Disruption of BACH1 Protects AC16 Cardiomyocytes Against Hypoxia/Reoxygenation-Evoked Injury by Diminishing CDKN3 Transcription.

Reperfusion after myocardial infarction (MI) can lead to myocardial ischemia/reperfusion (I/R) damage. The transcription factor (TF) broad-complex, tramtrack, and bric-a-brac (BTB) and cap'n'collar (CNC) homology 1 (BACH1) is implicated in the injury. However, the downstream mechanisms of BACH1 in affecting myocardial hypoxia/reoxygenation (H/R) damage are still fully understood. AC16 cells were stimulated with H/R conditions to model cardiomyocytes under H/R. mRNA analysis was performed by quantitative real-time PCR. Protein levels were gauged by immunoblot analysis. The effect of BACH1/cyclin-dependent kinase inhibitor 3 (CDKN3) on H/R-evoked injury was assessed by measuring cell viability via Cell Counting Kit-8 (CCK-8), apoptosis (flow cytometry and caspase 3 activity), ferroptosis via Fe2+, glutathione (GSH), reactive oxygen species (ROS) and malondialdehyde (MDA) markers and inflammation cytokines interleukin-1beta (IL-1ß) and tumor necrosis factor alpha (TNF-α). The BACH1/CDKN3 relationship was examined by chromatin immunoprecipitation (ChIP) experiment and luciferase assay. BACH1 was increased in MI serum and H/R-stimulated AC16 cardiomyocytes. Functionally, disruption of BACH1 mitigated H/R-evoked in vitro apoptosis, ferroptosis and inflammation of AC16 cardiomyocytes. Mechanistically, BACH1 activated CDKN3 transcription and enhanced CDKN3 protein expression in AC16 cardiomyocytes. Our rescue experiments validated that BACH1 disruption attenuated H/R-evoked AC16 cardiomyocyte apoptosis, ferroptosis and inflammation by downregulating CDKN3. Additionally, BACH1 disruption could activate the adenosine monophosphate-activated protein kinase (AMPK) signaling by downregulating CDKN3 in H/R-stimulated AC16 cardiomyocytes. Our study demonstrates that BACH1 activates CDKN3 transcription to induce H/R-evoked damage of AC16 cardiomyocytes partially via AMPK signaling.

Research progress of drug eluting balloon in arterial circulatory system.

The arterial circulatory system diseases are common in clinical practice, and their treatment options have been of great interest due to their high morbidity and mortality. Drug-eluting balloons, as a new type of endovascular interventional treatment option, can avoid the long-term implantation of metal stents and is a new type of angioplasty without stents, so drug-eluting balloons have better therapeutic effects in some arterial circulatory diseases and have been initially used in clinical practice. In this review, we first describe the development, process, and mechanism of drug-eluting balloons. Then we summarize the current studies on the application of drug-eluting balloons in coronary artery lesions, in-stent restenosis, and peripheral vascular disease. As well as the technical difficulties and complications in the application of drug-eluting balloons and possible management options, in order to provide ideas and help for future in-depth studies and provide new strategies for the treatment of more arterial system diseases.

The Profiles of Venous Thromboembolism at Different High Altitudes.

Xiong, Shiqiang, Jun Hou, Haixia Yang, Meiting Gong, Xin Ma, Xuhu Yang, Hongyang Zhang, Yao Ma, Liang Gao, and Haifeng Pei. The profiles of venous thromboembolism at different high altitudes High Alt Med Biol. 00:000-000, 2024.-This study investigated the incidence of venous thromboembolism (VTE) in high altitude (HA) and very HA areas. Patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) diagnosed between 2004 and 2022 in Yecheng, China, were retrospectively analyzed. The results showed that patients with PE at very HA had a higher risk of lower extremity DVT (OR 16.3 [95% CI 1.2-223.2], p = 0.036), than those at HA, especially in the early stages of very HA entry, and the harsh environment of very HA further exacerbated the risk of VTE. These findings emphasize the higher risk of PE development in very HA and the need for enhanced prevention and treatment in this area.

