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BACKGROUND: Mitochondria play a crucial role in adapting to fluctuating energy demands, particularly in various heart diseases. This study investigates mitochondrial morphology near intercalated discs in left ventricular (LV) heart tissues, comparing samples from patients with sinus rhythm (SR), atrial fibrillation (AF), dilated cardiomyopathy (DCM), and ischemic cardiomyopathy (ICM). METHODS: Transmission electron microscopy was used to analyze mitochondria within 0-3.5 µm and 3.5-7 µm of intercalated discs in 9 SR, 10 AF, 9 DCM, and 8 ICM patient samples. Parameters included mean size in µm2 and elongation, count, percental mitochondrial area in the measuring frame, and a conglomeration score. RESULTS: AF patients exhibited higher counts of small mitochondria in the LV myocardium, resembling SR. DCM and ICM groups had fewer, larger, and often hydropic mitochondria. Accumulation rates and percental mitochondrial area were similar across groups. Significant positive correlations existed between other defects/size and hydropic mitochondria and between count/area and conglomeration score, while negative correlations between count and size/other defects and between hydropic mitochondria and count could be seen as well. CONCLUSION: Mitochondrial parameters in the LV myocardium of AF patients were similar to those of SR patients, while DCM and ICM displayed distinct changes, including a decrease in number, an increase in size, and compromised mitochondrial morphology. Further research is needed to fully elucidate the pathophysiological role of mitochondrial morphology in different heart diseases, providing deeper insights into potential therapeutic targets and interventions.
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Mitocondrias Cardíacas , Humanos , Masculino , Femenino , Proyectos Piloto , Persona de Mediana Edad , Anciano , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Cardiomiopatía Dilatada/patología , Cardiomiopatía Dilatada/metabolismo , Cardiopatías/metabolismo , Cardiopatías/patología , Microscopía Electrónica de Transmisión , Adulto , Ventrículos Cardíacos/patología , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/ultraestructura , Fibrilación Atrial/metabolismo , Fibrilación Atrial/patología , Fibrilación Atrial/fisiopatología , Miocardio/metabolismo , Miocardio/patología , Miocardio/ultraestructuraRESUMEN
BACKGROUND: Clinical studies demonstrated beneficial effects of sodium-glucose-transporter 2 inhibitors on the risk of cardiovascular death in patients with heart failure with preserved ejection fraction (HFpEF). However, underlying processes for cardioprotection remain unclear. The present study focused on the impact of empagliflozin (Empa) on myocardial function in a rat model with established HFpEF and analyzed underlying molecular mechanisms. METHODS: Obese ZSF1 (Zucker fatty and spontaneously hypertensive) rats were randomized to standard care (HFpEF, n=18) or Empa (HFpEF/Empa, n=18). ZSF1 lean rats (con, n=18) served as healthy controls. Echocardiography was performed at baseline and after 4 and 8 weeks, respectively. After 8 weeks of treatment, hemodynamics were measured invasively, mitochondrial function was assessed and myocardial tissue was collected for either molecular and histological analyses or transmission electron microscopy. RESULTS: In HFpEF Empa significantly improved diastolic function (E/é: con: 17.5±2.8; HFpEF: 24.4±4.6; P<0.001 versus con; HFpEF/Empa: 19.4±3.2; P<0.001 versus HFpEF). This was accompanied by improved hemodynamics and calcium handling and by reduced inflammation, hypertrophy, and fibrosis. Proteomic analysis demonstrated major changes in proteins involved in mitochondrial oxidative phosphorylation. Cardiac mitochondrial respiration was significantly impaired in HFpEF but restored by Empa (Vmax complex IV: con: 0.18±0.07 mmol O2/s/mg; HFpEF: 0.13±0.05 mmol O2/s/mg; P<0.041 versus con; HFpEF/Empa: 0.21±0.05 mmol O2/s/mg; P=0.012 versus HFpEF) without alterations of mitochondrial content. The expression of cardiolipin, an essential stability/functionality-mediating phospholipid of the respiratory chain, was significantly decreased in HFpEF but reverted by Empa (con: 15.9±1.7 nmol/mg protein; HFpEF: 12.5±1.8 nmol/mg protein; P=0.002 versus con; HFpEF/Empa: 14.5±1.8 nmol/mg protein; P=0.03 versus HFpEF). Transmission electron microscopy revealed a reduced size of mitochondria in HFpEF, which was restored by Empa. CONCLUSIONS: The study demonstrates beneficial effects of Empa on diastolic function, hemodynamics, inflammation, and cardiac remodeling in a rat model of HFpEF. These effects were mediated by improved mitochondrial respiratory capacity due to modulated cardiolipin and improved calcium handling.
