PIAS1 protects against myocardial ischemia-reperfusion injury by stimulating PPARγ SUMOylation

Cellular and molecular biology of posttranslational modifications in cardiovascular disease

Cardiovascular disease (CVD) has now become the leading cause of death worldwide, and its high morbidity and mortality rates pose a great threat to society. Although numerous studies have reported the pathophysiology of CVD, the exact pathogenesis of all types of CVD is not fully understood. Therefore, much more research is still needed to explore the pathogenesis of CVD. With the development of proteomics, many studies have successfully identified the role of posttranslational modifications in the pathogenesis of CVD, including key processes such as apoptosis, cell metabolism, and oxidative stress. In this review, we summarize the progress in the understanding of posttranslational modifications in cardiovascular diseases, including novel protein posttranslational modifications such as succinylation and nitrosylation. Furthermore, we summarize the currently identified histone deacetylase (HDAC) inhibitors used to treat CVD, providing new perspectives on CVD treatment modalities. We critically analyze the roles of posttranslational modifications in the pathogenesis of CVD-related diseases and explore future research directions related to posttranslational modifications in cardiovascular diseases.

Peptides Are Cardioprotective Drugs of the Future: The Receptor and Signaling Mechanisms of the Cardioprotective Effect of Glucagon-like Peptide-1 Receptor Agonists

The high mortality rate among patients with acute myocardial infarction (AMI) is one of the main problems of modern cardiology. It is quite obvious that there is an urgent need to create more effective drugs for the treatment of AMI than those currently used in the clinic. Such drugs could be enzyme-resistant peptide analogs of glucagon-like peptide-1 (GLP-1). GLP-1 receptor (GLP1R) agonists can prevent ischemia/reperfusion (I/R) cardiac injury. In addition, chronic administration of GLP1R agonists can alleviate the development of adverse cardiac remodeling in myocardial infarction, hypertension, and diabetes mellitus. GLP1R agonists can protect the heart against oxidative stress and reduce proinflammatory cytokine (IL-1β, TNF-α, IL-6, and MCP-1) expression in the myocardium. GLP1R stimulation inhibits apoptosis, necroptosis, pyroptosis, and ferroptosis of cardiomyocytes. The activation of the GLP1R augments autophagy and mitophagy in the myocardium. GLP1R agonists downregulate reactive species generation through the activation of Epac and the GLP1R/PI3K/Akt/survivin pathway. The GLP1R, kinases (PKCε, PKA, Akt, AMPK, PI3K, ERK1/2, mTOR, GSK-3β, PKG, MEK1/2, and MKK3), enzymes (HO-1 and eNOS), transcription factors (STAT3, CREB, Nrf2, and FoxO3), KATP channel opening, and MPT pore closing are involved in the cardioprotective effect of GLP1R agonists.

Protein inhibitor of activated STAT1 (PIAS1) alleviates cerebral infarction and inflammation after cerebral ischemia in rats

Background

Ischemic stroke is a severe disorder with high incidence, disability rate and mortality. Multiple pathogenesis mechanisms are involved in ischemic stroke, such as inflammation and neuronal cell apoptosis. Protein inhibitor of activated signal transducer and activators of transcription 1 (PIAS1) plays a crucial role in various biological processes, including inflammation. PIAS1 is also downregulated in ischemia-reperfusion injury and involved in the disease processes. However, the role of PIAS1 in cerebral ischemia is unclear.

Methods

Sprague-Dawley (SD) rats were induced with middle cerebral artery occlusion (MCAO). The role and mechanisms of PIAS1 in ischemic cerebral infarction were explored by Longa test, 2,3,5-triphenyltetrazolium chloride (TTC) staining, Morris water maze (MWM) test, hematoxylin-eosin (HE) staining, quantification of brain water content, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL), Western blot and immunofluorescence assays.

Results

The expression of PIAS1 in MCAO-induced rat was declined compared to sham rats. Overexpression of PIAS1 reduced the Longa neurological scores, the percent of infarction area, the pathological abnormality, the escape latency of swimming and the percent of brain water content, and increased the number of platform crossings and time in the target quadrant in the MCAO-induced rats. Besides, overexpression of PIAS1 decreased the MCAO-induced the contents of IL-1β, IL-6 and TNF-α, but further elevated the concentrations of IL-10 in both sera and brain tissues. Moreover, overexpression of PIAS1 reversed the MCAO-induced apoptosis rate and the relative protein level of Bax, cleaved caspase3 and Bcl-2. Overexpression of PIAS1 also reversed the level of proteins involved in NF-κB pathway.

Conclusion

PIAS1 reduced inflammation and apoptosis, thereby alleviating ischemic cerebral infarction in MCAO-induced rats through regulation NF-κB pathway.

UBIAD1 effectively alleviated myocardial ischemia reperfusion injury by activating SIRT1/PGC1α

BACKGROUND AND OBJECTIVES

Myocardial ischemia-reperfusion injury (MIRI) threatens global health and lowers people's sense of happiness. Till now, the mechanism of MIRI has not been well-understood. Therefore, this study was designed to explore the role of UBIAD1 in MIRI as well as its detailed reaction mechanism.

