肌肉再生过程中YAP/TAZ-NPAT信号轴调控细胞衰老的作用及机理研究

近期研究发现暂时性细胞衰老对组织发育及再生至关重要，但具体调控机理尚不清楚。NPAT蛋白是稳定核内组蛋白基体结构的关键分子。申请人前期研究发现NPAT受到促进肌肉再生的Cpn10/HSP10分子调控，提示NPAT参与肌肉再生。我们因此构建了肌肉特异性NPAT敲基因小鼠，发现该小鼠肌肉的再生能力受损，且肌肉再生过程中衰老水平上升。我们进而发现细胞衰老会导致NPAT出核并抑制组蛋白基因转录。酵母双杂交筛选发现TAZ和NPAT具有相互作用，且抑制YAP/TAZ活性也会导致NPAT出核。我们计划在以上预实验研究的基础上，解析YAP/TAZ与NPAT之间互作的关键氨基酸位点，阐明YAP/TAZ调控NPAT在细胞内定位的机理；在体内验证肌肉再生过程中，YAP/TAZ通过NPAT调控暂时性细胞衰老的生理作用。本项目将有助于阐明细胞衰老在肌肉再生中的作用及机理，为开发治疗肌肉相关疾病的新方法提供理论基础。

Recent studies revealed that the transient cellular senescence is essential for development and tissue/organ regeneration. However, the underlying molecular mechanism remains elusive. NPAT protein locates in cell nuclear and plays critical roles in maintaining histone locus body, a nuclear structure for histone transcription. Our previous report found that NPAT interacts with a pro-myogenic protein Cpn10/Hsp10, indicating the involvement of NPAT in myogenesis. We thus created a muscle-specific NPAT knockout mouse line and found that the muscle regeneration ability was impaired. Moreover, we observed higher cellular senescence levels in regenerating muscles of NPAT knockout mice. We further found that cellular senescence results in the nuclear export of NPAT and suppression of histone transcription. By yeast-two-hybridization screening, we identified that TAZ is a novel interacting partner of NPAT. Inhibition of YAP/TAZ led to nuclear export of NPAT and impairment of histone transcription. We aim to identify the essential amino acid residues mediating YAP/TAZ-NPAT interaction, elucidate the mechanism by which YAP/TAZ regulates the nuclear export of NPAT, and verify the physiological functions of YAP/TAZ-NPAT axis in muscle regeneration. Our study will provide a novel therapeutic target for muscle-related diseases.