Pact在胚胎期小鼠外耳软骨膜CSPCs凋亡中的作用机制

外耳软骨膜中的种子细胞（CSPCs）具有间充质干细胞特性。CSPCs数目持续减少导致软骨生长渐缓，当胚胎期外耳CSPCs凋亡减弱时，软骨可持续生长表现为巨耳。Pact基因参与了早期胚胎发育及细胞凋亡，且Pact-/-小鼠外耳软骨发育迟缓表现为小耳畸形，前期工作已明确Pact为小耳畸形患者易感基因，但其机制尚不清楚。我们认为Pact通过凋亡作用调控胚胎期小鼠外耳软骨膜CSPCs数目，其数目异常降低导致小耳畸形的发生。为了验证该假说，进行以下研究：①比较野生型（Pact+/+）和Pact-/-小鼠胚胎不同发育时期外耳软骨膜CSPCs数目；②比较野生型和Pact-/-小鼠胚胎不同发育时期外耳软骨膜凋亡相关因子的表达；③在野生型小鼠胚胎期使用细胞凋亡诱导剂，Pact-/-小鼠使用细胞凋亡抑制剂，观察外耳发育情况。通过以上研究，期望阐明Pact在胚胎期小鼠外耳软骨膜CSPCs凋亡中的作用机制。

Seed cells (CSPCs) in the outer ear cartilage have mesenchymal stem cell properties. Sustained reduction in the number of CSPCs leads to slowing of cartilage growth. When the apoptosis of CSPCs in the outer ear of the embryo declines, the sustainable growth of the cartilage appears as a giant ear. Pact gene is involved in early embryonic development and apoptosis, and Pact - / - mice exhibit small ear deformities in their outer ear cartilage. Pact has been identified as susceptible genes in patients with microtia, but its mechanism is unclear. We think that Pact regulates the number of CSPCs in the outer ear perichondrium through apoptosis, which leads to the occurrence of small ear deformity. To verify the hypothesis, the following studies were carried out: (1) To compare the numbers of CSPCs in the external auricular peritoneum at different developmental stages of wild-type (Pact + / +) and Pact - / - mouse embryos; (2)The outer ear cartilage membrane apoptosis-related factor expression; (3) Using apoptosis inducing agent in wild-type mouse embryos, Pact - / - mice using apoptosis inhibitor to observe the development of the outer ear. Through the above studies, we hope to elucidate the mechanism of action of Pact in apoptosis of CSPCs in the outer ear perichondrium in embryonic mice.