Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
Mol Biol Cell. 2022 Sep 1;33(10):ar86. doi: 10.1091/mbc.E22-05-0165. Epub 2022 Jul 13.
The -Golgi network must coordinate sorting and secretion of proteins and lipids to intracellular organelles and the plasma membrane. During polarization of epithelial cells, changes in the lipidome and the expression and distribution of proteins contribute to the formation of apical and basolateral plasma membrane domains. Previous studies using HeLa cells show that the syndecan-1 transmembrane domain confers sorting within sphingomyelin-rich vesicles in a sphingomyelin secretion pathway. In polarized Madin-Darby canine kidney cells, we reveal differences in the sorting of syndecan-1, whereupon the correct trafficking of the protein is not dependent on its transmembrane domain and changes in sphingomyelin content of cells during polarization. Instead, we reveal that correct basolateral targeting of syndecan-1 requires a full-length PDZ motif in syndecan-1 and the PDZ domain golgin protein GOPC. Moreover, we reveal changes in Golgi morphology elicited by GOPC overexpression. These results suggest that the role of GOPC in sorting syndecan-1 is indirect and likely due to GOPC effects on Golgi organization.
高尔基网络必须协调蛋白质和脂质的分拣和分泌，以将其分配到细胞内细胞器和质膜中。在上皮细胞极化过程中，脂质组和蛋白质的表达和分布的变化有助于形成顶端和基底外侧质膜区域。先前使用 HeLa 细胞的研究表明，连接蛋白-1 的跨膜结构域赋予富含神经鞘磷脂的囊泡中的分拣，这是在神经鞘磷脂分泌途径中。在极化的 Madin-Darby 犬肾细胞中，我们揭示了连接蛋白-1的分拣差异，在此过程中，蛋白质的正确运输不依赖于其跨膜结构域，并且在极化过程中细胞内神经鞘磷脂含量发生变化。相反，我们揭示了连接蛋白-1的正确基底外侧靶向需要连接蛋白-1中的全长 PDZ 基序和 PDZ 结构域高尔基体蛋白 GOPC。此外，我们揭示了 GOPC 过表达引起的高尔基形态变化。这些结果表明，GOPC 在分拣连接蛋白-1中的作用是间接的，可能是由于 GOPC 对高尔基组织的影响。
