MOLECULAR PHYSIOLOGY OF RESPIRATORY MUSCLES

描述(改编自申请人的摘要)：尽管最近取得了进展， 呼吸肌发育、衰老和疾病残留的最新知识 不完整。例如，肌茎的分子和功能特性 细胞没有被研究出来，肌肉损伤和衰老的机制还不完全 了解到，细胞凋亡在肌肉细胞死亡中的作用仍不清楚。这个 拟议的实验旨在扩展以下关键领域的知识 肌肉分子生理学。根据目标1和目标2，调查人员将 确定细胞死亡途径的靶向改变是否可以抑制 疾病中发生的肌纤维死亡或肌肉表型 老化过程中发生的变化。营养不良中可见凋亡核。 肌肉，但细胞凋亡在营养不良肌纤维死亡中的重要性是 不清楚。在衰老过程中，肌肉纤维也会因为未知的机制而丢失。通过 分析过表达或缺乏Bax的营养不良或老化的肌纤维， 研究人员将确定抑制细胞凋亡是否会抑制营养不良 肌纤维死亡或与年龄相关的肌肉表型变化。结果可能是 可能导致疾病和衰老中肌纤维死亡的治疗 细胞死亡途径的改变。根据目标3和4，调查人员将 确定SCA-1+和Bcl-2+肌肉细胞的小亚群是否具有 肌肉干细胞的特性及Bcl2的调控作用 肌肉细胞中的细胞凋亡和细胞周期进展。Sca-1和Bcl2是 由有限的单核肌肉细胞表达，这些细胞是 在肌肉发生的早期阶段。研究人员将提纯SCA-2+细胞 (带有抗SCA-1免疫珠子)和已被修饰的Bcl-2+细胞 表达可选择的标记(用免疫珠子或流式细胞仪)，他们将确定 这些罕见的早期肌源性细胞的功能与 在更多的成肌细胞中，处于肌肉发生的后期阶段。这个 肌肉干细胞的鉴定和特性是 增加了对肌肉发生的理解。

DESCRIPTION (Adapted from the applicant's abstract): Despite recent advances, current knowledge of respiratory muscle development, aging and disease remains incomplete. For example, the molecular and functional properties of muscle stem cells are not worked out, mechanisms of muscle injury and aging are not fully understood, and the role of apoptosis in muscle cell death remains unclear. The proposed experiments are designed to extend knowledge in these key areas of muscle molecular physiology. Under Aims 1 and 2, the investigators will determine whether targeted alterations of cell death pathways can inhibit either the myofiber death that occurs in disease or the muscle phenotype changes that occur during aging. Apoptotic nuclei are found in dystrophic muscles, but the importance of apoptosis in dystrophic myofiber death is unclear. Muscle fibers are also lost by unknown mechanisms during aging. By analyzing dystrophic or aged myofibers that overexpress Bcl-2 or lack Bax, the investigators will determine if inhibition of apoptosis will inhibit dystrophic myofiber death or age-related changes in muscle phenotype. The results could potentially lead to therapies of myofiber death in disease and aging based on alteration of cell death pathways. Under Aims 3 and 4, the investigators will determine if the small subset of Sca-1+ and Bcl-2+ muscle cells have the properties of muscle stem cells and how Bcl-2 may function to regulate apoptosis and cell cycle progression in muscle cells. Sca-1 and Bcl-2 are expressed by a limited subset of mononuclear muscle cells, and these cells are at an early stage of myogenesis. The investigators will purify Sca-2+ cells (with anti-Sca-1 immunobeads) and Bcl-2+ cells that have been modified to express selectable markers (with immunobeads or FACS) and they will determine how the functions of these rare early myogenic cells differ from the functions of the more numerous myoblasts that are at a later stage of myogenesis. The identification and characterization of muscle stem cells is central to increasing the understanding of myogenesis.