BACKGROUND:Doxorubicin (DOX) cardiotoxicity increases cardiovascular risk in cancer patients, mainly through mitochondrial damage. However, the underlying mechanisms remain unclear, and whether mitochondrial short open reading frame-encoded peptides can mitigate DOX-induced cardiotoxicity is unknown. METHODS:Five adeno-associated viruses expressing mitochondrial short open reading frame-encoded peptides under the cardiac troponin T promoter, including MODICA (mito-SEP protector against DOX-induced cardiac injury), were screened in a DOX-induced cardiotoxicity mouse model (n=3-5 per group). Male and female mice were randomized to adeno-associated virus-CTRL or adeno-associated virus-MODICA, respectively, combined with saline or DOX treatment. Sample sizes were: males-saline-CTRL (n=4), saline-MODICA (n=4), DOX-CTRL (n=11), DOX-MODICA (n=10); females-saline-CTRL (n=8), saline-MODICA (n=10), DOX-CTRL (n=10), DOX-MODICA (n=13). MODICA-heterozygous mice generated by CRISPR/Cas9 were also included: saline-WT (n=7), saline-heterozygous (n=4), DOX-WT (n=11), DOX-heterozygous (n=8). Echocardiography was performed at baseline and after 2 weeks of DOX treatment; myocardial tissue and serum samples were collected for molecular and histological analyses. RESULTS:The mitochondrial short open reading frame-encoded peptide MODICA was identified through biochemical analysis and functional screening in a DOX-induced cardiac injury model. MODICA localizes to the outer mitochondrial membrane and is significantly downregulated by DOX (1.00±0.08 versus 0.42±0.09; P<0.001). Cardiac-specific overexpression of MODICA via adeno-associated viruses significantly attenuated DOX-induced cardiac injury in both males and females (fractional shortening: males 38.86% versus 51.54%, P<0.001; females 39.81% versus 51.39%, P<0.001, DOX-CTRL versus DOX-MODICA) and was supported by bulk RNA-seq analysis. Conversely, MODICA deficiency exacerbated DOX-induced injury, resulting in reduced fractional shortening (40.37% versus 31.85%, P<0.001; DOX-WT versus DOX-heterozygous) and increased cardiac fibrosis (P=0.009). Proteomic analyses revealed that MODICA interacts with apoptosis-related voltage-dependent anion channel proteins, inhibiting their DOX-induced oligomerization (P<0.001) on the outer mitochondrial membrane, thereby reducing mitochondrial permeability, decreasing cardiomyocyte apoptosis and improving calcium handling. CONCLUSIONS:Our study shows that the mitochondrial short open reading frame-encoded peptide MODICA alleviates DOX-induced cardiac dysfunction and may represent a therapeutic target against DOX cardiotoxicity.

BACKGROUND:Cardiogenic shock requiring mechanical circulatory support is a life-threatening complication of cardiac surgery with cardiopulmonary bypass (CPB). This study aimed to determine the role of myoglobin in predicting the occurrence of postoperative cardiogenic shock requiring mechanical circulatory support within 14 days. METHODS:A total of 4,610 patients undergoing cardiac surgery with CPB were included and analyzed. Mechanical circulatory support included the form of intra-aortic balloon pump and extracorporeal membrane oxygenation. Cox regression with a natural cubic spline was used to assess the relationship between postoperative myoglobin levels and the 14-day risk of mechanical circulatory support for cardiogenic shock. RESULTS:Of 4,610 patients, 279 (6.1%) required mechanical circulatory support within 14 days after surgery. The 14-day risk of using mechanical circulatory support increased with the postoperative peak myoglobin levels. Among the patients who underwent aortic surgery, the threshold myoglobin level measured within 1 day after surgery, associated with an adjusted hazard ratio greater than 1.00 for using mechanical circulatory support within 14 days, was 1,568 ng/mL (95% confidence interval [CI], 195-6,040). Among the patients who underwent non-aortic surgery, the corresponding threshold myoglobin level was 419 ng/mL (95% CI, 180-452). CONCLUSIONS:Postoperative myoglobin levels are closely related to the 14-day risk of using mechanical circulatory support after cardiac surgery. When postoperative myoglobin exceeds certain thresholds, the 14-day risk of using mechanical circulatory support after surgery starts to increase with the myoglobin level. Myoglobin has potential value in predicting postoperative cardiogenic shock requiring mechanical circulatory support within 14 days after cardiac surgery.

