组蛋白去甲基化酶LSD1调控甲状腺相关眼病眼眶脂肪细胞分化作用及机制研究

甲状腺相关眼病(TAO)是可致盲的眼眶疾病，眼眶脂肪组织异常增生压迫眼球外突是TAO重要病因，但因机制不清，目前尚无FDA批准的药物抑制脂肪增生。申请人前期建立人源眼眶脂肪前体细胞系，通过siRNA文库筛选发现组蛋白去甲基化酶LSD1下调抑制眼眶脂肪前体细胞分化；体外眼眶脂肪细胞分化过程中LSD1表达量升高；过表达LSD1促进脂肪细胞分化。人群相关性也显示，TAO患者眼眶脂肪组织中LSD1蛋白表达升高，组蛋白修饰H3K9me2水平下降。由此推测，LSD1通过去组蛋白H3K9me2调控眼眶脂肪细胞分化靶基因的表达，从而促进TAO眼眶脂肪细胞分化和脂质堆积。本项目拟从人群、动物和细胞水平，探讨LSD1对TAO眼眶脂肪细胞分化的调控作用，通过ChIP-seq发现和阐明LSD1去组蛋白H3K9me2修饰影响细胞分化的靶基因及分子机制，为表观遗传角度揭示TAO的致病机理和靶点开发提供新思路。

Thyroid-Associated Ophthalmopathy (TAO) is periocular disease which can lead to blindness, adipose tissue hyperplasia is a pathological feature of TAO, however, the mechanism is unclear, and there is no available drugs approved by FDA to remove expanded orbital fats. Through siRNA mediated knocking down epigenetic enzymes in human orbital preadipocytes, applicant found that knockdown of histone lysine specific demethylase1(LSD1) can inhibit adipogenesis of orbital preadipocytes, its expression is increased under adipocyte differentiation of primary orbital preadipocytes in vitro, and moreover, overexpression of LSD1 can promote the process of adipogenesis. Clinical study also revealed that LSD1 is highly expressed in TAO orbital adipose tissues, and the level of H3K9me2 is decreased. All together, we hypothesize that LSD1 regulates target gene expression through modulating H3K9me2 level, resulting in alteration of gene expression and consequently promoting of adipogenesis in TAO orbital fats. To test this, we will define the roles of LSD1 in TAO orbital adipocyte differentiation at the level of molecules, cells, tissues and animals; illuminate the target genes of LSD1 and the related molecular mechanism through high throughput sequencing; verify the inhibition of LSD1 blocks the orbital fat expression in TAO mice. The project aims to providing new theories in TAO and potential drug targets for TAO therapy.