METHODS

The mRNA and protein expressions of UBIAD1 before or after transfection were measured using RT-qPCR and western blot. Western blot was also adopted to measure the expressions of signaling pathway-, mitochondrial damage- and apoptosis-related proteins. Moreover, mitochondrial membrane potential and ATP level were verified by JC-1 immunofluorescence and ATP kits, respectively. With the application of CCK-8, LDH and CK-MB assays, the cell viability, LDH and CK-MB levels were evaluated, respectively. In addition, the cell apoptosis was detected using TUNEL. Finally, the expressions of ROS, SOD, MDA and CAT were measured using DCFH-DA, SOD, MDA and CAT assays, respectively.

RESULTS

In the present study, we found that UBIAD1 was downregulated in hypoxia-reoxygenation (H/R) -induced H9C2 cells and its upregulation could activate SIRT1/PGC1α signaling pathway. It was also found that UBIAD1 regulated mitochondrial membrane potential and ATP level via activating SIRT1/PGC1α signaling pathway. In addition, the injury of H/R-induced H9C2 cells could be relieved by UBIAD1 through the activation of SIRT1/PGC1α signaling pathway. Moreover, UBIAD1 exhibited inhibitory effects on apoptosis and oxidative stress of H/R-induced H9C2 cells through activating SIRT1/PGC1α signaling pathway.

CONCLUSION

To sum up, UBIAD1 could alleviate apoptosis, oxidative stress and H9C2 cell injury by activating SIRT1/PGC1α, which laid experimental foundation for the clinical treatment of MIRI.

PIAS1 upregulation confers protection against Cerulein-induced acute pancreatitis via FTO downregulation by enhancing sumoylation of Foxa2

OBJECTIVE

This research discussed the specific mechanism by which PIAS1 affects acute pancreatitis (AP).

METHODS

PIAS1, Foxa2, and FTO expression was assessed in Cerulein-induced AR42J cells and mice. Loss- and gain-of-function assays and Cerulein induction were conducted in AR42J cells and mice for analysis. The relationship among PIAS1, Foxa2, and FTO was tested. Cell experiments run in triplicate, and eight mice for each animal group.

RESULTS

Cerulein-induced AP cells and mice had low PIAS1 and Foxa2 and high FTO. Cerulein induced pancreatic injury in mice and inflammation and oxidative stress in pancreatic tissues, which could be reversed by PIAS1 or Foxa2 upregulation or FTO downregulation. PIAS1 elevated SUMO modification of Foxa2 to repress FTO transcription. FTO upregulation neutralized the ameliorative effects of PIAS1 or Foxa2 upregulation on Cerulein-induced AR42J cell injury, inflammation, and oxidative stress.

CONCLUSION

PIAS1 upregulation diminished FTO transcription by increasing Foxa2 SUMO modification, thereby ameliorating Cerulein-induced AP.

Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

Myosin 1b Participated in the Modulation of Hypoxia/Reoxygenation-Caused H9c2 Cell Apoptosis and Autophagy

Myocardial ischemia/reperfusion (I/R) injury seriously threats the health and life of patients with ischemia heart disease. Herein, we probed the potential influence of myosin 1b (myo1b) on hypoxia/reoxygenation- (H/R-) stimulated cardiomyocyte H9c2 cell apoptosis and autophagy. After H/R stimulation, the myo1b mRNA level in H9c2 cells was tested via qRT-PCR. Myo1b overexpression plasmid (OE-myo1b) and small interfering RNA (siRNA) targeting myo1b (si-myo1b) were transfected into H9c2 cells to alter myo1b expression in H9c2 cells. Following H/R stimulation and/or OE-myo1b (or si-myo1b) transfection, H9c2 cell apoptosis, proliferation, and autophagy were detected, respectively. We found that H/R stimulation reduced the mRNA level of myo1b in H9c2 cells and resulted in H9c2 cell apoptosis, proliferation inhibition, and autophagy. Overexpression of myo1b reversed the H/R-resulted H9c2 cell apoptosis, proliferation inhibition, and autophagy. Silence of myo1b had opposite effects, which promoted H9c2 cell apoptosis, reduced cell proliferation, and accelerated cell autophagy. Taken together, Myo1b took part in the modulation of H/R-stimulated cardiomyocyte apoptosis and autophagy, which might be serve as a potential endogenous target for prevention and therapy of I/R injury.

SUMOylation does not affect cardiac troponin I stability but alters indirectly the development of force in response to Ca2

Post-translational modification of the myofilament protein troponin I by phosphorylation is known to trigger functional changes that support enhanced contraction and relaxation of the heart. We report for the first time that human troponin I can also be modified by SUMOylation at lysine 177. Functionally, TnI SUMOylation is not a factor in the development of passive and maximal force generation in response to calcium, however this modification seems to act indirectly by preventing SUMOylation of other myofilament proteins to alter calcium sensitivity and cooperativity of myofilaments. Utilising a novel, custom SUMO site-specific antibody that recognises only the SUMOylated form of troponin I, we verify that this modification occurs in human heart and that it is upregulated during disease.