INTRODUCTION:Vascular calcification is prevalent in chronic kidney disease (CKD), but existing medical treatments fail to achieve satisfactory therapeutic effects. Vascular calcification is now recognized as an active multifactorial process involving diverse mechanisms. Alpha-ketoglutarate (AKG), an intermediate in tricarboxylic acid cycle, has been demonstrated to extend lifespan and ameliorate age-related osteoporosis. However, whether AKG inhibits vascular calcification remains unknown. METHODS:Here, mineral deposition was studied with AKG treatment in rodent and human vascular smooth muscle cells (VSMCs) under osteogenic conditions in vivo and in vitro. RESULTS:AKG treatment remarkably ameliorated calcification of rat and human arterial rings ex vivo and aortic calcification in CKD rats and mice. Mechanistically, AKG treatment upregulated DNA demethylase ten-eleven translocation 2 (TET2) expression during vascular calcification. Knockdown of TET2 by siRNA and pharmacological inhibition of TET2 by Bobcat339 promoted vascular calcification in rat VSMCs. Bobcat339 also enhanced rat aortic ring calcification. Conversely, TET2 overexpression ameliorated vascular calcification in rat VSMCs, rat aortic rings and CKD rats. Furthermore, VSMC-specific TET2 deficiency promoted aortic calcification in CKD mice. Both TET2 siRNA and Bobcat339 independently counteracted the inhibitory effect of AKG on vascular calcification of rat VSMCs. Inhibitory effect of AKG administration on vascular calcification was reduced in TET2 knockout mice. TET2 overexpression reduced the levels of the NLRP3 inflammasome pathway, cleaved Caspase-1 and IL-1β protein expression in VSMCs and NLRP3 agonist Nigericin-induced cell calcification. CONCLUSIONS:Our study demonstrate that AKG attenuates vascular calcification partially via upregulation of TET2 and inhibition of NLRP3 inflammasome, indicating the critical role of epigenetic modifier in vascular calcification. Modulation of TET2 may become a promising strategy for the treatment of vascular calcification.

Inflammation is a critical pathological process in myocardial infarction. Although immunosuppressive therapies can mitigate inflammatory responses and improve outcomes in myocardial infarction, they also increase the risk of infections. Identifying novel regulators of local cardiac inflammation could provide safer therapeutic targets for myocardial ischemia/reperfusion injury. In this study, we identified a previously uncharacterized micropeptide, which we named Inflammation Associated MicroPeptide (IAMP). IAMP is predominantly expressed in cardiac fibroblasts, and its expression is closely associated with cardiac inflammation. Downregulation of IAMP promotes, whereas its overexpression prevents, the transformation of cardiac fibroblasts into a more inflammatory phenotype under stressed/stimulated conditions, as evidenced by changes in the expression and secretion of proinflammatory cytokines. Consequently, loss of IAMP function leads to uncontrolled inflammation and worsens cardiac injury following ischemia/reperfusion surgery. Mechanistically, IAMP promotes the degradation of HIF-1α by interacting with its stabilizing partner HSP90 and, thus, suppresses the transcription of proinflammatory genes downstream of HIF-1α. This study underscores the significance of fibroblast-mediated inflammation in cardiac ischemia/reperfusion injury and highlights the therapeutic potential of targeting micropeptides for myocardial infarction.

