RESUMO
BACKGROUND: Shortly after birth, cardiomyocytes exit the cell cycle and cease proliferation. At present, the regulatory mechanisms for this loss of proliferative capacity are poorly understood. CBX7 (chromobox 7), a polycomb group (PcG) protein, regulates the cell cycle, but its role in cardiomyocyte proliferation is unknown. METHODS: We profiled CBX7 expression in the mouse hearts through quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry. We overexpressed CBX7 in neonatal mouse cardiomyocytes through adenoviral transduction. We knocked down CBX7 by using constitutive and inducible conditional knockout mice (Tnnt2-Cre;Cbx7fl/+ and Myh6-MCM;Cbx7fl/fl, respectively). We measured cardiomyocyte proliferation by immunostaining of proliferation markers such as Ki67, phospho-histone 3, and cyclin B1. To examine the role of CBX7 in cardiac regeneration, we used neonatal cardiac apical resection and adult myocardial infarction models. We examined the mechanism of CBX7-mediated repression of cardiomyocyte proliferation through coimmunoprecipitation, mass spectrometry, and other molecular techniques. RESULTS: We explored Cbx7 expression in the heart and found that mRNA expression abruptly increased after birth and was sustained throughout adulthood. Overexpression of CBX7 through adenoviral transduction reduced proliferation of neonatal cardiomyocytes and promoted their multinucleation. On the other hand, genetic inactivation of Cbx7 increased proliferation of cardiomyocytes and impeded cardiac maturation during postnatal heart growth. Genetic ablation of Cbx7 promoted regeneration of neonatal and adult injured hearts. Mechanistically, CBX7 interacted with TARDBP (TAR DNA-binding protein 43) and positively regulated its downstream target, RBM38 (RNA Binding Motif Protein 38), in a TARDBP-dependent manner. Overexpression of RBM38 inhibited the proliferation of CBX7-depleted neonatal cardiomyocytes. CONCLUSIONS: Our results demonstrate that CBX7 directs the cell cycle exit of cardiomyocytes during the postnatal period by regulating its downstream targets TARDBP and RBM38. This is the first study to demonstrate the role of CBX7 in regulation of cardiomyocyte proliferation, and CBX7 could be an important target for cardiac regeneration.
Assuntos
Proteínas de Ligação a DNA , Miócitos Cardíacos , Animais , Camundongos , Animais Recém-Nascidos , Proliferação de Células , Proteínas de Ligação a DNA/metabolismo , Camundongos Knockout , Miócitos Cardíacos/metabolismo , Proteínas do Grupo Polycomb/metabolismoRESUMO
Primary cardiomyocytes are invaluable for understanding postnatal heart development. However, a universal method to obtain freshly purified cardiomyocytes without using different age-dependent isolation procedures and cell culture, is lacking. Here, we report the development of a standardised method that allows rapid isolation and purification of high-quality cardiomyocytes from individual neonatal through to adult C57BL/6J murine hearts. Langendorff retrograde perfusion, which is currently limited to adult hearts, was adapted for use in neonatal and infant hearts by developing an easier in situ aortic cannulation technique. Tissue digestion conditions were optimised to achieve efficient digestion of hearts of all ages in a comparable timeframe (<14 min). This resulted in a high yield (1.56-2.2 × 106 cells/heart) and viability (~70-100%) of cardiomyocytes post-isolation. An immunomagnetic cell separation step was then applied to yield highly purified cardiomyocytes (~95%) as confirmed by immunocytochemistry, flow cytometry, and qRT-PCR. For cell type-specific studies, cardiomyocyte DNA, RNA, and protein could be extracted in sufficient yields to conduct molecular experiments. We generated transcriptomic datasets for neonatal cardiomyocytes from individual hearts, for the first time, which revealed nine sex-specific genes (FDR < 0.05) encoded on the sex chromosomes. Finally, we also developed an in situ fixation protocol that preserved the native cytoarchitecture of cardiomyocytes (~94% rod-shaped post-isolation), and used it to evaluate cell morphology during cardiomyocyte maturation, as well as capture spindle-shaped neonatal cells undergoing cytokinesis. Together, these procedures allow molecular and morphological profiling of high-quality cardiomyocytes from individual hearts of any postnatal age.