Cardiac remodeling in patients with atrial fibrillation reversing bradycardia-induced cardiomyopathy: A case report.

BACKGROUND: Bradycardia-induced cardiomyopathy (BIC), which is a disease resulting from bradycardia, is characterized by cardiac chamber enlargement and diminished cardiac function. The correction of bradycardia can allow for significant improvements in both cardiac function and structure; however, this disease has been infrequently documented. In this case, we conducted a longitudinal follow-up of a patient who had been enduring BIC for more than 40 years to heighten awareness and prompt timely diagnosis and rational intervention. CASE SUMMARY: A woman who presented with postactivity fatigue and dyspnea was diagnosed with bradycardia at the age of 7. Since she had no obvious symptoms, she did not receive any treatment to improve her bradycardia during the 42-year follow-up, except for the implantation of a temporary pacemaker during labor induction surgery. As time progressed, the patient's heart gradually expanded due to her low ventricular rate, and she was diagnosed with BIC. In 2014, the patient developed atrial fibrillation, her ventricular rate gradually increased, and her heart shape gradually returned to normal. This report describes the cardiac morphological changes caused by the heart rate changes in BIC patients older than 40 years, introduces another possible outcome of BIC, and emphasizes the importance of early intervention in treating BIC. CONCLUSION: BIC can induce atrial fibrillation, causing an increased ventricular rate and leading to positive cardiac remodeling.

Exploring the ECG "6+2" Phenomenon in Coronary Artery Disease and Coronary Artery Spasm: A Case Report Analysis and Treatment Implications.

BACKGROUND Although coronary artery disease and coronary artery spasm (CAS) can lead to acute myocardial infarction, there are clear differences in treatment between coronary heart disease and CAS, and the therapeutic schedule should not be confused. Furthermore, electrocardiogram (ECG) "6+2" phenomenon is recommend as a specific ECG indicator for lesions in the left main coronary artery or multiple vessels. Currently, no reports of this phenomenon in CAS exist. CASE REPORT A 72-year-old man had history of recurrent chest pain for over 6 years, with episodes lasting about 10 min and resolving with rest. He experienced symptom recurrence and exacerbation due to substance abuse. He was admitted to our Emergency Department for chest pain at rest. His emergency ECG revealed a 6+2 phenomenon, accompanied by troponin levels exceeding 18 times the reference value. Promptly, we conducted coronary angiography, with unexpected normal findings. Following thorough assessment, we postulated the patient could have CAS. Subsequent to medical team intervention, the patient's ECG normalized, leading to his discharge upon condition stabilization. CONCLUSIONS We report a case of CAS in a patient with ECG 6+2 phenomenon, without significant coronary artery stenosis. This differs from transient ST-segment elevation on ECG, a well-recognized hallmark of CAS; however, such a presentation has not been documented before. Additionally, treatment strategies for myocardial ischemic conditions stemming from coronary atherosclerosis diverge from those employed for CAS. Therefore, clinicians should advocate for coronary angiography whenever feasible. This approach serves to elucidate the underlying disease etiology and facilitates the administration of precision-targeted interventions for patients.

Comprehensive viewpoints on heart rate variability at high altitude.

