Polycystin-2 Activity Is Controlled by Transcriptional Coactivator with PDZ Binding Motif and PALS1-associated Tight Junction Protein

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent monogenic cause of kidney failure, characterized by the development of renal cysts. ADPKD is caused by mutations of the polycystin-1 (PC1) or polycystin-2 (PC2) genes. PC2 encodes a Ca 2؉ -permeable cation channel, and its dysfunction has been implicated in cyst development. The transcriptional coactivator with PDZ binding motif (TAZ) is required for the integrity of renal cilia. Its absence results in the development of renal cysts in a knock-out mouse model. TAZ directly interacts with PC2, and it has been suggested that another yet unidentified PDZ domain protein may be involved in the TAZ/PC2 interaction. Here we describe a novel interaction of TAZ with the multi-PDZ-containing PALS1-associated tight junction protein (PATJ). TAZ interacts with both the N-terminal PDZ domains 1-3 and the C-terminal PDZ domains 8 -10 of PATJ, suggesting two distinct TAZ binding domains. We also show that the C terminus of PC2 strongly interacts with PDZ domains 8 -10 and to a weaker extent with PDZ domains 1-3 of PATJ. Finally, we demonstrate that both TAZ and PATJ impair PC2 channel activity when co-expressed with PC2 in oocytes of Xenopus laevis. These results implicate TAZ and PATJ as novel regulatory elements of the PC2 channel and might thus be involved in ADPKD pathology.

Integrating developmental signals: a Hippo in the (path)way

“…Given that many of these polarityassociated proteins possess PDZ-binding motifs, these interactions are likely to have an important role in Hippo pathway regulation. For example, the PDZbinding domain of TAZ/YAP also mediates interactions with PATJ (Duning et al, 2010). Additionally, this motif regulates binding to the tight junction protein ZO-2 Remue et al, 2010).…”

The Vac14-interaction Network Is Linked to Regulators of the Endolysosomal and Autophagic Pathway

“…Cell Culture and Transient Transfection-HEK293T and HeLa (SS6) cells and the Retro-X packing cell line GP2-293 (Clontech) were cultivated in standard medium (Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal calf serum or iron-supplemented calf serum (HEK293) and 1% antibiotics (Pen/Strep) as described elsewhere (35,36). Transient transfection of HeLa cells with various expression constructs for live cell imaging and immunofluorescence analyses were performed using Lipofectamine 2000 (Invitrogen) according to the manufacturer's instructions.…”

“…Transient transfection of HeLa cells with various expression constructs for live cell imaging and immunofluorescence analyses were performed using Lipofectamine 2000 (Invitrogen) according to the manufacturer's instructions. GP2-293 (for retrovirus production; Retro-X system) and HEK293 cells (for lentivirus production; pINDUCER system) were transiently transfected using the calcium-phosphate method (35,36).…”

The transcriptional coactivator TAZ regulates mesenchymal differentiation in malignant glioma

“…This kinase cascade causes cytoplasmic sequestration of phospho-TAZ by 14-3-3-e. Phosphorylation of TAZ by LATS on Ser 311 also primes subsequent phosphorylation by casein kinase I (CKId/e), which induces recruitment of SCF b-TRCP E3 ligase, leading to the ubiquitination and degradation of TAZ (Liu et al 2010). Recently discovered membrane sequestration of TAZ/YAP by PDZ domain-containing tight junction proteins adds another complex layer of control of these crucial transcription coactivators (Duning et al 2010;Remue et al 2010;Varelas et al 2010b;Chan et al 2011;Zhao et al 2011). Upon translocation to the nucleus, TAZ induces cell proliferation, migration, invasion, and EMT (Lei et al 2008;Zhang et al 2009).…”