Assuntos
Técnicas de Cultura de Células , Miócitos Cardíacos , Animais , Feminino , Citometria de Fluxo , Humanos , Masculino , Camundongos , Miócitos Cardíacos/metabolismo , RNA/metabolismo , TranscriptomaRESUMO
Renewal of the myocardium by preexisting cardiomyocytes is a powerful strategy for restoring the architecture and function of hearts injured by myocardial infarction. To advance this strategy, we show that combining two clinically approved drugs, but neither alone, muscularizes the heart through cardiomyocyte proliferation. Specifically, in adult murine cardiomyocytes, metoprolol, a cardioselective ß1-adrenergic receptor blocker, when given with triiodothyronine (T3, a thyroid hormone) accentuates the ability of T3 to stimulate ERK1/2 phosphorylation and proliferative signaling by inhibiting expression of the nuclear phospho-ERK1/2-specific phosphatase, dual-specificity phosphatase-5. While short-duration metoprolol plus T3 therapy generates new heart muscle in healthy mice, in mice with myocardial infarction-induced left ventricular dysfunction and pathological remodeling, it remuscularizes the heart, restores contractile function and reverses chamber dilatation; outcomes that are enduring. If the beneficial effects of metoprolol plus T3 are replicated in humans, this therapeutic strategy has the potential to definitively address ischemic heart failure.
Assuntos
Infarto do Miocárdio , Disfunção Ventricular Esquerda , Antagonistas de Receptores Adrenérgicos beta 1/farmacologia , Antagonistas de Receptores Adrenérgicos beta 1/uso terapêutico , Animais , Metoprolol/farmacologia , Metoprolol/uso terapêutico , Camundongos , Infarto do Miocárdio/patologia , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Tri-Iodotironina/metabolismo , Tri-Iodotironina/farmacologia , Disfunção Ventricular Esquerda/patologia , Remodelação VentricularRESUMO
Heart failure in adults is a leading cause of morbidity and mortality worldwide. It can arise from a variety of diseases, with most resulting in a loss of cardiomyocytes that cannot be replaced due to their inability to replicate, as well as to a lack of resident cardiomyocyte progenitor cells in the adult heart. Identifying and exploiting mechanisms underlying loss of developmental cardiomyocyte replicative capacity has proved to be useful in developing therapeutics to effect adult cardiac regeneration. Of course, effective regeneration of myocardium after injury requires not just expansion of cardiomyocytes, but also neovascularization to allow appropriate perfusion and resolution of injury-induced inflammation and interstitial fibrosis, but also reversal of adverse left ventricular remodeling. In addition to overcoming these challenges, a regenerative therapy needs to be safe and easily translatable. Failure to address these critical issues will delay the translation of regenerative approaches. This review critically analyzes current regenerative approaches while also providing a framework for future experimental studies aimed at enhancing success in regenerating the injured heart.
RESUMO
Rationale: Doxorubicin is a widely used anticancer drug. However, its major side effect, cardiotoxicity, results from cardiomyocyte loss that causes left ventricle (LV) wall thinning, chronic LV dysfunction and heart failure. Cardiomyocyte number expansion by thyroid hormone (T3) during preadolescence is suppressed by the developmental induction of an ERK1/2-specific dual specificity phosphatase 5 (DUSP5). Here, we sought to determine if a brief course of combined DUSP5 suppression plus T3 therapy replaces cardiomyocytes lost due to preexisting doxorubicin injury and reverses heart failure. Methods: We used in vivo-jetPEI to deliver DUSP5 or scrambled siRNA to ~5-week-old C57BL6 mice followed by 5 daily injections of T3 (2 ng/µg body weight). Genetic lineage tracing using Myh6-MerCreMer::Rosa26fs-Confetti mice and direct cardiomyocyte number counting, along with cell cycle inhibition (danusertib), was used to test if this treatment leads to de novo cardiomyocyte generation and improves LV contractile function. Three doses of doxorubicin (20 µg/g) given at 2-weekly intervals, starting at 5-weeks of age in C57BL6 mice, caused severe heart failure, as evident by a decrease in LV ejection fraction. Mice with an ~40 percentage point decrease in LVEF post-doxorubicin injury were randomized to receive either DUSP5 siRNA plus T3, or scrambled siRNA plus vehicle for T3. Age-matched mice without doxorubicin injury served as controls. Results: In uninjured adult mice, transient therapy with DUSP5 siRNA and T3 increases cardiomyocyte numbers, which is required for the associated increase in LV contractile function, since both are blocked by danusertib. In mice with chronic doxorubicin injury, DUSP5 siRNA plus T3 therapy rebuilds LV muscle by increasing cardiomyocyte numbers, which reverses LV dysfunction and prevents progressive chamber dilatation. Conclusion: RNA therapies are showing great potential. Importantly, a GMP compliant in vivo-jetPEI system for delivery of siRNA is already in use in humans, as is T3. Given these considerations, our findings provide a potentially highly translatable strategy for addressing doxorubicin cardiomyopathy, a currently untreatable condition.
