Muscarinic receptors transform NIH 3T3 cells through a Ras-dependent signalling pathway inhibited by the Ras-GTPase-activating protein SH3 domain.

摘要: Expression of certain subtypes human muscarinic receptors in NIH 3T3 cells provides an agonist-dependent model cellular transformation by formation foci response to carbachol. Although focus correlates with the ability activate phospholipase C, actual mitogenic signal transduction pathway is unknown. Through cotransfection experiments and measurement activation state native epitope-tagged Ras proteins, contributions GTPase-activating protein (Ras-GAP) receptor-dependent were defined. Transforming able Ras, such was required for because inhibited coexpression either a dominant-negative mutation or constructs Ras-GAP that include catalytic domain. Coexpression N-terminal region GAP its isolated SH3 (Src homology 3) domain, but not SH2 also sufficient suppress formation. Point mutations at conserved residues domain reversed action, leading increase carbachol-dependent transformation. The inhibitory effect expression occurs proximal selective activated carbachol, as v-Ras trkA/nerve growth factor unaffected.