PIAS1 Alleviates Hepatic Ischemia-Reperfusion Injury in Mice through a Mechanism Involving NFATc1 SUMOylation

Recently, attentions have come to the alleviatory effect of protein inhibitor of activated STAT1 (PIAS1) in hepatic ischemia-reperfusion injury (HIRI), but the underlying molecular mechanistic actions remain largely unknown, which were illustrated in the present study. Microarray-based analysis predicted a possible regulatory mechanism involving the PIAS1/NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis in HIRI. Then, growth dynamics of hypoxia/reoxygenation- (H/R-) exposed hepatocytes and liver injury of HIRI-like mice were delineated after the alteration of the PIAS1 expression. We validated that PIAS1 downregulation occurred in H/R-exposed hepatocytes and HIRI-like mice, while the expression of NFATc1, HDAC1, and IRF-1 and phosphorylation levels of p38 were increased. PIAS1 inactivated p38 MAPK signaling by inhibiting HDAC1-mediated IRF-1 through NFATc1 SUMOylation, thereby repressing the inflammatory response and apoptosis of hepatocytes in vitro, and alleviated liver injury in vivo. Collectively, the NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis is highlighted as a promising therapeutic target for potentiating hepatoprotective effects of PIAS1 against HIRI.

Role of Posttranslational Modifications of Proteins in Cardiovascular Disease

Cardiovascular disease (CVD) has become a leading cause of mortality and morbidity globally, making it an urgent concern. Although some studies have been performed on CVD, its molecular mechanism remains largely unknown for all types of CVD. However, recent in vivo and in vitro studies have successfully identified the important roles of posttranslational modifications (PTMs) in various diseases, including CVD. Protein modification, also known as PTMs, refers to the chemical modification of specific amino acid residues after protein biosynthesis, which is a key process that can influence the activity or expression level of proteins. Studies on PTMs have contributed directly to improving the therapeutic strategies for CVD. In this review, we examined recent progress on PTMs and highlighted their importance in both physiological and pathological conditions of the cardiovascular system. Overall, the findings of this review contribute to the understanding of PTMs and their potential roles in the treatment of CVD.

LncRNA UCA1 epigenetically suppresses APAF1 expression to mediate the protective effect of sevoflurane against myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MI/RI) is a leading cause of death globally. Whereas some long noncoding RNAs (lncRNAs) are known to participate in the progression of MI/RI, the role of urothelial carcinoma associated 1 (UCA1) in conjunction with sevoflurane treatment remains largely unknown. H9C2 cardiomyocytes were subjected to hypoxia/reoxygenation (H/R) to establish an in vitro MI/RI model, and sevoflurane was then added. Cell viability, apoptosis, SOD activity, and MDA levels were measured. Levels of inflammatory cytokines and methylation of apoptosis protease-activating factor 1 (APAF1) were determined. Interactions among lncRNA UCA1, enhancer of zeste homologue 2 (EZH2), DNA methyltransferase-1 (DNMT1), and APAF1 were analyzed. After H/R treatment, the viability of H9C2 cardiomyocytes decreased and apoptosis rate, oxidative stress factor levels, inflammatory cytokine levels, and apoptosis-related protein levels all increased. Sevoflurane treatment reversed these changes. LncRNA UCA1 knockdown attenuated the therapeutic effect of sevoflurane on H/R-treated cardiomyocytes, and silencing of APAF1 reversed this role of UCA1 knockdown. Moreover, lncRNA UCA1 recruited DNMT1 through EZH2, thus promoting methylation of the APAF1 promoter region. LncRNA UCA1 recruits DNMT1 to promote methylation of the APAF1 promoter through EZH2, thus strengthening the protective effect of sevoflurane on H/R-induced cardiomyocyte injury.

SUMOylation in peripheral tissues under low perfusion-related pathological states

SUMOylation is described as a posttranslational protein modification (PTM) that is involved in the pathophysiological processes underlying several conditions related to ischemia- and reperfusion-induced damage. Increasing evidence suggests that, under low oxygen levels, SUMOylation might be part of an endogenous mechanism, which is triggered by injury to protect cells within the central nervous system. However, the role of ischemia-induced SUMOylation in the periphery is still unclear. This article summarizes the results of recent studies regarding SUMOylation profiles in several diseases characterized by impaired blood flow to the cardiorenal, gastrointestinal, and respiratory systems. Our review shows that although ischemic injury per se does not always increase SUMOylation levels, as seen in strokes, it seems that in most cases the positive modulation of protein SUMOylation after peripheral ischemia might be a protective mechanism. This complex relationship warrants further investigation, as the role of SUMOylation during hypoxic conditions differs from organ to organ and is still not fully elucidated.

Natural Products Against Renal Fibrosis via Modulation of SUMOylation

Renal fibrosis is the common and final pathological process of kidney diseases. As a dynamic and reversible post-translational modification, SUMOylation and deSUMOylation of transcriptional factors and key mediators significantly affect the development of renal fibrosis. Recent advances suggest that SUMOylation functions as the promising intervening target against renal fibrosis, and natural products prevent renal fibrosis via modulating SUMOylation. Here, we introduce the mechanism of SUMOylation in renal fibrosis and therapeutic effects of natural products. This process starts by summarizing the key mediators and enzymes during SUMOylation and deSUMOylation and its regulation role in transcriptional factors and key mediators in renal fibrosis, then linking the mechanism findings of SUMOylation and natural products to develop novel therapeutic candidates for treating renal fibrosis, and concludes by commenting on promising therapeutic targets and candidate natural products in renal fibrosis via modulating SUMOylation, which highlights modulating SUMOylation as a promising strategy for natural products against renal fibrosis.