BACKGROUND AND PURPOSE:Disturbed blood flow is a critical factor in activation of vascular smooth muscle cells (VSMCs) and initiation of neointimal hyperplasia. The Piezo1 channel is a recent yet well-characterised mechanosensor that plays a vital role in vascular development and homeostasis. However, the role of VSMC Piezo1 in neointima development remains largely unknown. The purpose of this study is to investigate the functional role of Piezo1 channel in neointimal hyperplasia. EXPERIMENTAL APPROACH:We measured the expression of Piezo1 in VSMC-rich neointima from human coronary artery samples and two mouse neointimal hyperplasia models which were induced by cast implantation or guidewire injury. We utilised VSMC-specific Piezo1 knockout mice to explore its function and the underlying mechanism of neointimal hyperplasia, both in vivo and in vitro. KEY RESULTS:In human and mouse neointima samples, we observed a significant up-regulation of Piezo1 expression in the VSMC-rich neointima compared to the medial layer. VSMC-specific knockout of Piezo1 significantly reduced neointimal hyperplasia in both animal models. Activation of Piezo1 facilitates, whereas Piezo1 deficiency inhibits disturbed flow-induced cell proliferation, migration and synthetic phenotype switch. Mechanistic studies suggest that Piezo1 activates YAP and TAZ through Ca2+ and its downstream effectors calmodulin kinase II and calcineurin, which in turn drive VSMC proliferation and migration, thereby facilitating neointimal hyperplasia. CONCLUSIONS AND IMPLICATIONS:These findings demonstrate a critical role of mechanosensitive Piezo1 channel in neointimal hyperplasia via modulating VSMC phenotype. Piezo1 channels may represent a novel therapeutic target for maladaptive vascular remodelling and occlusive vascular diseases.

Small-diameter vascular grafts (SDVGs) are severely lacking in clinical settings. Therefore, our study investigates a new source of biological vessels—bovine and porcine decellularized intercostal arteries (DIAs)—as potential SDVGs. We utilized a combination of SDS and Triton X-100 to perfuse the DIAs, establishing two different time protocols. The results show that perfusing with 1% concentrations of each decellularizing agent for 48 h yields DIAs with excellent biocompatibility and mechanical properties. The porcine decellularized intercostal arteries (PDIAs) we obtained had a length of approximately 14 cm and a diameter of about 1.5 mm, while the bovine decellularized intercostal arteries (BDIAs) were about 29 cm long with a diameter of approximately 2.2 mm. Although the lengths and diameters of both the PDIAs and BDIAs are suited for coronary artery bypass grafting (CABG), as the typical diameter of autologous arteries used in CABG is about 2 mm and the grafts required are at least 10 cm long, our research indicates that BDIAs possess more ideal mechanical characteristics for CABG than PDIAs, showing significant potential. Further enhancements may be necessary to address their limited hemocompatibility.

Coronary artery bypass grafting is acknowledged as a major clinical approach for treatment of severe coronary artery atherosclerotic heart disease. This procedure typically requires autologous small-diameter vascular grafts. However, the limited availability of the donor vessels and associated trauma during tissue harvest underscore the necessity for artificial arterial alternatives. Herein, decellularized bovine intercostal arteries were successfully fabricated with lengths ranging from 15 to 30 cm, which also closely match the inner diameters of human coronary arteries. These decellularized arterial grafts exhibited great promise following poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) grafting from the inner surface. Such surface modification endowed the decellularized arteries with superior mechanical strength, enhanced anticoagulant properties and improved biocompatibility, compared to the decellularized bovine intercostal arteries alone, or even those decellularized grafts modified with both heparin and vascular endothelial growth factor. After replacement of the carotid arteries in rabbits, all surface-modified vascular grafts have shown good patency within 30 days post-implantation. Notably, strong signal was observed after alpha-SMA immunofluorescence staining on the PMPC-grafted vessels, indicating significant potential for regenerating the vascular smooth muscle layer and thereby restoring full structures of the artery. Consequently, the decellularized bovine intercostal arteries surface modified by PMPC can emerge as a potent candidate for small-diameter artificial blood vessels, and have shown great promise to serve as viable substitutes of arterial autografts.

