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KMID : 0578319960060030259
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Molecules and Cells
1996 Volume.6 No. 3 p.259 ~ p.265
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Overexpression of SH2-SH2-SH3 Domain of Phospholipase C-γ1 Blocks PDGF-induced Inositol Phophate Generation in NJH 3T3 Cells
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Chang, Jong-Soo
Min, Do Sik/Bac, Sun-Sik/Kim, Jae-Ho/Lee, Young Han/Ryu, Sung Ho/Suh, Pann-Ghill
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Abstract
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Src homology (SH) 2 and 3 domains are known to be binding motife for protein-protein interaction in signaling molecules. Among several PLC isozymes. Only PLC-γ contains the SH domain between the X and Y domains, which are known to have catalytic activity. To elucidate the functional roles of the SH2-SH2-SH3 domain of PLC-γ1 in cellular signaling, we constructed a truncated cDNA encoding the SH2-SH2-SH3 domain of PLC-γ1 (p60^(SH2/SH3)) and expressed it in NIH 3T3 cells. Cells expressing p60^(SH2/SH3) did not show any change in cell shape no oncogenesity. Even though in a serum depleted condition, a portion of p60^(SH2/SH3) existed as constitutively phosphorylated on its tyrosine residues. Furthermore, cells expressing p60^(SH2/SH3) did not respond to PDGF-induced IPs formation whereas vector- transfected control cells showed dose-dependent IPs generation upon PDGF stimulation. The tyrosine phosphorylation level of endogenous PLC-γ1 by PDGF, however, was comparable to that of the control cells. On the other hand, IPs accumulation by PLC-β activation occurred to a comparable level. Taken together, p60^(SH2/SH3) molecules selectively inhibited the IPs accumulation catalyzed by PLC-γ1. This result suggests that the SH2-SH2-SH3 domain is essential for PLC-γ1-mediated cellular signaling, including its own catalytic activity by protein-protein interaction.
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