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1.
JAMIA Open ; 7(1): ooae015, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38414534

ABSTRACT

Objectives: In the United States, end-stage kidney disease (ESKD) is responsible for high mortality and significant healthcare costs, with the number of cases sharply increasing in the past 2 decades. In this study, we aimed to reduce these impacts by developing an ESKD model for predicting its occurrence in a 2-year period. Materials and Methods: We developed a machine learning (ML) pipeline to test different models for the prediction of ESKD. The electronic health record was used to capture several kidney disease-related variables. Various imputation methods, feature selection, and sampling approaches were tested. We compared the performance of multiple ML models using area under the ROC curve (AUCROC), area under the Precision-Recall curve (PR-AUC), and Brier scores for discrimination, precision, and calibration, respectively. Explainability methods were applied to the final model. Results: Our best model was a gradient-boosting machine with feature selection and imputation methods as additional components. The model exhibited an AUCROC of 0.97, a PR-AUC of 0.33, and a Brier score of 0.002 on a holdout test set. A chart review analysis by expert physicians indicated clinical utility. Discussion and Conclusion: An ESKD prediction model can identify individuals at risk for ESKD and has been successfully deployed within our health system.

2.
JCI Insight ; 9(1)2023 Nov 28.
Article in English | MEDLINE | ID: mdl-38015634

ABSTRACT

Pulmonary fibrosis is a chronic and often fatal disease. The pathogenesis is characterized by aberrant repair of lung parenchyma, resulting in loss of physiological homeostasis, respiratory failure, and death. The immune response in pulmonary fibrosis is dysregulated. The gut microbiome is a key regulator of immunity. The role of the gut microbiome in regulating the pulmonary immunity in lung fibrosis is poorly understood. Here, we determine the impact of gut microbiota on pulmonary fibrosis in substrains of C57BL/6 mice derived from different vendors (C57BL/6J and C57BL/6NCrl). We used germ-free models, fecal microbiota transplantation, and cohousing to transmit gut microbiota. Metagenomic studies of feces established keystone species between substrains. Pulmonary fibrosis was microbiota dependent in C57BL/6 mice. Gut microbiota were distinct by ß diversity and α diversity. Mortality and lung fibrosis were attenuated in C57BL/6NCrl mice. Elevated CD4+IL-10+ T cells and lower IL-6 occurred in C57BL/6NCrl mice. Horizontal transmission of microbiota by cohousing attenuated mortality in C57BL/6J mice and promoted a transcriptionally altered pulmonary immunity. Temporal changes in lung and gut microbiota demonstrated that gut microbiota contributed largely to immunological phenotype. Key regulatory gut microbiota contributed to lung fibrosis, generating rationale for human studies.


Subject(s)
Gastrointestinal Microbiome , Microbiota , Pulmonary Fibrosis , Mice , Animals , Humans , Gastrointestinal Microbiome/physiology , Mice, Inbred C57BL , Lung , Microbiota/physiology
3.
Redox Biol ; 68: 102949, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37922764

ABSTRACT

Hydropersulfide and hydropolysulfide metabolites are increasingly important reactive sulfur species (RSS) regulating numerous cellular redox dependent functions. Intracellular production of these species is known to occur through RSS interactions or through translational mechanisms involving cysteinyl t-RNA synthetases. However, regulation of these species under cell stress conditions, such as hypoxia, that are known to modulate RSS remain poorly understood. Here we define an important mechanism of increased persulfide and polysulfide production involving cystathionine gamma lyase (CSE) phosphorylation at serine 346 and threonine 355 in a substrate specific manner, under acute hypoxic conditions. Hypoxic phosphorylation of CSE occurs in an AMP kinase dependent manner increasing enzyme activity involving unique inter- and intramolecular interactions within the tetramer. Importantly, both cellular hypoxia and tissue ischemia result in AMP Kinase dependent CSE phosphorylation that regulates blood flow in ischemic tissues. Our findings reveal hypoxia molecular signaling pathways regulating CSE dependent persulfide and polysulfide production impacting tissue and cellular response to stress.


Subject(s)
Hydrogen Sulfide , Humans , Hydrogen Sulfide/metabolism , Phosphorylation , Adenylate Kinase/metabolism , Cystathionine gamma-Lyase/genetics , Hypoxia
4.
Redox Biol ; 57: 102480, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36167027

ABSTRACT

Methamphetamine (METH) is an addictive illicit drug used worldwide that causes significant damage to blood vessels resulting in cardiovascular dysfunction. Recent studies highlight increased prevalence of cardiovascular disease (CVD) and associated complications including hypertension, vasospasm, left ventricular hypertrophy, and coronary artery disease in younger populations due to METH use. Here we report that METH administration in a mouse model of 'binge and crash' decreases cardiovascular function via cystathionine gamma lyase (CSE), hydrogen sulfide (H2S), nitric oxide (NO) (CSE/H2S/NO) dependent pathway. METH significantly reduced H2S and NO bioavailability in plasma and skeletal muscle tissues co-incident with a significant reduction in flow-mediated vasodilation (FMD) and blood flow velocity revealing endothelial dysfunction. METH administration also reduced cardiac ejection fraction (EF) and fractional shortening (FS) associated with increased tissue and perivascular fibrosis. Importantly, METH treatment selectively decreased CSE expression and sulfide bioavailability along with reduced eNOS phosphorylation and NO levels. Exogenous sulfide therapy or endothelial CSE transgenic overexpression corrected cardiovascular and associated pathological responses due to METH implicating a central molecular regulatory pathway for tissue pathology. These findings reveal that therapeutic intervention targeting CSE/H2S bioavailability may be useful in attenuating METH mediated cardiovascular disease.