One of the features of pathological cardiac hypertrophy is enhanced translation and protein synthesis. Translational inhibition has been shown to be an effective means of treating cardiac hypertrophy, although system -wide side effects are common. Regulators of translation, such as cardiac -specific long noncoding RNAs (lncRNAs), could provide new, more targeted therapeutic approaches to inhibit cardiac hypertrophy. Therefore, we generated mice lacking a previously identified lncRNA named CARDINAL to examine its cardiac function. We demonstrate that CARDINAL is a cardiacspecific, ribosome -associated lncRNA and show that its expression was induced in the heart upon pathological cardiac hypertrophy and that its deletion in mice exacerbated stress -induced cardiac hypertrophy and augmented protein translation. In contrast, overexpression of CARDINAL attenuated cardiac hypertrophy in vivo and in vitro and suppressed hypertrophy -induced protein translation. Mechanistically, CARDINAL interacted with developmentally regulated GTPbinding protein 1 (DRG1) and blocked its interaction with DRG family regulatory protein 1 (DFRP1); as a result, DRG1 was downregulated, thereby modulating the rate of protein translation in the heart in response to stress. This study provides evidence for the therapeutic potential of targeting cardiac -specific lncRNAs to suppress disease -induced translational changes and to treat cardiac hypertrophy and heart failure.

The mechanism by which aging induces aortic aneurysm and dissection (AAD) remains unclear. A total of 430 participants were recruited for the screening of differentially expressed plasma microRNAs (miRNAs). We found that miR-1204 is significantly increased in both the plasma and aorta of elder patients with AAD and is positively correlated with age. Cell senescence induces the expression of miR-1204 through p53 interaction with plasmacytoma variant translocation 1, and miR-1204 induces vascular smooth muscle cell (VSMC) senescence to form a positive feedback loop. Furthermore, miR-1204 aggravates angiotensin II-induced AAD formation, and inhibition of miR-1204 attenuates β-aminopropionitrile monofumarate-induced AAD development in mice. Mechanistically, miR-1204 directly targets myosin light chain kinase (MYLK), leading to the acquisition of a senescence-associated secretory phenotype (SASP) by VSMCs and loss of their contractile phenotype. MYLK overexpression reverses miR-1204-induced VSMC senescence, SASP and contractile phenotypic changes, and the decrease of transforming growth factor-β signaling pathway. Our findings suggest that aging aggravates AAD via the miR-1204-MYLK signaling axis.

Diabetic foot ulcers (DFUs) are a serious vascular disease. Currently, no effective methods are available for treating DFUs. Pro-protein convertase subtilisin/kexin type 9 (PCSK9) regulates lipid levels to promote atherosclerosis. However, the role of PCSK9 in DFUs remains unclear. In this study, we found that the expression of PCSK9 in endothelial cells (ECs) increased significantly under high glucose (HG) stimulation and in diabetic plasma and vessels. Specifically, PCSK9 promotes the E3 ubiquitin-protein ligase NEDD4 binding to vascular endothelial growth factor receptor 2 (VEGFR2), which led to the ubiquitination of VEGFR2, resulting in its degradation and downregulation in ECs. Furthermore, PCSK9 suppresses the expression and activation of AKT, endothelial nitric oxide synthase (eNOS), and ERK1/2, leading to decreased nitric oxide (NO) production and increased superoxide anion (O2._) generation, which impairs vascular endothelial function and angiogenesis. Importantly, using evolocumab to limit the increase in PCSK9 expression blocked the HG-induced inhibition of NO production and the increase in O2._ production, as well as inhibited the phosphorylation and expression of AKT, eNOS, and ERK1/2. Moreover, evolocumab improved vascular endothelial function and angiogenesis, and promoted wound healing in diabetes. Our findings suggest that targeting PCSK9 is a novel therapeutic approach for treating DFUs.