Knockdown of XIST up-regulates 263294miR-340-5p to relieve myocardial ischaemia-reperfusion injury via inhibiting cyclin D1

Aim

Long non‐coding RNAs (lncRNAs) are known to participate in various human diseases, while the role of X inactive‐specific transcript (XIST) binding microRNA‐340‐5p (miR‐340‐5p) remains seldom studied. We aim to identify the role of the XIST/miR‐340‐5p/cyclin D1 (CCND1) axis in the myocardial ischaemia–reperfusion injury (MIRI).

Methods and results

The mouse MIRI models were established. The expression of XIST, miR‐340‐5p, and CCND1 in mouse myocardial tissues in MIRI mice was assessed. The MIRI mice were respectively treated with altered XIST, miR‐340‐5p, or CCND1. The changes of myocardial enzyme activity were assessed, and the cardiac function was evaluated. Myocardial pathological changes, cardiomyocyte apoptosis and related apoptotic factors, oxidative stress and inflammatory factors were observed in myocardial tissues in mice with MIRI. The binding relationships between XIST and miR‐340‐5p, and between miR‐340‐5p and CCND1 were confirmed. XIST and CCND1 were up‐regulated while miR‐340‐5p was down‐regulated in MIRI mice. Silenced XIST could elevated miR‐340‐5p expression and reduced CCND1 expression, so as to promoted cardiac function and suppressed myocardial enzyme activity, ameliorated pathological changes, decelerated cardiomyocyte apoptosis by elevating Bcl‐2 but reducing the levels of Bax and Caspase‐3, attenuated inflammatory response by repressing IL‐6 and TNF‐α levels, and mitigated oxidative stress by reducing MDA contents and increasing CAT, GSH‐Px, and SOD levels in MIRI mice. XIST sponged miR‐340‐5p and miR‐340‐5p targeted CCND1.

Conclusions

Knockdown of XIST up‐regulates miR‐340‐5p to relieve MIRI via inhibiting CCND1.

PAK5 promotes RNA helicase DDX5 sumoylation and miRNA-10b processing in a kinase-dependent manner in breast cancer

P21-activated kinase 5 (PAK5) plays an important role in tumors. However, the functional role of PAK5 in mammary tumorigenesis in vivo remains unclear. Here, we show that PAK5 deficiency represses MMTV-PyVT-driven breast tumorigenesis. DEAD-box RNA helicase 5 (DDX5) is a substrate of PAK5, which is phosphorylated on threonine 69. PAK5-mediated DDX5 phosphorylation promotes breast cancer cell proliferation and metastasis. The increased expression levels of PAK5 and phospho-DDX5 threonine 69 are associated with metastasis and poor clinical outcomes of patients. PAK5 facilitates the phosphorylation-dependent sumoylation of DDX5 to stabilize DDX5. Both the phosphorylation and sumoylation of DDX5 enhance the formation of a DDX5/Drosha/DGCR8 complex, thus promoting microRNA-10b processing. Finally, we verify decreased expression of DDX5 phosphorylation and sumoylation and mature miR-10b in PAK5-/-/MMTV-PyVT transgenic mice. Our findings provide insights into the function of PAK5 in microRNA (miRNA) biogenesis, which might be a potential therapeutic target for breast cancer.

SUMO-specific Isopeptidases Tuning Cardiac SUMOylation in Health and Disease

SUMOylation is a transient posttranslational modification with small-ubiquitin like modifiers (SUMO1, SUMO2 and SUMO3) covalently attached to their target-proteins via a multi-step enzymatic cascade. SUMOylation modifies protein-protein interactions, enzymatic-activity or chromatin binding in a multitude of key cellular processes, acting as a highly dynamic molecular switch. To guarantee the rapid kinetics, SUMO target-proteins are kept in a tightly controlled equilibrium of SUMOylation and deSUMOylation. DeSUMOylation is maintained by the SUMO-specific proteases, predominantly of the SENP family. SENP1 and SENP2 represent family members tuning SUMOylation status of all three SUMO isoforms, while SENP3 and SENP5 are dedicated to detach mainly SUMO2/3 from its substrates. SENP6 and SENP7 cleave polySUMO2/3 chains thereby countering the SUMO-targeted-Ubiquitin-Ligase (StUbL) pathway. Several biochemical studies pinpoint towards the SENPs as critical enzymes to control balanced SUMOylation/deSUMOylation in cardiovascular health and disease. This study aims to review the current knowledge about the SUMO-specific proteases in the heart and provides an integrated view of cardiac functions of the deSUMOylating enzymes under physiological and pathological conditions.

