1
|
Karimkhani H, Shojaolsadati P, Yiğitbaşı T, Kolbası B, Emekli N. The effect of calpain inhibitor-I on copper oxide nanoparticle-induced damage and cerebral ischemia-reperfusion in a rat model. Biomed Pharmacother 2024; 174:116539. [PMID: 38615610 DOI: 10.1016/j.biopha.2024.116539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/18/2024] [Accepted: 03/29/2024] [Indexed: 04/16/2024] Open
Abstract
This study aimed to investigate the effects of the calpain inhibitor N-Acetyl-Leu-Leu-norleucinal (ALLN) on neuroapoptotic cell damage caused by Copper Oxide Nanoparticles (CuO-NP) and exacerbation of damage through brain ischemia/reperfusion (I/R) in a rat model. Male Wistar Albino rats (n=80) were divided into eight groups: Control, I/R, CuO-NP, CuO-NP+I/R, I/R+ALLN, CuO-NP+ALLN, CuO-NP+I/R+ALLN, and DMSO. Biochemical markers (MBP, S100B, NEFL, NSE, BCL-2, Cyt-C, Calpain, TNF-α, Caspase-3, MDA, and CAT) were measured in serum and brain tissue samples. Histological examinations (H&E staining), DNA fragmentation analysis (TUNEL) were performed, along with Caspase-3 assessment. The ALLN-treated groups exhibited significant improvements in biochemical markers and a remarkable reduction in apoptosis compared to the damaged groups (CuO-NP and I/R). H&E and Caspase-3 staining revealed damage-related morphological changes and reduced apoptosis in the ALLN-treated group. However, no differences were observed among the groups with TUNEL staining. The findings suggest that ALLN, as a calpain inhibitor, has potential implications for anti-apoptotic treatment, specifically in mitigating neuroapoptotic cell damage caused by CuO-NP and I/R.
Collapse
Affiliation(s)
- Hadi Karimkhani
- Department of Biochemistry, School of Medicine, Istanbul Okan University, Istanbul, Turkey; Department of Stem Cell, School of Medicine, Eskisehir Osmangazi University, Eskisehir, Turkey.
| | - Paria Shojaolsadati
- Department of Anatomy, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Türkan Yiğitbaşı
- Department of Biochemistry, School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - Bircan Kolbası
- Department of Histology and Embryology, School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - Neslin Emekli
- Department of Biochemistry, School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| |
Collapse
|
2
|
Ivleva IS, Ivlev AP, Pestereva NS, Tyutyunnik TV, Karpenko MN. Protective effect of calpain inhibitors against manganese-induced toxicity in rats. Metab Brain Dis 2022; 37:1003-1013. [PMID: 35089484 DOI: 10.1007/s11011-022-00916-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/17/2022] [Indexed: 10/19/2022]
Abstract
Development of manganism is a major complication of manganese exposure in which neurological dysfunction is linked to accumulation of metal in the brain. Current therapies do not prevent progression of the disease. Therefore, development of effective therapeutic strategies for treatment of manganism is of utmost importance. Since the hyperactivation of calpain family proteases in CNS during manganism in an animal model is observed, we assumed that inhibition of calpains can suppress the development of Mn-induced neurological disturbances. The goal of this study is to delineate protective effect and the mechanism of neuroprotection of calpain inhibitor in rat model of Mn-induced neurological symptoms. Using the Gait analysis test, we found that chronic intranasal administration of the calpain inhibitor Cast (184-210) (peptide, which is corresponding to the 184-210 amino acid of the endogenous inhibitor of calpains-human calpastatin) to Mn-treated rats contributed to a significant decrease in the severity of gait disorders, although it did not lead to a decrease in the Mn deposition in the striatum and hippocampus. Accordingly to the results of PCR-RT, this effect was accompanied by a partial reduction in the content of neuro-inflammatory markers (IL-1β, TNF-α, NFκB mRNA in the hippocampus and, additionally, IBA-1 mRNA in the striatum), as well as normalization of the content of dopamine and its metabolites in the hippocampus and striatum, which was assessed by HPLC. In striatum cells, the application of Cast (184-210) also led to a significant increase in the production of tyrosine hydroxylase, which was analyzed by immunoblotting method. These findings suggest that calpain inhibitors may be a valid therapeutic agent in manganism.
