1
|
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.
Collapse
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
| |
Collapse
|
2
|
Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
Collapse
Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
| |
Collapse
|
3
|
van Galen G, Olsen E, Siwinska N. Biomarkers of Kidney Disease in Horses: A Review of the Current Literature. Animals (Basel) 2022; 12:2678. [PMID: 36230418 PMCID: PMC9559299 DOI: 10.3390/ani12192678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/20/2022] [Accepted: 09/29/2022] [Indexed: 11/15/2022] Open
Abstract
Creatinine only allows detection of kidney disease when 60 to 75% of the glomerular function is lost and is therefore not an ideal marker of disease. Additional biomarkers could be beneficial to assess kidney function and disease. The objectives are to describe new equine kidney biomarkers. This systematic review assesses the available literature, including the validation process and reference values, following which the authors suggest recommendations for clinical use. SDMA may have some potential as equine kidney biomarker, but there is currently a lack of evidence that SDMA offers any advantage compared to creatinine in detecting Acute Kidney Injury (AKI). Cystatin C and podocin show potential as biomarkers for kidney disease (including detecting AKI earlier than creatinine) and should be studied further. NGAL has potential as a biomarker of kidney disease (including detecting AKI earlier than creatinine), and potential as an inflammatory marker. Literature on MMP-9 does not allow for conclusive statements about its potential as a biomarker for kidney disease. The future may show that NAG has potential. For all biomarkers, at this stage, available scientific information is limited or too scarce to support clinical use, and only SDMA can be measured for clinical purposes. In conclusion, there are multiple new biomarkers with the potential to diagnose kidney problems. However, there are only a few studies available and more data is needed before these biomarkers can be applied and recommended in our daily practice.
Collapse
Affiliation(s)
- Gaby van Galen
- Sydney School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
- Goulburn Valley Equine Hospital, Congupna, VIC 3633, Australia
| | - Emil Olsen
- Veterinary Teaching Hospital (Universitetsdjursjukhuset, UDS), Swedish Veterinary Agricultural University (SLU), 750 07 Uppsala, Sweden
| | - Natalia Siwinska
- Department of Internal Medicine, Clinic of Diseases of Horses, Dogs and Cats, Faculty of Veterinary Medicine, University of Environmental and Life Sciences Wroclaw, 50-375 Wroclaw, Poland
| |
Collapse
|
4
|
Zheng Z, Tsvetkov D, Bartolomaeus TUP, Erdogan C, Krügel U, Schleifenbaum J, Schaefer M, Nürnberg B, Chai X, Ludwig FA, N'diaye G, Köhler MB, Wu K, Gollasch M, Markó L. Role of TRPC6 in kidney damage after acute ischemic kidney injury. Sci Rep 2022; 12:3038. [PMID: 35194063 PMCID: PMC8864023 DOI: 10.1038/s41598-022-06703-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 02/03/2022] [Indexed: 12/11/2022] Open
Abstract
Transient receptor potential channel subfamily C, member 6 (TRPC6), a non-selective cation channel that controls influx of Ca2+ and other monovalent cations into cells, is widely expressed in the kidney. TRPC6 gene variations have been linked to chronic kidney disease but its role in acute kidney injury (AKI) is unknown. Here we aimed to investigate the putative role of TRPC6 channels in AKI. We used Trpc6-/- mice and pharmacological blockade (SH045 and BI-749327), to evaluate short-term AKI outcomes. Here, we demonstrate that neither Trpc6 deficiency nor pharmacological inhibition of TRPC6 influences the short-term outcomes of AKI. Serum markers, renal expression of epithelial damage markers, tubular injury, and renal inflammatory response assessed by the histological analysis were similar in wild-type mice compared to Trpc6-/- mice as well as in vehicle-treated versus SH045- or BI-749327-treated mice. In addition, we also found no effect of TRPC6 modulation on renal arterial myogenic tone by using blockers to perfuse isolated kidneys. Therefore, we conclude that TRPC6 does not play a role in the acute phase of AKI. Our results may have clinical implications for safety and health of humans with TRPC6 gene variations, with respect to mutated TRPC6 channels in the response of the kidney to acute ischemic stimuli.
Collapse
Affiliation(s)
- Zhihuang Zheng
- Department of Nephrology/Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany.,Department of Nephrology, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Dmitry Tsvetkov
- Department of Nephrology/Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany. .,Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany. .,Department of Geriatrics, University of Greifswald, University District Hospital Wolgast, Greifswald, Germany.
| | - Theda Ulrike Patricia Bartolomaeus
- Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany.,Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Cem Erdogan
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ute Krügel
- Rudolf Boehm Institute for Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Johanna Schleifenbaum
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Schaefer
- Rudolf Boehm Institute for Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Xiaoning Chai
- Rudolf Boehm Institute for Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Friedrich-Alexander Ludwig
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Leipzig, Germany
| | - Gabriele N'diaye
- Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany.,Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - May-Britt Köhler
- Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany.,Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Kaiyin Wu
- Department of Pathology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Maik Gollasch
- Department of Nephrology/Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany. .,Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany. .,Department of Geriatrics, University of Greifswald, University District Hospital Wolgast, Greifswald, Germany.
| | - Lajos Markó
- Experimental and Clinical Research Center (ECRC), Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité Universitätsmedizin, Berlin, Germany. .,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Berlin, Germany. .,Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin, Germany. .,Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.
| |
Collapse
|
5
|
Mulukala SKN, Kambhampati V, Qadri AH, Pasupulati AK. Evolutionary conservation of intrinsically unstructured regions in slit-diaphragm proteins. PLoS One 2021; 16:e0254917. [PMID: 34288970 PMCID: PMC8294545 DOI: 10.1371/journal.pone.0254917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 07/06/2021] [Indexed: 01/19/2023] Open
Abstract
Vertebrate kidneys contribute to homeostasis by regulating electrolyte, acid-base balance, removing toxic metabolites from blood, and preventing protein loss into the urine. Glomerular podocytes constitute the blood-urine barrier, and podocyte slit-diaphragm (SD), a modified tight junction, contributes to the glomerular permselectivity. Nephrin, KIRREL1, podocin, CD2AP, and TRPC6 are crucial members of the SD that interact with each other and contribute to the SD's structural and functional integrity. This study analyzed the distribution of these five essential SD proteins across the organisms for which the genome sequence is available. We found a diverse distribution of nephrin and KIRREL1 ranging from nematodes to higher vertebrates, whereas podocin, CD2AP, and TRPC6 are restricted to the vertebrates. Among invertebrates, nephrin and its orthologs consist of more immunoglobulin-3 domains, whereas in the vertebrates, CD80-like C2-set domains are predominant. In the case of KIRREL1 and its orthologs, more Ig domains were observed in invertebrates than vertebrates. Src Homology-3 (SH3) domain of CD2AP and SPFH domain of podocin are highly conserved among vertebrates. TRPC6 and its orthologs had conserved ankyrin repeats, TRP, and ion transport domains, except Chondrichthyes and Echinodermata, which do not possess the ankyrin repeats. Intrinsically unstructured regions (IURs) are conserved across the SD orthologs, suggesting IURs importance in the protein complexes that constitute the slit-diaphragm. For the first time, a study reports the evolutionary insights of vertebrate SD proteins and their invertebrate orthologs.
Collapse
Affiliation(s)
- Sandeep K N Mulukala
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Vaishnavi Kambhampati
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Abrar H Qadri
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Anil K Pasupulati
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| |
Collapse
|