PIAS1 alleviates diabetic peripheral neuropathy through SUMOlation of PPAR-γ and miR-124-induced downregulation of EZH2/STAT3

Diabetic peripheral neuropathy (DPN) is a frequently occurring chronic complication of diabetes. In this study, we aim to explore the regulatory mechanism of protein inhibitor of activated STAT1 (PIAS1) in DPN in terms of autophagy and apoptosis of Schwann cells. The SUMOlation of PPAR-γ by PIAS1 was examined, and ChIP was performed to verify the binding of PPAR-γ to miR-124 promoter region. Dual-luciferase gene reporter assay was used to validate the binding affinity between miR-124 and EZH2/STAT3. Following loss‐ and gain‐of-function experiments, in vitro assays in high glucose-treated Schwann cells (SC4) and in vivo assays in db/db and ob/ob mice were performed to detect the effects of PIAS1 on autophagy and apoptosis of Schwann cells as well as symptoms of DPN by regulating the PPAR-γ-miR-124-EZH2/STAT3. The expression of PIAS1, PPAR-γ, and miR-124 was downregulated in the sciatic nerve tissue of diabetic mice. PIAS1 enhanced the expression of PPAR-γ through direct binding and SUMOlation of PPAR-γ. PPAR-γ enhanced the expression of miR-124 by enhancing the promoter activity of miR-124. Furthermore, miR-124 targeted and inversely modulated EZH2 and STAT3, promoting the autophagy of Schwann cells and inhibiting their apoptosis. In vivo experiments further substantiated that PIAS1 could promote the autophagy and inhibit the apoptosis of Schwann cells through the PPAR-γ-miR-124-EZH2/STAT3 axis. In conclusion, PIAS1 promoted SUMOlation of PPAR-γ to stabilize PPAR-γ expression, which upregulated miR-124 to inactivate EZH2/STAT3, thereby inhibiting apoptosis and promoting autophagy of Schwann cells to suppress the development of DPN.

Silencing miR-181b-5p upregulates PIAS1 to repress oxidative stress and inflammatory response in rats with alcoholic fatty liver disease through inhibiting PRMT1

OBJECTIVE

This study aimed to probe the function of microRNA-181b-5p (miR-181b-5p)/protein inhibitor of activated STAT1 (PIAS1)/protein arginine methyltransferase 1 (PRMT1) axis in the progression of alcoholic fatty liver disease (AFLD).

METHODS

A rat model of AFLD was established and treated with altered miR-181b-5p, PIAS1 or PRMT1 expression constructs to identify their effects on liver function, serum inflammation, liver tissue oxidative stress, hepatocyte apoptosis and pathological changes of liver tissue in rats using a series of assays. miR-181b-5p, PIAS1 and PRMT1 levels were detected, and the targeting relationship between miR-181b-5p and PIAS1 was confirmed.

RESULTS

MiR-181b-5p and PRMT1 were elevated while PIAS1 was reduced in AFLD rat liver tissues, miR-181b-5p inhibition, PIAS1 overexpression or PRMT1 inhibition improved liver function, attenuated inflammation, oxidative stress, pathological changes and hepatocyte apoptosis in AFLD rat liver tissues. The impacts of miR-181b-5p inhibition on AFLD rats were reversed by PIAS1 silencing. PIAS1 was confirmed as a target gene of miR-181b-5p, and miR-181b-5p regulated PRMT1 expression through binding to PIAS1.

CONCLUSION

Inhibiting miR-181b-5p can promote the expression of PIAS1, thereby inhibiting PRMT1 and ultimately improving AFLD.

miR-135b-3p Promotes Cardiomyocyte Ferroptosis by Targeting GPX4 and Aggravates Myocardial Ischemia/Reperfusion Injury

Ferroptosis is a form of cell death induced by excess iron and accumulation of reactive oxygen species in cells. Recently, ferroptosis has been reported to be associated with cancer and ischemia/reperfusion (I/R) injury in multiple organs. However, the regulatory effects and underlying mechanisms of myocardial I/R injury are not well-understood. The role of miR-135b-3p as an oncogene that accelerates tumor development has been confirmed; however, its role in myocardial I/R is not fully understood. In this study, we established an in vivo myocardial I/R rat model and an in vitro hypoxia/reoxygenation (H/R)-induced H9C2 cardiomyocyte injury model and observed that ferroptosis occurred in tissues and cells during I/R myocardial injury. We used database analysis to find miR-135b-3p and validated its inhibitory effect on the ferroptosis-related gene glutathione peroxidase 4 (Gpx4), using a luciferase reporter assay. Furthermore, miR-135b-3p was found to promote the myocardial I/R injury by downregulating GPX4 expression. The results of this study elucidate a novel function of miR-135b-3p in exacerbating cardiomyocyte ferroptosis, providing a new therapeutic target for improving I/R injury.

SUMOylation as a Therapeutic Target for Myocardial Infarction

Myocardial infarction is a prevalent and life-threatening cardiovascular disease. The main goal of existing interventional therapies is to restore coronary reperfusion while few are designed to ameliorate the pathology of heart diseases via targeting the post-translational modifications of those critical proteins. Small ubiquitin-like modifier (SUMO) proteins are recently discovered to form a new type of protein post-translational modifications (PTM), known as SUMOylation. SUMOylation and deSUMOylation are dynamically balanced in the maintenance of various biological processes including cell division, DNA repair, epigenetic transcriptional regulation, and cellular metabolism. Importantly, SUMOylation plays a critical role in the regulation of cardiac functions and the pathology of cardiovascular diseases, especially in heart failure and myocardial infarction. This review summarizes the current understanding on the effects of SUMOylation and SUMOylated proteins in the pathophysiology of myocardial infarction and identifies the potential treatments against myocardial injury via targeting SUMO. Ultimately, this review recommends SUMOylation as a key therapeutic target for treating cardiovascular diseases.

