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Qadri AH, Prajapati J, Faheem I, Bhattacharjee U, Padmanaban HK, Mulukala SKN, Pasupulati AK. Biophysical characterization and insights into the oligomeric nature of CD2-associated protein. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 15:20-33. [PMID: 38765876 PMCID: PMC11101965 DOI: 10.62347/uvsh8436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 02/27/2024] [Indexed: 05/22/2024]
Abstract
INTRODUCTION Glomerular podocytes are specialized epithelial cells localized to the blood-urine interface of the kidney. Podocyte slit-diaphragm (SD), a size-and-charge-selective junction, is instrumental in blood ultrafiltration and the formation of protein-free urine. The SD consists of macromolecular complexes of several proteins, such as nephrin, podocin, and CD2-associated protein (CD2AP). CD2AP is an adapter protein and is considered to be crucial for the integrity of SD. Mutations in the SD proteins cause nephrotic syndrome (NS), characterized by proteinuria. SD proteins' structural features must be elucidated to understand the mechanism of proteinuria in NS. In this study, we expressed, purified, and biophysically characterized heterologously expressed human CD2AP. METHODS Codon-optimized human CD2AP was expressed in E. coli Rosetta cells. The recombinant protein was induced with 1 mM IPTG and purified by Ni-NTA affinity chromatography. Analytical size-exclusion chromatography, blue native-PAGE, circular dichroism, and fluorescence spectroscopy were performed to decipher the oligomeric nature, secondary structural content, and tertiary packing of CD2AP. RESULTS Our analysis revealed that CD2AP adopts a predominantly disordered secondary structure despite exhibiting moderate tertiary packing, characterized by low helical and β-sheet content. CD2AP readily assembles into homo-oligomers, with octamers and tetramers constituting the primary population. Interestingly, the inherent flexibility of CD2AP's secondary structural elements appears resistant to thermal denaturation. Frameshift mutation (p.K579Efs*7) that leads to loss of the coiled-coil domain promotes aberrant oligomerization of CD2AP through SH3 domains. CONCLUSION We successfully expressed full-length human CD2AP in a heterologous system, wherein the secondary structure of CD2AP is predominantly disordered. CD2AP can form higher-order oligomers, and the significance of these oligomers and the impact of mutations in the context of size-selective permeability of SD needs further investigation.
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Affiliation(s)
- Abrar H Qadri
- Department of Biochemistry, University of HyderabadHyderabad 500046, India
| | - Jyotsana Prajapati
- Department of Biochemistry, University of HyderabadHyderabad 500046, India
| | - Iqball Faheem
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBangalore 560012, India
| | - Utsa Bhattacharjee
- Department of Biochemistry, University of HyderabadHyderabad 500046, India
| | | | | | - Anil K Pasupulati
- Department of Biochemistry, University of HyderabadHyderabad 500046, India
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Preston R, Naylor RW, Stewart G, Bierzynska A, Saleem MA, Lowe M, Lennon R. A role for OCRL in glomerular function and disease. Pediatr Nephrol 2020; 35:641-648. [PMID: 31811534 PMCID: PMC7056711 DOI: 10.1007/s00467-019-04317-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 07/15/2019] [Accepted: 07/23/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Lowe syndrome and Dent-2 disease are caused by mutations in the OCRL gene, which encodes for an inositol 5-phosphatase. The renal phenotype associated with OCRL mutations typically comprises a selective proximal tubulopathy, which can manifest as Fanconi syndrome in the most extreme cases. METHODS Here, we report a 12-year-old male with nephrotic-range proteinuria and focal segmental glomerulosclerosis on renal biopsy. As a glomerular pathology was suspected, extensive investigation of tubular function was not performed. RESULTS Surprisingly, whole exome sequencing identified a genetic variant in OCRL (c1467-2A>G) that introduced a novel splice mutation leading to skipping of exon 15. In situ hybridisation of adult human kidney tissue and zebrafish larvae showed OCRL expression in the glomerulus, supporting a role for OCRL in glomerular function. In cultured podocytes, we found that OCRL associated with the linker protein IPIP27A and CD2AP, a protein that is important for maintenance of the podocyte slit diaphragm. CONCLUSION Taken together, this work suggests a previously under-appreciated role for OCRL in glomerular function and highlights the importance of investigating tubular function in patients with persistent proteinuria.
