title: The ubiquitin ligase Ubr4 controls stability of podocin/MEC-2 supercomplexes.
abstract: The PHB-domain protein podocin maintains the renal filtration barrier and its mutation is an important cause of hereditary nephrotic syndrome. Podocin and its Caenorhabditis elegans orthologue MEC-2 have emerged as key components of mechanosensitive membrane protein signalling complexes. Whereas podocin resides at a specialized cell junction at the podocyte slit diaphragm, MEC-2 is found in neurons required for touch sensitivity. Here, we show that the ubiquitin ligase Ubr4 is a key component of the podocin interactome purified both from cultured podocytes and native glomeruli. It colocalizes with podocin and regulates its stability. In C. elegans, this process is conserved. Here, Ubr4 is responsible for the degradation of mislocalized MEC-2 multimers. Ubiquitylomic analysis of mouse glomeruli revealed that podocin is ubiquitylated at two lysine residues. These sites were Ubr4-dependent and were conserved across species. Molecular dynamics simulations revealed that ubiquitylation of one site, K301, do not only target podocin/MEC-2 for proteasomal degradation, but may also affect stability and disassembly of the multimeric complex. We suggest that Ubr4 is a key regulator of podocyte foot process proteostasis.
authors.affiliation: Department II of Internal Medicine, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany, markus.rinschen@uk-koeln.de thomas.benzing@uk-koeln.de.
authors.forename: Markus M
authors.initials: MM
authors.lastname: Rinschen
authors.affiliation: Department II of Internal Medicine, Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany.
authors.forename: Puneet
authors.initials: P
authors.lastname: Bharill
authors.affiliation: Laboratory of Computational Biology, National Heart, Blood, and Lung Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Xiongwu
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department II of Internal Medicine, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Kohli
authors.affiliation: Department II of Internal Medicine.
authors.forename: Matthäus J
authors.initials: MJ
authors.lastname: Reinert
authors.affiliation: Renal Division, University Hospital Freiburg, Freiburg, Germany, Neuroanatomy, University of Freiburg, Freiburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kretz
authors.affiliation: Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and.
authors.forename: Isabel
authors.initials: I
authors.lastname: Saez
authors.affiliation: Department II of Internal Medicine, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schermer
authors.affiliation: Department II of Internal Medicine, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Höhne
authors.affiliation: Department II of Internal Medicine.
authors.forename: Malte P
authors.initials: MP
authors.lastname: Bartram
authors.affiliation: Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany and.
authors.forename: Sriram
authors.initials: S
authors.lastname: Aravamudhan
authors.affiliation: Laboratory of Computational Biology, National Heart, Blood, and Lung Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Brooks
authors.affiliation: Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and.
authors.forename: David
authors.initials: D
authors.lastname: Vilchez
authors.affiliation: Renal Division, University Hospital Freiburg, Freiburg, Germany, BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany.
authors.forename: Tobias B
authors.initials: TB
authors.lastname: Huber
authors.affiliation: Department II of Internal Medicine, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany.
authors.forename: Roman-Ulrich
authors.initials: RU
authors.lastname: Müller
authors.affiliation: Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and.
authors.forename: Marcus
authors.initials: M
authors.lastname: Krüger
authors.affiliation: Department II of Internal Medicine, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany, markus.rinschen@uk-koeln.de thomas.benzing@uk-koeln.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Benzing
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009404:Nephrotic Syndrome / Q000378:metabolism; D000091402:Prohibitins; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D029742:Caenorhabditis elegans Proteins; D002148:Calmodulin-Binding Proteins; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C096705:MEC-2 protein, C elegans; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C407223:NPHS2 protein; C000717328:PHB protein, human; D000091402:Prohibitins; C000613551:ubiquitin ligase Ubr4, C elegans; C505833:UBR4 protein, human; D044767:Ubiquitin-Protein Ligases; C528904:Ubr4 protein, mouse