BBS8蛋白参与衣藻鞭毛膜蛋白的运输

Bardet-Biedl syndrome protein-8 is involved in flagellar membrane protein transport in Chlamydomonas reinhardtii

摘要:

真核细胞的纤毛 (也称鞭毛) 是一种突出于细胞表面的极性细胞器，纤毛不仅参与细胞运动，还参与信号传导等过程，其结构或功能异常引发的一系列人类疾病称为“纤毛相关性疾病”。纤毛相关性疾病巴德-毕德氏综合征(Bardet-Biedl syndrome，简称BBS) 由BBS相关基因缺陷导致，为了研究致病基因BBS8的生理作用和功能，构建模式生物莱茵衣藻BBS8基因缺陷突变体，利用性状观测和生化分析检测突变体的表现型和生理功能。免疫荧光表明BBS8蛋白是一种鞭毛蛋白且在基体有特异性定位；bbs8突变体感光极性运动消失，并在解聚诱导实验中鞭毛解聚缓慢；鞭毛的银染和质谱结果表明突变体的鞭毛膜蛋白在鞭毛内异常积累。文中通过实验证据说明BBS8蛋白在参与鞭毛内膜蛋白运输中起到重要作用，并极可能通过介导膜蛋白反向运输发挥生理功能。

Abstract:

Cilia and flagella on eukaryotic cells are polarized organelles extending from the surfaces of cells, which participate not only in cell motility, but also in signal transduction and other processes. Structural or functional abnormalities of cilia can cause various human diseases, termed ciliopathies. Bardet-Biedl syndrome (BBS) is a ciliopathic human genetic disorder, and the pathogenesis is that mutated BBS genes result in abnormal cilia function. In order to study the pathogenic genes BBS8, we screened bbs8 mutant in Chlamydomonas reinhardtii and did a lot of physiology and biochemistry experiments. We affirmed that BBS8 protein was a cilia protein and had specific localization in the basal body by immunofluorescence (IF). The bbs8 mutant lost photokinesis, and it was defective in flagella shortening with drug induction. The results of silver staining and mass spectrometric analysis showed aberrant accumulation of flagellar proteins in the mutant flagella. We concluded that the BBS8 protein plays a significant role in flagellar membrane proteins transport, and the BBS8 protein might mediate retrograde transport to exert physiological function in the process.