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Srcasm modulates EGF and Src-kinase signaling in keratinocytes.

Author	Weijie Li, Christine Marshall, Lijuan Mei, Leonard Dzubow, Chrysalene Schmults, Michael Dans, John Seykora
Citation Information	The Journal of biological chemistry, 280:6036-46 (2005)
Keywords	Adaptor Proteins, Signal Transducing, Cell Differentiation, Cell Proliferation, Cells, Cultured, DNA, DNA Replication, DNA-Binding Proteins, Enzyme Activation, Epidermal Growth Factor, Gene Expression Regulation, Humans, Intermediate Filament Proteins, Keratinocytes, Ligands, Mitogen-Activated Protein Kinase 1, Models, Biological, Phosphorylation, Phosphotyrosine, Proto-Oncogene Proteins, Receptor, Epidermal Growth Factor, Response Elements, Signal Transduction, Transcription Factors, Transcription, Genetic, ets-Domain Protein Elk-1, src-Family Kinases
Applications	Immunoprecipitation
Related Products	17-131
Pub Med ID	15579470

The Src-activating and signaling molecule (Srcasm) is a recently described activator and substrate of Src-family tyrosine kinases (SFKs). When phosphorylated at specific tyrosines, Srcasm associates with Grb2 and p85, the regulatory subunit of phosphoinositide 3-kinase; however, little is known about the role of Srcasm in cellular signaling. Data presented here demonstrate that epidermal growth factor (EGF) receptor ligands promote the tyrosine phosphorylation of endogenous and adenovirally transduced Srcasm in keratinocytes, and that increased levels of Srcasm activate endogenous SFKs, with a preference for Fyn and Src. In addition, Srcasm potentiates EGF-dependent signals transmitted by SFKs in keratinocytes. Tyrosine phosphorylation of Srcasm is dependent on growth factors and the activity of EGFR and SFKs. Increased Srcasm expression enhances p44/42 mitogen-activated protein kinase activity and Elk-1-dependent transcriptional events. Elevated Srcasm levels inhibit keratinocyte proliferation while promoting specific aspects of keratinocyte differentiation. Lastly, Srcasm levels are decreased in human cutaneous neoplasia. Collectively, these data demonstrate that Srcasm plays a role in linking EGF receptor- and SFK-dependent signaling to differentiation in keratinocytes.