College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China.
Animal Science, School of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Genomics. 2020 Mar;112(2):1575-1587. doi: 10.1016/j.ygeno.2019.09.007. Epub 2019 Sep 12.
Intramuscular fat is the an important factor that defines meat quality; however, enhancing its deposition without increasing the other three adipose depots (subcutaneous, visceral, and intermuscular fat) is a challenge for animal science and the meat industry. The TORC1 is a key regulator of adipogenesis and its regulation in bovine intramuscular preadipocytes has not been studied. The TORC1 is a member of the gene family that codes for a binding proteins which regulate transcription of cAMP which, is a key regulator of adipogenesis. In the present study, expression and sub-cellular localization of the TORC1 gene was analyzed in bovine preadipocytes. Bioinformatics tools were applied to characterize TORC1. To investigate the molecular mechanism of bovine TORC1 gene regulation, we cloned a 1008 bp of the 5'UTR regulatory region into a luciferase reporter vector. Different fragments were amplified using 5'UTR unidirectional deletion of the TORC1 promoter. Site directed mutation, dual luciferase reporter assay, RNAi interference and DNA-protein interaction (EMSA) were used to validate the regulatory roles of Smad3 and NRF1 in the regulation of TORC1 gene in bovine preadipocytes. The core promoter region of the TORC1 gene was identified at a location -410 to -155 bp upstream of transcription start site. Different vectors were constructed through serial deletion of the 5'UTR flanking region and in combination with site directed mutations and transcription interference through siRNA or shRNA, two transcription factors of NRF1 and Smad3 were found to be repressors in the promoter of the TORC1 gene. These findings were further confirmed through Electrophoretic Mobility Shift Assay (EMSA) within nuclear extracts of bovine adipocytes. The core promoter region of the TORC1 gene, spanning from -410 to -155 bp upstream of the transcription start site was specified in this study and this information will provide opportunity for the improvement of intramuscular fat in cattle.
肌内脂肪是定义肉质的一个重要因素;然而,在不增加其他三个脂肪库(皮下、内脏和肌间脂肪)的情况下增加其沉积是动物科学和肉类工业面临的一个挑战。TORC1 是脂肪生成的关键调节剂,但其在牛肌内前体脂肪细胞中的调节作用尚未得到研究。TORC1 是编码结合蛋白的基因家族的成员,这些结合蛋白调节 cAMP 的转录,cAMP 是脂肪生成的关键调节剂。在本研究中,分析了 TORC1 基因在牛前体脂肪细胞中的表达和亚细胞定位。应用生物信息学工具对 TORC1 进行了特征描述。为了研究牛 TORC1 基因调控的分子机制,我们将 TORC1 基因的 5'UTR 调控区克隆到荧光素酶报告载体中。使用 TORC1 启动子的 5'UTR 单向缺失扩增不同片段。通过点突变、双荧光素酶报告基因检测、RNAi 干扰和 DNA-蛋白质相互作用(EMSA)验证 Smad3 和 NRF1 在牛前体脂肪细胞中对 TORC1 基因的调控作用。确定了 TORC1 基因的核心启动子区域位于转录起始位点上游-410 到-155bp 处。通过连续缺失 5'UTR 侧翼区域构建不同载体,并结合点突变和 siRNA 或 shRNA 转录干扰,发现两个转录因子 NRF1 和 Smad3 是 TORC1 基因启动子的抑制剂。通过牛脂肪细胞核提取物中的电泳迁移率变动分析(EMSA)进一步证实了这一发现。本研究明确了 TORC1 基因的核心启动子区域,跨越转录起始位点上游的-410 到-155bp,这一信息将为提高牛的肌内脂肪提供机会。