ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: We used a catecholaminergic neuron-like cell line (CATH.a cells) as a model system to investigate the likelihood that pituitary adenylate cyclase-activating polypeptide (PACAP) may participate in the regulation of specific gene expression in catecholaminergic neurons. Analysis by reverse transcriptase-PCR amplification revealed the presence in these cells of type I PACAP receptors, with a short isoform, together with a heavier so-called Hop splice variant. PACAP38 and PACAP27 enhanced, in a dose-dependent manner, both cyclic AMP formation and phosphoinositide breakdown, with EC50 values of, respectively, 0.6 × 10−10 and 2 × 10−9M. These peptides, in addition, also elevated [Ca2+]i by mobilizing intracellular calcium pools. Vasoactive intestinal peptide (VIP) was ∼1,000-fold less potent in stimulating cyclic AMP (with EC50 = 2 × 10−7M) and failed to change the turnover of phosphoinositides and to alter [Ca2+]i. Both forms of PACAP, as well as forskolin, stimulated transcriptional induction of tyrosine hydroxylase (TH) and c-fos promoters fused to a chloramphenicol acetyltransferase (CAT) reporter gene in transiently transfected cells (p 〈 0.01 vs. controls). Induction of CAT activity linked to both TH and c-fos promoters was obliterated upon coexpression of a dominant inhibitory mutant (Mt-RAB) of cyclic AMP-dependent protein kinase. We conclude that CATH.a cells do express functional PACAP type I receptors, the activation of which impinges on TH and c-fos transcription according to a process that is primarily dependent on the cyclic AMP-PKA pathway.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.1997.68041696.x
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