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Rinschen MM, Bharill P, Wu X, Kohli P, Reinert MJ, Kretz O, Saez I, Schermer B, Höhne M, Bartram MP, Aravamudhan S, Brooks BR, Vilchez D, Huber TB, Müller RU, Krüger M, Benzing T. The ubiquitin ligase Ubr4 controls stability of podocin/MEC-2 supercomplexes. Hum Mol Genet 2016; 25:1328-44. [PMID: 26792178 DOI: 10.1093/hmg/ddw016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/16/2016] [Indexed: 11/13/2022] Open
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.
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Affiliation(s)
- Markus M Rinschen
- 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,
| | - Puneet Bharill
- Department II of Internal Medicine, Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany
| | - Xiongwu Wu
- Laboratory of Computational Biology, National Heart, Blood, and Lung Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Priyanka Kohli
- Department II of Internal Medicine, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and
| | | | - Oliver Kretz
- Renal Division, University Hospital Freiburg, Freiburg, Germany, Neuroanatomy, University of Freiburg, Freiburg, Germany
| | - Isabel Saez
- Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and
| | - Bernhard Schermer
- 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
| | - Martin Höhne
- 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
| | | | - Sriram Aravamudhan
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany and
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Blood, and Lung Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Vilchez
- Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and
| | - Tobias B Huber
- Renal Division, University Hospital Freiburg, Freiburg, Germany, BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Roman-Ulrich Müller
- 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
| | - Marcus Krüger
- Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and
| | - Thomas Benzing
- 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,
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Parsons K, Nakatani Y, Nguyen MD. p600/UBR4 in the central nervous system. Cell Mol Life Sci 2015; 72:1149-60. [PMID: 25424645 PMCID: PMC11113099 DOI: 10.1007/s00018-014-1788-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 11/06/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
A decade ago, the large 600 kDa mammalian protein p600 (also known as UBR4) was discovered as a multifunctional protein with roles in anoikis, viral transformation and protein degradation. Recently, p600 has emerged as a critical protein in the mammalian brain with roles in neurogenesis, neuronal migration, neuronal signaling and survival. How p600 integrates these apparently unrelated functions to maintain tissue homeostasis and murine survival remains unclear. The common molecular basis underlying many of the actions of p600 suggests, however, certain conservation and transposition of these functions across systems. In this review, we summarize the central nervous system functions of p600 and propose new perspectives on its biological complexity in neuronal physiology and neurological diseases.
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Affiliation(s)
- Kari Parsons
- Department of Clinical Neurosciences, University of Calgary, Hotchkiss Brain Institute, 3330 Hospital Drive NW, Calgary, T2N 4N1, Canada,
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