Role of Follistatin during Androgen Regulation of Body Composition

卵泡抑素在雄激素调节身体成分中的作用

• 批准号: 7886057
• 负责人: RAJAN SINGH
• 金额: $ 18.48万
• 依托单位: CHARLES R. DREW UNIVERSITY OF MED & SCI
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7886057
• 关键词: Adult; Age; Androgen Receptor; Androgens; Aromatase; Biological Assay; Blocking Antibodies; Body Composition; Castration; Cell Fractionation; Cells; Clinical Trials; DEXA; Dose; Estradiol; Fatty acid glycerol esters; Follistatin; Genes; HIV; Human; Image Analysis; Immunofluorescence Immunologic; Immunoprecipitation; In Vitro; Infusion procedures; Luciferases; Malignant neoplasm of prostate; Measures; Mediating; Mesenchymal; Mesenchymal Stem Cells; Molecular; Multipotent Stem Cells; Mus; Muscle; Nuclear Translocation; Operative Surgical Procedures; Orchiectomy; Pathway interactions; Phosphorylation; Prostate-Specific Antigen; Proteins; Pump; Recombinants; Regulation; Reporter; Risk; Role; Sampling; Serum; Signal Pathway; Signal Transduction; Stem cells; Supplementation; TCF7L2 gene; Techniques; Testing; Testosterone; Transcriptional Activation; Transforming Growth Factor beta; Transforming Growth Factors; Up-Regulation; Weight; Western Blotting; beta catenin; dosage; immunocytochemistry; in vitro Model; in vivo; insight; lipid biosynthesis; men; multipotent cell; muscle form; myogenesis; myostatin; novel; older men; research study; response

DESCRIPTION (provided by applicant): Testosterone (T) supplementation increases muscle mass and decreases fat mass in a variety of clinical trials using healthy young men, hypogonadal men, and in older men with low serum T levels. However, the molecular mechanisms by which T regulates body composition are not well known. We identified that T increases muscle mass and decreases fat mass in mesenchymal multipotent cells via androgen receptor (AR)-mediated pathway and activates AR/beta-catenin/TCF-4 pathway in preadipocyte cells to inhibit adipogenesis that was associated with up-regulation of follistatin (Fst). We hypothesize that T activates AR/beta-catenin/TCF-4 pathway both in vitro and in vivo to activate Fst, which regulates body composition by inhibiting Mst/TGF-beta signaling. We will employ two validated in vitro models of adult, mesenchymal stem cells to test whether T and DHT activate Fst via activation of AR/beta-catenin/TCF-4 pathway to regulate cell differention, and inhibition of beta-catenin by SiRNA abolishes these effects. We will determine the interaction between AR, beta-catenin, and TCF-4 by immunoprecipitation and their nuclear translocation by immunofluorescence and cell fractionation. TCF-4 transcriptional activation in response to androgen will be measured by using TCF-4 luciferase reporter assay. We will determine whether these androgens inhibit TGF-beta/Mst signaling in vitro through up-regulation of Fst. We will test whether T and DHT inhibit Mst bioactivity, Smad2/3 phosphorylation and activate Smad7 in vitro and inhibition of Fst levels either by Fst SiRNA or use of anti-Fst antibody blocks the effects of these androgens on myogenic differentiation. We will investigate whether castration-induced effects on body composition in C57/BL6J mice are accompanied by parallel decrease in Fst levels and supplementation of T or recombinant follistatin in these castrated mice significantly block castration-induced effects on fat-free mass and overall body composition. These studies will provide novel insights into the mechanisms of androgen action and have direct relevance to the application of either Fst alone or in combination of low doses of T for the treatment of HIV and aging-associated muscle loss as high supraphysiological doses of T are associated with its pleotropic effects including increased risk of prostate cancer by elevating prostate-specific antigen.

描述（由申请人提供）：补充睾丸激素（T）使用健康的年轻男性，性腹部男性以及血清T水平较低的老年男性中的多种临床试验中增加肌肉质量并减少脂肪量。但是，尚不清楚调节体形组成的分子机制。我们确定T可通过雄激素受体（AR）介导的途径增加肌肉质量并减少间质多能细胞中的脂肪量，并激活前脂肪细胞中的AR/β-catenin/tcf-4途径，以抑制脂肪源性的脂肪剂，从而抑制与Follistatin（Follistatin（FST）上调相关的脂肪）。我们假设t在体外和体内激活AR/β-catenin/tcf-4途径以激活FST，从而通过抑制MST/TGF-BETA信号传导来调节身体组成。我们将采用两种经过验证的成人，间充质干细胞的体外模型，以测试T和DHT是否通过激活AR/β-catenin/tcf-4途径激活FST，以调节细胞差异，并通过siRNA抑制β-catenin抑制这些效果。我们将通过免疫沉淀和通过免疫荧光和细胞分馏的AR，β-catenin和TCF-4之间的相互作用来确定AR，β-catenin和TCF-4之间的相互作用。通过使用TCF-4荧光素酶报告基因测定，将测量对雄激素的TCF-4转录激活。我们将确定这些雄激素是否通过FST上调在体外抑制TGF-beta/MST信号传导。我们将测试T和DHT是否抑制MST生物活性，SMAD2/3磷酸化，并在体外激活SMAD7并通过FST siRNA或使用抗FST抗体来抑制FST水平，或者使用抗FST抗体阻止了这些雄激素对肌源分化的影响。我们将调查castration诱导的对C57/BL6J小鼠中身体成分的影响是否伴随着FST水平的平行降低，并补充了这些cast骨小鼠T或重组follistatin的补充，显着阻止了cast割诱导的脂肪无脂肪质量和整体身体成分。这些研究将提供有关雄激素作用机制的新颖见解，并与单独使用FST或低剂量T的应用直接相关，以治疗HIV和与衰老相关的肌肉损失，因为T的高超副本生物学剂量T与其精神效应相关，包括其在升高前列腺抗液中的风险，包括增强的Prostate癌症风险。