Vascular calcification is an actively regulated biological process resembling bone formation, and osteogenic differentiation of vascular smooth muscle cells (VSMCs) plays a crucial role in this process. 1-Palmitoyl-2-(5 '-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC), an oxidized phospholipid, is found in atherosclerotic plaques and has been shown to induce oxidative stress. However, the effects of POVPC on osteogenic differentiation and calcification of VSMCs have yet to be studied. In the present study, we investigated the role of POVPC in vascular calcification using in vitro and ex vivo models. POVPC increased mineralization of VSMCs and arterial rings, as shown by alizarin red staining. In addition, POVPC treatment increased expression of osteogenic markers Runx2 and BMP2, indicating that POVPC promotes osteogenic transition of VSMCs. Moreover, POVPC increased oxidative stress and impaired mitochondria function of VSMCs, as shown by increased ROS levels, impairment of mitochondrial membrane potential, and decreased ATP levels. Notably, ferroptosis triggered by POVPC was confirmed by increased levels of intracellular ROS, lipid ROS, and MDA, which were decreased by ferrostatin-1, a ferroptosis inhibitor. Furthermore, ferrostatin-1 attenuated POVPC-induced calcification of VSMCs. Taken together, our study for the first time demonstrates that POVPC promotes vascular calcification via activation of VSMC ferroptosis. Reducing the levels of POVPC or inhibiting ferroptosis might provide a novel strategy to treat vascular calcification.

One of the features of pathological cardiac hypertrophy is enhanced translation and protein synthesis. Translational inhibition has been shown to be an effective means of treating cardiac hypertrophy, although system-wide side effects are common. Regulators of translation, such as cardiac-specific long noncoding RNAs (lncRNAs), could provide new, more targeted therapeutic approaches to inhibit cardiac hypertrophy. Therefore, we generated mice lacking a previously identified lncRNA named CARDINAL to examine its cardiac function. We demonstrate that CARDINAL is a cardiac-specific, ribosome-associated lncRNA and show that its expression was induced in the heart upon pathological cardiac hypertrophy and that its deletion in mice exacerbated stress-induced cardiac hypertrophy and augmented protein translation. In contrast, overexpression of CARDINAL attenuated cardiac hypertrophy in vivo and in vitro and suppressed hypertrophy-induced protein translation. Mechanistically, CARDINAL interacted with developmentally regulated GTP-binding protein 1 (DRG1) and blocked its interaction with DRG family regulatory protein 1 (DFRP1); as a result, DRG1 was downregulated, thereby modulating the rate of protein translation in the heart in response to stress. This study provides evidence for the therapeutic potential of targeting cardiac-specific lncRNAs to suppress disease-induced translational changes and to treat cardiac hypertrophy and heart failure.

Acute lung injury (ALI) including acute respiratory distress syndrome (ARDS) is a major complication and increase the mortality of patients with cardiac surgery. We previously found that the protein cargoes enriched in circulating extracellular vesicles (EVs) are closely associated with cardiopulmonary disease. We aimed to evaluate the implication of EVs on cardiac surgery-associated ALI/ARDS. The correlations between “oncoprotein-induced transcript 3 protein (OIT3) positive” circulating EVs and postoperative ARDS were assessed. The effects of OIT3-overexpressed EVs on the cardiopulmonary bypass (CPB) -induced ALI in vivo and inflammation of human bronchial epithelial cells (BEAS-2B) were detected. OIT3 enriched in circulating EVs is reduced after cardiac surgery with CPB, especially with postoperative ARDS. The “OIT3 positive” EVs negatively correlate with lung edema, hypoxemia and CPB time. The OIT3-overexpressed EVs can be absorbed by pulmonary epithelial cells and OIT3 transferred by EVs triggered K48- and K63-linked polyubiquitination to inactivate NOD-like receptor protein 3 (NLRP3) inflammasome, and restrains pro-inflammatory cytokines releasing and immune cells infiltration in lung tissues, contributing to the alleviation of CPB-induced ALI. Overexpression of OIT3 in human bronchial epithelial cells have similar results. OIT3 promotes the E3 ligase Cbl proto-oncogene B associated with NLRP3 to induce the ubiquitination of NLRP3. Immunofluorescence tests reveal that OIT3 is reduced in the generation from the liver sinusoids endothelial cells (LSECs) and secretion in liver-derived EVs after CPB. In conclusion, OIT3 enriched in EVs is a promising biomarker of postoperative ARDS and a therapeutic target for ALI after cardiac surgery.

