Pituitary adenylate cyclase-activating polypeptide 38-mediated Rin activation requires Src and contributes to the regulation of HSP27 signaling during neuronal differentiation.
Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) is a potent neuropeptide that acts through G-protein-coupled receptors. While it is well established that PACAP mediates both neurotrophic and neurodevelopmental effects, the signaling cascades that underlie these diverse actions remain incompletely characterized. Here we show that the Ras-related Rin GTP-binding protein, a GTPase that is expressed predominantly in neurons, is regulated by PACAP38 signaling, and loss-of-function analysis demonstrates that Rin makes an essential contribution to PACAP38-mediated pheochromocytoma cell differentiation. Rin is activated following stimulation of both Gsalpha and Gialpha cascades but does not rely upon cyclic AMP (cAMP)-, Ca(2+)-, or Epac-dependent signaling pathways. Instead, Rin is activated in a Src kinase-dependent manner. Surprisingly, Rin knockdown significantly inhibits PACAP38-mediated neurite outgrowth, without affecting mitogen-activated protein kinase signaling cascades. Instead, Rin loss attenuates PACAP38-mediated HSP27 activation by disrupting a cAMP-protein kinase A cascade. RNA interference-mediated HSP27 silencing suppresses both PACAP38- and Rin-mediated neurite outgrowth, while expression of a constitutively active Rin mutant increases both HSP27 protein and phospho-HSP27 levels, supporting a role for Rin-HSP27 signaling in neuronal differentiation. Together, these observations identify an unsuspected role for Rin in neuronal PACAP signaling and establish a novel Galpha-Src-Rin-HSP27 signal transduction pathway as a critical element in PACAP38-mediated neuronal differentiation signaling.
Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
Geng-Xian
GX
Shi
Ling
L
Jin
Douglas A
DA
Andres
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000201:enzymology; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; C490450:Rin1 protein, rat; D000242:Cyclic AMP; D016392:Proto-Oncogene Proteins pp60(c-src); D017868:Cyclic AMP-Dependent Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs; D020691:rab GTP-Binding Proteins