5.
Am J Pathol ; 192(1): 160-177, 2022 01.
Article in English | MEDLINE | ID: mdl-34710383

ABSTRACT

Sigma 1 receptor (Sigmar1) is a widely expressed, multitasking molecular chaperone protein that plays functional roles in several cellular processes. Mutations in the Sigmar1 gene are associated with several distal neuropathies with strong manifestation in skeletal muscle dysfunction with phenotypes like muscle wasting and atrophy. However, the physiological function of Sigmar1 in skeletal muscle remains unknown. Herein, the physiological role of Sigmar1 in skeletal muscle structure and function in gastrocnemius, quadriceps, soleus, extensor digitorum longus, and tibialis anterior muscles was determined. Quantification of myofiber cross-sectional area showed altered myofiber size distribution and changes in myofiber type in the skeletal muscle of the Sigmar1-/- mice. Interestingly, ultrastructural analysis by transmission electron microscopy showed the presence of abnormal mitochondria, and immunostaining showed derangements in dystrophin localization in skeletal muscles from Sigmar1-/- mice. In addition, myopathy in Sigmar1-/- mice was associated with an increased number of central nuclei, increased collagen deposition, and fibrosis. Functional studies also showed reduced endurance and exercise capacity in the Sigmar1-/- mice without any changes in voluntary locomotion, markers for muscle denervation, and muscle atrophy. Overall, this study shows, for the first time, a potential physiological function of Sigmar1 in maintaining healthy skeletal muscle structure and function.


Subject(s)
Muscle, Skeletal/metabolism , Muscle, Skeletal/physiopathology , Receptors, sigma/deficiency , Animals , Collagen/metabolism , Dystrophin/metabolism , Fibrosis , Mice, Inbred C57BL , Mice, Knockout , Mitochondria/metabolism , Mitochondria/ultrastructure , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/ultrastructure , Physical Conditioning, Animal , Protein Transport , Receptors, sigma/metabolism , Sigma-1 Receptor
6.
Mitochondrion ; 62: 159-175, 2022 01.
Article in English | MEDLINE | ID: mdl-34902622

ABSTRACT

Sigmar1 is a widely expressed molecular chaperone protein in mammalian cell systems. Accumulating research demonstrated the cardioprotective roles of pharmacologic Sigmar1 activation by ligands in preclinical rodent models of cardiac injury. Extensive biochemical and immuno-electron microscopic research demonstrated Sigmar1's sub-cellular localization largely depends on cell and organ types. Despite comprehensive studies, Sigmar1's direct molecular role in cardiomyocytes remains elusive. In the present study, we determined Sigmar1's subcellular localization, transmembrane topology, and function using complementary microscopy, biochemical, and functional assays in cardiomyocytes. Quantum dots in transmission electron microscopy showed Sigmar1 labeled quantum dots on the mitochondrial membranes, lysosomes, and sarcoplasmic reticulum-mitochondrial interface. Subcellular fractionation of heart cell lysates confirmed Sigmar1's localization in purified mitochondria fraction and lysosome fraction. Immunocytochemistry confirmed Sigmar1 colocalization with mitochondrial proteins in isolated adult mouse cardiomyocytes. Sigmar1's mitochondrial localization was further confirmed by Sigmar1 colocalization with Mito-Tracker in isolated mouse heart mitochondria. A series of biochemical experiments, including alkaline extraction and proteinase K treatment of purified heart mitochondria, demonstrated Sigmar1 as an integral mitochondrial membrane protein. Sigmar1's structural requirement for mitochondrial localization was determined by expressing FLAG-tagged Sigmar1 fragments in cells. Full-length Sigmar1 and Sigmar1's C terminal-deletion fragments were able to localize to the mitochondrial membrane, whereas N-terminal deletion fragment was unable to incorporate into the mitochondria. Finally, functional assays using extracellular flux analyzer and high-resolution respirometry showed Sigmar1 siRNA knockdown significantly altered mitochondrial respiration in cardiomyocytes. Overall, we found that Sigmar1 localizes to mitochondrial membranes and is indispensable for maintaining mitochondrial respiratory homeostasis in cardiomyocytes.


