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Ono Y, Doi N, Shindo M, Pánico P, Salazar AM. Cryptic splicing events result in unexpected protein products from calpain-10 (CAPN10) cDNA. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119188. [PMID: 34906616 DOI: 10.1016/j.bbamcr.2021.119188] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/13/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
Calpain-10 (CAPN10) belongs to the calpain superfamily. Genetic polymorphisms of the CAPN10 gene are associated with susceptibility to develop type 2 diabetes mellitus. Although the role of CAPN10 in the pathophysiology of diabetes has been extensively investigated, its biochemical properties are largely unknown. In this report, we made the surprising discovery that CAPN10 cDNA transcripts are subject to cryptic splicing and unexpected protein products were expressed. The same set of splicing products was reproducibly detected in four types of cultured cells including the primary culture of mouse myoblast. At least, one of the products was identical to a natural splicing variant. Sequence analysis of the splicing potential of CAPN10 cDNA, together with mutagenesis studies, resulted in the identification of a powerful splicing acceptor site at the junction of the sequences encoded by exons 9 and 10. We successfully extended the analysis to create expression construct resistant to splicing for both human and mouse CAPN10. The construct allowed us to analyze two major CAPN10 isoforms and reveal their difference in substrate proteolysis and potential cell functions. These results demonstrate that proteins produced from cDNA do not necessarily reflect the original nucleotide sequence. We provide insight into the property of recombinantly expressed CAPN10 proteins in cultured cells circumventing unexpected protein products.
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Affiliation(s)
- Yasuko Ono
- Calpain Project, Department of Basic Medical Sciences, Tokyo Metropolitan Institute of Medical Science (TMiMS), 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 1568506, Japan.
| | - Naoko Doi
- Calpain Project, Department of Basic Medical Sciences, Tokyo Metropolitan Institute of Medical Science (TMiMS), 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 1568506, Japan
| | - Mayumi Shindo
- Advanced Technical Support Department, Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science (TMiMS), 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 1568506, Japan
| | - Pablo Pánico
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; Department of Cognitive Neurosciences, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Ana María Salazar
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
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Bensaada I, Robin B, Perez J, Salemkour Y, Chipont A, Camus M, Lemoine M, Guyonnet L, Lazareth H, Letavernier E, Hénique C, Tharaux PL, Lenoir O. Calpastatin prevents Angiotensin II-mediated podocyte injury through maintenance of autophagy. Kidney Int 2021; 100:90-106. [PMID: 33675847 DOI: 10.1016/j.kint.2021.02.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 01/29/2021] [Accepted: 02/10/2021] [Indexed: 12/20/2022]
Abstract
The strong predictive value of proteinuria in chronic glomerulopathies is firmly established as well as the pathogenic role of angiotensin II promoting progression of glomerular disease with an altered glomerular filtration barrier, podocyte injury and scarring of glomeruli. Here we found that chronic angiotensin II-induced hypertension inhibited autophagy flux in mouse glomeruli. Deletion of Atg5 (a gene encoding a protein involved autophagy) specifically in the podocyte resulted in accelerated angiotensin II-induced podocytopathy, accentuated albuminuria and glomerulosclerosis. This indicates that autophagy is a key protective mechanism in the podocyte in this condition. Angiotensin-II induced calpain activity in podocytes inhibits autophagy flux. Podocytes from mice with transgenic expression of the endogenous calpain inhibitor calpastatin displayed higher podocyte autophagy at baseline that was resistant to angiotensin II-dependent inhibition. Also, sustained autophagy with calpastatin limited podocyte damage and albuminuria. These findings suggest that hypertension has pathogenic effects on the glomerular structure and function, in part through activation of calpains leading to blockade of podocyte autophagy. These findings uncover an original mechanism whereby angiotensin II-mediated hypertension inhibits autophagy via calcium-induced recruitment of calpain with pathogenic consequences in case of imbalance by calpastatin activity. Thus, preventing a calpain-mediated decrease in autophagy may be a promising new therapeutic strategy for nephropathies associated with high renin-angiotensin system activity.
