ABSTRACT
BACKGROUND Calpains are present in almost all organisms and comprise a family of calcium-dependent cysteine peptidases implicated in crucial cellular functions. Trypanosoma cruzi, the causative agent of Chagas disease, presents an expansion on this gene family with unexplored biological properties. OBJECTIVES Here, we searched for calpains in the T. cruzi genome, evaluated the mRNA levels, calpain activity and the protein expression and determined the cellular localisation in all three parasite life cycle forms. METHODS/FINDINGS Sixty-three calpain sequences were identified in T. cruzi CL Brener genome, with fourteen domain arrangements. The comparison of calpain mRNA abundance by quantitative polymerase chain reaction (qPCR) revealed seven up-regulated sequences in amastigotes and/or bloodstream trypomastigotes and five in epimastigotes. Western Blotting analysis revealed seven different molecules in the three parasite forms, and one amastigote-specific, while no proteolytic activity could be detected. Flow cytometry assays revealed a higher amount of intracellular calpains in amastigotes and/or trypomastigotes in comparison to epimastigotes. Finally, ultrastructural analysis revealed the presence of calpains in the cytoplasm, vesicular and plasma membranes of the three parasite forms, and in the paraflagellar rod in trypomastigotes. CONCLUSION Calpains are differentially expressed and localised in the T. cruzi life cycle forms. This study adds data on the calpain occurrence and expression pattern in T. cruzi.
Subject(s)
Animals , Trypanosoma cruzi/genetics , Calpain/genetics , RNA, Messenger , Calpain/metabolism , Blotting, Western , Chagas Disease , Life Cycle StagesABSTRACT
BACKGROUND Calpains are proteins belonging to the multi-gene family of calcium-dependent cysteine peptidases that undergo tight on/off regulation, and uncontrolled proteolysis of calpains is associated with severe human pathologies. Calpain orthologues are expanded and diversified in the trypanosomatids genome. OBJECTIVES Here, we characterised calpains in Leishmania braziliensis, the main causative agent of cutaneous leishmaniasis in Brazil. METHODS/FINDINGS In total, 34 predicted calpain-like genes were identified. After domain structure evaluation, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) during in vitro metacyclogenesis revealed (i) five genes with enhanced expression in the procyclic stage, (ii) one augmented gene in the metacyclic stage, and (iii) one procyclic-exclusive transcript. Western blot analysis revealed that an antibody against a consensus-conserved peptide reacted with multiple calpain-like proteins, which is consistent with the multi-gene family characteristic. Flow cytometry and immunocytochemistry analyses revealed the presence of calpain-like molecules mainly in the cytoplasm, to a lesser extent in the plasma membrane, and negligible levels in the nucleus, which are all consistent with calpain localisation. Eventually, the calpain inhibitor MDL28170 was used for functional studies revealing (i) a leishmaniostatic effect, (ii) a reduction in the association index in mouse macrophages, (iii) ultra-structural alterations conceivable with autophagy, and (iv) an enhanced expression of the virulence factor GP63. CONCLUSION This report adds novel insights into the domain structure, expression, and localisation of L. braziliensis calpain-like molecules.
