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1.
Physiol Rep ; 12(6): e15989, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38538007

RESUMO

Cardiac fibroblasts (CFs) are an attractive target for reducing pathological cardiac remodeling, and understanding the underlying mechanisms of these processes is the key to develop successful therapies for treating the pressure-overloaded heart. CF-specific knockout (KO) mouse lines with a Cre recombinase under the control of human TCF21 (hTCF21) promoter and/or an adeno-associated virus serotype 9 (AAV9)-hTCF21 system provide a powerful tool for understanding CF biology in vivo. Although a variety of rat disease models are vital for the research of cardiac fibrosis similar to mouse models, there are few rat models that employ cardiac cell-specific conditional gene modification, which has hindered the development and translational relevance of cardiac disease models. In addition, to date, there are no reports of gene manipulation specifically in rat CFs in vivo. Here, we report a simplified CF-specific rat transgenic model using an AAV9-hTCF21 system that achieved a CF-specific expression of transgene in adult rat hearts. Moreover, we successfully applied this approach to specifically manipulate mitochondrial morphology in quiescent CFs. In summary, this model will allow us to develop fast and simple rat CF-specific transgenic models for studying cardiovascular diseases in vivo.


Assuntos
Cardiomiopatias , Cardiopatias , Camundongos , Animais , Ratos , Humanos , Miócitos Cardíacos/metabolismo , Dependovirus/genética , Cardiopatias/patologia , Camundongos Knockout , Fibroblastos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo
2.
bioRxiv ; 2023 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-37577584

RESUMO

MCU is widely recognized as a responsible gene for encoding a pore-forming subunit of highly mitochondrial-specific and Ca 2+ -selective channel, mitochondrial Ca 2+ uniporter complex (mtCUC). Here, we report a novel short variant derived from the MCU gene (termed MCU-S) which lacks mitochondria-targeted sequence and forms a Ca 2+ - permeable channel outside of mitochondria. MCU-S was ubiquitously expressed in all cell-types/tissues, with particularly high expression in human platelets. MCU-S formed Ca 2+ channels at the plasma membrane, which exhibited similar channel properties to those observed in mtCUC. MCU-S channels at the plasma membrane served as an additional Ca 2+ influx pathway for platelet activation. Our finding is completely distinct from the originally reported MCU gene function and provides novel insights into the molecular basis of MCU variant-dependent cellular Ca 2+ handling.

3.
JCI Insight ; 6(12)2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-33974567

RESUMO

Right ventricular (RV) fibrosis is a key feature of maladaptive RV hypertrophy and dysfunction and is associated with poor outcomes in pulmonary hypertension (PH). However, mechanisms and therapeutic strategies to mitigate RV fibrosis remain unrealized. Previously, we identified that cardiac fibroblast α7 nicotinic acetylcholine receptor (α7 nAChR) drives smoking-induced RV fibrosis. Here, we sought to define the role of α7 nAChR in RV dysfunction and fibrosis in the settings of RV pressure overload as seen in PH. We show that RV tissue from PH patients has increased collagen content and ACh expression. Using an experimental rat model of PH, we demonstrate that RV fibrosis and dysfunction are associated with increases in ACh and α7 nAChR expression in the RV but not in the left ventricle (LV). In vitro studies show that α7 nAChR activation leads to an increase in adult ventricular fibroblast proliferation and collagen content mediated by a Ca2+/epidermal growth factor receptor (EGFR) signaling mechanism. Pharmacological antagonism of nAChR decreases RV collagen content and improves RV function in the PH model. Furthermore, mice lacking α7 nAChR exhibit improved RV diastolic function and have lower RV collagen content in response to persistently increased RV afterload, compared with WT controls. These finding indicate that enhanced α7 nAChR signaling is an important mechanism underlying RV fibrosis and dysfunction, and targeted inhibition of α7 nAChR is a potentially novel therapeutic strategy in the setting of increased RV afterload.


Assuntos
Ventrículos do Coração , Hipertensão Pulmonar , Receptor Nicotínico de Acetilcolina alfa7 , Animais , Feminino , Fibrose , Células HEK293 , Ventrículos do Coração/metabolismo , Ventrículos do Coração/patologia , Humanos , Hipertensão Pulmonar/metabolismo , Hipertensão Pulmonar/patologia , Masculino , Ratos , Ratos Sprague-Dawley , Função Ventricular Direita/fisiologia , Receptor Nicotínico de Acetilcolina alfa7/genética , Receptor Nicotínico de Acetilcolina alfa7/metabolismo
4.
Am J Physiol Renal Physiol ; 318(1): F67-F75, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31682172

RESUMO

Renal proximal tubular angiotensinogen (AGT) is increased by hyperglycemia (HG) in diabetes mellitus, which augments intrarenal angiotensin II formation, contributing to the development of hypertension and kidney injury. Sodium-glucose cotransporter 2 (SGLT2) is abundantly expressed in proximal tubular cells (PTCs). The present study investigated the effects of canagliflozin (CANA), a SGLT2 inhibitor, on HG-induced AGT elevation in cultured PTCs. Mouse PTCs were treated with 5-25 mM glucose. CANA (0-10 µM) was applied 1 h before glucose treatment. Glucose (10 mM) increased AGT mRNA and protein levels at 12 h (3.06 ± 0.48-fold in protein), and 1 and 10 µM CANA as well as SGLT2 shRNA attenuated the AGT augmentation. CANA did not suppress the elevated AGT levels induced by 25 mM glucose. Increased AGT expression induced by treatment with pyruvate, a glucose metabolite that does not require SGLT2 for uptake, was not attenuated by CANA. In HG-treated PTCs, intracellular reactive oxygen species levels were elevated compared with baseline (4.24 ± 0.23-fold), and these were also inhibited by CANA. Furthermore, tempol, an antioxidant, attenuated AGT upregulation in HG-treated PTCs. HG-induced AGT upregulation was not inhibited by an angiotensin II receptor antagonist, indicating that HG stimulates AGT expression in an angiotensin II-independent manner. These results indicate that enhanced glucose entry via SGLT2 into PTCs elevates intracellular reactive oxygen species generation by stimulation of glycolysis and consequent AGT augmentation. SGLT2 blockade limits HG-induced AGT stimulation, thus reducing the development of kidney injury in diabetes mellitus.