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Compuestos de Bencidrilo , Diástole , Modelos Animales de Enfermedad , Glucósidos , Insuficiencia Cardíaca , Mitocondrias Cardíacas , Ratas Zucker , Inhibidores del Cotransportador de Sodio-Glucosa 2 , Volumen Sistólico , Animales , Glucósidos/farmacología , Compuestos de Bencidrilo/farmacología , Inhibidores del Cotransportador de Sodio-Glucosa 2/farmacología , Insuficiencia Cardíaca/tratamiento farmacológico , Insuficiencia Cardíaca/fisiopatología , Insuficiencia Cardíaca/metabolismo , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Diástole/efectos de los fármacos , Volumen Sistólico/efectos de los fármacos , Masculino , Función Ventricular Izquierda/efectos de los fármacos , Ratas Endogámicas SHR , Transporte de Electrón/efectos de los fármacos , RatasRESUMEN
Osimertinib, an irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) used for cancer treatment, can cause significant cardiac toxicity. However, the specific mechanism of osimertinib-induced cardiotoxicity is not fully understood. In this study, we administered osimertinib to mice and neonatal rat ventricular myocytes (NRVMs). We observed significant structural and functional damage to the hearts of these mice, along with a marked increase in cardiac injury biomarkers and accompanying ultrastructural damage to mitochondria. We integrated 4D label-free protein quantification and RNA-Seq methods to analyze the sequencing data of NRVMs under osimertinib treatment (0 and 2.5⯵M). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis evidenced that differentially expressed genes (DEGs)and differentially expressed proteins (DEPs) were distinctly enriched for oxidative phosphorylation (OXPHOs). Simultaneously, osimertinib primarily affected the contents of adenosine triphosphate (ATP). Further investigations revealed that osimertinib disrupts the functions of the ATP synthase (complex V), leading to a reduction in ATP production. Taken together, our data demonstrated that osimertinib causes mitochondrial dysfunction, which in turn leads to the onset of cardiac toxicity.
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Acrilamidas , Compuestos de Anilina , Cardiotoxicidad , Mitocondrias Cardíacas , Miocitos Cardíacos , Proteómica , Animales , Acrilamidas/toxicidad , Compuestos de Anilina/toxicidad , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miocitos Cardíacos/ultraestructura , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Proteómica/métodos , Ratones , Ratas , Masculino , Transcriptoma/efectos de los fármacos , Ratones Endogámicos C57BL , Inhibidores de Proteínas Quinasas/toxicidad , Inhibidores de Proteínas Quinasas/farmacología , Ratas Sprague-Dawley , Adenosina Trifosfato/metabolismo , Indoles , PirimidinasRESUMEN
AIMS: Changes in myocardial mitochondrial morphology and function in premature ventricular contractions (PVCs)-induced cardiomyopathy (PVCCM) remain poorly studied. Here, we investigated the effects of PVCs with different coupling intervals (CIs) on myocardial mitochondrial remodelling in a canine model of PVCCM. METHODS AND RESULTS: Twenty-one beagles underwent pacemaker implantation and were randomised into the sham (n = 7), short-coupled PVCs (SCP, n = 7), and long-coupled PVCs (LCP, n = 7) groups. Right ventricular (RV) apical bigeminy was produced for 12-week to induce PVCCM in the SCP (CI, 250 ms) and LCP (CI, 350 ms) groups. Echocardiography was performed at baseline and biweekly thereafter to evaluate cardiac function. Masson's trichrome staining measured ventricular interstitial fibrosis. The ultrastructural morphology of the myocardial mitochondria was analysed using transmission electron microscopy. Mitochondrial Ca2+ concentration, reactive oxygen species (ROS) levels, adenosine triphosphate (ATP) content, membrane potential, and electron transport chain (ETC) complex activity were measured to assess myocardial mitochondrial function. Twelve-week-PVCs led to left ventricular (LV) enlargement with systolic dysfunction, disrupted mitochondrial morphology, increased mitochondrial Ca2+ concentration and ROS levels, decreased mitochondrial ATP content and membrane potential, and impaired ETC complex activity in both the SCP and LCP groups (all p < 0.01 vs the sham group). Ventricular fibrosis was observed only in canines with LCP. Worse cardiac function and more pronounced abnormalities in mitochondrial morphology and function were observed in the LCP group than to the SCP group (all p < 0.05). CONCLUSION: We demonstrated myocardial mitochondrial abnormalities in dogs with PVCCM, characterised by abnormal mitochondrial morphology, mitochondrial Ca2+ overload, oxidative stress, and impaired mitochondrial energy metabolism. Compared to SCP, long-term LCP exposure resulted in more severe mitochondrial remodelling and cardiac dysfunction in dogs.
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Calcio , Cardiomiopatías , Modelos Animales de Enfermedad , Mitocondrias Cardíacas , Especies Reactivas de Oxígeno , Complejos Prematuros Ventriculares , Animales , Perros , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Mitocondrias Cardíacas/patología , Cardiomiopatías/fisiopatología , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Cardiomiopatías/etiología , Complejos Prematuros Ventriculares/fisiopatología , Complejos Prematuros Ventriculares/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Calcio/metabolismo , Masculino , Adenosina Trifosfato/metabolismo , Potencial de la Membrana Mitocondrial , EcocardiografíaRESUMEN
Mitochondria within a cardiomyocyte form a highly dynamic network that undergoes fusion and fission events in response to acute and chronic stressors, such as hyperglycemia and diabetes mellitus. Changes in mitochondrial architecture and morphology not only reflect their capacity for oxidative phosphorylation and ATP synthesis but also impact their subcellular localization and interaction with other organelles. The role of these ultrastructural abnormalities in modulating electrophysiological properties and excitation-contraction coupling remains largely unknown and warrants direct investigation considering the growing appreciation of the functional and structural coupling between the mitochondrial network, the calcium cycling machinery, and sarcolemmal ion channels in the cardiac myocyte. In this Methods in Molecular Biology chapter, we provide a protocol that allows for a quantitative assessment of mitochondrial shape and morphology in control and diabetic hearts that had undergone detailed electrophysiological measurements using high resolution optical action potential (AP) mapping.
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Potenciales de Acción , Mitocondrias Cardíacas , Miocitos Cardíacos , Animales , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Potenciales de Acción/fisiología , Diabetes Mellitus Experimental/fisiopatología , Diabetes Mellitus Experimental/patología , Ratas , Fenómenos Electrofisiológicos , Miocardio/patología , Miocardio/metabolismoRESUMEN
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease associated with cardiomyopathy. DMD cardiomyopathy is characterized by abnormal intracellular Ca2+ homeostasis and mitochondrial dysfunction. We used dystrophin and utrophin double-knockout (mdx:utrn-/-) mice in a sarcolipin (SLN) heterozygous-knockout (sln+/-) background to examine the effect of SLN reduction on mitochondrial function in the dystrophic myocardium. Germline reduction of SLN expression in mdx:utrn-/- mice improved cardiac sarco/endoplasmic reticulum (SR) Ca2+ cycling, reduced cardiac fibrosis, and improved cardiac function. At the cellular level, reducing SLN expression prevented mitochondrial Ca2+ overload, reduced mitochondrial membrane potential loss, and improved mitochondrial function. Transmission electron microscopy of myocardial tissues and proteomic analysis of mitochondria-associated membranes showed that reducing SLN expression improved mitochondrial structure and SR-mitochondria interactions in dystrophic cardiomyocytes. These findings indicate that SLN upregulation plays a substantial role in the pathogenesis of cardiomyopathy and that reducing SLN expression has clinical implications in the treatment of DMD cardiomyopathy.
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Cardiomiopatías , Distrofina , Ratones Endogámicos mdx , Ratones Noqueados , Proteínas Musculares , Distrofia Muscular de Duchenne , Proteolípidos , Utrofina , Animales , Masculino , Ratones , Calcio/metabolismo , Cardiomiopatías/metabolismo , Cardiomiopatías/genética , Cardiomiopatías/patología , Modelos Animales de Enfermedad , Distrofina/genética , Distrofina/metabolismo , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Mitocondrias Cardíacas/genética , Proteínas Musculares/metabolismo , Proteínas Musculares/genética , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/patología , Miocardio/metabolismo , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Proteolípidos/metabolismo , Proteolípidos/genética , Utrofina/genética , Utrofina/metabolismoRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Xinyang tablet (XYT) has been used for heart failure (HF) for over twenty years in clinical practice, but the underlying molecular mechanism remains poorly understood. AIMS OF THE STUDY: In the present study, we aimed to explore the protective effects of XYT in HF in vivo and in vitro. MATERIALS AND METHODS: Transverse aortic constriction was performed in vivo to establish a mouse model of cardiac pressure overload. Echocardiography, tissue staining, and real-time quantitative PCR (qPCR) were examined to evaluate the protective effects of XYT on cardiac function and structure. Adenosine 5'-triphosphate production, reactive oxygen species staining, and measurement of malondialdehyde and superoxide dismutase was used to detect mitochondrial damage. Mitochondrial ultrastructure was observed by transmission electron microscope. Immunofluorescence staining, qPCR, and Western blotting were performed to evaluate the effect of XYT on the mitochondrial unfolded protein response and mitophagy, and to identify its potential pharmacological mechanism. In vitro, HL-1 cells and neonatal mouse cardiomyocytes were stimulated with Angiotensin II to establish the cell model. Western blotting, qPCR, immunofluorescence staining, and flow cytometry were utilized to determine the effects of XYT on cardiomyocytes. HL-1 cells overexpressing receptor-interacting serum/three-protein kinase 3 (RIPK3) were generated by transfection of RIPK3-overexpressing lentiviral vectors. Cells were then co-treated with XYT to determine the molecular mechanisms. RESULTS: In the present study, XYT was found to exerta protective effect on cardiac function and structure in the pressure overload mice. And it was also found XYT reduced mitochondrial damage by enhancing mitochondrial unfolded protein response and restoring mitophagy. Further studies showed that XYT achieved its cardioprotective role through regulating the RIPK3/FUN14 domain containing 1 (FUNDC1) signaling. Moreover, the overexpression of RIPK3 successfully reversed the XYT-induced protective effects and significantly attenuated the positive effects on the mitochondrial unfolded protein response and mitophagy. CONCLUSIONS: Our findings indicated that XYT prevented pressure overload-induced HF through regulating the RIPK3/FUNDC1-mediated mitochondrial unfolded protein response and mitophagy. The information gained from this study provides a potential strategy for attenuating mitochondrial damage in the context of pressure overload-induced heart failure using XYT.
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Modelos Animales de Enfermedad , Medicamentos Herbarios Chinos , Ratones Endogámicos C57BL , Mitofagia , Miocitos Cardíacos , Respuesta de Proteína Desplegada , Animales , Mitofagia/efectos de los fármacos , Respuesta de Proteína Desplegada/efectos de los fármacos , Ratones , Masculino , Medicamentos Herbarios Chinos/farmacología , Medicamentos Herbarios Chinos/uso terapéutico , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Insuficiencia Cardíaca/tratamiento farmacológico , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/fisiopatología , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Comprimidos , Línea Celular , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismoRESUMEN
Diabetic cardiomyopathy is a leading cause of heart failure in diabetes. At the cellular level, diabetic cardiomyopathy leads to altered mitochondrial energy metabolism and cardiomyocyte ultrastructure. We combined electron microscopy (EM) and computational modelling to understand the impact of diabetes-induced ultrastructural changes on cardiac bioenergetics. We collected transverse micrographs of multiple control and type I diabetic rat cardiomyocytes using EM. Micrographs were converted to finite-element meshes, and bioenergetics was simulated over them using a biophysical model. The simulations also incorporated depressed mitochondrial capacity for oxidative phosphorylation (OXPHOS) and creatine kinase (CK) reactions to simulate diabetes-induced mitochondrial dysfunction. Analysis of micrographs revealed a 14% decline in mitochondrial area fraction in diabetic cardiomyocytes, and an irregular arrangement of mitochondria and myofibrils. Simulations predicted that this irregular arrangement, coupled with the depressed activity of mitochondrial CK enzymes, leads to large spatial variation in adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio profile of diabetic cardiomyocytes. However, when spatially averaged, myofibrillar ADP/ATP ratios of a cardiomyocyte do not change with diabetes. Instead, average concentration of inorganic phosphate rises by 40% owing to lower mitochondrial area fraction and dysfunction in OXPHOS. These simulations indicate that a disorganized cellular ultrastructure negatively impacts metabolite transport in diabetic cardiomyopathy. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Diabetes Mellitus , Cardiomiopatías Diabéticas , Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Creatina Quinasa/metabolismo , Diabetes Mellitus/metabolismo , Cardiomiopatías Diabéticas/etiología , Cardiomiopatías Diabéticas/metabolismo , Metabolismo Energético , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Miocitos Cardíacos/metabolismo , Fosfatos/metabolismo , RatasRESUMEN
The sinoatrial node (SAN), the leading pacemaker region, generates electrical impulses that propagate throughout the heart. SAN dysfunction with bradyarrhythmia is well documented in heart failure (HF). However, the underlying mechanisms are not completely understood. Mitochondria are critical to cellular processes that determine the life or death of the cell. The release of Ca2+ from the ryanodine receptors 2 (RyR2) on the sarcoplasmic reticulum (SR) at mitochondria-SR microdomains serves as the critical communication to match energy production to meet metabolic demands. Therefore, we tested the hypothesis that alterations in the mitochondria-SR connectomics contribute to SAN dysfunction in HF. We took advantage of a mouse model of chronic pressure overload-induced HF by transverse aortic constriction (TAC) and a SAN-specific CRISPR-Cas9-mediated knockdown of mitofusin-2 (Mfn2), the mitochondria-SR tethering GTPase protein. TAC mice exhibited impaired cardiac function with HF, cardiac fibrosis, and profound SAN dysfunction. Ultrastructural imaging using electron microscope (EM) tomography revealed abnormal mitochondrial structure with increased mitochondria-SR distance. The expression of Mfn2 was significantly down-regulated and showed reduced colocalization with RyR2 in HF SAN cells. Indeed, SAN-specific Mfn2 knockdown led to alterations in the mitochondria-SR microdomains and SAN dysfunction. Finally, disruptions in the mitochondria-SR microdomains resulted in abnormal mitochondrial Ca2+ handling, alterations in localized protein kinase A (PKA) activity, and impaired mitochondrial function in HF SAN cells. The current study provides insights into the role of mitochondria-SR microdomains in SAN automaticity and possible therapeutic targets for SAN dysfunction in HF patients.
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Conectoma , Insuficiencia Cardíaca , Mitocondrias Cardíacas , Retículo Sarcoplasmático , Síndrome del Seno Enfermo , Nodo Sinoatrial , Animales , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/fisiopatología , Ratones , Mitocondrias Cardíacas/ultraestructura , Miocitos Cardíacos/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/patología , Síndrome del Seno Enfermo/patología , Síndrome del Seno Enfermo/fisiopatología , Nodo Sinoatrial/fisiopatologíaRESUMEN
Type 2 diabetes (T2D) patients with SARS-CoV-2 infection hospitalized develop an acute cardiovascular syndrome. It is urgent to elucidate underlying mechanisms associated with the acute cardiac injury in T2D hearts. We performed bioinformatic analysis on the expression profiles of public datasets to identify the pathogenic and prognostic genes in T2D hearts. Cardiac RNA-sequencing datasets from db/db or BKS mice (GSE161931) were updated to NCBI-Gene Expression Omnibus (NCBI-GEO), and used for the transcriptomics analyses with public datasets from NCBI-GEO of autopsy heart specimens with COVID-19 (5/6 with T2D, GSE150316), or dead healthy persons (GSE133054). Differentially expressed genes (DEGs) and overlapping homologous DEGs among the three datasets were identified using DESeq2. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses were conducted for event enrichment through clusterProfile. The protein-protein interaction (PPI) network of DEGs was established and visualized by Cytoscape. The transcriptions and functions of crucial genes were further validated in db/db hearts. In total, 542 up-regulated and 485 down-regulated DEGs in mice, and 811 up-regulated and 1399 down-regulated DEGs in human were identified, respectively. There were 74 overlapping homologous DEGs among all datasets. Mitochondria inner membrane and serine-type endopeptidase activity were further identified as the top-10 GO events for overlapping DEGs. Cardiac CAPNS1 (calpain small subunit 1) was the unique crucial gene shared by both enriched events. Its transcriptional level significantly increased in T2D mice, but surprisingly decreased in T2D patients with SARS-CoV-2 infection. PPI network was constructed with 30 interactions in overlapping DEGs, including CAPNS1. The substrates Junctophilin2 (Jp2), Tnni3, and Mybpc3 in cardiac calpain/CAPNS1 pathway showed less transcriptional change, although Capns1 increased in transcription in db/db mice. Instead, cytoplasmic JP2 significantly reduced and its hydrolyzed product JP2NT exhibited nuclear translocation in myocardium. This study suggests CAPNS1 is a crucial gene in T2D hearts. Its transcriptional upregulation leads to calpain/CAPNS1-associated JP2 hydrolysis and JP2NT nuclear translocation. Therefore, attenuated cardiac CAPNS1 transcription in T2D patients with SARS-CoV-2 infection highlights a novel target in adverse prognostics and comprehensive therapy. CAPNS1 can also be explored for the molecular signaling involving the onset, progression and prognostic in T2D patients with SARS-CoV-2 infection.
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COVID-19/epidemiología , Biología Computacional , Diabetes Mellitus Tipo 2/epidemiología , Diabetes Mellitus Tipo 2/genética , Cardiomiopatías Diabéticas/epidemiología , SARS-CoV-2 , Adulto , Anciano , Anciano de 80 o más Años , Animales , Calpaína/genética , Calpaína/fisiología , Comorbilidad , Diabetes Mellitus Tipo 2/fisiopatología , Cardiomiopatías Diabéticas/genética , Cardiomiopatías Diabéticas/fisiopatología , Humanos , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Mitocondrias Cardíacas/ultraestructura , Proteínas Musculares/metabolismo , Miocardio/química , Miocardio/metabolismo , Miocardio/ultraestructura , Pronóstico , Análisis de Secuencia de ARN , TranscriptomaRESUMEN
Mitochondrial dysfunction is a feature of type I and type II diabetes, but there is a lack of consistency between reports and links to disease development. We aimed to investigate if mitochondrial structure-function remodelling occurs in the early stages of diabetes by employing a mouse model (GENA348) of Maturity Onset Diabetes in the Young, exhibiting hyperglycemia, but not hyperinsulinemia, with mild left ventricular dysfunction. Employing 3-D electron microscopy (SBF-SEM) we determined that compared to wild-type, WT, the GENA348 subsarcolemma mitochondria (SSM) are ~ 2-fold larger, consistent with up-regulation of fusion proteins Mfn1, Mfn2 and Opa1. Further, in comparison, GENA348 mitochondria are more irregular in shape, have more tubular projections with SSM projections being longer and wider. Mitochondrial density is also increased in the GENA348 myocardium consistent with up-regulation of PGC1-α and stalled mitophagy (down-regulation of PINK1, Parkin and Miro1). GENA348 mitochondria have more irregular cristae arrangements but cristae dimensions and density are similar to WT. GENA348 Complex activity (I, II, IV, V) activity is decreased but the OCR is increased, potentially linked to a shift towards fatty acid oxidation due to impaired glycolysis. These novel data reveal that dysregulated mitochondrial morphology, dynamics and function develop in the early stages of diabetes.
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Diabetes Mellitus Experimental/patología , Diabetes Mellitus Tipo 2/patología , Mitocondrias Cardíacas/ultraestructura , Dinámicas Mitocondriales , Miocardio/ultraestructura , Animales , Diabetes Mellitus Experimental/fisiopatología , Diabetes Mellitus Tipo 2/fisiopatología , Ratones , Mitocondrias Cardíacas/fisiologíaRESUMEN
Dietary restriction (DR) exerts healthy benefits, including heart functions. However, the cardioprotective role of DR is till controversial among researchers due to the variation of DR conditions. The present study focuses on the protective effect of early-onset DR on cardiac injury using mitochondrial structure and expression of protein associated with mitochondrial homeostasis, autophagy and endoplasmic reticulum (ER) function as measures. 2-month-old mice were fed with a breeding diet ad libitum (AL) or DR (60% of AL) for 3 (Young) or 20 (Aged) months. Body weight increased with aging, whereas DR treatment kept body weight consistent. DR mice exhibited a higher relative heart weight than AL mice. DR mice displayed lower plasma glucose levels, compared with AL groups. Furthermore, Aged-AL, but not Aged-DR mice, had increased collagen content and morphological distortions in the left ventricle (LV). Aged-DR mice had a higher ATP and lower TBARS in the LV than Aged-AL mice. Mitochondrial morphology was detected by electron microscopy; Aged-AL mice had increased abnormal morphology of mitochondria. Treatment with DR reduced abnormal mitochondrial accumulation. Aging elevated the protein expressions of mitochondrial functions and ER-induced apoptosis. Aging downregulated autophagy related proteins and chaperones in the heart. Dietary restriction reversed those protein expressions. The present study demonstrated a beneficial effect of early onset DR on cardiac aging. The age-dependent mitochondrial dysfunction and protein quality control dysregulation was significantly reversed by long-term DR, demonstrating a concordance with the beneficial effect in the heart.