Subject(s)
Mitochondria, Heart/physiology , Myocytes, Cardiac/metabolism , Protein Transport/physiology , Receptors, sigma/metabolism , Animals , Energy Metabolism/physiology , Female , Gene Knockdown Techniques , HEK293 Cells , Humans , Male , Mice , RNA, Small Interfering , Rats , Receptors, sigma/genetics , Sigma-1 Receptor
7.
J Am Heart Assoc ; 9(23): e017195, 2020 12.
Article in English | MEDLINE | ID: mdl-33208022

ABSTRACT

Background The mutated α-B-Crystallin (CryABR120G) mouse model of desmin-related myopathy (DRM) shows an age-dependent onset of pathologic cardiac remodeling and progression of heart failure. CryABR120G expression in cardiomyocytes affects the mitochondrial spatial organization within the myofibrils, but the molecular perturbation within the mitochondria in the relation of the overall course of the proteotoxic disease remains unclear. Methods and Results CryABR120G mice show an accumulation of electron-dense aggregates and myofibrillar degeneration associated with the development of cardiac dysfunction. Though extensive studies demonstrated that these altered ultrastructural changes cause cardiac contractility impairment, the molecular mechanism of cardiomyocyte death remains elusive. Here, we explore early pathological processes within the mitochondria contributing to the contractile dysfunction and determine the pathogenic basis for the heart failure observed in the CryABR120G mice. In the present study, we report that the CryABR120G mice transgenic hearts undergo altered mitochondrial dynamics associated with increased level of dynamin-related protein 1 and decreased level of optic atrophy type 1 as well as mitofusin 1 over the disease process. In association with these changes, an altered level of the components of mitochondrial oxidative phosphorylation and pyruvate dehydrogenase complex regulatory proteins occurs before the manifestation of pathologic adverse remodeling in the CryABR120G hearts. Mitochondria isolated from CryABR120G transgenic hearts without visible pathology show decreased electron transport chain complex activities and mitochondrial respiration. Taken together, we demonstrated the involvement of mitochondria in the pathologic remodeling and progression of DRM-associated cellular dysfunction. Conclusions Mitochondrial dysfunction in the form of altered mitochondrial dynamics, oxidative phosphorylation and pyruvate dehydrogenase complex proteins level, abnormal electron transport chain complex activities, and mitochondrial respiration are evident on the CryABR120G hearts before the onset of detectable pathologies and development of cardiac contractile dysfunction.


Subject(s)
Cardiomyopathies/etiology , Cardiomyopathies/pathology , Mitochondrial Dynamics/physiology , Oxidative Phosphorylation , Animals , Cardiomyopathies/metabolism , Desmin , Disease Models, Animal , Mice , Mice, Transgenic , alpha-Crystallin B Chain
8.
Commun Biol ; 3(1): 682, 2020 11 17.
Article in English | MEDLINE | ID: mdl-33203971

ABSTRACT

Methamphetamine-associated cardiomyopathy is the leading cause of death linked with illicit drug use. Here we show that Sigmar1 is a therapeutic target for methamphetamine-associated cardiomyopathy and defined the molecular mechanisms using autopsy samples of human hearts, and a mouse model of "binge and crash" methamphetamine administration. Sigmar1 expression is significantly decreased in the hearts of human methamphetamine users and those of "binge and crash" methamphetamine-treated mice. The hearts of methamphetamine users also show signs of cardiomyopathy, including cellular injury, fibrosis, and enlargement of the heart. In addition, mice expose to "binge and crash" methamphetamine develop cardiac hypertrophy, fibrotic remodeling, and mitochondrial dysfunction leading to contractile dysfunction. Methamphetamine treatment inhibits Sigmar1, resulting in inactivation of the cAMP response element-binding protein (CREB), decreased expression of mitochondrial fission 1 protein (FIS1), and ultimately alteration of mitochondrial dynamics and function. Therefore, Sigmar1 is a viable therapeutic agent for protection against methamphetamine-associated cardiomyopathy.


Subject(s)
Cardiomyopathies/chemically induced , Methamphetamine/toxicity , Mitochondria/drug effects , Receptors, sigma/metabolism , Animals , Cardiomyopathies/prevention & control , Cyclic AMP Response Element-Binding Protein/genetics , Cyclic AMP Response Element-Binding Protein/metabolism , Drug Administration Schedule , Gene Expression Regulation/drug effects , Heart/drug effects , Humans , Methamphetamine/administration & dosage , Mice , Mitochondria/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Myocardium/pathology , Myocytes, Cardiac/drug effects , Receptors, sigma/genetics , Sigma-1 Receptor
9.
Mol Pharm ; 17(12): 4676-4690, 2020 12 07.
Article in English | MEDLINE | ID: mdl-33151075

ABSTRACT

The molecular architecture of pH-responsive amphiphilic block copolymers, their self-assembly behavior to form nanoparticles (NPs), and doxorubicin (DOX)-loading technique govern the extent of DOX-induced cardiotoxicity. We observed that the choice of pH-sensitive tertiary amines, surface charge, and DOX-loading techniques within the self-assembled NPs strongly influence the release and stimulation of DOX-induced cardiotoxicity in primary cardiomyocytes. However, covalent conjugation of DOX to a pH-sensitive nanocarrier through a "conditionally unstable amide" linkage (PCPY-cDOX; PC = polycarbonate and PY = 2-pyrrolidine-1-yl-ethyl-amine) significantly reduced the cardiotoxicity of DOX in cardiomyocytes as compared to noncovalently encapsulated DOX NPs (PCPY-eDOX). When these formulations were tested for drug release in serum-containing media, the PCPY-cDOX systems showed prolonged control over drug release (for ∼72 h) at acidic pH compared to DOX-encapsulated nanocarriers, as expected. We found that DOX-encapsulated nanoformulations triggered cardiotoxicity in primary cardiomyocytes more acutely, while conjugated systems such as PCPY-cDOX prevented cardiotoxicity by disabling the nuclear entry of the drug. Using 2D and 3D (spheroid) cultures of an ER + breast cancer cell line (MCF-7) and a triple-negative breast cancer cell line (MDA-MB-231), we unravel that, similar to encapsulated systems (PCPY-eDOX-type) as reported earlier, the PCPY-cDOX system suppresses cellular proliferation in both cell lines and enhances trafficking through 3D spheroids of MDA-MB-231 cells. Collectively, our studies indicate that PCPY-cDOX is less cardiotoxic as compared to noncovalently encapsulated variants without compromising the chemotherapeutic properties of the drug. Thus, our studies suggest that the appropriate selection of the nanocarrier for DOX delivery may prove fruitful in shifting the balance between low cardiotoxicity and triggering the chemotherapeutic potency of DOX.


Subject(s)
Cardiotoxicity/prevention & control , Doxorubicin/administration & dosage , Drug Carriers/chemistry , Neoplasms/drug therapy , Polymers/chemistry , Animals , Animals, Newborn , Cardiotoxicity/etiology , Cell Line, Tumor , Doxorubicin/pharmacokinetics , Doxorubicin/toxicity , Drug Compounding/methods , Drug Liberation , Drug Screening Assays, Antitumor , Humans , Hydrogen-Ion Concentration , Myocytes, Cardiac , Nanoparticles/chemistry , Neoplasms/pathology , Polycarboxylate Cement , Primary Cell Culture , Pyrrolidines/chemistry , Rats , Spheroids, Cellular , Toxicity Tests, Acute
10.
Front Physiol ; 11: 1054, 2020.
Article in English | MEDLINE | ID: mdl-32982788

ABSTRACT

Mitochondria are the key to properly functioning energy generation in the metabolically demanding cardiomyocytes and thus essential to healthy heart contractility on a beat-to-beat basis. Mitochondria being the central organelle for cellular metabolism and signaling in the heart, its dysfunction leads to cardiovascular disease. The healthy mitochondrial functioning critical to maintaining cardiomyocyte viability and contractility is accomplished by adaptive changes in the dynamics, biogenesis, and degradation of the mitochondria to ensure cellular proteostasis. Recent compelling evidence suggests that the classical protein quality control system in cardiomyocytes is also under constant mitochondrial control, either directly or indirectly. Impairment of cytosolic protein quality control may affect the position of the mitochondria in relation to other organelles, as well as mitochondrial morphology and function, and could also activate mitochondrial proteostasis. Despite a growing interest in the mitochondrial quality control system, very little information is available about the molecular function of mitochondria in cardiac proteostasis. In this review, we bring together current understanding of the adaptations and role of the mitochondria in cardiac proteostasis and describe the adaptive/maladaptive changes observed in the mitochondrial network required to maintain proteomic integrity. We also highlight the key mitochondrial signaling pathways activated in response to proteotoxic stress as a cellular mechanism to protect the heart from proteotoxicity. A deeper understanding of the molecular mechanisms of mitochondrial adaptations and their role in cardiac proteostasis will help to develop future therapeutics to protect the heart from cardiovascular diseases.

11.
Redox Biol ; 36: 101660, 2020 09.
Article in English | MEDLINE | ID: mdl-32750667

ABSTRACT

Mitochondria are highly dynamic organelles that constantly undergo fission and fusion events to adapt to changes in the cellular environment. Aberrant mitochondrial fission has been associated with several types of cardiovascular dysfunction; inhibition of pathologically aberrant mitochondrial fission has been shown to be cardioprotective. Pathological fission is mediated by the excessive activation of GTPase dynamin-related protein 1 (Drp1), making it an attractive therapeutic target in numerous cardiovascular diseases. Mitochondrial division inhibitor (mdivi-1) is widely used small molecule reported to inhibit Drp1-dependent fission, elongate mitochondria, and mitigate injury. The purpose of our study was to understand the pleiotropic effects of mdivi-1 on mitochondrial dynamics, mitochondrial respiration, electron transport activities, and macro-autophagy. In this study, we found that mdivi-1 treatment decreased Drp1 expression, proteolytically cleaved L-OPA1, and altered the expression of OXPHOS complex proteins, resulting in increased superoxide production. The altered expression of OXPHOS complex proteins may be directly associated with decreased Drp1 expression, as Drp1 siRNA knockdown in cardiomyocytes showed similar effects. Results from an autophagy flux assay showed that mdivi-1 induced impaired autophagy flux that could be restored by Atg7 overexpression, suggesting that mdivi-1 mediated inhibition of macro-autophagy in cardiomyocytes. Treatment with mdivi-1 resulted in increased expression of p62, which is required for Atg7 overexpression-induced rescue of mdivi-1-mediated impaired autophagy flux. In addition, mdivi-1-dependent proteolytic processing of L-OPA1 was associated with increased mitochondrial superoxide production and altered expression of mitochondrial serine/proteases. Overall, the novel pleiotropic effect of mdivi-1 in cardiomyocytes included proteolytically cleaved L-OPA1, altered expression of OXPHOS complex proteins, and increased superoxide production, which together resulted in defects in mitochondrial respiration and inhibition of macro-autophagy.


