title: Pituitary adenylate cyclase activating polypeptide and PAC1 receptor signaling increase Homer 1a expression in central and peripheral neurons.
abstract: Pituitary adenylate cyclase activating polypeptides (PACAP) and PAC1 receptor signaling have diverse roles in central and peripheral nervous system development and function. In recent microarray analyses for PACAP and PAC1 receptor modulation of neuronal transcripts, the mRNA of Homer 1a (H1a), which encodes the noncrosslinking and immediate early gene product isoform of Homer, was identified to be strongly upregulated in superior cervical ganglion (SCG) sympathetic neurons. Given the prominent roles of Homer in synaptogenesis, synaptic protein complex assembly and receptor/channel signaling, we have examined the ability for PACAP to induce H1a expression in sympathetic, cortical and hippocampal neurons to evaluate more comprehensively the roles of PACAP in synaptic function. In both central and peripheral neuronal cultures, PACAP peptides increased transiently H1a transcript levels approximately 3.5- to 6-fold. From real-time quantitative PCR measurements, the temporal patterns of PACAP-mediated H1a mRNA induction among the different neuronal cultures appeared similar although the onset of sympathetic H1a transcript expression appeared protracted. The increase in H1a transcripts was accompanied by increases in H1a protein levels. Comparative studies with VIP and PACAP(6-38) antagonist demonstrated that the PACAP effects reflected PAC1 receptor activation and signaling. The PAC1 receptor isoforms expressed in central and peripheral neurons can engage diverse intracellular second messenger systems, and studies using selective signaling pathway inhibitors demonstrated that the cyclic AMP/PKA and MEK/ERK cascades are principal mediators of the PACAP-mediated H1a induction response. In modulating H1a transcript and protein expression, these studies may implicate broad roles for PACAP and PAC1 receptor signaling in synaptic development and plasticity.
authors.affiliation: Departments of Anatomy and Neurobiology, and Pharmacology, University of Vermont College of Medicine, 149 Beaumont Avenue, HSRF 428, Burlington, VT 05405, USA.
authors.forename: Beatrice M
authors.initials: BM
authors.lastname: Girard
authors.forename: Emily T
authors.initials: ET
authors.lastname: Keller
authors.forename: Kristin C
authors.initials: KC
authors.lastname: Schutz
authors.forename: Victor
authors.initials: V
authors.lastname: May
authors.forename: Karen M
authors.initials: KM
authors.lastname: Braas
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D000072233:Homer Scaffolding Proteins; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D010525:Peripheral Nerves / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D015398:Signal Transduction / Q000187:drug effects; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C495403:Adcyap1 protein, rat; C495505:Adcyap1r1 protein, rat; D002352:Carrier Proteins; D018076:DNA, Complementary; D000072233:Homer Scaffolding Proteins; D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I