Assuntos
Fosfatases de Especificidade Dupla/genética , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Tri-Iodotironina/farmacologia , Função Ventricular Esquerda/efeitos dos fármacos , Animais , Antibióticos Antineoplásicos/toxicidade , Benzamidas/farmacologia , Cardiotoxicidade/etiologia , Contagem de Células , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Doxorrubicina/toxicidade , Fosfatases de Especificidade Dupla/antagonistas & inibidores , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Contração Miocárdica/genética , Miócitos Cardíacos/citologia , Inibidores de Proteínas Quinases/farmacologia , Pirazóis/farmacologia , RNA Interferente Pequeno , Disfunção Ventricular Esquerda/induzido quimicamente , Função Ventricular Esquerda/genética , Remodelação Ventricular/efeitos dos fármacos , Remodelação Ventricular/genéticaRESUMO
Cardiomyocytes of newborn mice proliferate after injury or exposure to growth factors. However, these responses are diminished after postnatal day-6 (P6), representing a barrier to building new cardiac muscle in adults. We have previously shown that exogenous thyroid hormone (T3) stimulates cardiomyocyte proliferation in P2 cardiomyocytes, by activating insulin-like growth factor-1 receptor (IGF-1R)-mediated ERK1/2 signaling. But whether exogenous T3 functions as a mitogen in post-P6 murine hearts is not known. Here, we show that exogenous T3 increases the cardiomyocyte endowment of P8 hearts, but the proliferative response is confined to cardiomyocytes of the left ventricular (LV) apex. Exogenous T3 stimulates proliferative ERK1/2 signaling in apical cardiomyocytes, but not in those of the LV base, which is inhibited by expression of the nuclear phospho-ERK1/2-specific dual-specificity phosphatase, DUSP5. Developmentally, between P7 and P14, DUSP5 expression increases in the myocardium from the LV base to its apex; after this period, it is uniformly expressed throughout the LV. In young adult hearts, exogenous T3 increases cardiomyocyte numbers after DUSP5 depletion, which might be useful for eliciting cardiac regeneration.
Assuntos
Fosfatases de Especificidade Dupla/biossíntese , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Ventrículos do Coração/enzimologia , Miocárdio/enzimologia , Miócitos Cardíacos/enzimologia , Tri-Iodotironina/farmacologia , Animais , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos Transgênicos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismoRESUMO
Animal models of pressure overload are valuable for understanding hypertensive heart disease. We characterised a surgical model of pressure overload-induced hypertrophy in C57BL/6J mice produced by suprarenal aortic constriction (SAC). Compared to sham controls, at one week post-SAC systolic blood pressure was significantly elevated and left ventricular (LV) hypertrophy was evident by a 50% increase in the LV weight-to-tibia length ratio due to cardiomyocyte hypertrophy. As a result, LV end-diastolic wall thickness-to-chamber radius (h/R) ratio increased, consistent with the development of concentric hypertrophy. LV wall thickening was not sufficient to normalise LV wall stress, which also increased, resulting in LV systolic dysfunction with reductions in ejection fraction and fractional shortening, but no evidence of heart failure. Pathological LV remodelling was evident by the re-expression of fetal genes and coronary artery perivascular fibrosis, with ischaemia indicated by enhanced cardiomyocyte Hif1a expression. The expression of stem cell factor receptor, c-Kit, was low basally in cardiomyocytes and did not change following the development of robust hypertrophy, suggesting there is no role for cardiomyocyte c-Kit signalling in pathological LV remodelling following pressure overload.
