卵泡刺激素调控鸡腹脂和肌内脂肪沉积的分子机制研究

Intramuscular fat (IMF) is known as "popular fat" because it is one of the determinants of meat qualitywhereas extra abdominal fat is "unpopular" as it denotes excessive cost in meat production. To achieve the goal of breeding chicken with high IMF and low abdonimal fat is a challenging way and more studies on the meachnism of IMF and abdominal fat are required. Follicle stimulating hormone (FSH) belongs to the hormone which has remarkable biological activities and is well known to be an effector in reproductive tissues. The proposer including his group have found and reported a completely novel physiological action of FSH in a previously un-described target tissue for the hormone, abdominal and intramuscluar adipose tissues of chicken. The molecular mechanisms, however, are not clear. Thus, the study here aims to clarify the molecular pathways and key factors which mediate the FSH regulation on fat deposition. Preadipocytes and young chickens treated with FSH will be used. The main research emphases: ①activity changes of key mediators involved in the upstream（cAMP-PKA-CREB）of the signal pathways will be tested with techniques including phosphorylation western blot; ② the downstream genes those are directly controled by transcription factor CREB will be identified using chromatin immunoprecipitation and sequencing (ChIP-Seq) technique; ③identification of downstream genes/proteins which are changing corespondingly to the treatment of FSH in young chichen. Taken together, the upstream mediator of CREB complex and downstream signal pathways for FSH regulation will be clarified in this study. The similarities and differences of mechanism in FSH regulation on abdominal fat and IMF deposition will be deciphered and quality chicken meat will be supplied on the basis of molecular genetics.

腹脂和肌内脂肪沉积是肉鸡育种中涉及生产效率与鸡肉品质相互矛盾的重要科学难题，研究二者沉积机制将为肉鸡新品系培育奠定理论基础。卵泡刺激素（FSH）作为具有高效生物活性的激素，除有繁殖调控机能外，申请人课题组发现了其对肉鸡的腹脂和肌内脂肪沉积均具有较强的促进作用，但其分子作用机制还不明了。本研究将在前期工作基础上，以FSH刺激前脂肪细胞和雏鸡相应组织为试验材料，首先利用磷酸化Western杂交等技术检测细胞内信号传导上游（cAMP-PKA-CREB）关键因子活性变化；再利用免疫共沉淀（ChIP）-测序技术获得转录因子CREB在基因组上直接作用的靶基因；结合对FSH刺激后响应基因/蛋白及相关信号通路的鉴定，明确FSH调控脂肪沉积的核心通路，并对其中关键因子进行功能验证。最终阐明FSH调控腹脂和肌内脂肪沉积的主要机制，并通过比较分析揭示FSH调控腹脂和肌内脂肪沉积的分子机制的异同。

本研究在前期工作基础上，研究了卵泡刺激素(FSH)对肉鸡腹脂和肌内脂肪沉积的分子作用机制及其异同。首先本项目成员发明了鸡肌内前脂肪细胞的获得新方法，并制备去势鸡。利用去势鸡、腹脂前脂肪细胞和肌内前脂肪细胞，在成体和细胞水平上分析、鉴定了介导FSH调控腹脂和肌内脂肪沉积过程中的主要信号通路和关键调控因子，阐明了卵泡刺激素FSH调控肉鸡腹脂和肌内脂肪沉积的作用机理。结果显示，cAMP-PKA-CREB-PPARγ信号通路是FSH调控肉鸡腹脂和肌内脂肪沉积的共同的主要信号通路。FSH通过活化该通路，并上调下游脂肪代谢相关的功能基因的表达，最终导致脂肪沉积的增加。CREB和PPARγ是该过程中的关键调控因子。更进一步地，ChIP-PCR结果发现CREB通过靶向调控PPARγ基因的表达，进而调控脂肪细胞内脂肪的沉积。通过制备去势小鼠，并在成体和细胞水平进行了验证，进一步地揭示了GnRH-FSH性腺轴激素对动物腹脂和肌内脂肪沉积的调控具有物种的广泛性和统一性。腹脂和肌内脂肪沉积的分子机制均为肉鸡遗传育种研究的重要科学问题，结合对二者的比较研究，将为选育肉鸡新品系奠定基础。