OBJECTIVES: Hypoxia is a physiological state characterized by reduced oxygen levels in organs and tissues. It is a common clinicopathological process and a major cause of health problems in highland areas.  Heart rate variability (HRV) is a measure of the balance in autonomic innervation to the heart. It provides valuable information on the regulation of the cardiovascular system by neurohumoral factors, and changes in HRV reflect the complex interactions between multiple systems. In this review, we provide a comprehensive overview of the relationship between high-altitude hypoxia and HRV. We summarize the different mechanisms of diseases caused by hypoxia and explore the changes in HRV across various systems. Additionally, we discuss relevant pharmaceutical interventions. Overall, this review aims to provide research ideas and assistance for in-depth studies on HRV. By understanding the intricate relationship between high-altitude hypoxia and HRV, we can gain insights into the underlying mechanisms and potential therapeutic approaches to mitigate the effects of hypoxia on cardiovascular and other systems. METHODS: The relevant literature was collected systematically from scientific database, including PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), Baidu Scholar, as well as other literature sources, such as classic books of hypoxia. RESULTS: There is a close relationship between heart rate variability and high-altitude hypoxia. Heart rate variability is an indicator that evaluates the impact of hypoxia on the cardiovascular system and other related systems. By improving the observation of HRV, we can estimate the progress of cardiovascular diseases and predict the impact on other systems related to cardiovascular health. At the same time, changes in heart rate variability can be used to observe the efficacy of preventive drugs for altitude related diseases. CONCLUSIONS: HRV can be used to assess autonomic nervous function under various systemic conditions, and can be used to predict and monitor diseases caused by hypoxia at high altitude. Investigating the correlation between high altitude hypoxia and heart rate variability can help make HRV more rapid, accurate, and effective for the diagnosis of plateau-related diseases.

Impact of pre-procedural diastolic blood pressure on major adverse cardiovascular events in non ST-segment elevation myocardial infarction patients following revascularization.

Previous reports have observed a consistent J-shaped relationship between cardiac events and diastolic blood pressure (DBP). However, the EPHESUS study clearly showed that myocardial reperfusion abolished the J-shaped association, suggesting a different association pattern after revascularization. Therefore, in this study, we investigated the different patterns in which DBP affects cardiovascular risk in non ST-segment elevation myocardial infarction (NSTEMI) patients after revascularization, which may benefit the risk stratification for NSTEMI patients. We obtained the NSTEMI database from the Dryad data repository and analyzed the association between preprocedural DBP and long-term major adverse cardiovascular events (MACEs) in 1486 patients with NSTEMI following percutaneous coronary intervention (PCI). Multivariate regression models were used to assess the impact of DBP on outcomes in an adjusted fashion according to DBP tertiles. The p value for the trend was calculated using linear regression. When examined as a continuous variable, a multivariate regression analysis was repeated. Pattern stability was verified by interaction and stratified analyses. The median (interquartile range) age of the patients was 61.00 (53.00-68.00) years, and 63.32% were male. Cardiac death showed a graded increase as the DBP tertile increased (p for trend = 0.0369). When examined as a continuous variable, a 1 mmHg increase in DBP level was associated with an 18% higher risk of long-term cardiac death (95% CI: 1.01-1.36, p = 0.0311) and a 2% higher risk of long-term all-cause death (95% CI: 1.01-1.04; p = 0.0178). The association pattern remained stable when stratified by sex, age, diabetes, hypertension, and smoking status. An association between low DBP and higher cardiovascular risk was not observed in our study. We showed that higher preprocedural DBP increased the risk of long-term cardiac death and all-cause death in patients with NSTEMI following PCI.

Pathological Roles of Oxidative Stress in Cardiac Microvascular Injury.

Cardiac microvascular injury can be a fundamental pathological process that causes high incidence cardiovascular diseases such heart failure, diabetic cardiomyopathy, and hypertension. It is also an independent risk factor for cardiovascular disease. Oxidative stress is a significant pathological process in which the body interferes with the balance of the endogenous antioxidant defense system by producing reactive oxygen species, leading to property changes and dysfunction. It has been demonstrated that oxidative stress is one of the major causes of cardiac microvascular disease. Therefore, additional investigation into the relationship between oxidative stress and cardiac microvascular injury will direct clinical management in the future. In order to give suggestions and support for future in-depth studies, we give a basic overview of the cardiac microvasculature in relation to physiopathology in this review. We also summarize the role of oxidative stress of mitochondrial and non-mitochondrial origin in cardiac microvascular injury and related drug studies.

Positive regulation of endothelial Tom70 by metformin as a new mechanism against cardiac microvascular injury in diabetes.