Assuntos
Hipertrofia Ventricular Esquerda/patologia , Miócitos Cardíacos/patologia , Proteínas Proto-Oncogênicas c-kit/metabolismo , Animais , Aorta/fisiopatologia , Constrição Patológica , Regulação da Expressão Gênica , Hipertensão/etiologia , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pressão , Proteínas Proto-Oncogênicas c-kit/genética , Circulação Renal , Renina/genética , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologia , Remodelação Ventricular/genética , Remodelação Ventricular/fisiologiaRESUMO
Background DJ-1 is a ubiquitously expressed protein typically associated with the development of early onset Parkinson disease. Recent data suggest that it also plays a role in the cellular response to stress. Here, we sought to determine the role DJ-1 plays in the development of heart failure. Methods and Results Initial studies found that DJ-1 deficient mice (DJ-1 knockout; male; 8-10 weeks of age) exhibited more severe left ventricular cavity dilatation, cardiac dysfunction, hypertrophy, and fibrosis in the setting of ischemia-reperfusion-induced heart failure when compared with wild-type littermates. In contrast, the overexpression of the active form of DJ-1 using a viral vector approach resulted in significant improvements in the severity of heart failure when compared with mice treated with a control virus. Subsequent studies aimed at evaluating the underlying protective mechanisms found that cardiac DJ-1 reduces the accumulation of advanced glycation end products and activation of the receptor for advanced glycation end products-thus, reducing glycative stress. Conclusions These results indicate that DJ-1 is an endogenous cytoprotective protein that protects against the development of ischemia-reperfusion-induced heart failure by reducing glycative stress. Our findings also demonstrate the feasibility of using a gene therapy approach to deliver the active form of DJ-1 to the heart as a therapeutic strategy to protect against the consequences of ischemic injury, which is a major cause of death in western populations.
Assuntos
Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/metabolismo , Estresse Oxidativo/fisiologia , Proteína Desglicase DJ-1/metabolismo , Proteína Desglicase DJ-1/fisiologia , Animais , Modelos Animais de Doenças , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
Mitochondria-generated reactive oxygen species (mROS) are frequently associated with DNA damage and cell cycle arrest, but physiological increases in mROS serve to regulate specific cell functions. T3 is a major regulator of mROS, including hydrogen peroxide (H2O2). Here we show that exogenous thyroid hormone (T3) administration increases cardiomyocyte numbers in neonatal murine hearts. The mechanism involves signaling by mitochondria-generated H2O2 (mH2O2) acting via the redox sensor, peroxiredoxin-1, a thiol peroxidase with high reactivity towards H2O2 that activates c-Jun N-terminal kinase-2α2 (JNK2α2). JNK2α2, a relatively rare member of the JNK family of mitogen-activated protein kinases (MAPK), phosphorylates c-Jun, a component of the activator protein 1 (AP-1) early response transcription factor, resulting in enhanced insulin-like growth factor 1 (IGF-1) expression and activation of proliferative ERK1/2 signaling. This non-canonical mechanism of MAPK activation couples T3 actions on mitochondria to cell cycle activation. Although T3 is regarded as a maturation factor for cardiomyocytes, these studies identify a novel redox pathway that is permissive for T3-mediated cardiomyocyte proliferation-this because of the expression of a pro-proliferative JNK isoform that results in growth factor elaboration and ERK1/2 cell cycle activation.
Assuntos
Proliferação de Células , Sistema de Sinalização das MAP Quinases , Proteína Quinase 9 Ativada por Mitógeno/metabolismo , Miócitos Cardíacos/metabolismo , Hormônios Tireóideos/farmacologia , Animais , Células Cultivadas , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias Cardíacas/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia , Oxirredução , Peroxirredoxinas/metabolismoRESUMO
Background Lymphatic vessels interconnect with blood vessels to form an elaborate system that aids in the control of tissue pressure and edema formation. Although the lymphatic system has been known to exist in a heart, little is known about the role the cardiac lymphatic system plays in the development of heart failure. Methods and Results Mice (C57 BL /6J, male, 8 to 12 weeks of age) were subjected to either myocardial ischemia or myocardial ischemia and reperfusion for up to 28 days. Analysis revealed that both models increased the protein expression of vascular endothelial growth factor C and VEGF receptor 3 starting at 1 day after the onset of injury, whereas a significant increase in lymphatic vessel density was observed starting at 3 days. Further studies aimed to determine the consequences of inhibiting the endogenous lymphangiogenesis response on the development of heart failure. Using 2 different pharmacological approaches, we found that inhibiting VEGF receptor 3 with MAZ -51 and blocking endogenous vascular endothelial growth factor C with a neutralizing antibody blunted the increase in lymphatic vessel density, blunted lymphatic transport, increased inflammation, increased edema, and increased cardiac dysfunction. Subsequent studies revealed that augmentation of the endogenous lymphangiogenesis response with vascular endothelial growth factor C treatment reduced inflammation, reduced edema, and improved cardiac dysfunction. Conclusions These results suggest that the endogenous lymphangiogenesis response plays an adaptive role in the development of ischemic-induced heart failure and supports the emerging concept that therapeutic lymphangiogenesis is a promising new approach for the treatment of cardiovascular disease.
