血管内皮抑制素抑制饮食性肥胖的机理研究

发布时间：2018-06-10 09:37

  本文选题：血管内皮抑制素 + 饮食性肥胖　； 参考：《清华大学》2015年博士论文

【摘要】：血管内皮抑制素是一个被广为熟知的内源性血管新生抑制因子。尽管现在普遍认为脂肪组织中的血管新生是治疗肥胖的一个潜在靶点,但是血管内皮抑制素是否调控脂肪细胞分化和饮食性肥胖并不清楚。在本论文工作中,我们发现血管内皮抑制素能够抑制饮食性肥胖及其相关的代谢失调综合征,包括胰岛素抵抗、葡萄糖耐受和肝脂肪化。我们进一步的实验结果显示,血管内皮抑制素能够抑制高脂饮食肥胖小鼠脂肪组织中的血管密度。同时,它能够抑制高脂饮食小鼠脂肪组织中促血管生成因子(包括VEGF、FGF-2和PlGF)的表达。另外,体外Traswell吊篮迁移实验、划线愈合迁移实验、管腔形成实验和体内基质胶栓塞实验均证实血管内皮抑制素能够抑制脂肪细胞分泌物引起的内皮细胞血管新生活性。以上实验说明,血管内皮抑制素能够通过其抑制血管新生的功能抑制肥胖。本论文发现血管内皮抑制素能够抑制高脂饮食小鼠脂肪组织中脂肪细胞分化中心调控转录因子(PPARγ、C/EBPα和β)的表达。更加有趣的是,它能够直接体外抑制脂肪细胞分化。我们进一步发现,血管内皮抑制素的功能性受体—核仁素能够在处于分化状态的脂肪前体细胞的膜表面高表达,这使得它能够被脂肪前体细胞内吞。应用免疫共沉淀和免疫荧光实验,我们发现血管内皮抑制素能够与Sam68相互作用,并在脂肪前体细胞核中共定位。而且,血管内皮抑制素能够结合Sam68的NK结构域。文献报道,该结构域具有调控Sam68与RNA结合的特异性的重要功能。我们进一步揭示了血管内皮抑制素与Sam68的相互作用能够竞争性地抑制Sam68与mTOR前体RNA结合,从而导致mTOR的异常转录,野生型mTOR的表达水平降低。接下来的免疫印迹检测发现,血管内皮抑制素能够体内体外抑制mTOR/S6K信号通路的活性降低。综合以上结果,血管内皮抑制素是通过与Sam68相互作用抑制了mTOR的表达,进而抑制mTOR/S6K信号通路的活性,最终起到抑制脂肪细胞分化的作用。总之,血管内皮抑制素通过抑制脂肪细胞分化和血管新生两大生理过程,抑制了饮食性肥胖及其相关代谢失调综合征。其抑制脂肪细胞分化和抑制肥胖的新功能使我们对于血管内皮抑制素的生物学功能有了新的认识,也使得血管内皮抑制素具有了治疗和预防肥胖及其相关代谢失调综合征的潜在临床应用价值。
[Abstract]:Endotheliostatin is a well-known endogenous angiogenic inhibitor. Although angiogenesis in adipose tissue is now widely regarded as a potential target for the treatment of obesity, it is not clear whether vascular endothelin regulates adipocyte differentiation and dietary obesity. In this work, we found that vascular endothelin inhibits dietary obesity and its associated metabolic disorders, including insulin resistance, glucose tolerance, and liver fat. Our further results suggest that endothelin inhibits vascular density in adipose tissue of obese mice on a high fat diet. At the same time, it inhibited the expression of angiogenic factors (including VEGF FGF-2 and PlGF- 2) in adipose tissue of high fat diet mice. In addition, in vitro Traswell basket migration test, line healing migration test, lumen formation test and in vivo matrix glue embolization test all proved that vascular endothelin inhibits endothelial cell angiogenesis induced by adipocyte secretion. These results suggest that endothelin can inhibit obesity by inhibiting angiogenesis. In this study, we found that vascular endothelial inhibin could inhibit the expression of PPAR 纬 -C / EBP 伪 and 尾 in adipose tissue of high-fat diet mice. More interestingly, it can inhibit adipocyte differentiation directly in vitro. We further found that the functional receptor of vascular endothelin, nucleolipin, was highly expressed on the membrane of adipose progenitor cells in the differentiation state, which enabled it to be ingested by fat precursor cells. By means of immunoprecipitation and immunofluorescence assay, we found that vascular endothelin can interact with Sam68 and co-locate in the nucleus of fat precursor. Furthermore, endothelin can bind to the NK domain of Sam68. It is reported that this domain has the important function of regulating the specificity of Sam68 binding to RNA. We further revealed that the interaction between vascular endothelin and Sam68 could competitively inhibit the binding of Sam68 to mTOR precursor RNA, resulting in abnormal transcription of mTOR and decreased expression of wild-type mTOR. Subsequently, Western blotting showed that endothelin could inhibit the activity of mTOR-S6K signaling pathway in vivo and in vitro. Combined with the above results, endothelin inhibits the expression of mTOR by interacting with Sam68, which inhibits the activity of mTOR / S6K signaling pathway, and finally inhibits adipocyte differentiation. In conclusion, endothelin inhibits dietetic obesity and related metabolic disorders by inhibiting adipocyte differentiation and angiogenesis. Its new function of inhibiting adipocyte differentiation and obesity has given us a new understanding of the biological function of vascular endothelin. Vascular endothelin has potential clinical value in treating and preventing obesity and related metabolic disorders syndrome.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R589.2
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本文编号：2002763