弥漫性浅表性光敏性汗孔角化症（DSAP）是一种遗传性表皮角化异常性疾病。MVK编码甲羟戊酸激酶，其突变可导致DSAP和甲羟戊酸激酶缺陷症（MKD），已有研究显示MKD相关MVK突变可导致神经元的凋亡，但DSAP相关MVK突变导致皮肤角化异常的机制还不清楚。我们的研究假说是DSAP相关MVK突变可能通过影响线粒体呼吸链的功能导致角质形成细胞凋亡进而引起角化异常。本项目拟针对前期在DSAP家系中鉴定的2个新的导致MVK蛋白失去正常功能的突变，利用过表达的Hela细胞模型和CRISPR/Cas9技术构建的角质形成细胞点突变模型来研究MVK突变是否导致细胞凋亡及其发生的途径，并在患者来源的皮肤组织及原代培养的角质形成细胞模型中验证，以期阐明DSAP相关MVK突变导致皮肤角化异常的分子机制，对于认识DSAP的致病机制以及其他一些角化异常性皮肤病的机制有着重要的作用。

Disseminated superficial actinic porokeratosis (DSAP) is an inherited epidermal keratinization disorder. MVK gene encodes mevalonate kinase, and MVK mutations have been found to be associated with mevalonate kinase deficiency (MKD). It’s verified that MKD associated MVK mutations can lead to apoptosis of neurons, but the molecular mechanism of epidermal keratinization disorder resulted by DSAP associated MVK mutations is still unknown. We hypothesise that the DSAP associated mutations may cause the apoptosis of keratinocytes and abnomal cornification by inhibiting mitochondrial respiratory chain. Our previous studies have found two loss-of-function mutations. In this project we plan to use two cell models, the overexpression Hela cell model and the keratinocyte cell model including the MVK mutation knocked in by CRISPR/Cas9 system, to study whether the MVK mutations lead to cell apoptosis and to clarify its specific pathway. Additionally, we will also construct the model of primary cultured keratinocyte for further validation. Thus clarifying the mechanism of MVK mutations leading to DSAP, disorders characterized by dysregulation of keratinization, will help to understand the pathogenesis of DSAP and other skin disorders.

光敏性汗孔角化症(DSAP)是一种罕见的常染色体显性疾病，MVK被认为是该病的一个重要致病基因。本项目前期在一个中国DSAP家系中鉴定了MVK的一个新错义突变A189V（c.566 C>T)），通过对该突变和另一个错义突变H312R（c.935A>G）的功能预测分析显示，这两个错义突变均造成了保守型的氨基酸改变，本项目通过构建的 Hela 细胞/293细胞稳定表达突变型（A189V、H312R）蛋白和野生型蛋白的细胞系，对突变蛋白进行功能研究发现突变影响了蛋白的稳定性及蛋白形成同源二聚体的能力，突变蛋白影响了线粒体的功能；进一步我们通过CRISPR/Cas9技术构建的293细胞点突变模型进行深入研究发现，MVK突变导致凋亡细胞的增加。该结果对DSAP相关MVK错义突变导致皮肤角化异常的分子机制提供了科学依据，对于认识DSAP同时对认识这一类以皮肤角化异常为特征的疾病有重要的意义。