Assuntos
Insuficiência Cardíaca/etiologia , Linfangiogênese/fisiologia , Vasos Linfáticos/patologia , Isquemia Miocárdica/fisiopatologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Remodelação Ventricular/fisiologia , Animais , Western Blotting , Células Cultivadas , Modelos Animais de Doenças , Endotélio Vascular/patologia , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Isquemia Miocárdica/complicações , Isquemia Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/complicações , Traumatismo por Reperfusão Miocárdica/patologiaRESUMO
We have previously demonstrated that adult transgenic C57BL/6J mice with CM-restricted overexpression of the dominant negative W v mutant protein (dn-c-kit-Tg) respond to pressure overload with robust cardiomyocyte (CM) cell cycle entry. Here, we tested if outcomes after myocardial infarction (MI) due to coronary artery ligation are improved in this transgenic model. Compared to non-transgenic littermates (NTLs), adult male dn-c-kit-Tg mice displayed CM hypertrophy and concentric left ventricular (LV) hypertrophy in the absence of an increase in workload. Stroke volume and cardiac output were preserved and LV wall stress was markedly lower than that in NTLs, leading to a more energy-efficient heart. In response to MI, infarct size in adult (16-week old) dn-c-kit-Tg hearts was similar to that of NTL after 24 h but was half that in NTL hearts 12 weeks post-MI. Cumulative CM cell cycle entry was only modestly increased in dn-c-kit-Tg hearts. However, dn-c-kit-Tg mice were more resistant to infarct expansion, adverse LV remodelling and contractile dysfunction, and suffered no early death from LV rupture, relative to NTL mice. Thus, pre-existing cardiac hypertrophy lowers wall stress in dn-c-kit-Tg hearts, limits infarct expansion and prevents death from myocardial rupture.
Assuntos
Cardiomegalia/patologia , Infarto do Miocárdio/patologia , Animais , Cardiomegalia/genética , Modelos Animais de Doenças , Hipertrofia Ventricular Esquerda/genética , Hipertrofia Ventricular Esquerda/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Infarto do Miocárdio/genética , Miocárdio/patologia , Proteínas Proto-Oncogênicas c-kit/genética , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/patologiaRESUMO
Stimulating regeneration of complex tissues and organs after injury to effect complete structural and functional repair, is an attractive therapeutic option that would revolutionize clinical medicine. Compared to many metazoan phyla that show extraordinary regenerative capacity, which in some instances persists throughout life, regeneration in mammalians, particularly humans, is limited or absent. Here we consider recent insights in the elucidation of molecular mechanisms of regeneration that have come from studies of tissue homeostasis and injury repair in mammalian tissues that span the spectrum from little or no self-renewal, to those showing active cell turnover throughout life. These studies highlight the diversity of factors that constrain regeneration, including immune responses, extracellular matrix composition, age, injury type, physiological adaptation, and angiogenic and neurogenic capacity. Despite these constraints, much progress has been made in elucidating key molecular mechanisms that may provide therapeutic targets for the development of future regenerative therapies, as well as previously unidentified developmental paradigms and windows-of-opportunity for improved regenerative repair.
RESUMO
Heart disease is a leading cause of death in adults. Here, we show that a few days after coronary artery ligation and reperfusion, the ischemia-injured heart elaborates the cardioprotective polypeptide, insulin-like growth factor-1 (IGF-1), which activates IGF-1 receptor prosurvival signaling and improves cardiac left ventricular systolic function. However, this signaling is antagonized by the chymase, mouse mast cell protease 4 (MMCP-4), which degrades IGF-1. We found that deletion of the gene encoding MMCP-4 (Mcpt4), markedly reduced late, but not early, infarct size by suppressing IGF-1 degradation and, consequently, diminished cardiac dysfunction and adverse structural remodeling. Our findings represent the first demonstration to our knowledge of tissue IGF-1 regulation through proteolytic degradation and suggest that chymase inhibition may be a viable therapeutic approach to enhance late cardioprotection in postischemic heart disease.
