Androgen regulation of skeletal muscle regeneration

描述(由申请人提供)： 骨骼肌的一个基本的重要特性是损伤后的再生能力。不完全或延长的再生可导致骨骼肌功能下降和最终肌肉质量丧失，这与许多疾病状态下死亡和发病率增加的风险有关。最初，骨骼肌损伤后的再生涉及炎症、细胞外基质重塑和肌纤维生长的协调调节。炎症介质时间表达的改变已被证明延缓或减弱肌肉再生，并可能与纤维化和肌纤维生长的过程有关。无节制的纤维化也会抑制肌纤维再生。雄激素可以调节几个与伤口修复相关的过程，包括免疫反应和纤维化。免疫、成纤维细胞和卫星细胞的活性可以因雄激素状态而改变。目前还不确定循环中的雄激素水平是否以及如何调节骨骼肌再生。这项建议的总体目的是确定布比卡因注射诱导的小鼠骨骼肌再生是否对循环雄激素水平敏感，以及这种敏感性是否与卫星活动改变有关。工作假说是，增加循环中的雄激素将通过抑制炎症反应、与纤维化相关的细胞外基质重塑和卫星细胞分化等几个过程来诱导卫星细胞和肌源性前体细胞的可获得性，从而帮助肌肉再生。此外，研究人员假设雄激素受体将在调节这些再生过程中发挥核心作用。具体目标1将确定不同的雄激素可获得性如何影响布比卡因注射诱导的小鼠骨骼肌再生。对小鼠雄激素水平的实验操作将通过使用完整的、去势的或去势的加雄激素(2剂量)的处理组来执行。与卫星细胞活动相关的生化和形态标记物，肌肉的炎症反应，以及与纤维化相关的细胞外基质重塑，将被检测雄激素敏感性。具体目标2将研究雄激素受体在布比卡因注射后骨骼肌再生过程中的重要性。与AIM 2相关的初步实验将通过控制循环雄激素水平来检测再生过程中雄激素受体的表达、DNA结合活性以及蛋白质-蛋白质相互作用。雄激素受体信号在肌肉再生中的重要性将通过给予雄激素受体拮抗剂和雄激素受体过度表达来检验。生化和形态测量将与目标1相似。

DESCRIPTION (provided by applicant): A fundamentally important property of skeletal muscle is its ability to regenerate after damage-inducing injury. Incomplete or extended regeneration can lead to decreased skeletal muscle function and eventual muscle mass loss, which is related to an increased risk of mortality and morbidity in many disease states. Initially, skeletal muscle regeneration from injury involves the coordinated regulation of inflammation, extracellular matrix remodeling, and myofiber growth. Alterations in the temporal expression of inflammatory mediators have been shown to delay or attenuate muscle regeneration, and may be related to the processes of fibrosis and myofiber growth. Unregulated fibrosis can also inhibit myofiber regeneration. Androgens can modulate several processes related to wound repair, including the immune response and fibrosis. Immune, fibroblast, and satellite cell activity can be altered by androgen status. It is not certain if and how circulating androgen levels modulate skeletal muscle regeneration. This proposal's overall purpose is to determine if bupivacaine injection-induced mouse skeletal muscle regeneration is sensitive to circulating androgen levels, and if this sensitivity is related to altered satellite activity. The working hypothesis is that increased circulating androgens will aid in muscle regeneration by inducing satellite cell and myogenic precursor cell availability through the attenuation of several processes including: the inflammatory response, extracellular matrix remodeling related to fibrosis, and satellite cell differentiation. Additionally, the investigator hypothesizes that the androgen receptor will play a central role in regulating these regenerative processes. Specific aim 1 will determine how differential androgen availability affects mouse skeletal muscle regeneration induced by bupivacaine injection. Experimental manipulation of androgen levels in the mouse will be performed by using either intact, castrated, or castrated plus androgen (2 dosages) treatment groups. Biochemical and morphological markers related to satellite cell activity, the muscle's inflammatory response, and extracellular matrix remodeling related to fibrosis will be examined for androgen sensitivity. Specific aim 2 will examine the importance of the androgen receptor during skeletal muscle regeneration from bupivacaine injection. Initial experiments related to aim 2 will examine androgen receptor expression, DNA-binding activity, and protein-protein interactions during regeneration with manipulation of circulating androgen levels. The importance of androgen receptor signaling on components muscle regeneration will be examined by the administration of an androgen receptor antagonist and androgen receptor overexpression. The biochemical and morphological measurements will be similar as in aim 1.