/*physiology,gene
- expression
- factor,promoter
- genetic/*physiology,protein
- growth
- kinases/genetics/*metabolism,to_read,tyrosine
- knockdown
- membrane/enzymology/genetics,cnk1,gene
- metalloproteinase
- peptides
- phosphorylation,tyrosine/genetics/metabolism
- protein,signal
- proteins/genetics/*metabolism,matrix
- regions
- regulation
- signaling
- techniques,hek293
- transduction,src,src-family
- transport/physiology,scaffold
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