Premium
Neuritogenesis initiated via the GPCR PAC1 requires cAMP and ERK signaling organized in a single linear pathway independent of PKA or Epac
Author(s) -
Eiden Lee E.,
Emery Andrew C.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.lb563
Subject(s) - forskolin , mapk/erk pathway , creb , phosphorylation , microbiology and biotechnology , chemistry , protein kinase a , g protein coupled receptor , signal transduction , rap1 , receptor , biology , biochemistry , transcription factor , gene
Both cAMP and ERK are necessary for neuroendocrine cell neuritogenesis initiated through the PAC1 receptor, a family B GPCR activated by the neuropeptide PACAP (Ravni et al., Mol Pharmacology, 73:1688–16708). However, it is not yet known whether cAMP and ERK are arranged in two parallel pathways employing known signaling mechanisms, or a novel, linear pathway. We have measured cAMP elevation, ERK phosphorylation, CREB phosphorylation, neuritogenesis and cAMP/PKA‐dependent promoter‐reporter gene activation after treatment with forskolin, cAMP analogs, and PACAP in Neuroscreen‐1 (NS‐1) cells, a PC12 variant enabling simultaneous morphological, molecular biological, and biochemical analysis. Forskolin (25 μM) and cAMP analogs (8‐Br‐cAMP, db‐cAMP, 8‐ CPT‐cAMP) stimulated ERK phosphorylation and neuritogenesis in NS‐1 cells. Both ERK phosphorylation and neuritogenesis were MEK‐dependent (blocked by 10 μM U0126) and PKA‐independent (insensitive to 30 μM H‐89 or 100 nM PKI). CREB phosphorylation induced by PACAP was blocked by H‐89. The Epac‐selective 8‐pCPT‐2′‐O‐Me‐cAMP (100–500 μM) activated Rap1 without affecting the other cAMP‐dependent processes. Thus, PACAP‐38 potently stimulated two distinct and independent cAMP pathways leading to CREB or ERK activation in NS‐1 cells. We have thus identified a PKA‐ and Epac‐independent signaling pathway leading from cAMP elevation to ERK activation and thence neuritogenesis, that involves a novel cAMP sensor whose effects are insulated from those mediated by cAMP through PKA and Epac. Supported by NIMH‐IRP project ZO1‐MH002386.