The E3 Ligase PIAS1 Regulates p53 Sumoylation to Control Stress-Induced Apoptosis of Lens Epithelial Cells Through the Proapoptotic Regulator Bax

Protein sumoylation is one of the most important post-translational modifications regulating many biological processes (Flotho A & Melchior F. 2013. Ann Rev. Biochem. 82:357–85). Our previous studies have shown that sumoylation plays a fundamental role in regulating lens differentiation (Yan et al., 2010. PNAS, 107(49):21034-9.; Gong et al., 2014. PNAS. 111(15):5574–9). Whether sumoylation is implicated in lens pathogenesis remains elusive. Here, we present evidence to show that the protein inhibitor of activated STAT-1 (PIAS1), a E3 ligase for sumoylation, is implicated in regulating stress-induced lens pathogenesis. During oxidative stress-induced cataractogenesis, expression of PIAS1 is significantly altered at both mRNA and protein levels. Upregulation and overexpression of exogenous PIAS1 significantly enhances stress-induced apoptosis. In contrast, silence of PIAS1 with CRISPR/Cas9 technology attenuates stress-induced apoptosis. Mechanistically, different from other cells, PIAS1 has little effect to activate JNK but upregulates Bax, a major proapoptotic regulator. Moreover, Bax upregulation is derived from the enhanced transcription activity of the upstream transcription factor, p53. As revealed previously in other cells by different laboratories, our data also demonstrate that PIAS1 promotes SUMO1 conjugation of p53 at K386 residue in lens epithelial cells and thus enhances p53 transcription activity to promote Bax upregulation. Silence of Bax expression largely abrogates PIAS1-mediated enhancement of stress-induced apoptosis. Thus, our results demonstrated that PIAS1 promotes oxidative stress-induced apoptosis through positive control of p53, which specifically upregulates expression of the downstream proapoptotic regulator Bax. As a result, PIAS1-promoted apoptosis induced by oxidative stress is implicated in lens pathogenesis.

SENP1 modulates microglia-mediated neuroinflammation toward intermittent hypoxia-induced cognitive decline through the de-SUMOylation of NEMO

Intermittent hypoxia (IH)‐induced cognition decline is related to the neuroinflammation in microglia. SUMOylation is associated with multiple human diseases, which can be reversed by sentrin/SUMO‐specific proteases 1 (SENP1). Herein, we investigated the role of SENP1 in IH‐induced inflammation and cognition decline. BV‐2 microglial cells and mice were used for inflammatory response and cognition function evaluation following IH treatment. Biochemical analysis and Morris water maze methods were used to elaborate the mechanism of SENP1 in IH impairment. Molecular results revealed that IH induced the inflammatory response, as evidenced by the up‐regulation of NF‐κB activation, IL‐1β and TNF‐α in vitro and in vivo. Moreover, IH decreased the expression of SENP1, and increased the SUMOylation of NEMO, not NF‐κB P65. Moreover, SENP1 overexpression inhibited IH‐induced inflammatory response and SUMOylation of NEMO. However, the inhibitions were abolished by siRNA‐NEMO. In contrast, SENP1 depletion enhanced IH‐induced inflammatory response and SUMOylation of NEMO, accompanying with increased latency and reduced dwell time in mice. Overall, the results demonstrated that SENP1 regulated IH‐induced neuroinflammation by modulating the SUMOylation of NEMO, thus activating the NF‐κB pathway, revealing that targeting SENP1 in microglia may represent a novel therapeutic strategy for IH‐induced cognitive decline.

SUMOylation Connects Cell Stress Responses and Inflammatory Control: Lessons From the Gut as a Model Organ

Conjugation with the small ubiquitin-like modifier (SUMO) constitutes a key post-translational modification regulating the stability, activity, and subcellular localization of its target proteins. However, the vast numbers of identified SUMO substrates obscure a clear view on the function of SUMOylation in health and disease. This article presents a comprehensive review on the physiological relevance of SUMOylation by discussing how global SUMOylation levels—rather than specific protein SUMOylation—shapes the immune response. In particular, we highlight the growing body of work on SUMOylation in intestinal pathologies, because of the unique metabolic, infectious, and inflammatory challenges of this organ. Recent studies show that global SUMOylation can help restrain detrimental inflammation while maintaining immune defenses and tissue integrity. These results warrant further efforts to develop new therapeutic tools and strategies to control SUMOylation in infectious and inflammatory disorders.