Microvascular protection is the main mechanism of metformin against diabetic complications. Cardiac microvascular endothelial cells (CMECs) are the basic component of cardiac microvessels, and they suffer from oxidative stress and mitochondrial dysfunction under type 2 diabetes mellitus (T2DM). Translocase of the outer mitochondrial membrane 70 (Tom70) improves mitochondrial dysfunction, but its role in the hearts of T2DM patients remains unclear. The purpose of this study was to demonstrate the protective effect of metformin on diabetic cardiac microvascular injury and to identify the role of Tom70 in this effect. T2DM mice were established by multiple intraperitoneal injections of low-dose streptozotocin and 12-week high-fat feeding. CMECs were isolated and cultured with normal glucose (NG), high glucose (HG), and HG plus high fat (HG-HF) media. The results indicated that long-term metformin treatment partly reversed cardiovascular complication and mitigated cardiac microvascular injury in T2DM. In addition, exposure to HG-HF led to CMEC damage, aggravated oxidative stress, aggravated mitochondrial dysfunction, and reduced mitochondrial Tom70 expression, whereas upregulation of Tom70 significantly ameliorated these injuries. Furthermore, metformin treatment promoted Tom70 expression and effectively reversed CMEC injury induced by HG-HF. However, all of these effects were interrupted after Tom70 was knocked down. In conclusion, T2DM damages microvascular integrity by activating a cycle of decreased Tom70 expression, mitochondrial dysfunction, and reactive oxygen species (ROS) overload in CMECs. However, metformin suppresses oxidative stress, relieves mitochondrial dysfunction, and promotes the expression of Tom70, ultimately ameliorating diabetic microvascular injury and heart complications.

Plin5 Bidirectionally Regulates Lipid Metabolism in Oxidative Tissues.

Cytoplasmic lipid droplets (LDs) can store neutral lipids as an energy source when needed and also regulate the key metabolic processes of intracellular lipid accumulation, which is associated with several metabolic diseases. The perilipins (Plins) are a family of proteins that associate with the surface of LDs. As a member of Plins superfamily, perilipin 5 (Plin5) coats LDs in cardiomyocytes, which is significantly related to reactive oxygen species (ROS) production originated from mitochondria in the heart, consequently determining the progression of diabetic cardiomyopathy. Plin5 may play a bidirectional function in lipid metabolism which is in a state of dynamic balance. In the basic state, Plin5 inhibited the binding of comparative gene identification-58 (CGI-58) to adipose triglyceride lipase (ATGL) by binding CGI-58, thus inhibiting lipolysis. However, when the body is under stress (such as cold, fasting, exercise, and other stimuli), protein kinase A (PKA) phosphorylates and activates Plin5, which then causes Plin5 to release the binding site of CGI-58 and ATGL, prompting CGI-58 to bind to ATGL and activate ATGL activity, thus accelerating the lipolysis process, revealing the indispensable role of Plin5 in lipid turnover. Here, the purpose of this review is to summarize the present understanding of the bidirectional regulation role of Plin5 in oxidative tissues and to reveal its potential role in diabetic cardiomyopathy protection.

Oxidative Stress Signaling Mediated Pathogenesis of Diabetic Cardiomyopathy.

As a serious cardiovascular complication, diabetic cardiomyopathy (DCM) refers to diabetes-related changes in myocardial structure and function, which is obviously different from those cardiomyopathy secondary to hypertension, coronary heart disease, and valvular disease. The clinical features of DCM are left ventricular hypertrophy, myocardial fibrosis, and impaired diastolic function. DCM will lead to cardiac dysfunction, eventually progress to cardiac arrhythmia, heart failure, and sudden cardiac death. At present, the pathogenesis of DCM is complex and not fully elucidated, and oxidative stress (OS), inflammatory response, glucolipid metabolism disorder, etc., are considered as the potential pathophysiological mechanisms. As a consequence, there is no specific and effective treatment for DCM. OS refers to the imbalance between reactive oxygen species (ROS) accumulation and scavenging, oxidation, and antioxidants in vivo, which is widely studied in DCM. Numerous studies have pointed out that regulating the OS signaling pathways and reducing the generation and accumulation of ROS are potential directions for the treatment of DCM. This review summarizes the major OS signaling pathways that are related to the pathogenesis of DCM, providing ideas about further research and therapy.