Subject(s)
Animals , Mice , Leishmania braziliensis/chemistry , Calpain/genetics , Macrophages, Peritoneal/metabolism , Genome, Protozoan/genetics , Leishmania braziliensis/genetics , Leishmania braziliensis/metabolism , Leishmania braziliensis/ultrastructure , Immunohistochemistry , Calpain/drug effects , Calpain/metabolism , Calpain/ultrastructure , Cysteine Proteinase Inhibitors/pharmacology , Gene Expression Regulation , Blotting, Western , Reverse Transcriptase Polymerase Chain Reaction , Virulence Factors , Microscopy, Electron, Transmission , Dipeptides/pharmacology , Flow Cytometry , Mice, Inbred BALB CSubject(s)
Animals , Male , Mice , Apoptosis Inducing Factor/metabolism , Calpain/metabolism , Poly(ADP-ribose) Polymerases/physiology , Active Transport, Cell Nucleus/genetics , Apoptosis Inducing Factor/genetics , Cells, Cultured , Calpain/antagonists & inhibitors , Calpain/deficiency , Calpain/genetics , Cell Death/physiology , Enzyme Activation/genetics , Poly(ADP-ribose) Polymerases/geneticsABSTRACT
Objective: To establish the determinants of the peak VO2 in heart transplant recipients. Methods: Patient's assessment was performed in two consecutive days. In the first day, patients performed the heart rate variability assessment followed by a cardiopulmonary exercise test. In the second day, patients performed a resting echocardiography. Heart transplant recipients were eligible if they were in a stable condition and without any evidence of tissue rejection diagnosed by endomyocardial biopsy. Patients with pacemaker, noncardiovascular functional limitations such as osteoarthritis and chronic obstructive pulmonary disease were excluded from this study. Results: Sixty patients (68% male, 48 years and 64 months following heart transplantation) were assessed. Multivariate analysis selected the following variables: receptor's gender (P=0.001), receptor age (P=0.049), receptor Body Mass Index (P=0.005), heart rate reserve (P <0.0001), left atrium diameter (P=0.016). Multivariate analysis showed r=0.77 and r2=0.6 with P <0.001. Equation: peakVO2=32.851 - 3.708 (receptor gender) - 0.067 (receptor age) - 0.318 (receptor BMI) + 0.145 (heart rate reserve) - 0.111 (left atrium diameter). Conclusion: The determinants of the peak VO2 in heart transplant recipients were: receptor sex, age, Body Mass Index, heart rate reserve and left atrium diameter. Heart rate reserve was the unique variable positively associated with peak VO2. This data suggest the importance of the sympathetic reinnervation in peak VO2 in heart transplant recipients. .
Objetivo: Estabelecer os determinantes do VO2 pico em transplantados de coração. Métodos: Avaliação do paciente foi realizada em dois dias consecutivos. No primeiro dia, os pacientes realizaram a avaliação da variabilidade da frequência cardíaca seguida de um teste de esforço cardiopulmonar. No segundo dia, os pacientes realizaram ecocardiografia de repouso. Os transplantados foram elegíveis se estivessem em uma condição estável e sem qualquer evidência de rejeição diagnosticada por biópsia endomiocárdica. Pacientes com marca-passo, limitações funcionais não cardiovasculares, tais como osteoartrite e doença pulmonar obstrutiva crônica foram excluídos deste estudo. Resultados: Sessenta pacientes (68% do sexo masculino, 48 anos e 64 meses após o transplante cardíaco) foram avaliados. A análise multivariada selecionou as seguintes variáveis: sexo (P=0,001), idade (P=0,049), Índice de Massa Corporal (P=0,005), frequência cardíaca de reserva (P <0,0001), diâmetro do átrio esquerdo (P=0,016), variáveis do receptor. A análise multivariada mostrou r=0,77 e r2=0,6, com P <0,001. Equação: VO2=32,851 - 3,708 (sexo receptor) - 0,067 (idade receptor) - 0,318 (IMC receptor) + 0,145 (frequência cardíaca de reserva) - 0,111 (diâmetro de átrio esquerdo). Conclusão: Os determinantes do pico de VO2 em transplantados de coração foram: sexo receptor, idade, Índice de Massa Corporal, frequência cardíaca de reserva e diâmetro do átrio esquerdo. A frequência cardíaca de reserva foi a única variável positivamente associada com o pico de VO2. Estes dados sugerem a importância da reinervação simpática no pico de VO2 em transplantados de coração. .
Subject(s)
Animals , Female , Humans , Male , Mice , Asthma/immunology , Asthma/physiopathology , Calpain/metabolism , /metabolism , Poly(ADP-ribose) Polymerases/metabolism , /metabolism , Allergens/immunology , Asthma/metabolism , Disease Models, Animal , Eosinophilia/immunology , Inflammation/immunology , /antagonists & inhibitors , /immunology , Mice, Inbred BALB C , Mice, Knockout , Poly(ADP-ribose) Polymerases/genetics , Respiratory System/immunology , Respiratory System/physiopathologyABSTRACT
N-myristoyltransferase (NMT) is an essential eukaryotic enzyme which catalyzes the transfer of the myristoyl group to the terminal glycine residue of a number of proteins including those involved in signal transduction and apoptotic pathways. In higher eukaryotes, two isoforms of NMT have been identified (NMT1 and NMT2) which share about 76% amino acid sequence identity in humans. Protein-protein interactions of NMTs reveal that m-calpain interacts with NMT1 whereas caspase-3 interacts with NMT2. These findings reveal differential interactions of both isoforms of NMT with various signaling molecules. This minireview provides an overview of the regulation of N-myristoyltransferase by calpain and caspase systems.
Subject(s)
Acyltransferases/metabolism , Animals , Calpain/metabolism , Caspases/metabolism , Gene Expression Regulation, Enzymologic/physiology , Humans , Lipid Metabolism/physiology , Models, Biological , Signal Transduction/physiologyABSTRACT
OBJECTIVES: to analyze the Pelvic Floor Muscle Strength (PFMS) of pregnant women with one or more vaginal or cesarean deliveries; to compare the PFMS of these with pregnant women with the PFMS of primiparous women. METHODS: cross-sectional study with women up to 12 weeks pregnant, performed in Itapecerica da Serra, São Paulo state, from December 2012 to May 2013. The sample consisted of 110 pregnant women with one or more vaginal deliveries or cesarean sections and 110 primigravidae. The PFMS was evaluated by perineometry (Peritron(tm)) and vaginal digital palpation (modified Oxford scale). RESULTS: the average PFMS in pregnant women with a history of vaginal delivery or cesarean section was 33.4 (SD=21.2) cmH2O. From the Oxford scale, 75.4% of the pregnant women with previous vaginal or cesarean deliveries presented grade ≤ 2, and 5.5% grade ≥ 4; among the primiparae, 39.9% presented grade ≤ 2, and 50.9% grade ≥ 4, with a statistically significant difference (p<0.001). From the perineometry, there was no statistically significant difference between the PFMS and age, type of delivery, parity, body mass index, and genitourinary tract symptoms, however, there was a statistically significant difference between the pregnant women with and without a history of episiotomy (p=0.04). In the palpation, none of the variables showed a statistically significant difference. CONCLUSION: pregnancy and childbirth can reduce the PFMS. .
OBJETIVOS: analisar a força muscular do assoalho pélvico de gestantes com um ou mais partos normais ou cesarianas; comparar a a força muscular do assoalho pélvico dessas gestantes com a de primigestas. MÉTODO: estudo transversal com gestantes até 12 semanas de gravidez, realizado em Itapecerica da Serra, SP, de dezembro de 2012 a maio de 2013. A amostra foi composta por 110 gestantes, com um ou mais partos normais ou cesarianas e 110 primigestas. A força muscular do assoalho pélvico foi avaliada pela perineometria e palpação digital vaginal (Escala de Oxford modificada). RESULTADOS: a média da força muscular do assoalho pélvico em gestantes com antecedentes de parto normal ou cesariana foi 33,4 (desvio-padrão=21,2) cmH2O. Pela escala de Oxford, 75,4% das gestantes com partos ou cesarianas anteriores apresentaram grau ≤2 e 5,5%, grau ≥4; entre as primigestas, 39,9% apresentaram grau ≤2 e 50,9%, grau ≥4, com diferença estatisticamente significante (p<0,001). Pela perineometria, não houve diferença estatisticamente significante entre a força muscular do assoalho pélvico e idade, tipo de parto, paridade, índice de massa corpórea e sintomas do trato geniturinário, mas houve entre as gestantes com e sem antecedente de episiotomia (p=0,04). Na palpação, nenhuma das variáveis mostrou diferença estatisticamente significante. CONCLUSÃO: a gravidez e o parto podem reduzir a força muscular do assoalho pélvico. .
OBJETIVOS: analizar la Fuerza Muscular del Suelo Pélvico (FMSP) de embarazadas con uno o más partos normales o cesáreas; comparar la FMSP de estas embarazadas con la FMSP de primigestas. MÉTODO: estudio transversal con embarazadas hasta 12 semanas de embarazo, realizado en Itapecerica de la Serra, SP, de diciembre de 2012 a mayo de 2013. La muestra fue de 110 embarazadas con uno o más partos normales o cesáreas y 110 primigestas. La FMSP fue evaluada por la perineometría (Peritron(tm)) y palpación digital vaginal (escala de Oxford modificada). RESULTADOS: el promedio de la FMSP en embarazadas con antecedentes de parto normal o cesárea fue 33,4 (de=21,2) cmH2O. Por la escala de Oxford, 75,4% de las embarazadas con partos o cesáreas anteriores presentaron grado ≤ 2 y 5,5%, grado ≥ 4; entre las primigestas, 39,9% presentaron grado ≤ 2 y 50,9%, grado ≥ 4, con diferencia estadísticamente significativa (p<0,001). Por la perineometría, no hubo diferencia estadísticamente significativa entre la FMSP y edad, tipo de parto, número de partos anteriores, índice de masa corporal y síntomas del tracto genitourinario, pero hubo entre las embarazadas con y sin antecedente de episiotomía (p=0,04). En la palpación, ninguna de las variables mostró diferencia estadísticamente significativa. CONCLUSIÓN: el embarazo y el parto pueden reducir la FMSP. .
Subject(s)
Calcium , Calmodulin , Calpain , Binding Sites , Calcium/pharmacology , Calmodulin/antagonists & inhibitors , Calpain/antagonists & inhibitors , Calpain/metabolism , Fluorescent Dyes , Felodipine/pharmacology , In Vitro Techniques , Imidazoles/pharmacology , Leucine/analogs & derivatives , Leucine/pharmacology , Molecular Conformation , Naphthalenesulfonates/pharmacology , Spectrometry, FluorescenceABSTRACT
There is growing evidence that ouabain, a cardiotonic steroid may promote growth of cardiac and vascular myocytes, indicating its novel role in cell growth and proliferation, without appreciable inhibition of the sodium pump. The mechanism(s) by which low dose of ouabain produces pulmonary artery smooth muscle cell proliferation, a prerequisite for right ventricular hypertrophy, is currently unknown. Here, we analyzed the effects of low dose of ouabain (10 nM) on increase in [Ca2+]i, m-calpain and protein kinase C (PKC) activities on pulmonary artery smooth muscle cell proliferation and determined their sequential involvement in this scenario. We treated bovine pulmonary artery smooth muscle cells with a low dose of ouabain (10 nM) and determined [Ca2+]i in the cells by fluorometric assay using fura2-AM, m-calpain activity by fluorometric assay using SLLVY-AMC as the substrate, PKC activity using an assay kit and assay of Na+/K+ATPase activity spectrophotometrically. We purified m-calpain and PKCα by standard chromatographic procedure by HPLC and then studied cleavage of the purified PKCα by m-calpain using Western immunoblot method. Subsequently, we performed cell proliferation assay utilizing the redox dye resazunin. We used selective inhibitors of [Ca2+]i (BAPTA-AM), m-calpain (MDL28170), PKCα (Go6976) and determined their involvement in ouabain (10 nM)-mediated smooth muscle cell proliferation. Our results suggested that treatment of bovine pulmonary artery smooth muscle cells with a low dose of ouabain (10 nM) increased [Ca2+]i and subsequently stimulated m-calpain activity and proteolytically activated PKCα in caveolae (signaling microdomain also known as signalosomes) of the cells. Upon activation, PKCα increased the smooth muscle cell proliferation via Go/G1 to S/G2-M phase transition. Thus, [Ca2+]i-mCalpain-PKCα signaling axis plays a crucial role during low dose of ouabain-mediated pulmonary artery smooth muscle cell proliferation.