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Affiliation(s)
| | - Blaise Robin
- Université de Paris, PARCC, Inserm, Paris, France
| | - Joëlle Perez
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | | | - Anna Chipont
- Université de Paris, PARCC, Inserm, Paris, France
| | - Marine Camus
- Université de Paris, PARCC, Inserm, Paris, France
| | | | - Lea Guyonnet
- Université de Paris, PARCC, Inserm, Paris, France
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Abstract
BACKGROUND AND AIMS CAPN10 gene is associated with type 2 diabetes (T2D). Specific members of the calpain system (CAPN1, CAPN2 and CAPN10) are implicated in glucose metabolism. The aim of this study was to evaluate the calpain activity in leukocytes of control subjects and patients with T2D and its association with the calpain family members involved in glucose metabolism and with biochemical parameters that are altered in T2D. METHODS Calpain activity under extracellular glucose concentrations (70-280 mg/dL) was evaluated in leukocytes from subjects with and without T2D. Protein and mRNA levels of CAPN1, CAPN2 and CAPN10 were evaluated. Calpain inhibitors assays were performed in leukocytes from subjects without T2D to evaluate glucose uptake. Calpain activity at 100 mg/dL glucose was correlated with biochemical parameters by multivariate regression. RESULTS Calpain activity in control subjects increased with extracellular glucose concentration in a dose-dependent manner, showing a negative association with HbA1c levels and total amount of CAPN10 protein. In contrast, calpain activity is decreased in patients with T2D and do not respond to changes in glucose concentration. A reduction of CAPN1 autolytic fragments were observed in the subjects with diabetes. Calpain inhibitors decreased calpain activity but did not altered glucose uptake in leukocytes. CONCLUSIONS Calpain activity induced by glucose in leukocytes was associated with biochemical markers of glucose metabolism and with CAPN10 protein abundance. Calpain activity is low in subjects with T2D. Thus, calpain activity induced by extracellular glucose in leukocytes could be a potential marker for T2D early risk detection.
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Wang T, Gao Y, Wang X, Shi Y, Xu J, Wu B, He J, Li Y. Calpain-10 drives podocyte apoptosis and renal injury in diabetic nephropathy. Diabetes Metab Syndr Obes 2019; 12:1811-1820. [PMID: 31571956 PMCID: PMC6750010 DOI: 10.2147/dmso.s217924] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/19/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Diabetic nephropathy (DN) is a progressive microvascular complication of diabetes mellitus (DM), driven largely by podocyte apoptosis. The cysteine protease Calpain 10 is known to augment apoptosis and necrosis, and is a potential therapeutic target in DN. METHODS Type 2 diabetes was induced in SD rats by high-fat diet (HFD) feeding and streptozotocin (STZ) injections, and simulated in vitro by culturing conditionally immortalized mouse podocytes in hyperlipidemic (PA, 100 μM) conditions. The rate of apoptosis in the renal tissues and cultured podocytes was determined by TUNEL assay. The expression of Calpain 10 and its biological effects were assayed by real-time PCR, Western blotting, immunofluorescence and electron microscopy. RESULTS Calpain 10 was up-regulated in the kidneys of DN rats, as well as immortalized mouse podocytes. High levels of Calpain 10 was associated with renal dysfunction and tissue destruction, and podocyte injury and apoptosis. Knockdown of Calpain 10 protected podocytes by decreasing apoptosis rate, and upregulated nephrin. CONCLUSION Calpain 10 is a pro-apoptotic factor in DN, and can be targeted for treating glomerular diseases.
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Affiliation(s)
- Tao Wang
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Yanbin Gao
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
- Beijing Key Laboratory of TCM Collateral Disease Theory Research, Beijing, People’s Republic of China
- Correspondence: Yanbin GaoSchool of Traditional Chinese Medicine, Capital Medical University, No. 10, Youanmenwai, Xitoutiao, Fengtai District, Beijing100069, People’s Republic of ChinaTel +86 108 391 1720Email
| | - Xiaolei Wang
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Yimin Shi
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Jiayi Xu
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Bingjie Wu
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Jiaxin He
- School of Traditional Chinese Medicine, Capital Medical University, Beijing, People’s Republic of China
| | - Yimeng Li
- Beijing Key Laboratory of TCM Collateral Disease Theory Research, Beijing, People’s Republic of China
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