The possible involvement of protein kinase C(s) and inositol phosphate metabolism in the basal but not in the prolactin stimulated casein release by the lactating rabbit mammary epithelial cell.
The secretagogue effect of prolactin (PRL) on casein release by epithelial mammary cells has been previously related to stimulation of the phospholipase A2-arachidonic acid cascade. In order to determine whether other intracellular pathways are implicated in this secretagogue effect, different agents acting on protein kinase C (PKC) and phospholipase C (PLC) activity have been assessed in vitro in lactating rabbit mammary gland fragments. Phorbol ester (20 nm TPA and 1-oleoyl-2-acetyl-sn-glycerol (10 microM (OAG) stimulated newly synthesized casein secretion and potentiated the PRL secretatogue effect. However, 100 microM quercetin, 100 microM H-7 and 5 and 20 nM staurosporine did not inhibit the latter effect. Exogenous PLC did not stimulate casein secretion. PRL did not affect production of inositol phosphates (IPs) during 10 or 60 min exposure. These results show that PKC activation may increase basal levels of casein secretion, and demonstrate that PRL does not act primarily via PKC activation or by PLC activation to stimulate casein secretion.
Ollivier-Bousquet
M
M
INRA, Laboratoire de Biologie Cellulaire et Moléculaire, Jouy-en-Josas, France.
Aubourg
A
A
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002364:Caseins / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004848:Epithelium / Q000378:metabolism; D005260:Female; D007295:Inositol Phosphates / Q000378:metabolism*; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011794:Quercetin / Q000494:pharmacology; D011817:Rabbits; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D002364:Caseins; D004075:Diglycerides; D007295:Inositol Phosphates; C038237:1-oleoyl-2-acetylglycerol; D011388:Prolactin; D011794:Quercetin; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate