Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is characterized by formation of renal cysts that destroy the kidney. Mutations in PKD1 and PKD2, encoding polycystins-1 and -2, cause ADPKD. Polycystins are thought to function in primary cilia, but it is not well understood how these and other proteins are targeted to cilia. Here, we provide the first genetic and biochemical link between polycystins and the exocyst, a highly-conserved eight-protein membrane trafficking complex. We show that knockdown of exocyst component Sec10 yields cellular phenotypes associated with ADPKD, including loss of flow-generated calcium increases, hyperproliferation, and abnormal activation of MAPK. Sec10 knockdown in zebrafish phenocopies many aspects of polycystin-2 knockdown—including curly tail up, left-right patterning defects, glomerular expansion, and MAPK activation—suggesting that the exocyst is required for pkd2 function in vivo. We observe a synergistic genetic interaction between zebrafish sec10 and pkd2 for many of these cilia-related phenotypes. Importantly, we demonstrate a biochemical interaction between Sec10 and the ciliary proteins polycystin-2, IFT88, and IFT20 and co-localization of the exocyst and polycystin-2 at the primary cilium. Our work supports a model in which the exocyst is required for the ciliary localization of polycystin-2, thus allowing for polycystin-2 function in cellular processes.
Highlights
Autosomal dominant polycystic kidney disease (ADPKD) is the most common potentially lethal monogenetic disorder, affecting 12 million people worldwide [1]
Our work provides the first link between the exocyst, a conserved eight-protein complex involved in protein localization, and a disease gene, PKD2
Knockdown of the exocyst protein Sec10 results in a number of cellular- and cilia-related phenotypes that are seen upon pkd2 loss—both in kidney cells and zebrafish
Summary
ADPKD is the most common potentially lethal monogenetic disorder, affecting 12 million people worldwide [1]. While we know that mutations in PKD1 and PKD2 cause ADPKD [2,3], we are only beginning to understand how the proteins—polycystin-1 and polycystin-2— regulate the cellular phenotypes associated with cystogenesis. Interactions between polycystin-2, a calcium-permeable cation channel [4,5], and polycystin-1 may act to regulate calcium signaling in normal kidney cells [6]. Consistent with calcium regulation being relevant to cystogenesis, ADPKD cells show a lower basal intracellular calcium concentration [7]. Altered calcium regulation has been linked, through cyclic AMP (cAMP) signaling, to phenotypes observed during cystogenesis, such as increased cell proliferation and abnormal fluid secretion. Addition of cAMP agonists cause ADPKD cells, but not normal kidney cells, to stimulate proliferation via the MAPK pathway [6,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