Assuntos
Angiotensinogênio/metabolismo , Canagliflozina/farmacologia , Glucose/farmacologia , Túbulos Renais Proximais/efeitos dos fármacos , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Transportador 2 de Glucose-Sódio/metabolismo , Animais , Linhagem Celular , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Túbulos Renais Proximais/metabolismo , Masculino , Camundongos , Espécies Reativas de Oxigênio/metabolismo , Sistema Renina-Angiotensina/efeitos dos fármacos
5.
Am J Physiol Cell Physiol ; 316(5): C583-C604, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30758993

RESUMO

Mitochondrial fragmentation frequently occurs in chronic pathological conditions as seen in various human diseases. In fact, abnormal mitochondrial morphology and mitochondrial dysfunction are hallmarks of heart failure (HF) in both human patients and HF animal models. A link between mitochondrial fragmentation and cardiac pathologies has been widely proposed, but the physiological relevance of mitochondrial fission and fusion in the heart is still unclear. Recent studies have increasingly shown that posttranslational modifications (PTMs) of fission and fusion proteins are capable of directly modulating the stability, localization, and/or activity of these proteins. These PTMs include phosphorylation, acetylation, ubiquitination, conjugation of small ubiquitin-like modifier proteins, O-linked-N-acetyl-glucosamine glycosylation, and proteolysis. Thus, understanding the PTMs of fission and fusion proteins may allow us to understand the complexities that determine the balance of mitochondrial fission and fusion as well as mitochondrial function in various cell types and organs including cardiomyocytes and the heart. In this review, we summarize present knowledge regarding the function and regulation of mitochondrial fission and fusion in cardiomyocytes, specifically focusing on the PTMs of each mitochondrial fission/fusion protein. We also discuss the molecular mechanisms underlying abnormal mitochondrial morphology in HF and their contributions to the development of cardiac diseases, highlighting the crucial roles of PTMs of mitochondrial fission and fusion proteins. Finally, we discuss the future potential of manipulating PTMs of fission and fusion proteins as a therapeutic strategy for preventing and/or treating HF.


Assuntos
Cardiopatias/metabolismo , Dinâmica Mitocondrial/fisiologia , Proteínas Mitocondriais/metabolismo , Miócitos Cardíacos/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Animais , Cardiopatias/genética , Humanos , Proteínas Mitocondriais/genética
6.
Arch Biochem Biophys ; 663: 276-287, 2019 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-30684463

RESUMO

Recent discoveries of the molecular identity of mitochondrial Ca2+ influx/efflux mechanisms have placed mitochondrial Ca2+ transport at center stage in views of cellular regulation in various cell-types/tissues. Indeed, mitochondria in cardiac muscles also possess the molecular components for efficient uptake and extraction of Ca2+. Over the last several years, multiple groups have taken advantage of newly available molecular information about these proteins and applied genetic tools to delineate the precise mechanisms for mitochondrial Ca2+ handling in cardiomyocytes and its contribution to excitation-contraction/metabolism coupling in the heart. Though mitochondrial Ca2+ has been proposed as one of the most crucial secondary messengers in controlling a cardiomyocyte's life and death, the detailed mechanisms of how mitochondrial Ca2+ regulates physiological mitochondrial and cellular functions in cardiac muscles, and how disorders of this mechanism lead to cardiac diseases remain unclear. In this review, we summarize the current controversies and discrepancies regarding cardiac mitochondrial Ca2+ signaling that remain in the field to provide a platform for future discussions and experiments to help close this gap.


Assuntos
Cálcio/metabolismo , Homeostase , Mitocôndrias Cardíacas/metabolismo , Miocárdio/metabolismo , Trifosfato de Adenosina/biossíntese , Sinalização do Cálcio , Humanos , Transporte de Íons , Miócitos Cardíacos/metabolismo
7.
Antioxidants (Basel) ; 7(12)2018 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-30567380

RESUMO

Abnormal mitochondrial morphology, especially fragmented mitochondria, and mitochondrial dysfunction are hallmarks of a variety of human diseases including heart failure (HF). Although emerging evidence suggests a link between mitochondrial fragmentation and cardiac dysfunction, it is still not well described which cardiac signaling pathway regulates mitochondrial morphology and function under pathophysiological conditions such as HF. Mitochondria change their shape and location via the activity of mitochondrial fission and fusion proteins. This mechanism is suggested as an important modulator for mitochondrial and cellular functions including bioenergetics, reactive oxygen species (ROS) generation, spatiotemporal dynamics of Ca2+ signaling, cell growth, and death in the mammalian cell- and tissue-specific manners. Recent reports show that a mitochondrial fission protein, dynamin-like/related protein 1 (DLP1/Drp1), is post-translationally modified via cell signaling pathways, which control its subcellular localization, stability, and activity in cardiomyocytes/heart. In this review, we summarize the possible molecular mechanisms for causing post-translational modifications (PTMs) of DLP1/Drp1 in cardiomyocytes, and further discuss how these PTMs of DLP1/Drp1 mediate abnormal mitochondrial morphology and mitochondrial dysfunction under adrenergic signaling activation that contributes to the development and progression of HF.

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