Mechanism of Csk-mediated Down-regulation of Src Family Tyrosine Kinases in Epidermal Growth Factor Signaling

Csk-binding protein (Cbp) negatively regulates epidermal growth factor-induced cell transformation by controlling Src activation

“…These data suggest a close localization of EGFR, Src, Cbp, Csk and caveolin-1 in the microdomains. In NIH3T3 cells, EGF stimulation was able to increase the amount of Csk within microdomains (data not shown), which consistent with the published data by other group (Matsuoka et al, 2004;Zhang et al, 2004). To investigate the contribution of Cbp to recruitment of Csk to microdomains, we purified microdomains from EGF stimulated NIH3T3 cells ( Figure 5).…”

“…Although Src is not the central component of the Ras/ MEK/MAPKs pathway controlling cell proliferation, it can promote EGF-induced ERK1/2 activation through PLCg-1 or Raf-1 (Mason et al, 1999;Bivona et al, 2003). EGF-induced ERK1/2 activation was partially suppressed in cells treated with the Src family inhibitor, PP2 (Matsuoka et al, 2004). In SHP2 knockout cells, EGF-induced ERK1/2 activation was enhanced by expression of the Csk-binding deficient Cbp mutant (Zhang et al, 2004).…”

Potentiation of the ligand-binding activity of integrin α3β1 via association with tetraspanin CD151

“…Expression vectors for cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) were constructed as described (18). The CFP and YFP expression vectors were cleaved by NheI͞KpnI and HindIII͞KpnI, respectively, to insert the coding sequences for human integrin ␣3 chain and CD151, yielding the expression vectors for CFP-tagged integrin ␣3 and YFP-tagged CD151.…”

“…Cos7 cells were cotransfected with these expression vectors by using Lipofectamine 2000 (Invitrogen) and replated after 48 h on glass-bottom dishes coated with 50 g͞ml fibronectin in phenol red-free DMEM containing 5% FBS. Twelve hours after replating, the cells were imaged at 1-min intervals by using an Olympus IX71 microscope equipped with a cooled charge-coupled device camera (CoolSNAP HQ, Roper Scientific, Trenton, NJ) controlled by METAMORPH software (Universal Imaging, West Chester, PA) as described (18). The medium was replaced with medium containing control IgG (20 g͞ml) and then with medium containing one of the anti-CD151 mAbs (20 g͞ml each) at 5 and 15 min after the onset of recording, respectively.…”

Overexpression of Csk-binding protein contributes to renal cell carcinogenesis

“…SFKs phosphorylate multiple tyrosines of human Cbp including tyrosine 317, which recruits Csk, a negative regulator of SFKs, from the cytosol into lipid rafts where SFKs are localized, resulting in the inhibition of SFKs activation (Brdicka et al, 2000;Kawabuchi et al, 2000). This negative regulatory mechanism has been found in several systems, including T-cell activation, cell adhesion, spreading processes and growth factor signaling (Kawabuchi et al, 2000;Torgersen et al, 2001;Davidson et al, 2003;Shima et al, 2003;Matsuoka et al, 2004;Zhang et al, 2004). Besides recruiting Csk, Cbp also regulates SFKs activation by interacting directly with SFKs, such as Fyn and Lyn (Ingley et al, 2006;Davidson et al, 2007;Solheim et al, 2008).…”