Subject(s)
Amino Acid Sequence , Animals , Calpain/metabolism , Cattle , Caveolae/drug effects , Caveolae/metabolism , Cell Cycle/drug effects , Cell Proliferation/drug effects , Cell Survival/drug effects , Dose-Response Relationship, Drug , Enzyme Activation/drug effects , Molecular Sequence Data , Myocytes, Smooth Muscle/cytology , Myocytes, Smooth Muscle/drug effects , Myocytes, Smooth Muscle/metabolism , Ouabain/pharmacology , Protein Kinase C-alpha/chemistry , Protein Kinase C-alpha/metabolism , Proteolysis/drug effects , Pulmonary Artery/cytology , Sodium-Potassium-Exchanging ATPase/metabolismABSTRACT
OBJECTIVE@#To investigate the expressions of calpain1 and calpain2 during the skin incised wound healing in mice.@*METHODS@#Expression of calpain1 and calpain2 was evaluated by immunohistochemical method.@*RESULTS@#Both calpain1 and calpain2 were expressed in the skin cells in the control groups. The calpain1 positive cells were remarkably increased and reached the maximal level in day 1 after skin incised wound, decreased after day 3, markedly increased again in day 5, and then gradually decreased from day 7 to 14; the calpain2 positive cells were significantly increased in day 1 and decreased to the minimum in day 3, markedly increased again in day 5, and then gradually decreased from day 7 to 10.@*CONCLUSION@#The changes of calpain1 and calpain2 expressions appear to be bimodal after incised wound of skin in mice.
Subject(s)
Animals , Female , Male , Mice , Apoptosis , Calpain/metabolism , Disease Models, Animal , Immunohistochemistry , Random Allocation , Skin/metabolism , Staining and Labeling , Time Factors , Wound Healing , Wounds and Injuries/physiopathologyABSTRACT
Familial amyotrophic lateral sclerosis (fALS) is caused by mutations in Cu/Zn-superoxide dismutase (SOD1), and SOD1 aggregation and calcium toxicity are involved in neuronal death. However, the effect of altered calcium homeostasis on the SOD1 aggregation is unknown. To investigate whether calcium triggers mutant SOD1 aggregation in vitro, human mutant SOD1 (G93A) was transfected into motor neuronal cell line (VSC 4.1 cells). These cells were then treated with calcium ionophore A23187 or agents that induce intracellular calcium release like cyclic ADP ribose, ryanodine or thapsigargin. A23187 was found to increase mutant SOD1 aggregation and neuronal nitric oxide synthase (nNOS) expression. Moreover, the NOS inhibitor (L-NAME) and a NO-dependent cyclic GMP cascade inhibitor (ODQ) reduced SOD1 aggregation, whereas an exogenous NO donor (GSNO) increased mutant SOD1 aggregation, which was also prevented by NOS or cGMP cascade inhibitor. Our data demonstrate that calcium-influx increases SOD1 aggregation by upregulating NO in cultured motor neuronal cells.
