RESUMEN
In vitro studies have demonstrated an increase in GnRH gene expression associated with an elevated secretory response to kisspeptin administration, suggesting that kisspeptin mediates GnRH expression at both the secretory and pretranslational levels. However, the kisspeptin-mediated intracellular mechanisms associated with the dynamic chromatin modifications modulating GnRH gene expression are unclear. The studies in this manuscript describe specific histone modifications on the enhancer and promoter of the mouse GnRH (mGnRH) gene induced by kisspeptin in GnRH neuronal cell lines (GT1-7 cells). ChIP assays followed by quantitative real-time PCR (qPCR) demonstrate that 15 and 45 min of 10(-9) M kisspeptin significantly increased histone 3 acetylation (H3Ac) at the kisspeptin response element (KsRE) contained between -3446 and -2806 bp of the mGnRH enhancer (GnRHen) in GT1-7 cells, while no changes were observed in the downstream neuron-specific element (NSE). Moreover, kisspeptin specifically induced acetylation of H3AcK14 and K27 and trimethylation of H3 lysine 4 at the KsRE (markers of active chromatin) and no changes in dimethylation of H3K9 (a marker associated with gene repression). Occupancy of RNA Pol II (RNAPII) and a differential carboxyl-terminal domain (CTD) phosphorylation pattern was observed. An interaction between the NSE and the KsRE via a chromatin loop in the mGnRH gene by kisspeptin was detected by the chromosome conformation capture assay (3C). In conclusion, these results demonstrate that kisspeptin induces histone acetylation/methylation and consequently enhances the formation of a chromatin loop in the mGnRH gene which results in known increase in kisspeptin-dependent mGnRH expression.
Asunto(s)
Cromatina/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Hormona Liberadora de Gonadotropina/genética , Kisspeptinas/farmacología , Acetilación , Animales , Línea Celular , Cromatina/química , Elementos de Facilitación Genéticos/genética , Hormona Liberadora de Gonadotropina/metabolismo , Histonas/metabolismo , Lisina/metabolismo , Metilación , Ratones , Modelos Biológicos , Conformación de Ácido Nucleico , Fosforilación/efectos de los fármacos , Fosfoserina/metabolismo , ARN Polimerasa II/metabolismo , Elementos de Respuesta/genética , Transcripción GenéticaRESUMEN
The authors report the results of a study on ticks and hemoparasitoses among cattle, sheep and goats in the North-Guinean zone. During a period of 15 months, ticks were systematically removed from 40 cattle, 40 sheep and 40 goats in order to assess the population dynamics and to determine more accurately the preferential sites of settlement of the following different species collected from these animals: Amblyomma variegatum, Boophilus geigyi, Hyalomma truncatum, H. marginatum rufipes, Rhipicephalus sulcatus, Rh. senegalensis, Rh. lunulatus. Studies on hemoparasitoses were conducted simultaneously using blood smears and splenectomy. The following species were found in cattle: Anaplasma marginale, Ehrlichia bovis, Trypanosoma vivax, Theileria mutans, Theileria velifera. Infections detected in the small ruminants were Anaplasma ovis, Ehrlichia ovina, Trypanosoma congolense, Theileria ovis. The PCV values of apparently healthy animals as well as the seasonal variations in this haematological parameter were investigated.