Role of STAT3 signaling in muscle stem cell activation

STAT3信号传导在肌肉干细胞激活中的作用

• 批准号: 8631042
• 负责人: Alessandra Sacco
• 金额: $ 9.75万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-05 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8631042
• 关键词: Ablation; Acute; Adult; Animals; Binding; Biological Assay; Cell Nucleus; Cell Survival; Cell division; Cell physiology; Commit; Complement; DNA Binding; Development; Embryo; Enhancers; Equilibrium; Event; Exercise; Foundations; Gene Expression; Gene Targeting; Generations; Genetic; Genetic Transcription; Goals; Hematopoietic; Hypertrophy; Immunofluorescence Microscopy; In Vitro; Injection of therapeutic agent; Injury; Interleukin-6; Intestines; Janus kinase; Knowledge; LacZ Genes; Luciferases; Maintenance; Mediating; Microscopy; Molecular; Monitor; Mus; Muscle; Muscle satellite cell; MyoD Protein; Myogenic Regulatory Factors; Pathway interactions; Phosphorylation; Play; Proliferating; Proteins; Reporter; Research; Role; Running; STAT3 gene; Signal Transduction; Skeletal Muscle; Skeletal muscle injury; Source; Stem cell transplant; Stem cells; Stress; Tamoxifen; Testing; Therapeutic; Time; Tissues; Transcriptional Activation; Transcriptional Regulation; Up-Regulation; Wasting Syndrome; cytokine; hematopoietic tissue; in vivo; injury and repair; loss of function; muscle regeneration; mutant; notexin; novel; pluripotency; progenitor; public health relevance; repaired; satellite cell; self-renewal; therapeutic development; tissue regeneration; tool; transcription factor

DESCRIPTION (provided by applicant): Adult muscle stem cells (MuSC), also known as satellite cells, are the main source skeletal muscle regeneration. This is due to their ability to self-renew in vivo, i.e. to generate upon cell division more copies of themselves as well as give rise to committed progeny, as we have conclusively demonstrated by single MuSC transplantation. MuSC exist in healthy adult tissues in a quiescent state, and upon stress or injury they are activated to proliferate and generate large numbers of progenitors to repair the damaged tissue. Although the balance between quiescence and activation is a critical switch in MuSC function, the molecular mechanisms regulating this transition are still largely unknown. A more clear understanding of the regulatory networks underlying MuSC activation might provide novel targets that would aid in the development of therapeutic approaches to ameliorate muscle-wasting diseases. Our preliminary findings indicate for the first time that STAT3 plays a direct role in the transcriptional activation of the bHLH myogenic regulatory factor MyoD, a key event as MuSC exit the quiescent state. STAT3 is a transcription factor that plays a major role in self-renewal of several types of stem cells, including embryonic, intestinal and hematopoietic compartments. Upon cytokine stimulation, STAT3 is phosphorylated by JAK kinases, it homodimerizes, translocates to the nucleus and binds DNA to activate the transcription of target genes. Although it has been previously shown that STAT3 is activated upon skeletal muscle injury, its role in MuSC activation as well as its relevant downstream targets are still poorly understood. Accordingly, the focus of this proposal is to investigate the role of the JAK/STAT3 pathway in MuSC activation and its functional interaction with MyoD. Our research will take advantage of the following tools: (1) Loss of function studies in conjunction with time-lapse microscopy, to monitor MuSC activation, proliferation and survival in vitro, (2) Luciferase reporter assay using deletion mutants of the MyoD proximal enhancer, to validate the direct role of STAT3 in MyoD transcriptional activation, (3) Conditional genetic ablation of STAT3 in MuSC, in order to evaluate its role in MuSC function in vivo in the intact animal. Together, these studie would constitute a conceptual advancement in the field, as they would identify a direct functional interaction between JAK/STAT3 and MyoD, and further extend our knowledge of the regulatory network in MuSC activation. Finally, these findings would aid in the development of strategies aimed at promoting muscle stem cell-mediated tissue regeneration to ameliorate muscle-wasting diseases.

描述（申请人提供）：成体肌肉干细胞（MuSC），又称卫星细胞，是骨骼肌再生的主要来源。这是因为它们具有体内自我更新的能力，即在细胞分裂时产生更多的自身拷贝并产生定向后代，正如我们通过单次 MuSC 移植所最终证明的那样。 MuSC 以静止状态存在于健康成人组织中，在受到压力或损伤时，它们被激活增殖并产生大量祖细胞来修复受损组织。尽管静止和激活之间的平衡是 MuSC 功能的关键转换，但调节这种转变的分子机制仍然很大程度上未知。对 MuSC 激活背后的调控网络的更清晰了解可能会提供新的靶点，有助于开发改善肌肉萎缩疾病的治疗方法。我们的初步研究结果首次表明 STAT3 在 bHLH 生肌调节因子 MyoD 的转录激活中发挥直接作用，这是 MuSC 退出静止状态时的关键事件。 STAT3 是一种转录因子，在多种干细胞（包括胚胎干细胞、肠道干细胞和造血干细胞）的自我更新中发挥着重要作用。在细胞因子刺激下，STAT3 被 JAK 激酶磷酸化，同源二聚化，易位至细胞核并结合 DNA，激活靶基因的转录。尽管先前已表明 STAT3 在骨骼肌损伤时被激活，但其在 MuSC 激活中的作用及其相关下游靶标仍知之甚少。因此，本提案的重点是研究 JAK/STAT3 通路在 MuSC 激活中的作用及其与 MyoD 的功能相互作用。我们的研究将利用以下工具：（1）与延时显微镜相结合的功能丧失研究，以监测体外 MuSC 的激活、增殖和存活，（2）使用 MyoD 近端增强子的缺失突变体进行荧光素酶报告基因测定，以验证 STAT3 在 MyoD 转录激活中的直接作用，（3）MuSC 中 STAT3 的条件性基因消除，以评估其 在完整动物体内 MuSC 功能中的作用。总之，这些研究将构成该领域的概念性进步，因为它们将确定 JAK/STAT3 和 MyoD 之间的直接功能相互作用，并进一步扩展我们对 MuSC 激活调节网络的了解。最后，这些发现将有助于制定旨在促进肌肉干细胞介导的组织再生以改善肌肉萎缩疾病的策略。