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Envejecimiento , Autofagia , Restricción Calórica , Retículo Endoplásmico/metabolismo , Mitocondrias Cardíacas/metabolismo , Función Ventricular , Animales , Retículo Endoplásmico/ultraestructura , Estrés del Retículo Endoplásmico , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/ultraestructura , Masculino , Ratones , Ratones Endogámicos C57BL , Mitocondrias Cardíacas/ultraestructura , Proteínas Mitocondriales/metabolismo , Miocardio/metabolismo , Fosforilación OxidativaRESUMEN
Mitochondria-targeting positron emission tomography (PET) and fluorescent dual-modal probes are rarely reported. As one of the most promising lipophilic cations, F16 and its derivatives (F16s) have never been used for myocardial imaging. In this work, 14 F16s are synthesized and evaluated for cardiac imaging. In vitro cell fluorescence imaging revealed that the lead probe 5MEF is precisely localized in the mitochondria of cardiomyocytes. In addition, it shows excellent ex vivo fluorescence imaging quality with the heart-to-muscle and heart-to-liver ratios up to â¼2. Furthermore, the radiofluorinated probe 18F-5MEF is successfully prepared and shows a high initial heart uptake of 8.66 ± 0.34 % ID/g at 5 min post injection. It displays a high heart imaging performance, a long retention time in the heart, and a low background in the most normal tissues as revealed by PET. To our knowledge, this is the first time novel F16 analogues are designed and developed for myocardial dual-modal imaging.
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Colorantes/síntesis química , Colorantes/farmacología , Colorantes Fluorescentes/síntesis química , Colorantes Fluorescentes/farmacología , Corazón/diagnóstico por imagen , Mitocondrias Cardíacas/ultraestructura , Tomografía de Emisión de Positrones/métodos , Animales , Línea Celular , Colorantes/toxicidad , Diagnóstico por Imagen , Diseño de Fármacos , Femenino , Colorantes Fluorescentes/toxicidad , Humanos , Ratones , Ratones Endogámicos BALB C , Miocardio/metabolismo , Radiofármacos/síntesis química , Radiofármacos/farmacología , Radiofármacos/toxicidad , Bibliotecas de Moléculas PequeñasAsunto(s)
Cardiomiopatías/fisiopatología , Disfunción Cognitiva/fisiopatología , Pérdida Auditiva Sensorineural/fisiopatología , Hipertrofia Ventricular Izquierda/fisiopatología , Hipertrofia Ventricular Derecha/fisiopatología , Enfermedades Mitocondriales/fisiopatología , Disfunción Ventricular Izquierda/fisiopatología , Adulto , Atrofia , Cardiomiopatías/complicaciones , Cardiomiopatías/diagnóstico por imagen , Cardiomiopatías/genética , Enfermedades Cerebelosas/complicaciones , Enfermedades Cerebelosas/diagnóstico por imagen , Enfermedades Cerebelosas/fisiopatología , Disfunción Cognitiva/complicaciones , Ecocardiografía , Intolerancia a la Glucosa/complicaciones , Intolerancia a la Glucosa/fisiopatología , Pérdida Auditiva Sensorineural/complicaciones , Humanos , Hipertrofia Ventricular Izquierda/complicaciones , Hipertrofia Ventricular Izquierda/diagnóstico por imagen , Hipertrofia Ventricular Derecha/complicaciones , Hipertrofia Ventricular Derecha/diagnóstico por imagen , Hipotiroidismo/complicaciones , Hipotiroidismo/fisiopatología , Ácido Láctico/sangre , Imagen por Resonancia Magnética , Masculino , Mitocondrias Cardíacas/ultraestructura , Enfermedades Mitocondriales/complicaciones , Enfermedades Mitocondriales/diagnóstico , Enfermedades Mitocondriales/genética , Debilidad Muscular/complicaciones , Debilidad Muscular/fisiopatología , Miocardio/patología , Miocardio/ultraestructura , Ácido Pirúvico/sangre , Disfunción Ventricular Izquierda/complicaciones , Disfunción Ventricular Izquierda/diagnóstico por imagenRESUMEN
RBFOX2, which has a well-established role in alternative splicing, is linked to heart diseases. However, it is unclear whether RBFOX2 has other roles in RNA processing that can influence gene expression in muscle cells, contributing to heart disease. Here, we employ both 3'-end and nanopore cDNA sequencing to reveal a previously unrecognized role for RBFOX2 in maintaining alternative polyadenylation (APA) signatures in myoblasts. RBFOX2-mediated APA modulates mRNA levels and/or isoform expression of a collection of genes, including contractile and mitochondrial genes. Depletion of RBFOX2 adversely affects mitochondrial health in myoblasts, correlating with disrupted APA of mitochondrial gene Slc25a4. Mechanistically, RBFOX2 regulation of Slc25a4 APA is mediated through consensus RBFOX2 binding motifs near the distal polyadenylation site, enforcing the use of the proximal polyadenylation site. In sum, our results unveil a role for RBFOX2 in fine-tuning expression of mitochondrial and contractile genes via APA in myoblasts relevant to heart diseases.
