Semaphorin 4D signaling requires the recruitment of phospholipase C gamma into the plexin-B1 receptor complex.

The semaphorin 4D (Sema4D) receptor plexin-B1 constitutively interacts with particular Rho guanine nucleotide exchange factors (RhoGEFs) and thereby mediates Sema4D-induced RhoA activation, a process which involves the tyrosine phosphorylation of plexin-B1 by ErbB-2. It is, however, unknown how plexin-B1 phosphorylation regulates RhoGEF activity. We show here that activation of plexin-B1 ...
by Sema4D and its subsequent tyrosine phosphorylation creates docking sites for the SH2 domains of phospholipase Cgamma (PLCgamma). PLCgamma is thereby recruited into the plexin-B1 receptor complex and via its SH3 domain activates the Rho guanine nucleotide exchange factor PDZ-RhoGEF. PLCgamma-dependent RhoGEF activation is independent of its lipase activity. The recruitment of PLCgamma has no effect on the R-Ras GTPase-activating protein activity of plexin-B1 but is required for Sema4D-induced axonal growth cone collapse as well as for the promigratory effects of Sema4D on cancer cells. These data demonstrate a novel nonenzymatic function of PLCgamma as an important mechanism of plexin-mediated signaling which links tyrosine phosphorylation of plexin-B1 to the regulation of a RhoGEF protein and downstream cellular processes.
Mesh Terms:
Animals, Antigens, CD, Binding Sites, Cell Line, Cell Movement, Enzyme Activation, Growth Cones, Guanine Nucleotide Exchange Factors, Humans, Nerve Tissue Proteins, Phospholipase C gamma, Phosphotyrosine, Protein Binding, Receptors, Cell Surface, Semaphorins, Signal Transduction, ras Proteins, rhoA GTP-Binding Protein
Mol. Cell. Biol.
Date: Dec. 01, 2009
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