Subject(s)
Animals , Humans , Rats , Amyotrophic Lateral Sclerosis/genetics , Calcimycin/pharmacology , Calcium/metabolism , Calpain/metabolism , Caspase 3/metabolism , Cell Line , Ionophores/pharmacology , Motor Neurons/metabolism , Multiprotein Complexes , Mutation , Nitric Oxide/metabolism , Recombinant Proteins/chemistry , Superoxide Dismutase/chemistry , TransfectionABSTRACT
Clathrin-mediated vesicle formation is an essential step in the intracellular trafficking of the protein and lipid. Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicles (CCVs). In order to better understand a possible role of post-translational modification of CALM (clathrin assembly protein lymphoid myeloid), the homologue of AP180, in the assembly of CCVs, CALM was expressed in the cell-free reticulocyte translation system that is capable of carrying out post-translational modification. The apparent molecular weight of the expressed recombinant CALM was estimated as 105 kD. Alkaline phosphatase treatment of CALM resulted in a mobility shift on SDS-PAGE. We found that CALM was associated with the proteins harboring SH3 domain, promote assembly of clathrin triskelia into clathrin cage and bound to the preformed clathrin cage. CALM was also proteolyzed by caspase 3 and calpain but not by caspase 8. These results indicated that the post-translationally modified CALM, expressed in the eukaryotic cell-free reticulocyte translation system was able to mediate the assembly of clathrin and the coated-vesicle formation.
Subject(s)
Cattle , Alkaline Phosphatase/pharmacology , Animals , Brain/metabolism , Calpain/metabolism , Carrier Proteins/chemistry , Caspases/metabolism , Cell-Free System , Clathrin/chemistry , Electrophoresis, Polyacrylamide Gel , Glutathione Transferase/metabolism , Lipids/chemistry , Membrane Proteins/chemistry , Phosphorylation , Protein Binding , Protein Processing, Post-Translational , Protein Structure, Tertiary , Protein Transport , Recombinant Proteins/chemistry , Reticulocytes/metabolism , Protein Biosynthesis , src Homology DomainsABSTRACT
The most efficient means of protein internalization from the membrane are through clathrin-coated pits, which concentrate protein interactions with the clathrin-associated assembly protein complex AP-2 and internalization signals in the cytoplasmic domain of transmembrane proteins. Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicles (CCVs). Due to a difficulty of isolating clathrin molecules from their complex or assembly state in the cells, most of the studies were carried out with recombinant clathrin proteins, which may present different conformation and structural variation. In this study, we have developed an efficient method of isolating the native clathrin assembly protein lymphoid myeloid (CALM) from the bovine brain that is enriched with clathrin and clathrin associated proteins and characterized by their sensitivity to proteases and it's ability to form CCV. The purified CALM has molecular weight of approximately 100,000 dalton on SDS-PAGE, which is consistent with the result of in vitro translation. The purified CALM protein could promote the assembly of clathrin triskelia into clathrin cage, and cleaved CALM proteolysed by caspase 3 and calpain could not promote them. In this respect, our data support a model in which CALM functions like AP180 as a monomeric clathrin assembly protein and might take part in apoptotic process in neuronal cells.
Subject(s)
Cattle , Adaptor Proteins, Vesicular Transport , Animals , Brain Chemistry , Calpain/metabolism , Carrier Proteins , Caspases/metabolism , Clathrin/metabolism , Coated Pits, Cell-Membrane/metabolism , Hydrolysis , Membrane Proteins , Molecular Weight , Nerve Tissue Proteins/chemistry , Neurons/chemistry , Protein Binding , Protein Conformation , Recombinant Proteins/chemistryABSTRACT
The most efficient means of protein internalization from the membrane are through clathrin-coated pits, which concentrate protein interactions with the clathrin-associated assembly protein complex AP-2 and internalization signals in the cytoplasmic domain of transmembrane proteins. Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicles (CCVs). Due to a difficulty of isolating clathrin molecules from their complex or assembly state in the cells, most of the studies were carried out with recombinant clathrin proteins, which may present different conformation and structural variation. In this study, we have developed an efficient method of isolating the native clathrin assembly protein lymphoid myeloid (CALM) from the bovine brain that is enriched with clathrin and clathrin associated proteins and characterized by their sensitivity to proteases and it's ability to form CCV. The purified CALM has molecular weight of approximately 100,000 dalton on SDS-PAGE, which is consistent with the result of in vitro translation. The purified CALM protein could promote the assembly of clathrin triskelia into clathrin cage, and cleaved CALM proteolysed by caspase 3 and calpain could not promote them. In this respect, our data support a model in which CALM functions like AP180 as a monomeric clathrin assembly protein and might take part in apoptotic process in neuronal cells.