Asunto(s)
Mitocondrias Cardíacas/metabolismo , Proteínas Mitocondriales/metabolismo , Proteínas Musculares/metabolismo , Mioblastos Cardíacos/metabolismo , Poliadenilación , Factores de Empalme de ARN/metabolismo , Translocador 1 del Nucleótido Adenina/genética , Translocador 1 del Nucleótido Adenina/metabolismo , Animales , Regulación de la Expresión Génica , Células HEK293 , Humanos , Mitocondrias Cardíacas/genética , Mitocondrias Cardíacas/ultraestructura , Proteínas Mitocondriales/genética , Proteínas Musculares/genética , Mioblastos Cardíacos/ultraestructura , Factores de Empalme de ARN/genética , Ratas , Tropomiosina/genética , Tropomiosina/metabolismoRESUMEN
Mitochondria, abundant organelles in high energy demand cells such as cardiomyocytes, can determine cell death or survival by regulating the opening of mitochondrial permeability transition pore, mPTP. We addressed the hypothesis that the growth factor FGF2, known to reside in intracellular locations, can directly influence mitochondrial susceptibility to mPTP opening. Rat cardiac subsarcolemmal (SSM) or interfibrillar (IFM) mitochondrial suspensions exposed directly to rat 18 kDa low molecular weight (Lo-) FGF2 isoform displayed increased resistance to calcium overload-induced mPTP, measured spectrophotometrically as "swelling", or as cytochrome c release from mitochondria. Inhibition of mitochondrial protein kinase C epsilon abrogated direct Lo-FGF2 mito-protection. Exposure to the rat 23 kDa high molecular weight (Hi) FGF2 isoform promoted cytochrome c release from SSM and IFM under nonstressed conditions. The effect of Hi-FGF2 was prevented by mPTP inhibitors, pre-exposure to Lo-FGF2, and okadaic acid, a serine/threonine phosphatase inhibitor. Western blotting and immunoelectron microscopy pointed to the presence of immunoreactive FGFR1 in cardiac mitochondria in situ. The direct mito-protective effect of Lo-FGF2, as well as the deleterious effect of Hi-FGF2, were prevented by FGFR1 inhibitors and FGFR1 neutralizing antibodies. We propose that intracellular FGF2 isoforms can modulate mPTP opening by interacting with mito-FGFR1 and relaying isoform-specific intramitochondrial signal transduction.
Asunto(s)
Factor 2 de Crecimiento de Fibroblastos/metabolismo , Mitocondrias Cardíacas/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial/metabolismo , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/metabolismo , Animales , Calcio/metabolismo , Citocromos c/metabolismo , Masculino , Mitocondrias Cardíacas/ultraestructura , Isoformas de Proteínas/metabolismo , Proteína Quinasa C-epsilon/metabolismo , Ratas Sprague-Dawley , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/antagonistas & inhibidoresRESUMEN
Ageing is associated with an increase in the incidence of heart failure, even if the existence of a real age-related cardiomyopathy remains controversial. Effective contraction and relaxation of cardiomyocytes depend on efficient production of ATP (handled by mitochondria) and on proper Ca2+ supply to myofibrils during excitation-contraction (EC) coupling (handled by Ca2+ release units, CRUs). Here, we analyzed mitochondria and CRUs in hearts of adult (4 months old) and aged (≥24 months old) mice. Analysis by confocal and electron microscopy (CM and EM, respectively) revealed an age-related loss of proper organization and disposition of both mitochondria and EC coupling units: (a) mitochondria are improperly disposed and often damaged (percentage of severely damaged mitochondria: adults 3.5 ± 1.1%; aged 16.5 ± 3.5%); (b) CRUs that are often misoriented (longitudinal) and/or misplaced from the correct position at the Z line. Immunolabeling with antibodies that mark either the SR or T-tubules indicates that in aged cardiomyocytes the sarcotubular system displays an extensive disarray. This disarray could be in part caused by the decreased expression of Cav-3 and JP-2 detected by western blot (WB), two proteins involved in formation of T-tubules and in docking SR to T-tubules in dyads. By WB analysis, we also detected increased levels of 3-NT in whole hearts homogenates of aged mice, a product of nitration of protein tyrosine residues, recognized as marker of oxidative stress. Finally, a detailed EM analysis of CRUs (formed by association of SR with T-tubules) points to ultrastructural modifications, i.e., a decrease in their frequency (adult: 5.1 ± 0.5; aged: 3.9 ± 0.4 n./50 µm2) and size (adult: 362 ± 40 nm; aged: 254 ± 60 nm). The changes in morphology and disposition of mitochondria and CRUs highlighted by our results may underlie an inefficient supply of Ca2+ ions and ATP to the contractile elements, and possibly contribute to cardiac dysfunction in ageing.