Melatonin alleviates angiotensin-II-induced cardiac hypertrophy via activating MICU1 pathway.

Mitochondrial calcium uptake 1 (MICU1) is a pivotal molecule in maintaining mitochondrial homeostasis under stress conditions. However, it is unclear whether MICU1 attenuates mitochondrial stress in angiotensin II (Ang-II)-induced cardiac hypertrophy or if it has a role in the function of melatonin. Here, small-interfering RNAs against MICU1 or adenovirus-based plasmids encoding MICU1 were delivered into left ventricles of mice or incubated with neonatal murine ventricular myocytes (NMVMs) for 48 h. MICU1 expression was depressed in hypertrophic myocardia and MICU1 knockdown aggravated Ang-II-induced cardiac hypertrophy in vivo and in vitro. In contrast, MICU1 upregulation decreased cardiomyocyte susceptibility to hypertrophic stress. Ang-II administration, particularly in NMVMs with MICU1 knockdown, led to significantly increased reactive oxygen species (ROS) overload, altered mitochondrial morphology, and suppressed mitochondrial function, all of which were reversed by MICU1 supplementation. Moreover, peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α)/MICU1 expression in hypertrophic myocardia increased with melatonin. Melatonin ameliorated excessive ROS generation, promoted mitochondrial function, and attenuated cardiac hypertrophy in control but not MICU1 knockdown NMVMs or mice. Collectively, our results demonstrate that MICU1 attenuates Ang-II-induced cardiac hypertrophy by inhibiting mitochondria-derived oxidative stress. MICU1 activation may be the mechanism underlying melatonin-induced protection against myocardial hypertrophy.

Inhibition of GPR35 Preserves Mitochondrial Function After Myocardial Infarction by Targeting Calpain 1/2.

Ischemia and anoxia-induced mitochondrial impairment may be a key factor leading to heart injury during myocardial infarction (MI). Calpain 1 and 2 are involved in the MI-induced mitochondria injury. G protein-coupled receptor 35 (GPR35) could be triggered by hypoxia. Whether or not GPR35 regulates calpain 1/2 in the pathogenesis of MI is still unclear. In this study, we determined that MI increases GPR35 expression in myocardial tissue. Suppression of GPR35 protects heart from MI injury in mice through reduction of reactive oxygen species activity and mitochondria-dependent apoptosis. Further studies show that GPR35 regulates calpain 1/2. Suppression of GPR35 reduces the expression and activity of calpain 1/2, and alleviates calpain 1/2-associated mitochondrial injury to preserve cardiac function. Based on these data, we conclude that a functional inhibition of GPR35 downregulates calpain 1/2 and contributes to maintenance of cardiac function under pathologic conditions with mitochondrial disorder. In conclusion, our study showed that the identified regulation by GPR35 of calpain 1/2 has important implications for the pathogenesis of MI. Targeting the action of GPR35 and calpain 1/2 in mitochondria presents a potential therapeutic intervention for MI.

[Study of the Role and Mechanism of Asprosin/Spartin Pathway in Cardiac Microvascular Endothelial Injury Induced by Diabete Mellitus].

OBJECTIVE: To detect the effects and mechanism of asprosin (Asp) and spartin on the injury of mice cardiac microvascular endothelial cells (CMECs) induced by high glucose. METHODS: The cultured CMECs were divided into 2 groups, one group is normal group (5.5 mmol/L glucose in the medium) and another is HG group (30 mmol/L glucose in the medium). Real-time PCR (qRT-PCR) and Western blot were respectively used to detect the mRNA level of spastic paraplegia 20 (SPG20) and protein expression of spartin in CMECs. Upregulation or downregulation of the expression of spartin was achieved via transfection with adenovirus (Ad) or small interfering RNA (siRNA) respectively. CMECs with downregulation of spartin expression were firstly treated with anti-oxidant N-acetylcysteine (NAC) or Asp respectively for 48 h, and then were interfered with 30 mmol/L glucose for 24 h afterward. The apoptosis of cell was detected by flow cytometry. Nitric oxide (NO) production was detected by NO probe and ELISA kit. The intracellular reactive oxygen species (ROS) levels were tested by DHE staining and ELISA kit. Type 2 diabetic model mice were established and then divided into T2DM group and T2DM+Asp group. After the model mice were established successfully (random blood glucose was more than 16.7 mmol/L), Asp (1 µg/g) was intraperitoneally injected once a day. After 2 weeks, mice echocardiography was performed to test cardiac diastolic function. The integrity of the microvascular endothelium was observed by scanning electron microscopy. RESULTS: Compared with the normal group, the mRNA level of SPG20 and protein expression of spartin in mice CMECs of HG group were significantly reduced (P < 0.05). Under the condition of high glucose, Ad transfection induced significant decrease of the intracellular ROS level and the apoptosis level of the CMECs (P < 0.05), while NO increased after Ad transfection. In contrast, siRNA intervention resulted in opposite effect. In addition, the antioxidant NAC partly reversed the above changes caused by downregulating spartin. Asp upregulated the level of SPG20 mRNA and spartin protein expression in CMECs, reduced ROS production, reduced apoptosis and increased NO production. However, intervention effects of Asp, such as decreasing of ROS production, inhibiting apoptosis of CMECs and increasing of NO production, were partly reversed in spartin downregulated cells. In vivo, we found that Asp can improve cardiac function and increase the integrity and smoothness of cardiac microvascular endothelium in type 2 diabetic mice. CONCLUSION: Asp can inhibit oxidative stress in mice CMECs through upregulating spartin signaling pathway, thereby alleviating the damage of microvascular endothelium in diabetic heart.

Plin5/p-Plin5 Guards Diabetic CMECs by Regulating FFAs Metabolism Bidirectionally.

BACKGROUND: Hyper-free fatty acidemia (HFFA) impairs cardiac capillaries, as well as type 2 diabetes mellitus (T2DM). Perilipin 5 (Plin5) maintains metabolic balance of free fatty acids (FFAs) in high oxidative tissues via the states of nonphosphorylation and phosphorylation. However, when facing to T2DM-HFFA, Plin5's role in cardiac microvascular endothelial cells (CMECs) is not defined. METHODS: In mice of WT or Plin5-/-, T2DM models were rendered by high-fat diet combined with intraperitoneal injection of streptozocin. CMECs isolated from left ventricles were incubated with high glucose (HG) and high FFAs (HFFAs). Plin5 phosphorylation was stimulated by isoproterenol. Plin5 expression was knocked down by small interfering RNA (siRNA). We determined cardiac function by small animal ultrasound, apoptotic rate by flow cytometry, microvessel quantity by immunohistochemistry, microvascular integrity by scanning electron microscopy, intracellular FFAs by spectrophotometry, lipid droplets (LDs) by Nile red staining, mRNAs by quantitative real-time polymerase chain reaction, proteins by western blots, nitric oxide (NO) and reactive oxygen species (ROS) by fluorescent dye staining and enzyme-linked immunosorbent assay kits. RESULTS: In CMECs, HFFAs aggravated cell injury induced by HG and activated Plin5 expression. In mice with T2DM-HFFA, Plin5 deficiency reduced number of cardiac capillaries, worsened structural incompleteness, and enhanced diastolic dysfunction. Moreover, in CMECs treated with HG-HFFAs, both ablation and phosphorylation of Plin5 reduced LDs content, increased intracellular FFAs, stimulated mitochondrial ß-oxidation, added ROS generation, and reduced the expression and activity of endothelial nitric oxide synthase (eNOS), eventually leading to increased apoptotic rate and decreased NO content, all of which were reversed by N-acetyl-L-cysteine. CONCLUSION: Plin5 preserves lipid balance and cell survival in diabetic CMECs by regulating FFAs metabolism bidirectionally via the states of nonphosphorylation and phosphorylation.

Wild-type p53-induced phosphatase 1 promotes vascular smooth muscle cell proliferation and neointima hyperplasia after vascular injury via p-adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin complex 1 pathway.

OBJECTIVES: Vascular smooth muscle cell (VSMC) proliferation is a crucial cause of vascular neointima hyperplasia and restenosis, thus limiting the long-term efficacy of percutaneous vascular intervention. We explored the role of wild-type p53-induced phosphatase 1 (Wip1), a potent regulator of tumorigenesis and atherosclerosis, in VSMC proliferation and neointima hyperplasia. METHODS AND RESULTS: Animal model of vascular restenosis was established in wild type C57BL/6J and VSMC-specific Tuberous Sclerosis 1 (TSC1)-knockdown mice by wire injury. We observed increased protein levels of Wip1, phospho (p)-S6 Ribosomal Protein (S6), p-4EBP1 but decreased p-adenosine 5'-monophosphate-activated protein kinase (AMPK)α both in carotid artery at day 28 after injury and in VSMCs after 48 h of platelet derived growth factor-BB (PDGF-BB) treatment. By using hematoxylin-eosin staining, Ki-67 immunohistochemical staining, cell counting kit-8 assay and Ki-67 immunofluorescence staining, we found Wip1 antagonist GSK2830371 (GSK) or mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin both obviously reversed the neointima formation and VSMC proliferation induced by wire injury and PDGF-BB, respectively. GSK also reversed the increase in mRNA level of Collagen I after wire injury. However, GSK had no obvious effects on VSMC migration induced by PDGF-BB. Simultaneously, TSC1 knockdown as well as AMPK inhibition by Compound C abolished the vascular protective and anti-proliferative effects of Wip1 inhibition. Additionally, suppression of AMPK also reversed the declined mTORC1 activity by GSK. CONCLUSION: Wip1 promotes VSMC proliferation and neointima hyperplasia after wire injury via affecting AMPK/mTORC1 pathway.

Potential Protective Mechanism in the Cardiac Microvascular Injury.

Cardiac microvascular injury often occurs in patients with type 2 diabetes mellitus (T2DM) who develop hyperglycemia and hyperlipidemia. However, besides reported contradictory roles in cardiac diseases, the function of TRPV1 (transient receptor potential vanilloid 1) in cardiac microvessels is not well defined. This study was performed to determine the detailed role of TRPV1 in cardiac microvascular endothelial cells (CMECs) in T2DM. T2DM mice were established by multiple injections of low-dose streptozotocin and high-fat feeding. CMECs were cultured separately in mediums of normal glucose, high glucose (HG), high fatty acid (HF), and HG plus HF (HG-HF). HG-HF inhibited TRPV1 expression in CMECs, reducing cellular Ca2+ content ([Ca2+]i). T2DM impaired cardiac function, disturbed glucose uptake, and damaged microvascular barrier, which were further aggravated by TRPV1-/- Exposure to HG-HF, particularly in TRPV1-/- CMECs, led to a higher level of apoptosis and a lower level of nitric oxide production in viable CMECs. HG-HF markedly enhanced generation of reactive oxygen species and nitrotyrosine, especially in the absence of TRPV1. H2O2 administration reduced TRPV1 expression in CMECs. HG-HF significantly depressed expression of PGC-1α (peroxisome proliferator-activated receptor-γ coactivator-1α) and OPA1 (optic atrophy 1) by reducing [Ca2+]i, whereas OPA1 supplementation partly reversed those detrimental effects induced by TRPV1-/- Furthermore, capsaicin treatment not only attenuated CMECs injury induced by HG-HF but also mitigated cardiac microvascular injury induced by T2DM. Collectively, T2DM leads to cardiac microvascular injury by exacerbating the vicious circle of TRPV1 blockage and reactive oxygen species overload. Long-term capsaicin can protect cardiac microvessels against T2DM via suppressing oxidative/nitrative stress mediated by TRPV1/Ca2+/PGC-1α/OPA1 pathway in CMECs.