After birth, the heart undergoes a shift in energy metabolism and cytoarchitecture to enhance efficient energy production and cardiac contraction, which is essential for postnatal development and growth. However, the precise mechanisms regulating this process remain elusive. Here we show that the RNA modification enzyme Mettl1 is a critical regulator of postnatal metabolic reprogramming and cardiomyocyte maturation in mice, primarily through its influence on the translation of the rate-limiting ketogenesis enzyme Hmgcs2. Our findings reveal that ketogenesis is vital for the postnatal transition of fuel from glucose to fatty acids in cardiomyocytes, achieved by modulating tricarboxylic acid cycle-related enzymatic activity via lysine β-hydroxybutyrylation protein modification. Loss of Mettl1 results in aberrant metabolic reprogramming and cardiomyocyte immaturity, leading to heart failure, although some clinical features can be rescued by β-hydroxybutyrate supplementation. Our study provides mechanistic insights into how Mettl1 regulates metabolic reprogramming in neonatal cardiomyocytes and highlights the importance of ketogenesis in cardiomyocyte maturation.

Ferroptosis is a novel cell death mechanism that is mediated by iron-dependent lipid peroxidation. It may be involved in atherosclerosis development. Products of phospholipid oxidation play a key role in atherosclerosis. 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) is a phospholipid oxidation product present in atherosclerotic lesions. It remains unclear whether PGPC causes atherosclerosis by inducing endothelial cell ferroptosis. In this study, human umbilical vein endothelial cells (HUVECs) were treated with PGPC. Intracellular levels of ferrous iron, lipid peroxidation, superoxide anions (O2•-), and glutathione were detected, and expression of fatty acid binding protein-3 (FABP3), glutathione peroxidase 4 (GPX4), and CD36 were measured. Additionally, the mitochondrial membrane potential (MMP) was determined. Aortas from C57BL6 mice were isolated for vasodilation testing. Results showed that PGPC increased ferrous iron levels, the production of lipid peroxidation and O2•-, and FABP3 expression. However, PGPC inhibited the expression of GPX4 and glutathione production and destroyed normal MMP. These effects were also blocked by ferrostatin-1, an inhibitor of ferroptosis. FABP3 silencing significantly reversed the effect of PGPC. Furthermore, PGPC stimulated CD36 expression. Conversely, CD36 silencing reversed the effects of PGPC, including PGPC-induced FABP3 expression. Importantly, E06, a direct inhibitor of the oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine IgM natural antibody, inhibited the effects of PGPC. Finally, PGPC impaired endothelium-dependent vasodilation, ferrostatin-1 or FABP3 inhibitors inhibited this impairment. Our data demonstrate that PGPC impairs endothelial function by inducing endothelial cell ferroptosis through the CD36 receptor to increase FABP3 expression. Our findings provide new insights into the mechanisms of atherosclerosis and a therapeutic target for atherosclerosis.

VEGF-induced angiogenesis is impaired in hypercholesterolemia. Previous studies showed that an apolipoprotein A-I(ApoA-I) mimetic peptide, D-4F, is able to reduce HDL proinflammatory index in hypercholesterolemia. Whether D-4F promotes angiogenesis in hypercholesterolemia remains unclear. Low-density lipoprotein receptor null (LDLr−/−) mice and LDLr−/−/ApoA-I−/− mice were fed with high-fat diet with or without D-4F (1mg/kg·d). C57BL/6 mice fed with normal diet served as control. The myocardial infarction was induced by ligation coronary artery, and the VEGFA-AAV 9 was injected in heart. The plasma HDL proinflammatory index, cardiac function, infarct size, and angiogenesis related signaling pathways were examined. The HDL proinflammatory index increases in hypercholesterolemic mice. VEGFA stimulates angiogenesis and improves cardiac function in ischemic heart of C57BL/6 mice, but not in hypercholesterolemic mice. D-4F reduces HDL proinflammatory index. D-4F combined with VEGFA stimulates the expression of CD31 and eNOS, activates ERK1/2, reduces infarct size, and improves cardiac function in ischemic heart in hypercholesterolemic LDLr−/− mice but not in hypercholesterolemic LDLr−/−/ApoA-I−/− mice. D-4F restores the VEGF-induced angiogenesis by reducing HDL proinflammatory properties in hypercholesterolemic ischemic heart.

Background In the past decade, the biological functions of various RNA modifications in mammals have been uncovered. N4‐acetylcytidine (ac4C), a highly conserved RNA modification, has been implicated in human diseases. Despite this, the involvement of RNA ac4C modification in cardiac physiology and pathology remains incompletely understood. NAT10 (N‐acetyltransferase 10) stands as the sole acetyltransferase known to catalyze RNA ac4C modification. This study aims to explore the role of NAT10 and ac4C modification in cardiac physiology and pathology. Methods and Results Cardiac‐specific knockout of NAT10, leading to reduced RNA ac4C modification, during both neonatal and adult stages resulted in severe heart failure. NAT10 deficiency induced cardiomyocyte apoptosis, a crucial step in heart failure pathogenesis, supported by in vitro data. Activation of the p53 signaling pathway was closely associated with enhanced apoptosis in NAT10‐deficient cardiomyocytes. As ac4C modification on mRNA influences translational efficiency, we employed ribosome footprints coupled with RNA sequencing to explore genome‐wide translational efficiency changes caused by NAT10 deficiency. We identified and validated that the translational efficiency of Kmt5a was suppressed in NAT10 knockout hearts due to reduced ac4C modification on its mRNA. This finding was consistent with the observation that Kmt5a protein levels were reduced in heart failure despite unchanged mRNA expression. Knockdown of Kmt5a in cardiomyocytes recapitulated the phenotype of NAT10 deficiency, including increased cardiomyocyte apoptosis and activated p53 signaling. Finally, overexpression of Kmt5a rescued cardiomyocyte apoptosis and p53 activation induced by NAT10 inhibition. Conclusions Our study highlights the significance of NAT10 in cardiomyocyte physiology, demonstrating that NAT10 loss is sufficient to induce cardiomyocyte apoptosis and heart failure. NAT10 regulates the translational efficiency of Kmt5a , a key mediator, through mRNA ac4C modification during heart failure.

Background and Purpose: Atherosclerosis induced by cyclosporine A (CsA), an inhibitor of the calcineurin/nuclear factor of activated T cells (NFAT) pathway, is a major concern after organ transplantation. However, the atherosclerotic mechanisms of CsA remain obscure. We previously demonstrated that calcineurin/NFAT signalling inhibition contributes to atherogenesis via suppressing microRNA-204 (miR-204) transcription. We therefore hypothesised that miR-204 is involved in the development of CsA-induced atherosclerosis.Experimental Approach: ApoE(-/-) mice with macrophage-miR-204 overexpression were generated to determine the effects of miR-204 on CsA-induced atherosclerosis. Luciferase reporter assays and chromatin immunoprecipitation sequencing were performed to explore the targets mediating miR-204 effects.Key Results: CsA alone did not significantly affect atherosclerotic lesions or serum lipid levels. However, it exacerbated high-fat diet-induced atherosclerosis and hyperlipidemia in C57BL/6J and ApoE(-/-) mice, respectively. miR-204 levels decreased in circulating monocytes and plaque lesions during CsA-induced atherosclerosis. The upregulation of miR-204 in macrophages inhibited CsA-induced atherosclerotic plaque formation but did not affect serum lipid levels. miR-204 limited the CsA-induced foam cell formation by reducing the expression of the scavenger receptors SR-BII and CD36. SR-BII was post-transcriptionally regulated by mature miR-204-5p via 3 ' -UTR targeting. Additionally, nuclear-localised miR-204-3p prevented the CsA-induced binding of Ago2 to the CD36 promoter, suppressing CD36 transcription. SR-BII or CD36 expression restoration dampened the beneficial effects of miR-204 on CsA-induced atherosclerosis.Conclusion and Implications: Macrophage miR-204 ameliorates CsA-induced atherosclerosis, suggesting that miR-204 may be a potential target for the prevention and treatment of CsA-related atherosclerotic side effects.

Normal high-density lipoprotein (nHDL) can induce angiogenesis in healthy individuals. However, HDL from patients with coronary artery disease undergoes various modifications, becomes dysfunctional (dHDL), and loses its ability to promote angiogenesis. Here, we identified a long non-coding RNA, HDRACA, that is involved in the regulation of angiogenesis by HDL. In this study, we showed that nHDL downregulates the expression of HDRACA in endothelial cells by activating WW domain-containing E3 ubiquitin protein ligase 2, which catalyzes the ubiquitination and subsequent degradation of its transcription factor, Kruppel-like factor 5, via sphingosine 1-phosphate (S1P) receptor 1. In contrast, dHDL with lower levels of S1P than nHDL were much less effective in decreasing the expression of HDRACA. HDRACA was able to bind to Ras-interacting protein 1 (RAIN) to hinder the interaction between RAIN and vigilin, which led to an increase in the binding between the vigilin protein and proliferating cell nuclear antigen (PCNA) mRNA, resulting in a decrease in the expression of PCNA and inhibition of angiogenesis. The expression of human HDRACA in a hindlimb ischemia mouse model inhibited the recovery of angiogenesis. Taken together, these findings suggest that HDRACA is involved in the HDL regulation of angiogenesis, which nHDL inhibits the expression of HDRACA to induce angiogenesis, and that dHDL is much less effective in inhibiting HDRACA expression, which provides an explanation for the decreased ability of dHDL to stimulate angiogenesis.

We previously demonstrated that normal high-density lipoprotein (nHDL) can promote angiogenesis, whereas HDL from patients with coronary artery disease (dHDL) is dysfunctional and impairs angiogenesis. Autophagy plays a critical role in angiogenesis, and HDL regulates autophagy. However, it is unclear whether nHDL and dHDL regulate angiogenesis by affecting autophagy. Endothelial cells (ECs) were treated with nHDL and dHDL with or without an autophagy inhibitor. Autophagy, endothelial nitric oxide synthase (eNOS) expression, miRNA expression, nitric oxide (NO) production, superoxide anion (O 2 •− ) generation, EC migration, and tube formation were evaluated. nHDL suppressed the expression of miR-181a-5p, which promotes autophagy and the expression of eNOS, resulting in NO production and the inhibition of O 2 •− generation, and ultimately increasing in EC migration and tube formation. dHDL showed opposite effects compared to nHDL and ultimately inhibited EC migration and tube formation. We found that autophagy-related protein 5 (ATG5) was a direct target of miR-181a-5p. ATG5 silencing or miR-181a-5p mimic inhibited nHDL-induced autophagy, eNOS expression, NO production, EC migration, tube formation, and enhanced O 2 •− generation, whereas overexpression of ATG5 or miR-181a-5p inhibitor reversed the above effects of dHDL. ATG5 expression and angiogenesis were decreased in the ischemic lower limbs of hypercholesterolemic low-density lipoprotein receptor null (LDLr −/− ) mice when compared to C57BL/6 mice. ATG5 overexpression improved angiogenesis in ischemic hypercholesterolemic LDLr −/− mice. Taken together, nHDL was able to stimulate autophagy by suppressing miR-181a-5p, subsequently increasing eNOS expression, which generated NO and promoted angiogenesis. In contrast, dHDL inhibited angiogenesis, at least partially, by increasing miR-181a-5p expression, which decreased autophagy and eNOS expression, resulting in a decrease in NO production and an increase in O 2 •− generation. Our findings reveal a novel mechanism by which HDL affects angiogenesis by regulating autophagy and provide a therapeutic target for dHDL-impaired angiogenesis.