Growth factor-like action of lysophosphatidic acid: mitogenic signalling mediated by G proteins.

摘要: Several classes of growth factors can be distinguished that act through different signal transduction pathways. One class is constituted by the peptide bind to receptors with ligand-dependent protein tyrosine kinase activity. Another mitogens activates a phosphoinositide-specific phospholipase C via receptor-linked G protein. An intriguing member this lysophosphatidic acid (LPA). LPA mitogenicity not dependent on other and blocked pertussis toxin. evokes at least three separate signalling cascades: (i) activation toxin-insensitive mediating phosphoinositide hydrolysis; (ii) release arachidonic in GTP-dependent manner, but independent prior (iii) toxin-sensitive Gi inhibition adenylate cyclase. The bradykinin mimics inducing responses (ii), fails activate stimulate DNA synthesis. Our results suggest mitogenic action occurs or related toxin substrate that, unexpectedly, hydrolysis pathway neither required nor sufficient, itself, for mitogenesis.