Mechanism of Myostatin Action

肌肉生长抑制素的作用机制

• 批准号: 8040919
• 负责人: SHALENDER BHASIN
• 金额: $ 48.62万
• 依托单位: BOSTON MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-09 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8040919
• 关键词: Accounting; Adipocytes; Adult; Affect; Aging; Agriculture; Antibodies; Biological; Body Composition; Body Weight; Body Weight decreased; CCAAT-Enhancer-Binding Proteins; Cattle; Cell Cycle; Cell Differentiation Inhibition; Cell Differentiation process; Cell Line; Cell Nucleus; Cell Proliferation; Cells; Central obesity; Communication; Complementary DNA; Complex; Data; Differentiation Antigens; Dominant-Negative Mutation; Dose; Down-Regulation; EP300 gene; Fatty acid glycerol esters; Gene Targeting; Genes; Genetic Transcription; HIV; HIV Infections; Health; Human; In Vitro; Infection; Intramuscular; Investigation; Knockout Mice; Literature; Macaca; Marrow; Mediating; Mesenchymal; Mesenchymal Differentiation; Mesenchymal Stem Cells; Messenger RNA; Modeling; Molecular; Monkeys; Monoclonal Antibodies; Multipotent Stem Cells; Mus; Muscle; Mutation; Myoblasts; Myosin Heavy Chains; Nuclear Translocation; Obesity; Pathway interactions; Pharmacologic Substance; Phenotype; Phosphorylation; Physical Function; Placebos; Population; Primates; Principal Investigator; Protein Biosynthesis; Proteins; Randomized Controlled Trials; Recombinants; SIV; Signal Pathway; Signal Transduction; Skeletal Muscle; Stem cells; TCF7L2 gene; Testing; Therapeutic; Thinness; Time; Transforming Growth Factor beta; Vertebrates; beta catenin; experience; in vivo; in vivo Model; inhibitor/antagonist; insight; interest; lipid biosynthesis; mRNA Expression; multipotent cell; muscle form; myostatin; novel; oil red O; programs; protein expression; research study; sarcopenia; satellite cell; stem cell differentiation; wasting

DESCRIPTION (provided by applicant): Myostatin is an important regulator of body composition. Inhibition of myostatin expression in vertebrates increases muscle mass and decreases fat mass. These observations have formed the rationale for the applications of myostatin antagonists for HIV-associated weight loss and visceral obesity, and sarcopenia of aging. However, the mechanisms by which myostatin regulates muscle and fat mass are poorly understood. We will test the hypothesis that myostatin inhibits the differentiation of adult, multipotent mesenchymal progenitor cells into myogenic lineage and promotes their differentiation into adipogenic lineage. We hypothesize that myostatin regulates the differentiation of mesenchymal multipotent cells by activating SMAD pathway and cross-communicating the signal to Wnt pathway through 2 catenin and LEF/TCF-4. We will use both in vivo and in vitro approaches and employ two validated models of mesenchymal, stem cell differentiation, namely, mesenchymal multipotent C3H10T1/2 cells, and marrow-derived human mesenchymal stem cells (hMSCs). We will determine myostatin effects on myogenic and adipogenic differentiation of hMSCs, and assess whether these effects are blocked by anti-myostatin antibody. Specific Aim 2 will evaluate whether Smad2 and Smad3 act as substrates for myostatin-induced phosphorylation, form complexes with Smad4, which interacts with 2 catenin either directly or through p300. Specific Aim 3 will determine the effects of myostratin and anti-myostatin antibody on 2 catenin translocation into nucleus, a hallmark of Wnt activation. We will evaluate whether inhibition of 2 catenin by siRNA blocks myostatin effects on Wnt target genes. We will determine whether myostatin down regulates TCF4 transcription and whether inhibition of TCF4 by dominant negative cDNA blocks myostatin effects on hMSC differentiation. Specific Aim 4 will elucidate changes in intramuscular myostatin expression and signaling associated with SIV-infection and weight loss in a simian model of SIV-associated wasting. We will conduct a randomized controlled trial to determine the effects of a myostatin inhibitor on lean body mass and body weight in SIV-infected macaques experiencing weight loss. These studies will provide unique insights into the mechanisms of myostatin action and unveil novel targets for the discovery of function promoting anabolic therapies. The proposed investigations also will further our understanding of the mechanisms that regulate mesenchymal stem cell differentiation postnatally. PUBLIC HEALTH RELEVANCE: Myostatin is being explored as an attractive target for the discovery of function promoting anabolic therapies for conditions associated with loss of muscle mass and physical function, such as HIV-associated weight loss and wasting, and aging. This project aims to elucidate the mechanisms by which myostatin regulates skeletal muscle and fat mass. We will test the hypothesis that myostatin regulates mesenchymal stem cell differentiation through activation of the TGF-beta/SMAD pathway and cross-communication of the SMAD signal to the Wnt/beta-catenin/TCF-4 pathway and thereby modulating myogenic and adipogenic differentiation.