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Affiliation(s)
- Rebecca Preston
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Richard W Naylor
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Graham Stewart
- Renal Department, Ninewells Hospital, Dundee, DD1 9SY, UK
| | | | - Moin A Saleem
- Children's and Academic Renal Unit, University of Bristol, Bristol, UK
| | - Martin Lowe
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK.
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester, M13 9PT, UK.
- Department of Paediatric Nephrology, Royal Manchester Children's Hospital, Manchester Academic Health Science Centre, Manchester University Hospital NHS Foundation Trust, Manchester, UK.
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Wang JY, Zhang DQ, Cao Q, Qiao XQ, Zhou GP. miR-939-5p decreases the enrichment of RNA polymerase II in the promoter region of CD2AP involved in nephrotic syndrome. J Cell Biochem 2019; 120:11366-11374. [PMID: 30756418 DOI: 10.1002/jcb.28413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 12/03/2018] [Accepted: 12/06/2018] [Indexed: 01/24/2023]
Abstract
The expression changes of CD2-associated protein (CD2AP) can lead to kidney diseases with proteinuria, including nephrotic syndrome (NS). A recent study reported that miRNAs may be important transcriptional regulators. In this study, we found increased expression of miR-939-5p and decreased expression of CD2AP in the peripheral blood of patients with NS. However, miR-939-5p did not show a regulatory effect on the 3'-untranslated region of CD2AP. The expression levels of specific protein 1 and adenovirus E2 promoter-binding factor 1, important transcription regulators in the promoter region of CD2AP, were also not affected by microRNA (miR)-939-5p. We confirmed that miR-939-5p is in the nucleus by fluorescent in situ hybridization and cytoplasmic separation polymerase chain reaction. The promoter plasmid and miR-939-5p were cotransfected into HEK-293 cells, and the luciferase reporter gene assay was used to analyze the promoter activity. We found that miR-939-5p binds to a specific sequence in the CD2AP promoter. miR-939-5p was confirmed to reduce the recruitment of RNA polymerase II to the CD2AP promoter region by chromatin immunoprecipitation. These findings improve our understanding of the mechanism of miR-939-5p in NS and provide potential molecular therapeutic targets for NS.
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Affiliation(s)
- Jin-Ya Wang
- Department of Pediatrics, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Dao-Qi Zhang
- Department of Pediatrics, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Qian Cao
- Department of Pediatrics, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Xiao-Qin Qiao
- Department of Pediatrics, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Guo-Ping Zhou
- Department of Pediatrics, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
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Sala G, Badalamenti S, Ponticelli C. The Renal Connexome and Possible Roles of Connexins in Kidney Diseases. Am J Kidney Dis 2015; 67:677-87. [PMID: 26613807 DOI: 10.1053/j.ajkd.2015.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022]
Abstract
Connexins are membrane-spanning proteins that allow for the formation of cell-to-cell channels and cell-to-extracellular space hemichannels. Many connexin subtypes are expressed in kidney cells. Some mutations in connexin genes have been linked to various human pathologies, including cardiovascular, neurodegenerative, lung, and skin diseases, but the exact role of connexins in kidney disease remains unclear. Some hypotheses about a connection between genetic mutations, endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) in kidney pathology have been explored. The potential relationship of kidney disease to abnormal production of connexin proteins, mutations in their genes together with ER stress, or the UPR is still a matter of debate. In this scenario, it is tantalizing to speculate about a possible role of connexins in the setting of kidney pathologies that are thought to be caused by a deregulated podocyte protein expression, the so-called podocytopathies. In this article, we give examples of the roles of connexins in kidney (patho)physiology and propose avenues for further research concerning connexins, ER stress, and UPR in podocytopathies that may ultimately help refine drug treatment.