Up-regulating microRNA-138-5p enhances the protective role of dexmedetomidine on myocardial ischemia-reperfusion injury mice via down-regulating Ltb4r1

Both microRNAs (miRs) and dexmedetomidine (Dex) have been verified to exert functional roles in myocardial ischemia-reperfusion injury (MI/RI). Given that, we concretely aim to discuss the effects of Dex and miR-138-5p on ventricular remodeling in mice affected by MI/RI via mediating leukotriene B4 receptor 1 (Ltb4r1). MI/RI mouse model was established by ligating left anterior descending coronary artery. The cardiac function, inflammatory factors and collagen fiber contents were detected after Dex/miR-138-5p/Ltb4r1 treatment. MiR-138-5p and Ltb4r1 expression in myocardial tissues were tested by RT-qPCR and western blot assay. The target relationship between miR-138-5p and Ltb4r1 was verified by online software prediction and luciferase activity assay. MiR-138-5p was down-regulated while Ltb4r1 was up-regulated in myocardial tissues of MI/RI mice. Dex improved cardiac function, alleviated myocardial damage, reduced inflammatory factor contents, collagen fibers, and Ltb4r1 expression while increased miR-138-5p expression in myocardial tissues of mice with MI/RI. Restored miR-138-5p and depleted Ltb4r1 improved cardiac function, abated inflammatory factor contents, myocardial damage, and content of collagen fibers in MI/RI mice. MiR-138-5p directly targeted Ltb4r1. The work evidence that Dex could ameliorate ventricular remodeling of MI/RI mice by up-regulating miR-138-3p and down-regulating Ltb4r1. Thus, Dex and miR-138-3p/Ltb4r1 may serve as potential targets for the ventricular remodeling of MI/RI.

Attenuation of the Na/K‑ATPase/Src/ROS amplification signaling pathway by astaxanthin ameliorates myocardial cell oxidative stress injury

The 3S, 3′S-ASTaxanthin (3S, 3′S-AST) isomer has strong antioxidant activity; however, its protective roles and potential mechanisms against oxidative stress damage in cardiomyocytes have not been investigated. Na⁺/K⁺-ATPase (NKA)/Src signal activation has an important role in increasing reactive oxygen species (ROS) production. The aim of the present study was to investigate the protective effects and mechanism of 3S, 3′S-AST on hydrogen peroxide (H₂O₂)-induced oxidative stress injury in H9c2 myocardial cells. The protective effects of 3S, 3′S-AST on H₂O₂-induced H9c2 cell injury was observed by measuring lactate dehydrogenase and creatine kinase myocardial band content, cell viability and nuclear morphology. The antioxidant effect was investigated by analyzing ROS accumulation and malondialdehyde, glutathione (GSH) peroxidase, GSH and glutathione reductase activity levels. The protein expression levels of Bax, Bcl-2, caspase-3 and cleaved caspase-3 were analyzed using western blotting to determine cardiomyocyte apoptosis. Western blot analysis of the phosphorylation levels of Src and Erk1/2 were also performed to elucidate the molecular mechanism involved. The results showed that 3S, 3′S-AST reduced the release of LDH and promoted cell viability, and attenuated ROS accumulation and cell apoptosis induced by H₂O₂. Furthermore, 3S, 3′S-AST also restored apoptosis-related Bax and Bcl-2 protein expression levels in H₂O₂-treated H9c2 cells. The phosphorylation levels of Src and Erk1/2 were significantly higher in the H₂O₂ treatment group, whereas 3S, 3′S-AST pretreatment significantly decreased the levels of phosphorylated (p)-Src and p-ERK1/2. The results provided evidence that 3S, 3′S-AST exhibited a cardioprotective effect against oxidative stress injury by attenuating NKA/Src/Erk1/2-modulated ROS amplification.

SUMO proteins in the cardiovascular system: friend or foe?

Post-translational modifications (PTMs) are crucial for the adaptation of various signalling pathways to ensure cellular homeostasis and proper adaptation to stress. PTM is a covalent addition of a small chemical functional group such as a phosphate group (phosphorylation), methyl group (methylation), or acetyl group (acetylation); lipids like hydrophobic isoprene polymers (isoprenylation); sugars such as a glycosyl group (glycosylation); or even small peptides such as ubiquitin (ubiquitination), SUMO (SUMOylation), NEDD8 (neddylation), etc. SUMO modification changes the function and/or fate of the protein especially under stress conditions, and the consequences of this conjugation can be appreciated from development to diverse disease processes. The impact of SUMOylation in disease has not been monotonous, rather SUMO is found playing a role on both sides of the coin either facilitating or impeding disease progression. Several recent studies have implicated SUMO proteins as key regulators in various cardiovascular disorders. The focus of this review is thus to summarize the current knowledge on the role of the SUMO family in the pathophysiology of cardiovascular diseases.

Gene therapy for cardiovascular diseases in China: basic research

Cardiovascular disease has become a major disease affecting health in the whole world. Gene therapy, delivering foreign normal genes into target cells to repair damages caused by defects and abnormal genes, shows broad prospects in treating different kinds of cardiovascular diseases. China has achieved great progress of basic gene therapy researches and pathogenesis of cardiovascular diseases in recent years. This review will summarize the latest research about gene therapy of proteins, epigenetics, including noncoding RNAs and genome-editing technology in myocardial infarction, cardiac ischemia-reperfusion injury, atherosclerosis, muscle atrophy, and so on in China. We wish to highlight some important findings about the essential roles of basic gene therapy in this field, which might be helpful for searching potential therapeutic targets for cardiovascular disease.