Subject(s)
Mitochondrial Dynamics , Myocytes, Cardiac , Autophagy , Dynamins/genetics , Mitochondrial Proteins/genetics , Quinazolinones/pharmacology , Respiration
12.
Sci Rep ; 9(1): 2002, 2019 02 14.
Article in English | MEDLINE | ID: mdl-30765730

ABSTRACT

Doxorubicin (Dox) is a highly effective anticancer drug but cause acute ventricular dysfunction, and also induce late-onset cardiomyopathy and heart failure. Despite extensive studies, the pathogenic sequelae leading to the progression of Dox-associated cardiomyopathy remains unknown. We assessed temporal changes in autophagy, mitochondrial dynamics, and bioenergetics in mouse models of acute and chronic Dox-cardiomyopathy. Time course study of acute Dox-treatment showed accumulation of LC3B II in heart lysates. Autophagy flux assays confirmed that the Dox-induced accumulation of autophagosomes occurs due to blockage of the lysosomal degradation process. Dox-induced autophagosomes and autolysosome accumulation were confirmed in vivo by using GFP-LC3 and mRFP-GFP-LC3 transgenic (Tg) mice. Mitochondria isolated from acute Dox-treated hearts showed significant suppression of oxygen consumption rate (OCR). Chronic Dox-cardiotoxicity also exhibited time-dependent accumulation of LC3B II levels and increased accumulation of green puncta in GFP-LC3 Tg hearts. Mitochondria isolated from chronic Dox-treated hearts also showed significant suppression of mitochondrial OCR. The in vivo impairment of autophagic degradation process and mitochondrial dysfunction data were confirmed in vitro using cultured neonatal cardiomyocytes. Both acute and chronic Dox-associated cardiomyopathy involves a multifocal disease process resulting from autophagosomes and autolysosomes accumulation, altered expression of mitochondrial dynamics and oxidative phosphorylation regulatory proteins, and mitochondrial respiratory dysfunction.


Subject(s)
Autophagy/drug effects , Cardiomyopathies/chemically induced , Cardiomyopathies/pathology , Cell Respiration/drug effects , Doxorubicin/adverse effects , Mitochondria/drug effects , Animals , Autophagosomes/drug effects , Autophagosomes/metabolism , Female , Male , Mice , Mitochondria/metabolism , Mitochondria/pathology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/pathology , Oxidative Phosphorylation/drug effects
13.
J Am Heart Assoc ; 7(20): e009775, 2018 10 16.
Article in English | MEDLINE | ID: mdl-30371279

ABSTRACT

Background The Sigma 1 receptor (Sigmar1) functions as an interorganelle signaling molecule and elicits cytoprotective functions. The presence of Sigmar1 in the heart was first reported on the basis of a ligand-binding assay, and all studies to date have been limited to pharmacological approaches using less-selective ligands for Sigmar1. However, the physiological function of cardiac Sigmar1 remains unknown. We investigated the physiological function of Sigmar1 in regulating cardiac hemodynamics using the Sigmar1 knockout mouse (Sigmar1-/-). Methods and Results Sigmar1-/- hearts at 3 to 4 months of age showed significantly increased contractility as assessed by left ventricular catheterization with stimulation by increasing doses of a ß1-adrenoceptor agonist. Noninvasive echocardiographic measurements were also used to measure cardiac function over time, and the data showed the development of cardiac contractile dysfunction in Sigmar1 -/- hearts as the animals aged. Histochemistry demonstrated significant cardiac fibrosis, collagen deposition, and increased periostin in the Sigmar1 -/- hearts compared with wild-type hearts. Ultrastructural analysis of Sigmar1-/- cardiomyocytes revealed an irregularly shaped, highly fused mitochondrial network with abnormal cristae. Mitochondrial size was larger in Sigmar1-/- hearts, resulting in decreased numbers of mitochondria per microscopic field. In addition, Sigmar1-/- hearts showed altered expression of mitochondrial dynamics regulatory proteins. Real-time oxygen consumption rates in isolated mitochondria showed reduced respiratory function in Sigmar1-/- hearts compared with wild-type hearts. Conclusions We demonstrate a potential function of Sigmar1 in regulating normal mitochondrial organization and size in the heart. Sigmar1 loss of function led to mitochondrial dysfunction, abnormal mitochondrial architecture, and adverse cardiac remodeling, culminating in cardiac contractile dysfunction.


Subject(s)
Heart Diseases/physiopathology , Mitochondria, Heart/physiology , Mitochondrial Dynamics/physiology , Receptors, sigma/metabolism , Adenosine Triphosphate/metabolism , Adrenergic beta-1 Receptor Agonists/pharmacology , Animals , Biomarkers/metabolism , Cell Respiration/physiology , Dobutamine/pharmacokinetics , Echocardiography , Electron Transport/physiology , Energy Metabolism/physiology , Female , Fibrosis/physiopathology , Hemodynamics/physiology , Male , Mice, Knockout , Microscopy, Electron, Transmission , Mitochondria, Heart/ultrastructure , Mitochondrial Diseases/metabolism , Mitochondrial Diseases/physiopathology , Myocardial Contraction/physiology , Myocardium/pathology , Myocytes, Cardiac/physiology , Myocytes, Cardiac/ultrastructure , Oxygen Consumption/physiology , Sigma-1 Receptor
14.
J Am Heart Assoc ; 7(14)2018 07 09.
Article in English | MEDLINE | ID: mdl-29987122

ABSTRACT

BACKGROUND: Desmin filament proteins interlink the contractile myofibrillar apparatus with mitochondria, nuclei and the sarcolemma. Mutations in the human desmin gene cause cardiac disease, remodeling, and heart failure but the pathophysiological mechanisms remain unknown. METHODS AND RESULTS: Cardiomyocyte-specific overexpression of mutated desmin (a 7 amino acid deletion R172-E178, D7-Des Tg) causes accumulations of electron-dense aggregates and myofibrillar degeneration associated with cardiac dysfunction. Though extensive studies demonstrated that these altered ultrastructural changes cause impairment of cardiac contractility, the molecular mechanism of cardiomyocyte death remains elusive. In the present study, we report that the D7-Des Tg mouse hearts undergo aberrant mitochondrial fission associated with increased expression of mitochondrial fission regulatory proteins. Mitochondria isolated from D7-Des Tg hearts showed decreased mitochondrial respiration and increased apoptotic cell death. Overexpression of mutant desmin by adenoviral infection in cultured cardiomyocytes led to increased mitochondrial fission, inhibition of mitochondrial respiration, and activation of cellular toxicity. Inhibition of mitochondrial fission by mitochondrial division inhibitor mdivi-1 significantly improved mitochondrial respiration and inhibited cellular toxicity associated with D7-Des overexpression in cardiomyocytes. CONCLUSIONS: Aberrant mitochondrial fission results in mitochondrial respiratory defects and apoptotic cell death in D7-Des Tg hearts. Inhibition of aberrant mitochondrial fission using mitochondrial division inhibitor significantly preserved mitochondrial function and decreased apoptotic cell death. Taken together, our study shows that maladaptive aberrant mitochondrial fission causes desminopathy-associated cellular dysfunction.


Subject(s)
Cardiomyopathies/genetics , DNA/genetics , Desmin/genetics , Mitochondria, Heart/metabolism , Mutation , Myocytes, Cardiac/metabolism , Animals , Animals, Newborn , Blotting, Western , Cardiomyopathies/metabolism , Cardiomyopathies/pathology , Cells, Cultured , DNA Mutational Analysis , Desmin/metabolism , Disease Models, Animal , Immunohistochemistry , Mitochondria, Heart/pathology , Myocytes, Cardiac/pathology , Rats, Sprague-Dawley
15.
Biosci Rep ; 37(4)2017 Aug 31.
Article in English | MEDLINE | ID: mdl-28667101

ABSTRACT

C/EBP-homologous protein (CHOP) is a ubiquitously expressed stress-inducible transcription factor robustly induced by maladaptive endoplasmic reticulum (ER) stresses in a wide variety of cells. Here, we examined a novel function of Sigma 1 receptor (Sigmar1) in regulating CHOP expression under ER stress in cardiomyocytes. We also defined Sigmar1-dependent activation of the adaptive ER-stress pathway in regulating CHOP expression. We used adenovirus-mediated Sigmar1 overexpression as well as Sigmar1 knockdown by siRNA in neonatal rat ventricular cardiomyocytes (NRCs); to induce ER stress, cardiomyocytes were treated with tunicamycin. Sigmar1-siRNA knockdown significantly increased the expression of CHOP and significantly induced cellular toxicity by sustained activation of ER stress in cardiomyocytes. Sigmar1 overexpression decreased the expression of CHOP and significantly decreased cellular toxicity in cells. Using biochemical and immunocytochemical experiments, we also defined the specific ER-stress pathway associated with Sigmar1-dependent regulation of CHOP expression and cellular toxicity. We found that Sigmar1 overexpression significantly increased inositol requiring kinase 1α (IRE1α) phosphorylation and increased spliced X-box-binding proteins (XBP1s) expression as well as nuclear localization. In contrast, Sigmar1 knockdown significantly decreased IRE1α phosphorylation and decreased XBP1s expression as well as nuclear transport. Taken together, these results indicate that Sigmar1-dependent activation of IRE1α-XBP1s ER-stress response pathways are associated with inhibition of CHOP expression and suppression of cellular toxicity. Hence, Sigmar1 is an essential component of the adaptive ER-stress response pathways eliciting cellular protection in cardiomyocytes.