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Affiliation(s)
- Gabriele Sala
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy.
| | - Salvatore Badalamenti
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
| | - Claudio Ponticelli
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
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Rouka E, Simister PC, Janning M, Kumbrink J, Konstantinou T, Muniz JRC, Joshi D, O'Reilly N, Volkmer R, Ritter B, Knapp S, von Delft F, Kirsch KH, Feller SM. Differential Recognition Preferences of the Three Src Homology 3 (SH3) Domains from the Adaptor CD2-associated Protein (CD2AP) and Direct Association with Ras and Rab Interactor 3 (RIN3). J Biol Chem 2015; 290:25275-92. [PMID: 26296892 DOI: 10.1074/jbc.m115.637207] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Indexed: 11/06/2022] Open
Abstract
CD2AP is an adaptor protein involved in membrane trafficking, with essential roles in maintaining podocyte function within the kidney glomerulus. CD2AP contains three Src homology 3 (SH3) domains that mediate multiple protein-protein interactions. However, a detailed comparison of the molecular binding preferences of each SH3 remained unexplored, as well as the discovery of novel interactors. Thus, we studied the binding properties of each SH3 domain to the known interactor Casitas B-lineage lymphoma protein (c-CBL), conducted a peptide array screen based on the recognition motif PxPxPR and identified 40 known or novel candidate binding proteins, such as RIN3, a RAB5-activating guanine nucleotide exchange factor. CD2AP SH3 domains 1 and 2 generally bound with similar characteristics and specificities, whereas the SH3-3 domain bound more weakly to most peptide ligands tested yet recognized an unusually extended sequence in ALG-2-interacting protein X (ALIX). RIN3 peptide scanning arrays revealed two CD2AP binding sites, recognized by all three SH3 domains, but SH3-3 appeared non-functional in precipitation experiments. RIN3 recruited CD2AP to RAB5a-positive early endosomes via these interaction sites. Permutation arrays and isothermal titration calorimetry data showed that the preferred binding motif is Px(P/A)xPR. Two high-resolution crystal structures (1.65 and 1.11 Å) of CD2AP SH3-1 and SH3-2 solved in complex with RIN3 epitopes 1 and 2, respectively, indicated that another extended motif is relevant in epitope 2. In conclusion, we have discovered novel interaction candidates for CD2AP and characterized subtle yet significant differences in the recognition preferences of its three SH3 domains for c-CBL, ALIX, and RIN3.
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Affiliation(s)
- Evgenia Rouka
- From the Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Philip C Simister
- From the Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, Oxford OX3 9DS, United Kingdom,
| | - Melanie Janning
- From the Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - Joerg Kumbrink
- the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Tassos Konstantinou
- From the Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, Oxford OX3 9DS, United Kingdom
| | - João R C Muniz
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Dhira Joshi
- the Peptide Chemistry Laboratory, London Research Institute Cancer Research UK, London WC2A 3LY, United Kingdom
| | - Nicola O'Reilly
- the Peptide Chemistry Laboratory, London Research Institute Cancer Research UK, London WC2A 3LY, United Kingdom
| | - Rudolf Volkmer
- the Institute of Medical Immunology, Charité-Universitätsmedizin Berlin, 10115 Berlin, Germany
| | - Brigitte Ritter
- the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Stefan Knapp
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Frank von Delft
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, the Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom, and the Department of Biochemistry, University of Johannesburg, Auckland Park 2006, South Africa
| | - Kathrin H Kirsch
- the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Stephan M Feller
- From the Weatherall Institute of Molecular Medicine, Department of Oncology, University of Oxford, Oxford OX3 9DS, United Kingdom, the Institute of Molecular Medicine, Martin Luther University Halle-Wittenberg, D-06120 Halle, Germany,
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