Asunto(s)
Calcio/metabolismo , Mitocondrias Cardíacas/ultraestructura , Miocitos Cardíacos/ultraestructura , Envejecimiento , Animales , Senescencia Celular , Acoplamiento Excitación-Contracción , Masculino , Ratones Endogámicos C57BL , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patologíaRESUMEN
Diabetic cardiomyopathy is a primary cause of increased morbidity and mortality in diabetics. Evidence has suggested a pivotal role for interrupted mitochondrial dynamics and quality control machinery in the onset and development of diabetic cardiomyopathy. Sequestosome 1 (SQSTM1) is a major reporter of selective autophagic activity. Other than controlling the expression of genes involved in mitochondrial biogenesis, recently peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) was reported to directly affect SQSTM1 gene expression. Calcineurin, a pivotal mediator of cardiac hypertrophy, has been also linked to enhanced expression of SQSTM1. This study aimed to test the cardioprotective effects of adding ω-3 polyunsaturated fatty acids (PUFAs) to metformin in a rat model of type 2 diabetes mellitus and to evaluate the molecular mechanisms underlying their effects on mitochondrial quality. Diabetes was induced in male Sprague Dawley rats by a high-fat diet for 6 weeks, followed by a low-dose streptozotocin (35 mg/kg). Diabetic rats were either treated with metformin (150 mg/kg/d), ω-3 PUFAs (300 mg/kg/d), or their combination in the same doses for further 8 weeks. Along with metabolic and pathological derangements, we report that correlating with electron microscopic evidence of mitochondrial degeneration, gene expression of the autophagic indicators SQSTM1, PGC-1α, and calcineurin were decreased in the hearts of diabetic rats. Independent of its anti-hyperglycemic effects, metformin successfully preserved mitochondrial integrity and upregulated myocardial PGC-1α, calcineurin, and SQSTM1 gene expression. ω-3 PUFAs possess synergistic cardioprotection when added to metformin, suggested by improvements in myocardial ultrastructure, autophagic activity, and SQSTM1 gene expression.
Asunto(s)
Autofagia , Diabetes Mellitus Tipo 2/complicaciones , Cardiomiopatías Diabéticas/prevención & control , Ácidos Grasos Omega-3/administración & dosificación , Metformina/administración & dosificación , Animales , Calcineurina/genética , Calcineurina/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , Cardiomiopatías Diabéticas/metabolismo , Dieta Alta en Grasa , Masculino , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/ultraestructura , Miocardio/metabolismo , Miocardio/ultraestructura , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Ratas , Ratas Sprague-Dawley , Proteína Sequestosoma-1/genética , Proteína Sequestosoma-1/metabolismo , Regulación hacia ArribaRESUMEN
Mitochondrial transplantation is emerging as a novel cellular biotherapy to alleviate mitochondrial damage and dysfunction. Mitochondria play a crucial role in establishing cellular homeostasis and providing cell with the energy necessary to accomplish its function. Owing to its endosymbiotic origin, mitochondria share many features with their bacterial ancestors. Unlike the nuclear DNA, which is packaged into nucleosomes and protected from adverse environmental effects, mitochondrial DNA are more prone to harsh environmental effects, in particular that of the reactive oxygen species. Mitochondrial damage and dysfunction are implicated in many diseases ranging from metabolic diseases to cardiovascular and neurodegenerative diseases, among others. While it was once thought that transplantation of mitochondria would not be possible due to their semiautonomous nature and reliance on the nucleus, recent advances have shown that it is possible to transplant viable functional intact mitochondria from autologous, allogenic, and xenogeneic sources into different cell types. Moreover, current research suggests that the transplantation could positively modulate bioenergetics and improve disease outcome. Mitochondrial transplantation techniques and consequences of transplantation in cardiomyocytes are the theme of this review. We outline the different mitochondrial isolation and transfer techniques. Finally, we detail the consequences of mitochondrial transplantation in the cardiovascular system, more specifically in the context of cardiomyopathies and ischemia.
Asunto(s)
Cardiomiopatías/terapia , Diabetes Mellitus Experimental/terapia , Mitocondrias Cardíacas/trasplante , Infarto del Miocardio/terapia , Daño por Reperfusión Miocárdica/terapia , Miocitos Cardíacos/metabolismo , Animales , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Fraccionamiento Celular/métodos , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patología , Modelos Animales de Enfermedad , Humanos , Inyecciones Intralesiones , Mitocondrias Cardíacas/fisiología , Mitocondrias Cardíacas/ultraestructura , Dinámicas Mitocondriales/fisiología , Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Miocitos Cardíacos/patología , Fosforilación Oxidativa , Conejos , Ratas , Especies Reactivas de Oxígeno/metabolismo , PorcinosRESUMEN
Empagliflozin (EMPA) is a SGLT-2 inhibitor that has positive effects on cardiovascular outcomes. In this study, we aim to evaluate the possible protective effects of EMPA against doxorubicin (DOX)-induced acute cardiotoxicity. Non-diabetic Sprague-Dawley rats were randomized into four groups. The control group received serum physiologic (1 ml), the EMPA group received EMPA, the DOX group was administered cumulatively 18 mg/kg body weight DOX. The DOX+EMPA group was administered DOX and EMPA. In the DOX group, LVDED (P < 0.05) and LVSED (P < 0.01), QTc interval (P < 0.001), the ratio of karyolysis and karyorrhexis (P < 0.001) and infiltrative cell proliferation (P < 0.001) were found to be higher than; EF, FS and normal cell morphology were lower than the control group (P < 0.001). In the DOX+EMPA group, LVEDD (P < 0.05) and LVESD (P < 0.01) values, QTc interval (P < 0.001), karyolysis and karyorrhexis ratios (P < 0.001) and infiltrative cell proliferation were lower (P < 0.01); normal cell morphology and EF were higher compared to the DOX group (P < 0.001). Our results showed that empagliflozin significantly ameliorated DOX-induced acute cardiotoxicity.