Collapse
Affiliation(s)
- I S Ivleva
- Department of Physiology (Pavlov's), Institute of Experimental Medicine, St. Petersburg, Russia.
| | - A P Ivlev
- Sechenov Institute of Evolutionary Physiology and Biochemistry Russian Academy of Sciences, St. Petersburg, Russia
| | - N S Pestereva
- Department of Physiology (Pavlov's), Institute of Experimental Medicine, St. Petersburg, Russia
| | - T V Tyutyunnik
- Department of Physiology (Pavlov's), Institute of Experimental Medicine, St. Petersburg, Russia
| | - M N Karpenko
- Department of Physiology (Pavlov's), Institute of Experimental Medicine, St. Petersburg, Russia
| |
Collapse
|
3
|
Liu J, Wang Q, Wei Y, Zhang S, Chai E, Tang F. Calpain inhibitor prevents atherosclerosis in apolipoprotein E knockout mice by regulating mRNA expression of genes related to cholesterol uptake and efflux. Microvasc Res 2022; 140:104276. [PMID: 34742813 DOI: 10.1016/j.mvr.2021.104276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE We previously reported that a calpain inhibitor (CAI) prevents the development of atherosclerosis in rats. This study aimed to investigate the effects of CAI (1 mg/kg) on atherosclerosis in apolipoprotein E knockout (ApoE KO) mice that were fed a high-fat diet (HFD) and explore the underlying mechanism by analyzing the expression of genes related to the uptake and efflux of cholesterol. METHODS Atherosclerotic plaques were evaluated. The activity of calpain in the aorta and that of superoxide dismutase (SOD) in the serum were assessed. Lipid profiles in the serum and liver were examined. Serum oxidized low-density lipoprotein (oxLDL), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-6 (IL-6) levels were measured. The mRNA expressions of CD68, TNF-α, IL-6, CD36, scavenger receptor (SR-A), peroxisome proliferator-activated receptor gamma (PPAR-γ), liver-x-receptor alpha (LXR-α), and ATP-binding cassette transporter class A1 (ABCA1) in the aorta and peritoneal macrophages were also evaluated. RESULTS CAI reduced calpain activity in the aorta. CAI also impeded atherosclerotic lesion formation and mRNA expression of CD68 in the aorta and peritoneal macrophages of ApoE KO mice compared with those of mice receiving HFD. However, CAI had no effect on body weight and lipid levels in both the serum and liver. CAI significantly decreased MDA, oxLDL, TNF-α, and IL-6 levels and increased SOD activity in the serum. Moreover, CAI significantly inhibited the mRNA expression of TNF-α and IL-6 genes in the aorta and peritoneal macrophages. In addition, CAI significantly downregulated the mRNA expression of scavenger receptors CD36 and SR-A and upregulated the expression of genes involved in the cholesterol efflux pathway, i.e., PPAR-γ, LXR-α, and ABCA1 in the aorta and peritoneal macrophages. CONCLUSIONS CAI inhibited the development of atherosclerotic lesions in ApoE KO mice, and this effect might be related to the reduction of oxidative stress and inflammation and the improvement of cholesterol intake and efflux pathways.
