Phospholipase C activation in rat pituitary adenoma (GH) cells.
The presence of the pertussis toxin (PTX) insensitive GTP-binding proteins (C-proteins) G(q) alpha and/or G(11) alpha has been demonstrated in three different prolactin (PRL) and growth hormone (GH) producing pituitary adenoma cell lines. Immunoblocking of their coupling to hormone receptors indicates that G(q) and/or G(11) confer throliberin (TRH) responsive phospholipase C (PL-C) activity in these cells. The contention was substantiated by immunoprecipitation analyses showing that anti G(q)/11 alpha-sera coprecipitated PL-C activity. In essence, only G(q)/11 (but neither G(12) G(13) nor G(o)) seems to mediate the TRH-sensitive PL-C activity, while G(o) may be coupled to a basal or constitutive PL-C activity. Immunoblocking studies imply that the B gamma-complex also, to some extent, may stimulate GH(3) pituitary cell line PL-C activity. Finally, the steady state levels of G(q)/(11) alpha mRNA and protein were down regulated upon long term exposure of the GH(3) cells to TRH (but not to vasoactive intestinal peptide = VIP).
Gordeladze
J O
JO
Institute of Medical Biochemistry, University of Oslo, Norway.
Haugen
T
T
Paulssen
E J
EJ
Paulssen
R H
RH
D000236:Adenoma / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D037342:Pertussis Toxin; D010902:Pituitary Gland / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D012333:RNA, Messenger; D010566:Virulence Factors, Bordetella; D014660:Vasoactive Intestinal Peptide; D013973:Thyrotropin-Releasing Hormone; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins