Elevated CHCHD4 orchestrates mitochondrial oxidative phosphorylation to disturb hypoxic pulmonary hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a highly prevalent cardiopulmonary disorder characterized by vascular remodeling and increased resistance in pulmonary artery. Mitochondrial coiled-coil-helix-coiled-coil-helix domain (CHCHD)-containing proteins have various important pathophysiological roles. However, the functional roles of CHCHD proteins in hypoxic PAH is still ambiguous. Here, we aimed to investigate the role of CHCHD4 in hypoxic PAH and provide new insight into the mechanism driving the development of PAH. METHODS: Serotype 1 adeno-associated viral vector (AAV) carrying Chchd4 was intratracheally injected to overexpress CHCHD4 in Sprague Dawley (SD) rats. The Normoxia groups of animals were housed at 21% O2. Hypoxia groups were housed at 10% O2, for 8 h/day for 4 consecutive weeks. Hemodynamic and histological characteristics are investigated in PAH. Primary pulmonary artery smooth muscle cells of rats (PASMCs) are used to assess how CHCHD4 affects proliferation and migration. RESULTS: We found CHCHD4 was significantly downregulated among CHCHD proteins in hypoxic PASMCs and lung tissues from hypoxic PAH rats. AAV1-induced CHCHD4 elevation conspicuously alleviates vascular remodeling and pulmonary artery resistance, and orchestrates mitochondrial oxidative phosphorylation in PASMCs. Moreover, we found overexpression of CHCHD4 impeded proliferation and migration of PASMCs. Mechanistically, through lung tissues bulk RNA-sequencing (RNA-seq), we further identified CHCHD4 modulated mitochondrial dynamics by directly interacting with SAM50, a barrel protein on mitochondrial outer membrane surface. Furthermore, knockdown of SAM50 reversed the biological effects of CHCHD4 overexpression in isolated PASMCs. CONCLUSIONS: Collectively, our data demonstrated that CHCHD4 elevation orchestrates mitochondrial oxidative phosphorylation and antagonizes aberrant PASMC cell growth and migration, thereby disturbing hypoxic PAH, which could serve as a promising therapeutic target for PAH treatment.

The HIF-1α/miR-26a-5p/PFKFB3/ULK1/2 axis regulates vascular remodeling in hypoxia-induced pulmonary hypertension by modulation of autophagy.

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease characterized by pulmonary vascular remodeling, which may cause right heart failure and even death. Accumulated evidence confirmed that microRNA-26 family play critical roles in cardiovascular disease; however, their function in PAH remains largely unknown. Here, we investigated the expression of miR-26 family in plasma from PAH patients using quantitative RT-PCR, and identified miR-26a-5p as the most downregulated member, which was also decreased in hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) autophagy models and lung tissues of PAH patients. Furthermore, chromatin immunoprecipitation (ChIP) analysis and luciferase reporter assays revealed that hypoxia-inducible factor 1α (HIF-1α) specifically interacted with the promoter of miR-26a-5p and inhibited its expression in PASMCs. Tandem mRFP-GFP-LC3B fluorescence microscopy demonstrated that miR-26a-5p inhibited hypoxia-induced PAMSC autophagy, characterized by reduced formation of autophagosomes and autolysosomes. In addition, results showed that miR-26a-5p overexpression potently inhibited PASMC proliferation and migration, as determined by cell counting kit-8, EdU staining, wound-healing, and transwell assays. Mechanistically, PFKFB3, ULK1, and ULK2 were direct targets of miR-26a-5p, as determined by dual-luciferase reporter gene assays and western blots. Meanwhile, PFKFB3 could further enhance the phosphorylation level of ULK1 and promote autophagy in PASMCs. Moreover, intratracheal administration of adeno-miR-26a-5p markedly alleviated right ventricular hypertrophy and pulmonary vascular remodeling in hypoxia-induced PAH rat models in vivo. Taken together, the HIF-1α/miR-26a-5p/PFKFB3/ULK1/2 axis plays critical roles in the regulation of hypoxia-induced PASMC autophagy and proliferation. MiR-26a-5p may represent as an attractive biomarker for the diagnosis and treatment of PAH.

Therapeutic overexpression of miR-92a-2-5p ameliorated cardiomyocyte oxidative stress injury in the development of diabetic cardiomyopathy.

BACKGROUND: Diabetic cardiomyopathy (DCM) results from pathological changes in cardiac structure and function caused by diabetes. Excessive oxidative stress is an important feature of DCM pathogenesis. MicroRNAs (miRNAs) are key regulators of oxidative stress in the cardiovascular system. In the present study, we screened for the expression of oxidative stress-responsive miRNAs in the development of DCM. Furthermore, we aimed to explore the mechanism and therapeutic potential of miR-92a-2-5p in preventing diabetes-induced myocardial damage. METHODS: An experimental type 2 diabetic (T2DM) rat model was induced using a high-fat diet and low-dose streptozotocin (30 mg/kg). Oxidative stress injury in cardiomyocytes was induced by high glucose (33 mmol/L). Oxidative stress-responsive miRNAs were screened by quantitative real-time PCR. Intervention with miR-92a-2-5p was accomplished by tail vein injection of agomiR in vivo or adenovirus transfection in vitro. RESULTS: The expression of miR-92a-2-5p in the heart tissues was significantly decreased in the T2DM group. Decreased miR-92a-2-5p expression was also detected in high glucose-stimulated cardiomyocytes. Overexpression of miR-92a-2-5p attenuated cardiomyocyte oxidative stress injury, as demonstrated by increased glutathione level, and reduced reactive oxygen species accumulation, malondialdehyde and apoptosis levels. MAPK interacting serine/threonine kinase 2 (MKNK2) was verified as a novel target of miR-92a-2-5p. Overexpression of miR-92a-2-5p in cardiomyocytes significantly inhibited MKNK2 expression, leading to decreased phosphorylation of p38-MAPK signaling, which, in turn, ameliorated cardiomyocyte oxidative stress injury. Additionally, diabetes-induced myocardial damage was significantly alleviated by the injection of miR-92a-2-5p agomiR, which manifested as a significant improvement in myocardial remodeling and function. CONCLUSIONS: miR-92a-2-5p plays an important role in cardiac oxidative stress, and may serve as a therapeutic target in DCM.

Mechanistic Understanding of the Palmitoylation of Go Protein in the Allosteric Regulation of Adhesion Receptor GPR97.

Adhesion G-protein-coupled receptors (aGPCRs)-a major family of GPCRs-play critical roles in the regulation of tissue development and cancer progression. The orphan receptor GPR97, activated by glucocorticoid stress hormones, is a prototypical aGPCR. Although it has been established that the palmitoylation of the C-terminal Go protein is essential for Go's efficient engagement with the active GPR97, the detailed allosteric mechanism remains to be clarified. Hence, we performed extensive large-scale molecular dynamics (MD) simulations of the GPR97-Go complex in the presence or absence of Go palmitoylation. The conformational landscapes analyzed by Markov state models revealed that the overall conformation of GPR97 is preferred to be fully active when interacting with palmitoylated Go protein. Structural and energetic analyses indicated that the palmitoylation of Go can allosterically stabilize the critical residues in the ligand-binding pocket of GPR97 and increase the affinity of the ligand for GPR97. Furthermore, the community network analysis suggests that the palmitoylation of Go not only allosterically strengthens the internal interactions between Gαo and Gßγ, but also enhances the coupling between Go and GPR97. Our study provides mechanistic insights into the regulation of aGPCRs via post-translational modifications of the Go protein, and offers guidance for future drug design of aGPCRs.

XMU-MP-1 protects heart from ischemia/reperfusion injury in mice through modulating Mst1/AMPK pathway.

Up to now, there are few therapeutic approaches available to protect heart from ischemia/reperfusion (I/R) injury. The present work was designed to examine the protection of XMU-MP-1, an inhibitor of mammalian sterile 20-like kinase 1 (Mst1), against myocardial I/R injury in mice and investigate the underlying molecular mechanisms. The wild-type and Mst1 (-/-) mice were exposed to I/R injury and treated with XMU-MP-1 immediately after reperfusion. Treatment with XMU-MP-1 reduced infarct size, attenuated apoptosis and necrosis, and preserved cardiac function of I/R mice. XMU-MP-1 mitigated mitochondrial dysfunction in myocardium of I/R mice. In addition, XMU-MP-1 stimulated M2 macrophage polarization and suppressed inflammation in myocardium of I/R mice. Mst1 deficiency had similar benefits on myocardial I/R injury and XMU-MP-1 treatment did not provide further protection against I/R injury in Mst1 (-/-) mice. Both treatment with XMU-MP-1 and Mst1 deficiency promoted the activation of AMPKα in myocardium of I/R mice. More importantly, administration of Compound C (a specific AMPK signaling blocker) blunted the protective effects of XMU-MP-1 on myocardial I/R injury. Collectively, reperfusion therapy with XMU-MP-1 mitigated myocardial I/R injury and preserved myocardial function in mice through modulating Mst1/AMPK pathway.

The Application and Teaching Value of a Ventricular Septal Defect Canine Model Established by Transcatheter Puncture.

This study aimed to improve and further explore a ventricular septal defect (VSD) canine model on the basis of the transcatheter puncture method and to evaluate its application and teaching value.In order to lessen the complications of VSD closure, it is necessary to improve the currently available treatment devices using appropriate animal models.In this study, we used 16 healthy adult canines as our models. After anesthesia, the VSD puncture was performed, followed by balloon dilatation of the perforation. VSD was confirmed by angiography. The venous-artery orbit was established, and the VSD was then closed once the catheter and occluder were across the defect.Of the experimental canines, 14 of the 16 canines were successfully modeled, giving a success rate of 87.5%. The canines underwent an immediate creation of a venous-artery orbit for teaching practice and were implanted with an occluder during the procedure. After 4 weeks, 13 canines survived. As per our findings, most VSD types established by the puncture were perimembranous (10 of 13, 77%).The current model has a high success rate. The model can not only avoid the risk of infection and hemodynamic disorders associated with an open thoracotomy, but can also be effectively used in evaluating the impact of occluders. It can also directly measure the parameters of the devices during the procedure, thus having a very high experimental and teaching value.

Transcatheter aortic valve implantation assisted with microcatheter: a new method to avoid coronary artery obstruction.

BACKGROUND: Lack of fluoroscopic landmarks can make valve deployment more difficult in patients with absent aortic valve (AV) calcification. The goal of this article was to evaluate the feasibility and effectiveness of transcatheter implantation of a valved stent into the AV position of a goat, assisted with a microcatheter which provides accurate positioning of coronary artery ostia to help valved stent deployment. METHODS: The subjects were 10 healthy goats in this study. A microcatheter was introduced into the distal site of right coronary artery (RCA) through femoral artery sheath. A minimal thoracic surgery approach was used to access the apex of the heart. The apex of the left ventricle was punctured; a delivery catheter equipped with the valved stent was introduced over a stiff guidewire into the aorta arch. We could accurately locate the RCA ostia through the microcatheter placed in the RCA under fluoroscopy. After correct valve position was confirmed, the valved stent was implanted after rapid inflation of the balloon. The immediate outcome of the function of the valved stents was evaluated after implantation. RESULTS: All ten devices were successfully implanted into the AV position of the goats. Immediate observation after the procedure showed that the valved stents were in the desired position after implantation by angiography, echocardiogram. No obstruction of coronary artery ostia occurred, and no moderate to severe aortic regurgitation was observed. CONCLUSIONS: When the procedure of transcatheter implantation of a balloon-expandable valved stent into the AV position of goats is assisted with microcatheter positioning coronary artery ostia, the success rate of operation can be increased in those with noncalcified AV.

Balloon-expanding stent and delivery system for transcatheter aortic valve implantation: An animal study.