描述（由申请人提供）：Myostatin是身体成分的重要调节剂。抑制脊椎动物中肌生抑素的表达会增加肌肉质量并减少脂肪质量。这些观察结果已经形成了肌抑制蛋白拮抗剂在与HIV相关的体重减轻和内脏肥胖和衰老的肌肉减少症中的应用的基本原理。然而，肌生抑制素调节肌肉和脂肪质量的机制知之甚少。我们将检验以下假设：肌抑制素抑制成年，多能间充质祖细胞的分化为肌源性谱系，并促进其分化为脂肪生成谱系。我们假设Myostatin通过激活SMAD途径并通过2 Catenin和LEF/TCF-4的WNT途径进行跨沟通途径来调节间充质多能细胞的分化。我们将同时使用体内和体外方法，并采用两个经过验证的间充质细胞分化模型，即间质多能C3H10T1/2细胞，以及骨髓来源的人间质干细胞（HMSC）。我们将确定肌抑制素对HMSC的肌源性和成脂分化的影响，并评估这些作用是否被抗神经毒素抗体阻断。特定的目标2将评估SMAD2和SMAD3是肌抑制蛋白诱导的磷酸化的底物，与SMAD4形成复合物，该复合物直接与2个蛋白酶相互作用，或者直接通过P300相互作用。具体的目标3将确定肌间素和抗神经毒素抗体对2链链蛋白易位到Nucleus的影响，核是Wnt激活的标志。我们将评估siRNA对2个蛋白酶的抑制是否会阻止肌抑制素对Wnt靶基因的影响。我们将确定肌生抑制素向下调节TCF4转录以及通过显性阴性cDNA对TCF4的抑制是否会阻止肌生抑素对HMSC分化的影响。特定的目标4将阐明肌内肌抑制素表达和与SIV感染和体重减轻相关的信号传导的变化。我们将进行一项随机对照试验，以确定肌抑制剂抑制剂对体重减轻的SIV感染猕猴的瘦体重和体重的影响。这些研究将为迈诺斯替汀作用的机制提供独特的见解，并揭示出发现促进合成代谢疗法功能的新型目标。拟议的研究还将进一步了解我们对产后调节间充质干细胞分化的机制。公共卫生相关性：正在探索肌汀作为发现功能的有吸引力的目标，该目标促进了与肌肉质量和身体机能丧失相关的疾病（例如HIV相关的体重减轻和浪费和衰老）的疾病。该项目旨在阐明肌抑素调节骨骼肌和脂肪质量的机制。我们将检验以下假设：肌抑制素通过激活TGF-beta/smad途径调节间充质干细胞分化，并将SMAD信号的交叉沟通与Wnt/beta-catenin/tcf-4途径进行跨沟道，从而调节肌发核和脂肪生成性分化。