Department of Nephrology and Hypertension, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, 3901 Rainbow Blvd., Mail Stop 3018, KS 66160, USA.
Promega Corporation, 2800 Woods Hollow Road, Madison, WI 53711, USA.
Cells. 2023 Aug 29;12(17):2166. doi: 10.3390/cells12172166.
The gene, encoding protein polycystin-1 (PC1), is responsible for 85% of cases of autosomal dominant polycystic kidney disease (ADPKD). PC1 has been shown to be present in urinary exosome-like vesicles (PKD-ELVs) and lowered in individuals with germline mutations. A label-free mass spectrometry comparison of urinary PKD-ELVs from normal individuals and those with mutations showed that several proteins were reduced to a degree that matched the decrease observed in PC1 levels. Some of these proteins, such as polycystin-2 (PC2), may be present in a higher-order multi-protein assembly with PC1-the polycystin complex (PCC). CU062 (Q9NYP8) is decreased in ADPKD PKD-ELVs and, thus, is a candidate PCC component. CU062 is a small glycoprotein with a signal peptide but no transmembrane domain and can oligomerize with itself and interact with PC1. We investigated the localization of CU062 together with PC1 and PC2 using immunofluorescence (IF). In nonconfluent cells, all three proteins were localized in close proximity to focal adhesions (FAs), retraction fibers (RFs), and RF-associated extracellular vesicles (migrasomes). In confluent cells, primary cilia had PC1/PC2/CU062 + extracellular vesicles adherent to their plasma membrane. In cells exposed to mitochondrion-decoupling agents, we detected the development of novel PC1/CU062 + ring-like structures that entrained swollen mitochondria. In contact-inhibited cells under mitochondrial stress, PC1, PC2, and CU062 were observed on large, apically budding extracellular vesicles, where the proteins formed a reticular network on the membrane. CU062 interacts with PC1 and may have a role in the identification of senescent mitochondria and their extrusion in extracellular vesicles.
该基因编码蛋白多囊蛋白-1（PC1），负责 85%常染色体显性多囊肾病（ADPKD）病例。已经表明 PC1 存在于尿外体样小泡（PKD-ELVs）中，并在种系突变个体中降低。正常个体和突变个体的尿 PKD-ELVs 的无标记质谱比较显示，几种蛋白质的减少程度与 PC1 水平的下降相匹配。这些蛋白质中的一些，如多囊蛋白-2（PC2），可能存在于与 PC1 组成的多囊蛋白复合物（PCC）的高级多蛋白组装中。CU062（Q9NYP8）在 ADPKD PKD-ELVs 中减少，因此是 PCC 的候选成分。CU062 是一种带有信号肽但没有跨膜结构域的小糖蛋白，可以自身寡聚化并与 PC1 相互作用。我们使用免疫荧光（IF）研究了 CU062 与 PC1 和 PC2 的共定位。在非汇合细胞中，所有三种蛋白质都定位于靠近粘着斑（FA）、回缩纤维（RF）和 RF 相关的细胞外小泡（迁移小体）。在汇合细胞中，初级纤毛有 PC1/PC2/CU062+细胞外小泡附着在其质膜上。在用线粒体解偶联剂处理的细胞中，我们检测到新的 PC1/CU062+环状结构的形成，这些结构将肿胀的线粒体卷入其中。在受到线粒体应激的接触抑制细胞中，观察到 PC1、PC2 和 CU062 存在于大的、顶芽状的细胞外小泡上，这些蛋白质在膜上形成网状网络。CU062 与 PC1 相互作用，可能在识别衰老线粒体及其在细胞外小泡中的挤出中起作用。