OBJECTIVE: To evaluate the feasibility and satefy of transcatheter aortic valve implantation in animals by using a new balloon-expanding valved stent. METHODS: The balloon-expandable stent is made from cobalt-based alloy material and designed with a tubular, slotted structure. Fresh bovine pericardium was treated, sutured and fixed on the balloon-expandable stent. Ten healthy sheep (five males and five females), weighing an average of (25.16 ± 1.83) kg, were selected to undergo transcatheter implantation of the valve stents. The function of the valve stent was evaluated by angiography, echocardiography, and histology six months after the procedure. RESULTS: Of the ten experimental sheep, two sheep died during the operation because the higher position of the artificial valve affected the opening of the coronary artery. We successfully implanted the aortic valve stent in other eight sheep; however, one sheep died of heart failure two weeks after the operation due to the lower position of the valve stent. The valve stents were implanted in the desired position in seven sheep. Ascending aortic angiographic and autoptic findings immediately after the operation confirmed the satisfactory location and function of the valved stent. Echocardiography, angiography, and histology at six postoperative months confirmed the satisfactory location and function of the valve stent. CONCLUSION: We successfully implanted our new valve stent as a replacement of native aortic valve via the transcatheter route with satisfactory outcome.

[Experimental study of transcatheter aortic valve implantation assisted with snare to fix the delivery system].

OBJECTIVE: To evaluate the feasibility and effectiveness of transcatheter aortic valve implantation assisted with snare to fix the delivery system. METHODS: This study was made in 5 healthy goats. After the abdomen was opened and the abdominal aorta was exposed, a stiff guide wire was advanced into the apex of the left ventricle through abdominal arterial puncture points. The delivery catheter equipped with valved stent was inserted into the descending aorta under fluoroscopy along the stiff guide wire. A minimal thoracic surgery approach was used to access the apex of the heart. A J-type guidewire and 5 F multifunction catheter were placed transapically and across the aortic valve down to the descending aorta. The snare was introduced through the 5 F catheter into the ascending aorta and was controlled to seize the head of stent delivery catheter. Then the delivery catheter was advanced into the left ventricle. The valved stent was positioned in the desired position under aortography and then the balloon was dilated and the valved stent was deployed into the aortic annulus assisted with snare to fix the catheter to prevent stent dispositions. Aortic angiography and echocardiography were performed to evaluate of valve performance post procedure. RESULTS: The interventional procedure was completed successfully in all 5 goats. The mean aortic annulus diameter was (23.8 ± 2.6) mm, two valved stent of 23 mm diameter and three valved stent of 26 mm in diameter were implanted. The operation duration and X-ray exposure time were (112.3 ± 19.5) min and (16.8 ± 5.2) min, respectively. Immediate observation after procedure showed that the valved stents were in the desired position after implantation by angiography and echocardiography. No moderate to severe aortic regurgitation was observed. All goats were alive at 1 month post procedure. CONCLUSIONS: The procedure of transcatheter implantation of a balloon-expandable valved stent into the aortic valve position of goats assisted with snare to fix the delivery catheter is feasible and effective. This procedure might be suitable also for patients with noncalcified aortic stenosis.

[Construction and identification of HBD-2 transgenic mice].

Human beta defensin 2 (HBD-2) may play an important role in human defense against infection. Its antimicrobial capacity has been fully documented in in vitro study. In order to evaluae its in vivo effects, we developed an HBD-2 transgenic mouse model. The HBD-2 minigene containing CMV promoter, full length of HBD-2 cDNA and BGH polyA tail was generated by PCR amplification and introduced into the fertilized oocytes of C57 X ICR hybridized mouse by microinjection, and offspring were produced. DNA was isolated from the tails of the mouse pups, and the HBD-2 minigene incorporation was analyzed by PCR using HBD-2 specific primers. The HBD-2 gene expression in the multi-tissues of transgenic mice was determined at mRNA level by RT-PCR and at peptide level by immunohistological staining with the use of HBD-2 monoclonal antibody. The results showed that among 17 F0 transgenic mice, HBD-2 positive signal was determined by PCR in 4 mice, suggesting that HBD-2 minigene has been incorporated into the offspring mice. Meanwhile, a widespread expression of HBD-2 mRNA and peptide was detected in the F1 transgenic mice's multi-tissues such as trachea, lung, intestine, esophagus, testis, spleen, skin, endothelium and brain.