Collapse
MESH Headings
- ATP Binding Cassette Transporter 1/genetics
- ATP Binding Cassette Transporter 1/metabolism
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Aorta/drug effects
- Aorta/enzymology
- Aorta/pathology
- Aortic Diseases/enzymology
- Aortic Diseases/genetics
- Aortic Diseases/pathology
- Aortic Diseases/prevention & control
- Atherosclerosis/enzymology
- Atherosclerosis/genetics
- Atherosclerosis/pathology
- Atherosclerosis/prevention & control
- Calpain/antagonists & inhibitors
- Calpain/metabolism
- Cholesterol/metabolism
- Cysteine Proteinase Inhibitors/pharmacology
- Disease Models, Animal
- Gene Expression Regulation
- Leupeptins/pharmacology
- Lipid Metabolism/drug effects
- Lipid Metabolism/genetics
- Liver X Receptors/genetics
- Liver X Receptors/metabolism
- Macrophages, Peritoneal/drug effects
- Macrophages, Peritoneal/enzymology
- Macrophages, Peritoneal/pathology
- Male
- Mice, Inbred C57BL
- Mice, Knockout, ApoE
- PPAR gamma/genetics
- PPAR gamma/metabolism
- Plaque, Atherosclerotic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Scavenger Receptors, Class A/genetics
- Scavenger Receptors, Class A/metabolism
- Mice
Collapse
Affiliation(s)
- Jixin Liu
- Medical Department, Gansu Provincial Hospital, Lanzhou 730000, China
| | - Qiuning Wang
- Department of Pharmacology, Jinzhou Medical University, Jinzhou 121001, China
| | - Yujie Wei
- Department of Cardiovascular Diseases, Lanzhou University Second Hospital, Lanzhou 730030, China
| | - Shining Zhang
- Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou 730030, China
| | - Erqing Chai
- Emergency General Hospital, Beijing 100028, China.
| | - Futian Tang
- Department of Cardiovascular Diseases, Lanzhou University Second Hospital, Lanzhou 730030, China; Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou 730030, China.
| |
Collapse
|
4
|
Donkor IO, Xu J, Liu J, Cameron K. Synthesis and antiproliferative activity of sulfonamide-based peptidomimetic calpain inhibitors. Bioorg Med Chem 2020; 28:115433. [PMID: 32199690 DOI: 10.1016/j.bmc.2020.115433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/01/2020] [Accepted: 03/11/2020] [Indexed: 10/24/2022]
Abstract
The calpains are a conserved family of cysteine proteases that includes several isoforms of which µ-calpain and m-calpain are the most widely distributed in mammalian cells. Calpains have been implicated in normal physiological processes as well as cellular abnormalities such as neurodegenerative disorders, cataract, and cancer. Therefore, calpain inhibitors are of interest as potential therapeutic agents. We have synthesized four new sulfonamide-based peptidomimetic compounds 2-5 as inhibitors of μ-calpain that incorporate (E)-1-(phenyl)-2-phenyldiazene and (E)-1-(phenyl)-2-phenylethene functionalities as the N-terminal capping groups of the inhibitors. Compound 5 with Ki value of 9 nM versus μ-calpain was the most potent member of the group. The compounds were predicted to be more lipophilic compared to MDL28170 based on CLogP estimation. They displayed moderate to good antiproliferative activity versus melanoma cell lines (A-375 and B-16F1) and PC-3 prostate cancer cells in vitro. Additionally, one member of the group (compound 3) inhibited DU-145 cell invasion by 80% at 2 μM concentration in the Matrigel cell invasion assay.
Collapse
Affiliation(s)
- Isaac O Donkor
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, TN 38163, United States.
| | - Jin Xu
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, TN 38163, United States
| | - Jiuyu Liu
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, TN 38163, United States
| | - Keyuna Cameron
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, TN 38163, United States
| |
Collapse
|
5
|
Hu J, Chen L, Huang X, Wu K, Ding S, Wang W, Wang B, Smith C, Ren C, Ni H, ZhuGe Q, Yang J. Calpain inhibitor MDL28170 improves the transplantation-mediated therapeutic effect of bone marrow-derived mesenchymal stem cells following traumatic brain injury. Stem Cell Res Ther 2019; 10:96. [PMID: 30876457 PMCID: PMC6420775 DOI: 10.1186/s13287-019-1210-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/16/2019] [Accepted: 03/06/2019] [Indexed: 01/14/2023] Open
Abstract
