title: Relaxin stimulates protein kinase C zeta translocation: requirement for cyclic adenosine 3',5'-monophosphate production.
abstract: Relaxin is a polypeptide hormone that activates the leucine-rich repeat containing G protein-coupled receptors, LGR7 and LGR8. In an earlier study, we reported that relaxin produces a biphasic time course and the second wave of cAMP is highly sensitive to phosphoinositide-3 kinase inhibitors (LY294002 and wortmannin). LY294002 inhibits relaxin-mediated increases in cAMP production by 40-50% across a large range of relaxin concentrations. Here we show that protein kinase C zeta (PKCzeta) is a component of relaxin signaling in THP-1 cells. Sphingomyelinase increases cAMP production due to the release of ceramide, a direct activator of PKCzeta. Chelerythrine chloride (a general PKC inhibitor) inhibits relaxin induced cAMP production to the same degree (approximately 40%) as LY294002. Relaxin stimulates PKCzeta translocation to the plasma membrane in THP-1, MCF-7, pregnant human myometrial 1-31, and mouse mesangial cells, as shown by immunocytochemistry. PKCzeta translocation is phosphoinositide-3 kinase dependent and independent of cAMP production. Antisense PKCzeta oligodeoxynucleotides (PKCzeta-ODNs) deplete both PKCzeta transcript and protein levels in THP-1 cells. PKCzeta-ODNs abolish relaxin-mediated PKCzeta translocation and inhibit relaxin stimulation of cAMP by 40%, as compared with mock and random ODN controls. Treatment with LY294002 in the presence of PKCzeta-ODNs results in little further inhibition. In summary, we present a novel role for PKCzeta in relaxin-mediated stimulation of cAMP.
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, Texas 77030, USA.
authors.forename: Bao T
authors.initials: BT
authors.lastname: Nguyen
authors.forename: Carmen W
authors.initials: CW
authors.lastname: Dessauer
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009000:Monocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D012065:Relaxin / Q000494:pharmacology / Q000502:physiology*; D000099221:Protein Kinase C zeta
chemical_list: D002867:Chromones; D000242:Cyclic AMP; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D012065:Relaxin; D000099221:Protein Kinase C zeta; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one