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Exercise Mitigates Cardiac Dysfunction Post-MI in Ovariectomized Mice via miR-21/Sox7-Mediated Suppression of Cardiac Fibroblast Activation

ABSTRACT: Background: Postmenopausal women have higher risks of myocardial infarction (MI) and subsequent cardiac dysfunction. Exercise is widely recognized to protect the cardiovascular system, but its molecular mechanisms in postmenopausal MI remain not fully understood. This study explored the effects and mechanism of swimming exercise against cardiac dysfunction in ovariectomized (OVX) mice post-MI. Methods: OVX mice were subjected to a 3-week swimming training before MI induction via permanent ligation of left anterior descending artery. Cardiac systolic function was evaluated by echocardiography. Masson, HE, WGA staining, RT-qPCR, and Western blotting were combined to detect the extent of cardiomyocyte hypertrophy, myocardial fibrosis, and apoptosis. To explore the key exercise-effectors, we detected microRNAs (miR-21, miR-146a, miR-155) in serum samples of elderly post-MI women subsequent to exercise rehabilitation training. miR-21 expression was further investigated in heart sample of OVX plus MI mice. The role of miR-21 in vivo was elucidated through miR-21 knockout mice model and AAV9-mediated miR-21 overexpression mice model. The function of miR-21 in vitro were evaluated in cardiac fibroblasts isolated from OVX mice and treated with TGF-β to induce its activation. miR-21 targets were revealed by microarray analysis and verified by luciferase reporter and functional rescue assays. Results: Swimming significantly improved cardiac function in OVX mice post-MI, alleviated cardiomyocyte hypertrophy, reduced myocardial fibrosis, and inhibited apoptosis. miR-21 expression was downregulated by exercise training both in heart of OVX mice post-MI and in serum of elderly women after MI. miR-21 knockout mimicked swimming’s cardioprotective effects towards OVX mice post-MI, while miR-21 overexpression abolished these effects. The overexpression of miR-21 promoted the TGF-β-induced differentiation of cardiac fibroblasts into myofibroblasts and their proliferation, whereas its inhibition blocked TGF-β’s pro-fibrotic role. Microarray analysis and luciferase assays identified Sox7 as a direct miR-21 target, and Sox7 knockdown reversed anti-fibrotic effect of inhibiting miR-21. Conclusion: Swimming protects against post-MI cardiac dysfunction in OVX mice by downregulating myocardial miR-21, thereby upregulating its target gene Sox7 and inhibiting cardiac fibroblast activation. miR-21 and its downstream target Sox7 contributes to cardioprotective effects of swimming, offering a potential target for postmenopausal MI treatment.

ORGANISM(S): Mus musculus

PROVIDER: GSE319401 | GEO | 2026/06/01

REPOSITORIES: GEO

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Project description:Ischemic heart disease (IHD) remains a leading cause of mortality worldwide, often culminating in myocardial infarction (MI) and subsequent heart failure due to adverse fibrotic remodeling of the myocardium. Despite the lack of effective treatments, exercise has emerged as a promising strategy to reduce mortality risk and improve cardiac function post-MI. This study investigates the molecular mechanisms underlying exercise-induced cardioprotection by analyzing changes in several key cardiac cell populations after MI in a murine model. We assessed the effect of exercise preconditioning in mouse MI model through echocardiography, followed by single nuclei RNA-seq of cardiac cells, and validation by microscopy and flow cytometry. Our findings demonstrate that exercise significantly enhances cardiac function post-MI, as evidenced by improved ejection fraction and stroke volume in exercised mice. These improvements are linked to adaptive changes across multiple cardiac cell types. Notably, in infarcted mice, exercise caused a downregulation of cardiomyopathy-associated pathways, accompanied by changes in ECs, macrophages, fibroblasts and cardiomyocytes. Exercise stimulated formation of new capillaries which post-MI resulted in a more vascularized infarct border zone. Additionally, exercised hearts displayed a shift in macrophage populations towards a pro-regenerative phenotype, marked by an increase in resident CCR2- macrophages and a reduction in pro-inflammatory M1-gene expression. In cardiomyocytes, exercise enhanced pathways related to endothelial support and ATP biosynthesis, mitigating the upregulation of cardiomyopathy-associated pathways observed post-MI. Importantly, exercise also restored calcium signaling and reversed pathological potassium signaling, thereby preserving contractile function. Fibroblast analysis revealed that exercise stimulated activation of these cells to participate in scar formation. In conclusion, this study provides new insights into the cellular and molecular mechanisms through which exercise enhances cardiac function and provides cardio-protection post-MI, offering potential avenues for targeted therapies in patients with IHD.

Project description:Purpose: Using RNA-sequencing technology to screen the effect of moderate-intensity treadmill exercise on the key genes that affect bone mass in the peripheral blood mononuclear cells (PBMCs) of ovariectomized (OVX) rats. Methods: Three-month-old female Sprague–Dawley rats of Specific Pathogen Free (SPF) grade were randomly divided into the sham operation (SHAM) group, OVX group, and OVX combined exercise (OVX+EX) group. The OVX+EX group performed moderate-intensity treadmill exercise for 17 weeks. Upon completion of these exercises, the body composition and bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry, and the bone microstructure of the femur was observed using micro-computed tomography scanning. PBMCs were collected from the abdominal aorta, and the differential genes were analyzed by transcriptome sequencing. The Metascape software was used for gene ontology and pathway enrichment analysis to further screen key genes. Results: 1. In the OVX group, the body weight and body fat content were significantly higher than in the SHAM group and the body muscle content and BMD were significantly lower. 2. The trabecular bone parameters in the OVX group were significantly lower than in the SHAM group, and they were significantly higher in the OVX+EX group than in the OVX group. When compared with the SHAM group, the microstructure of the distal femur trabecular in the OVX group was severely damaged, the trabecular bones were sparse, and there was a large gap between the trabecular bones. The number and continuity of the trabecular bones were higher in OVX+EX group than in the OVX group. 3. A Venn diagram showed that there were 58 common differential genes, with a fold change ≥2 and p value <0.05. and the differential genes were mainly enriched in the PI3K-Akt signaling pathway. Five key genes were screened including CCL2, Nos3, Tgfb3, ITGb4, and LpL. Conclusion: Moderate-intensity treadmill exercise may improve the body composition and bone mass of the OVX group by upregulating CCL2 and other genes of the PBMC. The results also showed that the PBMCs in the peripheral blood can be a useful tool for monitoring the effect of exercise on bone health in postmenopausal osteoporosis.

Project description:OBJECTIVE: To explore the cardioprotective effects of exercise-derived β-aminoisobutyric (BAIBA) on cardiomyocyte apoptosis and energy metabolism in a rat model of heart failure (HF).METHODS: In male Sprague-Dawley rats (8-week-old), myocardial infarction (MI) was used to induce HF by ligating the left anterior descending branch of the coronary artery. In the Sham group, the coronary artery was threaded but not ligated. After HF development, Sham and HF rats were exercised 60 min daily, 5 days per week on a treadmill for 8 weeks (50-60% maximal intensity) and exercise-induced cardiac remodeling after MI were assessed using echocardiography, hematoxylin and eosin (H&E), Masson’s Trichrome and TUNEL staining for the detection of apoptosis-associated factors in cardiac tissue. High-throughput sequencing and mass spectrometry were used to measure BAIBA production and to explore its cardioprotective effects and molecular actions. To further characterize the cardioprotective effects of BAIBA, an in vitro model of apoptosis was generated by applying H2O2 to H9C2 cells to induce mitochondrial dysfunction. In addition, cells were transfected with either a miR-208b analogue or a miR-208b inhibitor. Apoptosis-related proteins were detected by Western Blotting (WB). ATP production was also assessed by luminometry. After administration of BAIBA and Compound C, the expression of proteins related to apoptosis, mitochondrial function, lipid uptake and β-oxidative were determined. Changes in the levels of reactive oxygen species (ROS) were assessed by fluorescence microscopy. In addition, alterations in membrane potential (δψm) were obtained by confocal microscopy.RESULTS: Rats with HF after MI are accompanied by mitochondrial dysfunction, metabolic stress and apoptosis. Reduced expression of apoptosis-related proteins was observed, together with increased ATP production and reduced mitochondrial dysfunction in the exercised compared with the Sham (non-exercised) HF group. Importantly, exercise increased the production of BAIBA, irrespective of the presence of HF. To assess whether BAIBA had similar effects to exercise in ameliorating HF-induced adverse cardiac remodeling, rats were treated with 75 mg/kg/day of BAIBA and we found BAIBA had a similar cardioprotective effect. Transcriptomic analyses found that the expression of miR-208b was increased after BAIBA administration, and subsequent transfection with an miR-208b analogue ameliorated both the expression of apoptosis-related proteins and energy metabolism in H2O2-treated H9C2 cells. In combining transcriptomic with metabolomic analyses, we identified AMPK as a downstream target for BAIBA in attenuating metabolic stress in HF. Further cell experiments confirmed that BAIBA increased AMPK phosphorylation and had a cardioprotective effect on downstream fatty acid uptake, oxidative efficiency and mitochondrial function, which was prevented by the AMPK inhibitor Compound C.CONCLUSION: Exercise-generated BAIBA can reduce cardiomyocyte metabolic stress and apoptosis induced by mitochondrial dysfunction through the miR-208b/AMPK pathway.

Project description:Postmenopausal osteoporosis is the main cause of fractures in women. Resistance exercise has a positive effect on bone mineral density in postmenopausal osteoporosis patients, but its mechanism is unclear. The purpose of this study was to explore the mechanism of resistance exercise in improving ovariectomized osteoporotic rats based on the transcriptome sequencing technique. Eighteen female Sprague-Dawley rats were randomly divided into the sham-operated group, the non-exercise group, and the resistance exercise group. The rat model of postmenopausal osteoporosis was established by bilateral ovariectomy. Ten weeks after the operation, the resistance exercise group received 2 weeks of adaptive training, and 12 weeks of resistance exercise began in the 13th week. The rats were trained 5 days per week, in 4 sets of 3 repetitions per day. After the intervention, all rats were sacrificed, and the body weight, bone mineral density, trabecular bone microarchitecture, and bone biomechanics were examined. At the same time, RNA-seq and enrichment analysis of gene ontology and Kyoto Encyclopedia of Genes and Genomes were performed on the left tibias, followed by Elisa and RT-qPCR verification. It had been found that resistance exercise can effectively counteract the weight gain of ovariectomized osteoporotic rats, and has a good effect on bone mineral density and trabecular bone microarchitecture. Enrichment analysis showed that regulation of gene expression and osteoclast differentiation is the most closely related biological process and signaling pathway shared by RE/Ovx and NE/Ovx groups. Our results revealed that resistance exercise can play a role in inhibiting osteoclast activation and preventing the enhancement of osteoclast bone resorption function in ovariectomized osteoporotic rats by inhibiting Fos/Fosb-regulated TRAP activation and relieving Calcr inhibition, which has important application value in preventing bone loss caused by estrogen deficiency.

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Exercise Mitigates Cardiac Dysfunction Post-MI in Ovariectomized Mice via miR-21/Sox7-Mediated Suppression of Cardiac Fibroblast Activation

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