Background Studies have shown that transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) protects against brain damage. However, the low survival number of transplanted BMSCs remains a pertinent challenge and can be attributed to the unfavorable microenvironment of the injured brain. It is well known that calpain activation plays a critical role in traumatic brain injury (TBI)-mediated inflammation and cell death; previous studies showed that inhibiting calpain activation is neuroprotective after TBI. Thus, we investigated whether preconditioning with the calpain inhibitor, MDL28170, could enhance the survival of BMSCs transplanted at 24 h post TBI to improve neurological function. Methods TBI rat model was induced by the weight-drop method, using the gravitational forces of a free falling weight to produce a focal brain injury. MDL28170 was injected intracranially at the lesion site at 30 min post TBI, and the secretion levels of neuroinflammatory factors were assessed 24 h later. BMSCs labeled with green fluorescent protein (GFP) were locally administrated into the lesion site of TBI rat brains at 24 h post TBI. Immunofluorescence and histopathology were performed to evaluate the BMSC survival and the TBI lesion volume. Modified neurological severity scores were chosen to evaluate the functional recovery. The potential mechanisms by which MDL28170 is involved in the regulation of inflammation signaling pathway and cell apoptosis were determined by western blot and immunofluorescence staining. Results Overall, we found that a single dose of MDL28170 at acute phase of TBI improved the microenvironment by inhibiting the inflammation, facilitated the survival of grafted GFP-BMSCs, and reduced the grafted cell apoptosis, leading to the reduction of lesion cavity. Furthermore, a significant neurological function improvement was observed when BMSCs were transplanted into a MDL28170-preconditioned TBI brains compared with the one without MDL28170-precondition group. Conclusions Taken together, our data suggest that MDL28170 improves BMSC transplantation microenvironment and enhances the neurological function restoration after TBI via increased survival rate of BMSCs. We suggest that the calpain inhibitor, MDL28170, could be pursued as a new combination therapeutic strategy to advance the effects of transplanted BMSCs in cell-based regenerative medicine. Electronic supplementary material The online version of this article (10.1186/s13287-019-1210-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jiangnan Hu
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China. .,Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA.
| | - Lefu Chen
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Xujun Huang
- Department of Intensive Care Unit (ICU), Hengdian Wenrong Hospital, Jinhua, 322100, China
| | - Ke Wu
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Saidan Ding
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Weikan Wang
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Brian Wang
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Charity Smith
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA
| | - Changhong Ren
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Haoqi Ni
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China
| | - Qichuan ZhuGe
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China.
| | - Jianjing Yang
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China.
| |
Collapse
|
6
|
Abstract
Calpains are signaling proteases that have relatively little sequence specificity but some preferences for certain residues on either side of the scissile bond. As with most proteases, they mainly cut unstructured or extended regions of their target proteins. The tendency for concentrated calpain to rapidly autoproteolyze when activated by calcium complicates the kinetic assessment of calpain activity. As calpain autoproteolyzes, the amount of fully active enzyme continuously decreases until all of the calpain molecules have been cut and their activity reduced to a tiny fraction of the starting rate. To accurately measure calpain kinetics, only the initial rate of substrate hydrolysis, where autoproteolysis is minimal, can be used. To accomplish this, a method for rapid, quantifiable determination of substrate cleavage is required. Many of the existing assays are lacking in their sensitivity to accurately quantify calpain activity within this timeframe. However, the FRET peptide substrates developed by Cuerrier et al. have been shown to have sufficiently high affinity between substrate and enzyme to accurately measure the initial enzyme reaction velocity at substrate concentrations above the Km value. With a suitably sensitive fluorimeter, sufficient data can be obtained to evaluate calpain kinetics and inhibition. Here we describe a facile, reliable calpain assay based on the continuous monitoring of FRET fluorescence from the highly sensitive calpain-specific substrate, (EDANS)-EPLFAERK-(DABCYL). We illustrate some difficulties associated with determining kinetic constants of whole calpains that are simultaneously undergoing autoproteolysis and how the assay can be used to help characterize calpain-specific inhibitors. We also present a variation of this fluorescence-based assay for high-throughput screening using the calpain protease core and a fluorescence plate reader.