MICU1 protects against myocardial ischemia/reperfusion injury and its control by the importer receptor Tom70.

Mitochondrial Ca2+ overload is a main contributor to mitochondrial damage hence cardiomyocyte death in myocardial ischemia/reperfusion (MI/R) injury. MICU1 has been recently identified as an important regulator of mitochondrial Ca2+ homeostasis. Here we try to identify the role of MICU1 in MI/R, and to investigate whether the mitochondrial importer receptor Tom70 possesses critical roles in the mitochondrial translocation of MICU1 and MI/R. Specific small interfering RNA (20 µg) against MICU1 and Tom70, and lentivirus vectors carrying the Tom70a sequences (3.3 × 107 TU) were delivered through intramyocardial injection. Seventy-two hours after injection, mice were subjected to 30 min of MI followed by 3 h (for cell apoptosis and mitochondrial damage assessment) or 24 h (for cardiac function and infarct size determination) of reperfusion. MI/R had no significant effect on total MICU1 expression, but caused significant reduction of MICU1 in mitochondria. Knockdown of MICU1 significantly aggravated MI/R injury, as evidenced by enlarged infarct size, depressed cardiac function and increased myocardial apoptosis. Moreover, MICU1 deficiency resulted in markedly aggravated mitochondrial Ca2+ overload, consequently destructed mitochondrial morphology and suppressed mitochondrial function (evidenced by decreased ATP production). Interestingly, mitochondrial Tom70 was also decreased in MI/R. Genetic loss-function study revealed that mitochondrial MICU1 expression was depressed by Tom70 ablation. Furthermore, Tom70 deficiency significantly aggravated MI/R injury and worsened mitochondrial Ca2+ overload. However, supplementation of Tom70 significantly attenuated MI/R injury, preserved mitochondrial morphology and function, and inhibited mitochondrial Ca2+ overload, all of which were abolished by MICU1 suppression. Mitochondrial Tom70/MICU1 pathway protects against MI/R injury, in which mitochondrial localization of MICU1 is governed by Tom70, and MICU1 serves as an indispensable factor in Tom70's cardioprotection.

Melatonin attenuates postmyocardial infarction injury via increasing Tom70 expression.

Mitochondrial dysfunction leads to reactive oxygen species (ROS) overload, exacerbating injury in myocardial infarction (MI). As a receptor for translocases in the outer mitochondrial membrane (Tom) complex, Tom70 has an unknown function in MI, including melatonin-induced protection against MI injury. We delivered specific small interfering RNAs against Tom70 or lentivirus vectors carrying Tom70a sequences into the left ventricles of mice or to cultured neonatal murine ventricular myocytes (NMVMs). At 48 h post-transfection, the left anterior descending coronary arteries of mice were permanently ligated, while the NMVMs underwent continuous hypoxia. At 24 h after ischemia/hypoxia, oxidative stress was assessed by dihydroethidium and lucigenin-enhanced luminescence, mitochondrial damage by transmission electron microscopy and ATP content, and cell apoptosis by terminal deoxynucleotidyl transferase dUTP nick-end labeling and caspase-3 assay. At 4 weeks after ischemia, cardiac function and fibrosis were evaluated in mice by echocardiography and Masson's trichrome staining, respectively. Ischemic/hypoxic insult reduced Tom70 expression in cardiomyocytes. Tom70 downregulation aggravated post-MI injury, with increased mitochondrial fragmentation and ROS overload. In contrast, Tom70 upregulation alleviated post-MI injury, with improved mitochondrial integrity and decreased ROS production. PGC-1α/Tom70 expression in ischemic myocardium was increased with melatonin alone, but not when combined with luzindole. Melatonin attenuated post-MI injury in control but not in Tom70-deficient mice. N-acetylcysteine (NAC) reversed the adverse effects of Tom70 deficiency in mitochondria and cardiomyocytes, but at a much higher concentration than melatonin. Our findings showed that Tom70 is essential for melatonin-induced protection against post-MI injury, by breaking the cycle of mitochondrial impairment and ROS generation.