Assuntos
Morte Celular , Fator de Crescimento Insulin-Like I/metabolismo , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/metabolismo , Serina Endopeptidases/metabolismo , Animais , Hidrólise , Camundongos , Serina Endopeptidases/genéticaRESUMO
BACKGROUND: Therapeutic strategies aimed at increasing hydrogen sulfide (H2S) levels exert cytoprotective effects in various models of cardiovascular injury. However, the underlying mechanism(s) responsible for this protection remain to be fully elucidated. Nuclear factor E2-related factor 2 (Nrf2) is a cellular target of H2S and facilitator of H2S-mediated cardioprotection after acute myocardial infarction. Here, we tested the hypothesis that Nrf2 mediates the cardioprotective effects of H2S therapy in the setting of heart failure. METHODS AND RESULTS: Mice (12 weeks of age) deficient in Nrf2 (Nrf2 KO; C57BL/6J background) and wild-type littermates were subjected to ischemic-induced heart failure. Wild-type mice treated with H2S in the form of sodium sulfide (Na2S) displayed enhanced Nrf2 signaling, improved left ventricular function, and less cardiac hypertrophy after the induction of heart failure. In contrast, Na2S therapy failed to provide protection against heart failure in Nrf2 KO mice. Studies aimed at evaluating the underlying cardioprotective mechanisms found that Na2S increased the expression of proteasome subunits, resulting in an increased proteasome activity and a reduction in the accumulation of damaged proteins. In contrast, Na2S therapy failed to enhance the proteasome and failed to attenuate the accumulation of damaged proteins in Nrf2 KO mice. Additionally, Na2S failed to improve cardiac function when the proteasome was inhibited. CONCLUSIONS: These findings indicate that Na2S therapy enhances proteasomal activity and function during the development of heart failure in an Nrf2-dependent manner and that this enhancement leads to attenuation in cardiac dysfunction.
Assuntos
Fármacos Cardiovasculares/farmacologia , Insuficiência Cardíaca/prevenção & controle , Sulfeto de Hidrogênio/farmacologia , Isquemia Miocárdica/tratamento farmacológico , Miocárdio/enzimologia , Fator 2 Relacionado a NF-E2/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Sulfetos/farmacologia , Animais , Fármacos Cardiovasculares/metabolismo , Modelos Animais de Doenças , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Insuficiência Cardíaca/enzimologia , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Sulfeto de Hidrogênio/metabolismo , Hipertrofia Ventricular Esquerda/enzimologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Hipertrofia Ventricular Esquerda/prevenção & controle , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Isquemia Miocárdica/enzimologia , Isquemia Miocárdica/genética , Isquemia Miocárdica/fisiopatologia , Fator 2 Relacionado a NF-E2/deficiência , Fator 2 Relacionado a NF-E2/genética , Estresse Oxidativo/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Sulfetos/metabolismo , Fatores de Tempo , Função Ventricular Esquerda/efeitos dos fármacosRESUMO
Recent data indicates that DJ-1 plays a role in the cellular response to stress. Here, we aimed to examine the underlying molecular mechanisms mediating the actions of DJ-1 in the heart following myocardial ischemia-reperfusion (I/R) injury. In response to I/R injury, DJ-1 KO mice displayed increased areas of infarction and worsened left ventricular function when compared to WT mice, confirming a protective role for DJ-1 in the heart. In an effort to evaluate the potential mechanism(s) responsible for the increased injury in DJ-1 KO mice, we focused on SUMOylation, a post-translational modification process that regulates various aspects of protein function. DJ-1 KO hearts after I/R injury were found to display enhanced accumulation of SUMO-1 modified proteins and reduced SUMO-2/3 modified proteins. Further analysis, revealed that the protein expression of the de-SUMOylation enzyme SENP1 was reduced, whereas the expression of SENP5 was enhanced in DJ-1 KO hearts after I/R injury. Finally, DJ-1 KO hearts were found to display enhanced SUMO-1 modification of dynamin-related protein 1, excessive mitochondrial fission, and dysfunctional mitochondria. Our data demonstrates that the activation of DJ-1 in response to myocardial I/R injury protects the heart by regulating the SUMOylation status of Drp1 and attenuating excessive mitochondrial fission.
