inositol-1-4-5-trisphosphate and Teratoma

Morphogen-induced decline in Gialpha triggers F9 teratocarcinoma stem cells to progress to primitive endoderm via activation of protein kinase C and mitogen-activated protein kinase (Gao, P., and Malbon, C. C. (1996) J. Biol. Chem. 271, 9002-9008). Constitutive expression of Gialpha2 blocks, whereas expression of Gsalpha provokes, progression to primitive endoderm, permitting identification of the effectors of the response-utilizing chimera created between Gialpha2 and Gsalpha. N-terminal substitution of Gsalpha with Gialpha2 sequence to create chimera Gialpha2 (1-54)/Gsalpha produced a chimera that activated adenylylcyclase but abolished progression to primitive endoderm and activation of phospholipase C. C-terminal substitution of Gsalpha with Gialpha2 sequence to Gsalpha/Gialpha2 (320-355) enhanced the ability of Gsalpha to promote progression. The Q205L-activated mutant of Gialpha2 suppresses, whereas the G225T-activated mutant of Gsalpha strongly activates phospholipase C and progression in these cells. The N-terminal region of Gsalpha (residues 62-86) appears to act as a dominant switch for the Gsalpha- (activation) versus Gialpha2- (suppression) mediated control of phospholipase C and progression to primitive endoderm.

Topics: Adenylyl Cyclases; Animals; Cell Differentiation; Cells, Cultured; Cyclic AMP; Diglycerides; Endoderm; Enzyme Activation; GTP-Binding Protein alpha Subunits, Gi-Go; GTP-Binding Protein alpha Subunits, Gs; Inositol 1,4,5-Trisphosphate; Mice; Models, Molecular; Protein Kinase C; Recombinant Fusion Proteins; Signal Transduction; Structure-Activity Relationship; Teratoma; Tissue Plasminogen Activator; Type C Phospholipases