Universität zu Köln

Ebert, Lena Kathrin (2022). The JADE protein family in renal epithelial cells in the context of cystic kidney disease. PhD thesis, Universität zu Köln.

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Abstract

Nephronophthisis (NPH) is the number one genetic cause of end-stage renal disease in children. Since there are no causative treatment options available, the disease usually leads to dialysis or kidney transplantation by the medium age of 13. By now, several genes (NPHP1-20) have been identified whose mutations lead to NPH. Characteristics for NPH are interstitial fibrosis, tubular basement membrane thickening, and cyst formation in the kidney. Renal cyst formation is a shared feature of NPH and several other inherited (poly)cystic kidney diseases (PKD), as well as von-Hippel-Lindau (VHL) disease. VHL disease is caused by mutations in the VHL gene encoding for the protein pVHL. Moreover, loss of pVHL is also observed in most cases of sporadic renal cell carcinoma (RCC), a very frequent urogenital tumor. Recent groundbreaking studies demonstrated that primary cilia play a pivotal role in the pathogenesis of PKD and cancer biology. As tiny sensory organelles projecting from almost all mammalian cells, primary cilia transmit signals from the environment into the cell and modulate multiple signaling pathways, including Sonic Hedgehog signaling, Hippo signaling, and Wnt signaling, as well as cell cycle progression. The putative E3 ubiquitin ligase JADE1 has been found to interact with various ciliopathy-associated proteins, including pVHL and NPH proteins encoded by the NPHP genes. Thus, JADE1 might be involved in the pathogenesis of both VHL disease and NPH. Importantly, JADE1 forms a protein family with JADE2 and JADE3, the functions of which are still largely unknown. The focus of this work was to unravel the functions of the JADE protein family members, including their shared and distinct role in transcriptional regulation in renal epithelial cells and their impact on the pathogenesis of NPH, VHL disease, and RCC. To this end, two individual loss-of-function cell lines for each of the JADE family members were generated using CRISPR/Cas9-mediated genome engineering. These cell lines were used to study the distinct and mutual functions of Jade1, Jade2, and Jade3 in differentiated renal tubular epithelial cells using unbiased transcriptomic and proteomic approaches followed by comprehensive bioinformatic analyses. Moreover, we generated transgenic mouse models to study the loss of each individual Jade protein in vivo. In addition, NPH mouse models were generated with the intention to resemble the human phenotype of NPH and to gain novel insights into the disease mechanisms. The analysis of the Jade-deficient cell lines provided new insight into the role of Jade proteins in several signaling pathways related to cyst formation and cancer development, including Rap1 signaling, focal adhesion and actin cytoskeleton regulation. In addition, we observed increased expression of proteasomal components and augmented proteasomal activity in all cell lines. Moreover, the newly generated Tmem218emKO/emKO mouse line closely resembles human NPH, which will be a highly valuable preclinical model to study molecular mechanisms of NPH.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Ebert, Lena Kathrin lena.ebert@uk-koeln.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-641319
Date:	2022
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	CECAD - Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases
Subjects:	Natural sciences and mathematics
Uncontrolled Keywords:	Keywords Language kidney English proteasome English primary cilium English PHD finger English Nephronophthisis English
Date of oral exam:	8 December 2021
Referee:	Name Academic Title Benzing, Thomas Prof. Dr. Hoppe, Thorsten Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/64131