Linked Life Data

8625900

Source:http://linkedlifedata.com/resource/pubmed/id/8625900

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1996-6-21
pubmed:abstractText
The hypothalamic peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), can efficiently increase cAMP levels in pituitary cells and release a number of pituitary hormones, suggesting an important physiological role for this peptide in pituitary function. Exposure of GH3 rat pituitary cells to PACAP results in increases in cellular cAMP levels, PRL promoter activity, and PRL messenger RNA levels. We have employed this system to further characterize PACAP regulation of PRL gene expression. RT-PCR analysis showed that GH3 cells express transcripts for two PACAP receptors, PACAP-R-hop1 and VIP2. As the former can couple PACAP to increases in both cAMP and inositol phosphates, we investigated whether either pathway mediates PACAP action on the PRL promoter. Our observations that TRH, but not PACAP, increases the intracellular Ca2+ concentration in GH3 cell cultures and that the optimal concentrations of TRH and PACAP have additive effects on transient expression of a PRL-CAT construct imply that the inositol trisphosphate-Ca2+ pathway is not significantly involved in PACAP action on the PRL promoter. Four kinase inhibitors exhibited similar profiles of inhibition of the activity on PRL-chloramphenicol acetyltransferase (PRL-CAT) of either the adenylyl cyclase activator forskolin (FSK) or PACAP, suggesting a transcriptional role for protein kinase A (PKA). The observations that coexpression of the dominant PKA inhibitor RAB completely blocked either FSK or PACAP action on PRL-CAT and that these actions of FSK and PACAP were completely nonadditive imply that the cAMP-PKA pathway plays a dominant role in PACAP regulation of PRL gene expression. Coexpression of low levels of KCREB, a cAMP response element (CRE)-binding protein (CREB) dominant inhibitor, partially blocked regulation of PRL-CAT activity by PACAP, but not TRH, implying that PACAP action is mediated at least in part by a CREB family member that can dimerize with CREB. The PRL promoter contains an asymmetric sequence at positions -99/-92 resembling a canonical CRE and termed here the CRE-like element (CLE). Mutation of either the left or right 4 bp of the CLE yielded a strong decrease in the response to either FSK or PACAP, but not to TRH. These data imply that PACAP and TRH employ independent pathways to regulate the PRL promoter, and that PACAP action is exerted virtually entirely via a cAMP/PKA-mediated pathway that is strongly dependent upon an intact CLE sequence and at least partially dependent upon the activity of a CREB-related protein.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
137
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1276-85
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:8625900-Animals, pubmed-meshheading:8625900-Base Sequence, pubmed-meshheading:8625900-Calcium, pubmed-meshheading:8625900-Cell Line, pubmed-meshheading:8625900-Cyclic AMP-Dependent Protein Kinases, pubmed-meshheading:8625900-Intracellular Membranes, pubmed-meshheading:8625900-Molecular Sequence Data, pubmed-meshheading:8625900-Neuropeptides, pubmed-meshheading:8625900-Osmolar Concentration, pubmed-meshheading:8625900-Pituitary Adenylate Cyclase-Activating Polypeptide, pubmed-meshheading:8625900-Pituitary Gland, pubmed-meshheading:8625900-Polymerase Chain Reaction, pubmed-meshheading:8625900-Prolactin, pubmed-meshheading:8625900-Promoter Regions, Genetic, pubmed-meshheading:8625900-Rats, pubmed-meshheading:8625900-Thyrotropin-Releasing Hormone, pubmed-meshheading:8625900-Transcription, Genetic
pubmed:year
1996
pubmed:articleTitle
Pituitary adenylate cyclase-activating polypeptide regulates prolactin promoter activity via a protein kinase A-mediated pathway that is independent of the transcriptional pathway employed by thyrotropin-releasing hormone.
pubmed:affiliation
Department of Physiology and Biophysics, Mount Sinai School of Medicine, City University of New York, 10029, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.