Collapse
Affiliation(s)
| | - Peter L Davies
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
| |
Collapse
|
7
|
Marinho FA, Sangenito LS, Oliveira SSC, De Arruda LB, D'Ávila-Levy CM, Santos ALS, Branquinha MH. The potent cell permeable calpain inhibitor MDL28170 affects the interaction of Leishmania amazonensis with macrophages and shows anti-amastigote activity. Parasitol Int 2017; 66:579-583. [PMID: 28663009 DOI: 10.1016/j.parint.2017.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 06/21/2017] [Accepted: 06/24/2017] [Indexed: 12/01/2022]
Abstract
Since the discovery of the28 first drugs used in leishmaniasis treatment up to now, the search for compounds with anti-Leishmania activity without toxic effects and able to overcome the emergency of resistant strains remains a major goal to combat this neglected disease. With this in mind, in the present work, we evaluated the effects of the calpain inhibitor MDL28170 on the interaction process of Leishmania amazonensis promastigote forms with murine peritoneal macrophages and on the intracellular amastigotes. Our results showed that the calpain inhibitor MDL28170 at 15 and 30μM significantly reduced the interaction process of promastigotes with macrophages by 16% and 41%, respectively. The inhibitor was also able to drastically reduce the number of infected macrophages in a time- and dose-dependent manner: after only 24h, MDL28170 was able to significantly diminish the infection rate, presenting an IC50 value of 18.2μM for amastigotes. The treatment with MDL28170 did not alter the nitric oxide production, but the production of TNF-α was significantly raised. Altogether, the results presented here contribute to the search of new proteolytic inhibitors able to act in a selective and effective manner against the diseases caused by trypanosomatids.
Collapse
Affiliation(s)
- Fernanda A Marinho
- Laboratório de Investigação de Peptidases, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil
| | - Leandro S Sangenito
- Laboratório de Investigação de Peptidases, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil
| | - Simone S C Oliveira
- Laboratório de Investigação de Peptidases, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil
| | - Luciana B De Arruda
- Laboratório de Genética e Imunologia das Infecções Virais, Departamento de Virologia, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil
| | - Claudia M D'Ávila-Levy
- Laboratório de Estudos Integrados em Protozoologia, Coleção de Protozoários, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - André L S Santos
- Laboratório de Investigação de Peptidases, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil; Programa de Pós-Graduação em Bioquímica, Instituto de Química, UFRJ, Rio de Janeiro, Brazil
| | - Marta H Branquinha
- Laboratório de Investigação de Peptidases, Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Brazil.
| |
Collapse
|
8
|
Derksen M, Vorwerk C, Siemen D. Calpeptin, not calpain, directly inhibits an ion channel of the inner mitochondrial membrane. Protoplasma 2016; 253:835-843. [PMID: 26108743 DOI: 10.1007/s00709-015-0846-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/08/2015] [Indexed: 06/04/2023]
Abstract
The permeability transition pore (PTP) of inner mitochondrial membranes is a large conductance pathway for ions up to 1500 Da which opening is responsible for ion equilibration and loss of membrane potential in apoptosis and thus in several neurodegenerative diseases. The PTP can be regulated by the Ca(2+)-activated mitochondrial K channel (BK). Calpains are Ca(2+)-activated cystein proteases; calpeptin is an inhibitor of calpains. We wondered whether calpain or calpeptin can modulate activity of PTP or BK. Patch clamp experiments were performed on mitoplasts of rat liver (PTP) and of an astrocytoma cell line (BK). Channel-independent open probability (P(o)) was determined (PTP) and, taking into account the number of open levels, NP(o) by single channel analysis (BK). We find that PTP in the presence of Ca(2+) (200 μM) is uninfluenced by calpain (13 nM) and shows insignificant decrease by the calpain inhibitor calpeptin (1 μM). The NP(o) of the BK is insensitive to calpain (54 nM), too. However, it is significantly and reversibly inhibited by the calpain inhibitor calpeptin (IC50 = 42 μM). The results agree with calpeptin-induced activation of the PTP via inhibition of the BK. Screening experiments with respirometry show calpeptin effects, fitting to inhibition of the BK by calpeptin, and strong inhibition of state 3 respiration.
Collapse
Affiliation(s)
- Maria Derksen
- Department of Neurology, Otto-von-Guericke-Universität, Leipziger Str. 44, D-39120, Magdeburg, Germany
| | | | - Detlef Siemen
- Department of Neurology, Otto-von-Guericke-Universität, Leipziger Str. 44, D-39120, Magdeburg, Germany.
| |
Collapse
|