Subject(s)
Endoplasmic Reticulum Stress , Gene Expression Regulation , Myocytes, Cardiac/metabolism , Receptors, sigma/metabolism , Transcription Factor CHOP/biosynthesis , Animals , Endoribonucleases/genetics , Endoribonucleases/metabolism , Multienzyme Complexes/genetics , Multienzyme Complexes/metabolism , Myocytes, Cardiac/cytology , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Rats, Sprague-Dawley , Receptors, sigma/genetics , Transcription Factor CHOP/genetics , X-Box Binding Protein 1/genetics , X-Box Binding Protein 1/metabolism , Sigma-1 Receptor
16.
Disaster Med Public Health Prep ; 11(1): 21-24, 2017 02.
Article in English | MEDLINE | ID: mdl-27181426

ABSTRACT

BACKGROUND: Rana Plaza building collapse is the worst industrial disaster of Bangladesh so far. The 9-storied structure collapsed suddenly on April 24, 2013, with more than 4000 people inside. Bangladesh Armed Forces played a key role in the massive rescue operations. METHODS: We conducted a cross-sectional study with 423 victims who were treated at a Combined Military Hospital to review the pattern of injuries and management provided. RESULTS: Middle-aged (35±12.75 years) females (68.32%) were the majority of the victims. Among the injured, 42.35% had soft tissue injury, 22.55% had abrasions, 18.79% had fractures, 3.75% had facial injuries, and 2.5% each had head and abdominal injuries. We treated the injured with various surgical approaches, such as soft tissue debridement (38.84%), fasciotomy (18.79%), amputation (3.75%), and other procedures. We had to refer 8.27% of the patients to different advanced centers. The mortality rate was 5.91%, including 1 volunteer rescuer. CONCLUSION: Pattern of injuries and modalities of management needed in an industrial disaster is a valuable experience which can be utilized in preparing to face disasters in the future and beyond. Death of a voluntary rescuer once again warrants the necessity of using a helmet and safety gear during any rescue operation. (Disaster Med Public Health Preparedness. 2017;11:21-24).


Subject(s)
Emergency Medical Services/methods , Mass Casualty Incidents/statistics & numerical data , Rescue Work/standards , Wounds and Injuries/epidemiology , Adolescent , Adult , Bangladesh/epidemiology , Cross-Sectional Studies , Emergency Medical Services/statistics & numerical data , Female , Hospitals, Military/organization & administration , Hospitals, Military/statistics & numerical data , Humans , Male , Middle Aged , Military Personnel/statistics & numerical data , Rescue Work/methods , Workforce , Wounds and Injuries/mortality
17.
Reprod Health ; 13(1): 129, 2016 Oct 06.
Article in English | MEDLINE | ID: mdl-27716260

ABSTRACT

BACKGROUND: Prior studies have shown that using uterotonics to augment or induce labor before arrival at comprehensive Emergency Obstetric and Neonatal Care (CEmONC) settings (henceforth, "outside uterotonics") may contribute to perinatal mortality in low- and middle-income countries. We estimate its effect on perinatal mortality in rural Bangladesh. METHODS: Using hospital records (23986 singleton term births, Jan 1, 2009-Dec 31, 2015) from rural Bangladesh, we use a logistic regression model to estimate the increased risk of perinatal death from uterotonics administered outside a CEmONC facility. RESULTS: Among term births (≥37 weeks gestation), the risk of perinatal death adjusted for key confounders is significantly increased among women reporting uterotonic use outside of CEmONC (OR = 3 · 0, 95 % CI = 2 · 4,3 · 7). This increased risk is particularly high for fresh stillbirths (OR = 4 · 0, 95 % CI = 3 · 0,5 · 3) and intrapartum-related causes of early neonatal deaths (birth asphyxia) (OR = 3 · 1, 95 % CI = 2 · 2,4 · 5). CONCLUSIONS: In this sample, outside uterotonic use was associated with substantially increased risk of fresh stillbirths, deaths due to birth asphyxia, and all perinatal deaths. In settings of high uterotonic use outside of controlled settings, substantial improvement in both stillbirth and early neonatal mortality may be made by reducing such use.


Subject(s)
Oxytocics/adverse effects , Perinatal Mortality , Bangladesh/epidemiology , Cross-Sectional Studies , Developing Countries , Drug Utilization/statistics & numerical data , Emergencies , Female , Humans , Obstetric Labor Complications/chemically induced , Obstetric Labor Complications/epidemiology , Oxytocics/administration & dosage , Pregnancy , Pregnancy Outcome/epidemiology , Risk Assessment/methods , Rural Health/statistics & numerical data , Stillbirth/epidemiology
18.
Environ Res ; 143(Pt A): 123-30, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26476787

ABSTRACT

BACKGROUND: Arsenic (As) methylation capacity in epidemiologic studies is typically indicated by the proportions of inorganic As (%InAs), monomethylarsonic acid (%MMA), and dimethylarsinic acid (%DMA) in urine as a fraction of total urinary As. The relationship between renal function and indicators of As methylation capacity has not been thoroughly investigated. OBJECTIVES: Our two aims were to examine (1) associations between estimated glomerular filtration rate (eGFR) and %As metabolites in blood and urine, and (2) whether renal function modifies the relationship of blood %As metabolites with respective urinary %As metabolites. METHODS: In a cross-sectional study of 375 As-exposed Bangladeshi adults, we measured blood and urinary As metabolites, and calculated eGFR from plasma cystatin C. RESULTS: In covariate-adjusted linear models, a 1 ml/min/1.73 m(2) increase in eGFR was associated with a 0.39% increase in urinary %InAs (p<0.0001) and a mean decrease in urinary %DMA of 0.07 (p=0.0005). In the 292 participants with measurable blood As metabolites, the associations of eGFR with increased blood %InAs and decreased blood %DMA did not reach statistical significance. eGFR was not associated with urinary or blood %MMA in covariate-adjusted models. For a given increase in blood %InAs, the increase in urinary %InAs was smaller in those with reduced eGFR, compared to those with normal eGFR (p=0.06); this effect modification was not observed for %MMA or %DMA. CONCLUSIONS: Urinary excretion of InAs may be impaired in individuals with reduced renal function. Alternatively, increased As methylation capacity (as indicated by decreased urinary %InAs) may be detrimental to renal function.


