title: Kisspeptin induction of somatolactin-α release in goldfish pituitary cells: functional role of cAMP/PKA-, PLC/PKC-, and Ca(2+)/calmodulin-dependent cascades.
abstract: Although the importance of kisspeptin in the pituitary is firmly established, the signaling mechanisms for the pituitary actions of kisspeptin are still largely unknown. Somatolactin (SL), a member of the growth hormone (GH)/prolactin (PRL) family, is a pituitary hormone with pleiotropic functions in fish, but its regulation by kisspeptin has not been examined. To investigate the functional role of kisspeptin in SL regulation, expression of two paralogues of goldfish Kiss1 receptors (Kiss1ra and Kiss1rb) were confirmed in immunoidentified SLα but not SLβ cells isolated by RT-PCR coupled with laser capture microdissection. In goldfish pituitary cells prepared from neurointermediate lobe (NIL), synthetic goldfish Kiss decapeptides (gKiss1-10 and gKiss2-10) could increase SLα release. Consistent with the lack of Kiss1r expression in SLβ cells, SLβ release was not altered by kisspeptin stimulation. In parallel experiments, goldfish gKiss1-10 could elevate cyclic adenosine monophosphate (cAMP) production, upregulate protein kinase A (PKA) and protein kinase C (PKC) activities, and trigger a rapid rise in intracellular Ca(2+) levels in goldfish NIL cells. Using a pharmacological approach, cAMP/PKA and phospholipase C (PLC)/PKC pathways and subsequent activation of Ca(2+)/calmodulin (CaM)-dependent cascades were shown to be involved in SLα release induced by gKiss1-10. Apparently, the Ca(2+)-dependent cascades were triggered by extracellular Ca(2+) entry via voltage-sensitive Ca(2+) channels and mobilization of inositol trisphosphate-sensitive intracellular Ca(2+) stores. Our results demonstrate that gKiss1-10 can act directly at the pituitary level to trigger SLα release via a complex network of post-receptor signaling mechanisms.
authors.affiliation: Key Laboratory of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China; and.
authors.forename: Quan
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: School of Biological Sciences, University of Hong Kong, Hong Kong, China.
authors.forename: Mulan
authors.initials: M
authors.lastname: He
authors.affiliation: School of Biological Sciences, University of Hong Kong, Hong Kong, China.
authors.forename: Wendy K W
authors.initials: WK
authors.lastname: Ko
authors.affiliation: School of Biological Sciences, University of Hong Kong, Hong Kong, China olwong@hku.hk.
authors.forename: Anderson O L
authors.initials: AO
authors.lastname: Wong
mesh_terms: D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D029941:Fish Proteins / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006054:Goldfish; D059648:Kisspeptins / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D052716:Pituitary Gland, Intermediate / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D006023:Glycoproteins; D059648:Kisspeptins; D010907:Pituitary Hormones; C064448:somatolactin protein, fish; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010738:Type C Phospholipases
keywords: kisspeptin; phospholipase C; pituitary; protein kinase A; protein kinase C; release; signal transduction; somatolactin