Assuntos
Mitocôndrias Cardíacas/genética , Mitocôndrias Cardíacas/metabolismo , Dinâmica Mitocondrial/genética , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/metabolismo , Proteína Desglicase DJ-1/genética , Proteína Desglicase DJ-1/metabolismo , Animais , Biópsia , Modelos Animais de Doenças , Regulação da Expressão Gênica , Masculino , Camundongos , Camundongos Knockout , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/metabolismo , Estresse Oxidativo , Proteína Desglicase DJ-1/deficiência , Proteólise , Ratos , Espécies Reativas de Oxigênio , SumoilaçãoRESUMO
Macrophages are an essential component of the immune response to ischaemic injury and play an important role in promoting inflammation and its resolution, which is necessary for tissue repair. The type I transmembrane glycoprotein CD163 is exclusively expressed on macrophages, where it acts as a receptor for haemoglobin:haptoglobin complexes. An extracellular portion of CD163 circulates in the blood as a soluble protein, for which no physiological function has so far been described. Here we show that during ischaemia, soluble CD163 functions as a decoy receptor for TWEAK, a secreted pro-inflammatory cytokine of the tumour necrosis factor family, to regulate TWEAK-induced activation of canonical nuclear factor-κB (NF-κB) and Notch signalling necessary for myogenic progenitor cell proliferation. Mice with deletion of CD163 have transiently elevated levels of TWEAK, which stimulate muscle satellite cell proliferation and tissue regeneration in their ischaemic and non-ischaemic limbs. These results reveal a role for soluble CD163 in regulating muscle regeneration after ischaemic injury.
Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Macrófagos/fisiologia , Músculo Esquelético/fisiologia , Receptores de Superfície Celular/metabolismo , Regeneração , Fatores de Necrose Tumoral/metabolismo , Animais , Citocina TWEAK , Masculino , Camundongos Knockout , NF-kappa B/metabolismo , Distribuição Aleatória , Receptores Notch/metabolismo , Traumatismo por ReperfusãoRESUMO
Thyroid hormone is a critical regulator of cardiac growth and development, both in fetal life and postnatally. Here we review the role of thyroid hormone in postnatal cardiac development, given recent insights into its role in stimulating a burst of cardiomyocyte proliferation in the murine heart in preadolescence; a response required to meet the massive increase in circulatory demand predicated by an almost quadrupling of body weight during a period of about 21 days from birth to adolescence. Importantly, thyroid hormone metabolism is altered by chronic diseases, such as heart failure and ischemic heart disease, as well as in very sick children requiring surgery for congenital heart diseases, which results in low T3 syndrome that impairs cardiovascular function and is associated with a poor prognosis. Therapy with T3 or thyroid hormone analogs has been shown to improve cardiac contractility; however, the mechanism is as yet unknown. Given the postnatal cardiomyocyte mitogenic potential of T3, its ability to enhance cardiac function by promoting cardiomyocyte proliferation warrants further consideration.
Assuntos
Coração/crescimento & desenvolvimento , Miócitos Cardíacos/metabolismo , Hormônios Tireóideos/metabolismo , Animais , Proliferação de Células , Humanos , Camundongos , Miócitos Cardíacos/citologiaRESUMO
It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases.
Assuntos
Diferenciação Celular , Proliferação de Células , Coração/crescimento & desenvolvimento , Miócitos Cardíacos/citologia , Animais , Separação Celular , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/fisiologia , Tri-Iodotironina/metabolismoRESUMO
Chymase, a serine protease found in mast cell granules, is released into the interstitium following injury or inflammation. Chymase is the primary ACE-independent pathway of angiotensin II formation, and also functions to activate TGF-beta and other promoters of extracellular matrix degradation, thereby playing a role in tissue remodeling. In the diseased kidney, chymase-containing mast cells markedly increase and their density correlates with tubulointerstitial fibrosis severity. Studies in humans support the pathologic role of chymase in diabetic nephropathy, while animal studies form the basis for the importance of increased chymase-dependent angiotensin II formation in progressive hypertensive, diabetic and inflammatory nephropathies. Moreover, humans with kidney disease express chymase in diseased blood vessels in concordance with significantly elevated plasma chymase levels. Conversely, specific chymase inhibitors attenuate angiotensin II production and renal fibrosis in animal models, suggesting their potential therapeutic benefit in human nephropathy, where chymase-containing mast cells accumulate and contribute to progressive disease.