线粒体翻译因子mtEF4调控毛囊干细胞增殖及分化的实验研究

Hair loss is a common disease in dermatology and marked by the abnormal differentiation of the hair follicle stem cell. Mitochondria regulate the differentiation of hair follicle stem cell and hair loss is closely related to mitochondria. We found in our pre-experiments that mtEF4 knockout mice have abnormalities in hair follicle. We hypothesized that mtEF4 supervises the mitochondrial translational process, knockout of mtEF4 result in the accumulation of the translational mistake and mitochondrial respiratory chain dysfunction, abnormal differentiation of hair follicle stem cell, and eventually cause hair follicle atrophy. To test this hypothesis, we plan to: construct the he epidermis specific mtEF4 knockout mice and observe the changes of hair follicle stem cell behavior; separation and analysis of the mitochondrial proteome in epidermal cell, assess the role of mtEF4 in regulating mitochondrial translation; immune-magnetic bead sorting and culture of hair follicle stem cell, construct mtEF4 lentivirus and adenovirus and infect hair follicle stem cells, detect the rate change in proliferation and differentiation; find out the related regulatory signal through bioinformatics analysis, verify the role of the signaling pathway by using small molecular compound and verify the role of mitochondrial translation in hair follicle stem cell homeostasis. This study will provide reference for clinical research of hair loss.

脱发是一种常见皮肤疾病，其特征是毛囊干细胞分化异常。线粒体参与毛囊干细胞分化调控，脱发的发生与线粒体密切相关。项目组预实验发现，线粒体翻译因子mtEF4基因敲除引起小鼠毛发脱落，我们提出假说：mtEF4监督毛囊干细胞线粒体蛋白质翻译，其功能缺失引起线粒体错误蛋白积累，呼吸链功能紊乱，导致毛囊干细胞异常分化、毛囊萎缩。为验证这一假说，我们计划：构建表皮特异性mtEF4基因敲除鼠并观察毛囊干细胞行为变化；分离毛囊干细胞线粒体并进行蛋白质组分析，评估mtEF4基因对线粒体蛋白翻译的作用；分离并培养毛囊干细胞，构建mtEF4干扰及过表达病毒并感染毛囊干细胞，检测干细胞增殖分化指标变化；经生物信息学分析寻找相关调节信号，验证该信号与毛囊干细胞分化调控的相关性。本研究可为脱发的临床研究提供参考。

脱发是近年来的热门话题，有发病率逐年增加、发病年龄逐年降低的趋势。毛囊萎缩是脱发发生的首要原因。对毛囊干细胞分化机理的全面揭示有助于提高脱发的治疗成功率。本研究发现，毛囊干细胞分化过程中，线粒体呼吸链复合物IV活性逐渐升高，而调控这种表达趋势的是线粒体翻译因子mtEF4。表皮特异性敲除mtEF4的小鼠具有静止期延长，毛发脱落的表型。进一步检测发现，mtEF4敲除破坏了呼吸链活性，引起毛囊干细胞分化紊乱，生长周期停滞于静止期，最终引起毛囊萎缩，毛干脱落。综上所述，线粒体翻译因子在毛囊干细胞分化过程中发挥重要作用。本研究可为脱发治疗提供靶点参考。此外，本研究还针对mtEF4在肿瘤中的功能进行探讨，发现mtEF4在肿瘤中表达上调，人为干扰mtEF4表达则可以抑制肿瘤细胞的生长，因此，mtEF4可作为肿瘤治疗的潜在靶点进行深入研究。