Subject(s)
Arsenic/toxicity , Arsenicals , Cacodylic Acid , Drinking Water/chemistry , Glomerular Filtration Rate/drug effects , Water Pollutants, Chemical/toxicity , Adult , Aged , Arsenic/blood , Arsenic/urine , Arsenicals/blood , Arsenicals/urine , Bangladesh , Cacodylic Acid/blood , Cacodylic Acid/urine , Cross-Sectional Studies , Female , Humans , Linear Models , Male , Methylation , Middle Aged , Water Pollutants, Chemical/blood , Water Pollutants, Chemical/urine
19.
Cancer Epidemiol Biomarkers Prev ; 24(11): 1748-57, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26364164

ABSTRACT

BACKGROUND: Depletion of global 5-hydroxymethylcytosine (5-hmC) is observed in human cancers and is strongly implicated in skin cancer development. Although arsenic (As)-a class I human carcinogen linked to skin lesion and cancer risk-is known to be associated with changes in global %5-methylcytosine (%5-mC), its influence on 5-hmC has not been widely studied. METHODS: We evaluated associations of As in drinking water, urine, and blood with global %5-mC and %5-hmC in two studies of Bangladeshi adults: (i) leukocyte DNA in the Nutritional Influences on Arsenic Toxicity study (n = 196; 49% male, 19-66 years); and (ii) peripheral blood mononuclear cell DNA in the Folate and Oxidative Stress study (n = 375; 49% male, 30-63 years). RESULTS: Overall, As was not associated with global %5-mC or %5-hmC. Sex-specific analyses showed that associations of As exposure with global %5-hmC were positive in males and negative in females (P for interaction < 0.01). Analyses examining interactions by elevated plasma total homocysteine (tHcys), an indicator of B-vitamin deficiency, found that tHcys also modified the association between As and global %5-hmC (P for interaction < 0.10). CONCLUSION: In two samples, we observed associations between As exposure and global %5-hmC in blood DNA that were modified by sex and tHcys. IMPACT: Our findings suggest that As induces sex-specific changes in 5-hmC, an epigenetic mark that has been associated with cancer. Future research should explore whether altered %5-hmC is a mechanism underlying the sex-specific influences of As on skin lesion and cancer outcomes.


Subject(s)
Arsenic/adverse effects , DNA Methylation/drug effects , Environmental Exposure/adverse effects , Leukocytes/drug effects , 5-Methylcytosine/analogs & derivatives , Adult , Aged , Arsenic/blood , Arsenic/urine , Bangladesh/epidemiology , Cytosine/analogs & derivatives , Cytosine/metabolism , Drinking Water/analysis , Environmental Exposure/statistics & numerical data , Female , Homocysteine/blood , Humans , Leukocytes/metabolism , Male , Middle Aged , Sex Factors , Young Adult
20.
Chem Biol Drug Des ; 86(5): 1242-52, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26031895

ABSTRACT

Using the transition from cytosine of BFP (blue fluorescent protein) gene to uridine of GFP (green fluorescent protein) gene at position 199 as a model, we successfully controlled photochemical RNA editing to effect site-directed deamination of cytidine (C) to uridine (U). Oligodeoxynucleotides (ODNs) containing 5'-carboxyvinyl-2'-deoxyuridine ((CV) U) were used for reversible photoligation, and single-stranded 100-nt BFP DNA and in vitro-transcribed full-length BFP mRNA were the targets. Photo-cross-linking with the responsive ODNs was performed using UV (366 nm) irradiation, which was followed by heat treatment, and the cross-linked nucleotide was cleaved through photosplitting (UV, 312 nm). The products were analyzed using restriction fragment length polymorphism (RFLP) and fluorescence measurements. Western blotting and fluorescence-analysis results revealed that in vitro-translated proteins were synthesized from mRNAs after site-directed RNA editing. We detected substantial amounts of the target-base-substituted fragment using RFLP and observed highly reproducible spectra of the transition-GFP signal using fluorescence spectroscopy, which indicated protein stability. ODNc restored approximately 10% of the C-to-U transition. Thus, we successfully used non-enzymatic site-directed deamination for genetic restoration in vitro. In the near future, in vivo studies that include cultured cells and model animals will be conducted to treat genetic disorders.


Subject(s)
Cytidine/genetics , Green Fluorescent Proteins/genetics , Mutagenesis, Site-Directed , RNA Editing , Uridine/genetics , Base Sequence , Cytidine/chemistry , Deoxyuridine/analogs & derivatives , Deoxyuridine/chemistry , Escherichia coli/chemistry , Escherichia coli/genetics , Green Fluorescent Proteins/chemistry , Molecular Sequence Data , Oligodeoxyribonucleotides, Antisense/chemistry , Oligodeoxyribonucleotides, Antisense/genetics , RNA, Messenger/chemistry , RNA, Messenger/genetics , Ultraviolet Rays , Uridine/chemistry
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