Subject(s)
Cattle , Adaptor Proteins, Vesicular Transport , Animals , Brain Chemistry , Calpain/metabolism , Carrier Proteins , Caspases/metabolism , Clathrin/metabolism , Coated Pits, Cell-Membrane/metabolism , Hydrolysis , Membrane Proteins , Molecular Weight , Nerve Tissue Proteins/chemistry , Neurons/chemistry , Protein Binding , Protein Conformation , Recombinant Proteins/chemistryABSTRACT
Calpain I (mu-calpain) and II (m-calpain) are well known calcium-activated neutral cysteine proteases. Many reports have shown that activation of calpain is related to cataract formation, neuronal degeneration, blood clotting, ischemic injuries, muscular dystrophy and cornified cell envelope (CE) formation. Here, we report that insoluble CE formation was reduced after treatment with calpain I inhibitor (N-acetyl-leucyl-leucyl-norleucinal) on normal human epidermal keratinocytes (NHEK), whereas serine and thiol protease inhibitors had no effect on the reduction of CE. When NHEK cells were confluent, keratinocytes were treated with various concentrations (0.5 microM-0.5 mM) of calpain I inhibitor or serine and thiol protease inhibitors under calcium induced differentiation. Insoluble CE formation was reduced about 90% in the 50 microM calpain inhibitor I treated group by day 9 of culture, whereas insoluble CE was reduced only 10% in the same condition. Interestingly TGase activity was blocked by 90% in the 0.5 mM calpain inhibitor treated group within 72 h, whereas TGase activity was retained by 80% in the 0.5 mM serine protease inhibitor treated group at 7 day treatment. Therefore it can be suggested that cysteine protease calpains might be responsible for the activation of the TGase 1 enzyme to complete insoluble CE formation during epidermal differentiation.
Subject(s)
Humans , Calcium/pharmacology , Calpain/metabolism , Calpain/antagonists & inhibitors , Cell Differentiation , Dose-Response Relationship, Drug , Epidermis/metabolism , In Vitro Techniques , Keratinocytes/metabolism , Keratinocytes/enzymology , Protease Inhibitors/pharmacology , Transglutaminases/metabolism , Transglutaminases/antagonists & inhibitors , Culture TechniquesABSTRACT
Heart tissue contains large amounts of the Ca²+ -activated protein-ase calpain which has been assigned a specific function in the turnover of muscle protein. The objective of the present study was to determine calpain (E.C. 3.4.22.17)-like activity in homogenates of left ventricle from hypertensive rats that developed ventricular hypertrophy. Calpain activity was assayed using heat-denaturated azocasein as a substrate in the presence of 1 mM calcium and corrected by subtraction of the Ca²+ -independent activities. Tha latter were measured in the presence of 1 mM EGTA and the products read at 440nm. Male Wistar rats (225g) were assgned to control (N=8, normal drinking water), salt (N=6, drinking water containing 1 percent NaCl) and DOCA-salt (N=6, deoxycorticosterone acetate, 8 mg/Kg, sc, twice a week for 20 days plus drinking water containing 1 percent NaCl) groups. SHR (N =6, spontaneously hypertensive rats) were also used. The calpain activity of the control group was at 3.90 ñ 0.22 mU/g wet weight tissue. Hypertension induced significant left ventricular hypertrophy in DOCA-salt rats (26 percent) and in SHR (54 percent) and a 30 percent decrease in calpain activity in both groups (P < 0.01). In the high salt load (salt group) calpain activity was also decreased, but this was not accompanied by hypertrophy...