β-Sitosterol Protects against Myocardial Ischemia/Reperfusion Injury via Targeting PPARγ/NF-κB Signalling

Myocardial ischemia/reperfusion (I/R) injury is a clinically severe complication, which can cause high rates of disability and mortality particularly in patients with myocardial infarction, yet the molecular mechanisms underlying this process remain unclear. This study aimed to explore the protective effects of β-sitosterol against myocardial I/R injury and to elucidate the underlying molecular mechanisms. Our results showed that hypoxia/reoxygenation (H/R) treatment suppressed cell viability, induced cell apoptosis and reactive oxygen species production, increased caspase-3 and -9 activities, upregulated caspase-3 and -9 protein expressions, downregulated the Bcl-2 protein expression, and reduced the mitochondrial membrane potential. β-Sitosterol treatment attenuated H/R-induced cardiomyocyte injury. Moreover, β-sitosterol treatment counteracted the inhibitory effects of H/R treatment on the peroxisome proliferator-activated receptor gamma (PPARγ) expression and enhanced effects of H/R treatment on the NF-κB expression in cardiomyocytes. Furthermore, inhibition of PPARγ impaired the protective actions of β-sitosterol against H/R-induced cardiomyocyte injury. In the I/R rats, β-sitosterol treatment reduced the myocardial infarcted size and apoptosis, which was attenuated by the inhibition of PPARγ. In conclusion, our results demonstrate that β-sitosterol protected against in vitro H/R-induced cardiomyocyte injury and in vivo myocardial I/R injury. The β-sitosterol-mediated cardioprotective effects may involve the modulation of PPARγ/NF-κB signalling during myocardial I/R injury. Further studies are required to further explore the clinical application of β-sitosterol in the myocardial I/R injury.

Effect of miR-181a-5p targeting PIAS1 on cerulein-induced acute pancreatitis-induced acinar cell injury

BACKGROUND

Acute inflammation caused by acute pancreatitis (AP) is extremely harmful to people's health and can be life-threatening in severe cases. Its pathogenesis is complex and not fully understood. MiRNAs have been involved in the pathogenesis of AP. It was found that miR-181a-5p can inhibit cancer cell migration, invasion, and angiogenesis. MiR-181a-5p can also inhibit gastric cancer cell proliferation, invasion, metastasis, and epithelial mesenchymal transition. Inhibition of miR-181a-5p expression inhibits cell proliferation and invasion by negatively targeting INPP5A, and enhances apoptosis of cervical cancer cells. In addition, miR-181a inhibits the growth of pancreatic cancer cell lines, reduces their migration, and increases their apoptosis. However, the effect and mechanism of miR-181a-5p on the proliferation and apoptosis of AP are still unclear.

AIM

To investigate the effect of miR-181a-5p on acinar cell injury in AP and the potential mechanism involved.

METHODS

An AP model was constructed by treating rat pancreatic acinar AR42J and MPC-83 cells with 100 nmol/L caerulein. Different groups of cells were included: Con group (normal cells), caerulein group (treated with caerulein), miR-NC group (transfected with miR-NC), miR-181a-5p group (transfected with miR-181a-5p mimic), anti-miR-NC group (transfected with anti-miR-NC), anti-miR-181a-5p group (transfected with anti-miR-181a-5p), caerulein + anti-miR-NC group (caerulein treatment after transfection with anti-miR-NC), caerulein + anti-miR-181a-5p group (caerulein treatment after transfection with anti-miR-181a-5p), caerulein + pcDNA group (caerulein treatment after transfection with pcDNA), caerulein + pcDNA-PIAS1 group (caerulein treatment after transfection with pcDNA-PIAS1), caerulein + anti-miR-181a-5p + si-NC group (caerulein treatment after anti-miR-181a-5p and si-NC co-transfection), and caerulein + anti-miR-181a-5p + si-PIAS1 group (caerulein treatment after anti-miR-181a-5p and si-PIAS1 co-transfection). Cell transfections were performed by the liposome method. The expression of TNF-α and IL-6 in AR42J and MPC-83 cells treated with caerulein was detected by enzyme-linked immunosorbent assay. qRT-PCR was used to detect miR-181a-5p and PIAS1 mRNA in AR42J and MPC-83 cells treated with cerulein. Western blot was used to detect protein expression. Flow cytometry was used to detect apoptosis. Dual luciferase reporter gene assay was used to detect fluorescence activity.

RESULTS

After treatment of AR42J and MPC-83 cells with caerulein, the expression of TNF-α and IL-6 was significantly increased, the expression level of miR-181a-5p was significantly increased, and the expression of PIAS1 mRNA and protein was significantly decreased. Inhibition of miR-181a-5p expression and overexpression of PIAS1 inhibited the expression of TNF-α and IL-6 and inhibited cell apoptosis. MiR-181a-5p negatively regulated the expression of PIAS1, and inhibition of PIAS1 expression reversed the inhibitory effect of miR-181a-5p on apoptosis of AR42J and MPC-83 cells treated with caerulein.

CONCLUSION

Inhibition of miR-181a-5p expression inhibits caerulein-induced AP-induced acinar cell injury via mechanisms that may be related to the targeted regulation of PIAS1. Our findings may provide new targets and new ideas for the diagnosis and treatment of AP.