Impact of Altered WNT2B Expression on Bladder Wall Fibroblasts: Implications for Apoptosis Regulation in the Stroma of the Lower Urinary Tract
UROLOGIA INTERNATIONALIS
Authors: Worst, Thomas Stefan; Daskalova, Kristina; Steidler, Annette; Berner-Leischner, Karin; Roeth, Ralph; Niesler, Beate; Kriegmair, Maximilian C.; Erben, Philipp; Pfalzgraf, Daniel
Abstract
Background: Little is known about the role of WNT signalling in pathological processes involving the urinary tract stroma. Here the impact of WNT signalling on bladder wall fibroblasts (BWFs) was studied using integrated expression profiling. Material and Methods: WNT ligand and downstream WNT pathway component expression was profiled in human BWFs using qRT-PCR. Highly expressed WNT2B was knocked down using siRNA in BWFs. The expression of 730 mRNAs and 800 miRNAs was analyzed on the nCounter MAX platform in # WNT2B and control transfected BWFs. qRT-PCR was used for validation in vitro and in matched scar and healthy bladder wall tissue samples of 12 patients with vesico- urethral anastomotic stricture (VUAS). Results: Thirteen genes and 9 miRNAs showed differential expression in # WNT2B cells. Among these were TNFSF10, a key apoptosis inductor, (0.22fold, p = 0.011) and miR-1246 (36.2fold, p = 0.031). miRNA target prediction indicated TNFSF10 to be regulated by miR-1246. qRT-PCR analysis confirmed differential expression of miR-1246 and TNFSF10 in # WNT2B BWFs. Furthermore, TNFSF10 was significantly underexpressed in VUAS tissue (p = 0.009). Conclusion: Perturbation of WNT signalling results in an altered expression of the apoptosis inductor TNFSF10. Similar changes are observed in VUAS. Further studies investigating the crosslink between WNT signalling and apoptosis regulation in the urinary tract stroma are warranted. (C) 2017 S. Karger AG, Basel
PARK7 modulates autophagic proteolysis through binding to the N-terminally arginylated form of the molecular chaperone HSPA5
AUTOPHAGY
Authors: Lee, Dae-Hee; Kim, Daeho; Kim, Sung Tae; Jeong, Soyeon; Kim, Jung Lim; Shim, Sang Mi; Heo, Ah Jung; Song, Xinxin; Guo, Zong Sheng; Bartlett, David L.; Oh, Sang Cheul; Lee, Junho; Saito, Yoshiro; Kim, Bo Yeon; Kwon, Yong Tae; Lee, Yong J.
Abstract
Macroautophagy is induced under various stresses to remove cytotoxic materials, including misfolded proteins and their aggregates. These protein cargoes are collected by specific autophagic receptors such as SQSTM1/p62 (sequestosome 1) and delivered to phagophores for lysosomal degradation. To date, little is known about how cells sense and react to diverse stresses by inducing the activity of SQSTM1. Here, we show that the peroxiredoxin-like redox sensor PARK7/DJ-1 modulates the activity of SQSTM1 and the targeting of ubiquitin (Ub)-conjugated proteins to macroautophagy under oxidative stress caused by TNFSF10/TRAIL (tumor necrosis factor [ligand] superfamily, member 10). In this mechanism, TNFSF10 induces the N-terminal arginylation (Nt-arginylation) of the endoplasmic reticulum (ER)-residing molecular chaperone HSPA5/BiP/GRP78, leading to cytosolic accumulation of Nt-arginylated HSPA5 (R-HSPA5). In parallel, TNFSF10 induces the oxidation of PARK7. Oxidized PARK7 acts as a co-chaperone-like protein that binds the ER-derived chaperone R-HSPA5, a member of the HSPA/HSP70 family. By forming a complex with PARK7 (and possibly misfolded protein cargoes), R-HSPA5 binds SQSTM1 through its Nt-Arg, facilitating self-polymerization of SQSTM1 and the targeting of SQSTM1-cargo complexes to phagophores. The 3-way interaction among PARK7, R-HSPA5, and SQSTM1 is stabilized by the Nt-Arg residue of R-HSPA5. PARK7-deficient cells are impaired in the targeting of R-HSPA5 and SQSTM1 to phagophores and the removal of Ub-conjugated cargoes. Our results suggest that PARK7 functions as a co-chaperone for R-HSPA5 to modulate autophagic removal of misfolded protein cargoes generated by oxidative stress.