ABSTRACT
Reproductive function is coordinated by kisspeptin (Kiss) and GnRH neurons. Phoenixin-20 amide (PNX) is a recently described peptide found to increase GnRH-stimulated LH secretion in the pituitary. However, the effects of PNX in the hypothalamus, the putative signaling pathways, and PNX receptor have yet to be identified. The mHypoA-GnRH/GFP and mHypoA-Kiss/GFP-3 cell lines represent populations of GnRH and Kiss neurons, respectively. PNX increased GnRH and GnRH receptor (GnRH-R) mRNA expression, as well as GnRH secretion, in the mHypoA-GnRH/GFP cell model. In the mHypoA-Kiss/GFP-3 cell line, PNX increased Kiss1 mRNA expression. CCAAT/enhancer-binding protein (C/EBP)-ß, octamer transcription factor-1 (Oct-1), and cAMP response element binding protein (CREB) binding sites are localized to the 5' flanking regions of the GnRH, GnRH-R, and Kiss1 genes. PNX decreased C/EBP-ß mRNA expression in both cell models and increased Oct-1 mRNA expression in the mHypoA-GnRH/GFP neurons. PNX increased CREB phosphorylation in both cell models and phospho-ERK1/2 in the mHypoA-GnRH/GFP cell model, whereas inhibiting the cAMP/protein kinase A pathway prevented PNX induction of GnRH and Kiss1 mRNA expression. Importantly, we determined that the G protein-coupled receptor, GPR173, was strongly expressed in both GnRH and kisspeptin cell models and small interfering RNA knockdown of GPR173 prevented the PNX-mediated up-regulation of GnRH, GnRH-R, and Kiss1 mRNA expression and the down-regulation of C/EBP-ß mRNA expression. PNX also increased GPR173 mRNA expression in the mHypoA-GnRH/GFP cells. Taken together, these studies are the first to implicate that PNX acts through GPR173 to activate the cAMP/protein kinase A pathway through CREB, and potentially C/EBP-ß and/or Oct-1 to increase GnRH, GnRH-R, and Kiss1 gene expression, ultimately having a stimulatory effect on reproductive function.
Subject(s)
Amides/pharmacology , Gonadotropin-Releasing Hormone/metabolism , Kisspeptins/metabolism , Neurons/metabolism , Peptides/pharmacology , Receptors, G-Protein-Coupled/metabolism , Amides/chemistry , Animals , Cell Line , Cells, Cultured , Cyclic AMP Response Element-Binding Protein/metabolism , Hypothalamus/drug effects , Hypothalamus/metabolism , Kisspeptins/genetics , Mice , Neurons/drug effects , Peptides/chemistry , Phosphorylation/drug effects , Receptors, G-Protein-Coupled/genetics , Receptors, LHRH/metabolismABSTRACT
Kisspeptin (Kiss) and G-protein-coupled receptor (Gpr)54 have emerged as key regulators of reproduction. 17ß-estradiol (E2)-mediated regulation of these neurons is nuclei specific, where anteroventral periventricular (AVPV) Kiss neurons are positively regulated by E2, whereas arcuate nucleus (ARC) neurons are inhibited. We have generated immortalized Kiss cell lines from male and female adult-derived murine hypothalamic primary culture, as well as cell lines from microdissected AVPV and ARC from female Kiss-green fluorescent protein (GFP) mice. All exhibit endogenous Kiss-1 expression, estrogen receptors (ER)s (ERα, ERß, and Gpr30), as well as known markers of AVPV Kiss neurons in the mHypoA-50 and mHypoA-Kiss/GFP-4, vs markers of ARC Kiss neurons in the mHypoA-55 and the mHypoA-Kiss/GFP-3 lines. There was an increase in Kiss-1 mRNA expression at 24 hours in the AVPV lines and a repression of Kiss-1 mRNA at 4 hours in the ARC lines. An E2-mediated decrease in ERα mRNA expression at 24 hours in the AVPV cell lines was detected, and a significant decrease in Gpr30, ERα, and ERß mRNA levels at 4 hours in the ARC cell lines was evident. ER agonists and antagonists determined the specific ERs responsible for mediating changes in gene expression. In the AVPV, ERα is required but not ERß or GPR30, vs the ARC Kiss-expressing cell lines that require GPR30, and either ERα and/or ERß. We determined cAMP response element-binding protein 1 was necessary for the down-regulation of Kiss-1 mRNA expression using small interfering RNA knockdown in the ARC cell model. These studies elucidate some of the molecular events involved in the differential E2-mediated regulation of unique and specific Kiss neuronal models.
Subject(s)
Arcuate Nucleus of Hypothalamus/metabolism , Estradiol/pharmacology , Gene Expression Regulation/drug effects , Hypothalamus, Anterior/metabolism , Kisspeptins/genetics , Receptors, Estrogen/metabolism , Animals , Arcuate Nucleus of Hypothalamus/drug effects , Binding Sites , Cell Line , Cell Membrane/drug effects , Cell Membrane/metabolism , Cyclic AMP Response Element-Binding Protein/metabolism , Female , Gene Expression Profiling , Gene Knockdown Techniques , Green Fluorescent Proteins/metabolism , Hypothalamus, Anterior/drug effects , Kisspeptins/metabolism , Male , Mice, Inbred C57BL , Mice, Transgenic , Models, Biological , Neurons/drug effects , Neurons/metabolism , Peptides/metabolism , Promoter Regions, Genetic/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Estrogen/genetics , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Sex Characteristics , Transcription Factor AP-1/metabolismABSTRACT
Mycophenolate mofetil (MMF) has become a major therapeutic option in the management of patients undergoing transplantation, as well as in the treatment of autoimmune conditions. Case reports have suggested that MMF use during pregnancy is associated with a specific pattern of congenital malformations. Because many pregnancies are unplanned, it is imperative to assess the teratogenic risk of MMF. Using the Organization of Teratology Information Specialists network, we prospectively identified and followed pregnant women exposed to MMF during pregnancy to update this teratogenic potential. Ten cases were identified and all received the drug during embryogenesis at the recommended doses (500 to 1500 mg daily). There were four miscarriages and one elective abortion due to fear of teratogenesis. None of the five live births had malformations. It is possible that, similar to other human teratogens discovered first by case reports, the absolute risk from MMF may be smaller than originally calculated based on case reports. Because the major malformations phenotypic of MMF may be visualized in utero (e.g., microtia, cleft palate, congenital diaphragmatic hernia, and cardiac malformation), diagnostic imaging should be performed.
