Notch1 protects against myocardial ischaemia-reperfusion injury via regulating mitochondrial fusion and function.

Mitochondrial fusion and fission dynamic are critical to the myocardial protection against ischaemia-reperfusion injury. Notch1 signalling plays an important role in heart development, maturation and repair. However, the role of Notch1 in the myocardial mitochondrial fusion and fission dynamic remains elusive. Here, we isolated myocardial cells from rats and established myocardial ischaemia-reperfusion injury (IRI) model. We modulated Notch1, MFN1 and DRP1 expression levels in myocardial cells via infection with recombinant adenoviruses. The results showed that Notch1 improves the cell viability and mitochondrial fusion in myocardiocytes exposed to IRI. These improvements were dependent on the regulation of MFN1 and DRP1. On the mechanism, we found that MNF1 is transcriptionally activated by RBP-Jk in myocardiocytes. Notch1 also improves the mitochondrial membrane potential in myocardiocytes exposed to IRI. Moreover, we further confirmed the protection of the Notch1-MFN1/Drp1 axis on the post-ischaemic recovery of myocardial performance is associated with the preservation of the mitochondrial structure. In conclusion, this study presented a detailed mechanism by which Notch1 signalling improves mitochondrial fusion during myocardial protection.

Inhibition of the Notch1 pathway induces peripartum cardiomyopathy.

Increased expression and activity of cardiac and circulating cathepsin D and soluble fms-like tyrosine kinase-1 (sFlt-1) have been demonstrated to induce and promote peripartum cardiomyopathy (PPCM) via promoting cleavage of 23-kD prolactin (PRL) to 16-kD PRL and neutralizing vascular endothelial growth factor (VEGF), respectively. We hypothesized that activation of Hes1 is proposed to suppress cathepsin D via activating Stat3, leading to alleviated development of PPCM. In the present study, we aimed to investigate the role of Notch1/Hes1 pathway in PPCM. Pregnant mice between prenatal 3 days and postpartum 3 weeks were fed with LY-411575 (a notch inhibitor, 10 mg/kg/d). Ventricular function and pathology were evaluated by echocardiography and histological analysis. Western blotting analysis was used to examine the expression at the protein level. The results found that inhibition of Notch1 significantly promoted postpartum ventricular dilatation, myocardial hypertrophy and myocardial interstitial fibrosis and suppressed myocardial angiogenesis. Western blotting analysis showed that inhibition of Notch1 markedly increased cathepsin D and sFlt-1, reduced Hes1, phosphorylated Stat3 (p-Stat3), VEGFA and PDGFB, and promoted cleavage of 23k-D PRL to 16-kD PRL. Collectively, inhibition of Notch1/Hes1 pathway induced and promoted PPCM via increasing the expressions of cathepsin D and sFlt-1. Notch1/Hes1 was a promising target for prevention and therapeutic regimen of PPCM.

Notch1-Nrf2 signaling crosstalk provides myocardial protection by reducing ROS formation.

Both the Notch1 and Keap1-Nrf2 signaling pathways have cardioprotective effects, but the role of Notch1-Nrf2 crosstalk in myocardial ischemia-reperfusion injury is unclear. In this study, we established hypoxia-reoxygenation in neonate rat myocardial cells and employed γ-secretase inhibitor and curcumin to inhibit and activate the Notch1 and Keap1-Nrf2 signaling pathways, respectively. We found that the combined action of the Notch1 and Keap1-Nrf2 signaling pathways significantly increased cardiomyocyte viability, inhibited cardiomyocyte apoptosis, reduced the formation of reactive oxygen species, and increased antioxidant activities. In conclusion, these findings suggest that Notch1-Nrf2 crosstalk exerts myocardial protection by reducing the formation of reactive oxygen species.

NSD2 promotes ventricular remodelling mediated by the regulation of H3K36me2.

Histone lysine methylation plays an important role in the regulation of ventricular remodelling. NSD2 is involved in many types of tumours through enhancing H3K36me2 expression. However, the role of NSD2 in the regulation of histone lysine methylation during ventricular remodelling remains unclear. In this study, we established cardiac hypertrophy model in C57BL/6 mice by transverse aortic constriction and found that histone lysine methylation participated in ventricular remodelling regulation via the up-regulation of H3K27me2 and H3K36me2 expression. In addition, we constructed transgenic C57BL/6 mice with conditional knockout of NSD2 (NSD2-/- ) in the myocardium. NSD2-/- C57BL/6 mice had milder ventricular remodelling and significantly improved cardiac function compared with wild-type mice, and the expression of H3K36me2 but not H3K27me2 was down-regulated. In conclusion, NSD2 promotes ventricular remodelling mediated by the regulation of H3K36me2.

Notch signaling inhibits cardiac fibroblast to myofibroblast transformation by antagonizing TGF-ß1/Smad3 signaling.

PURPOSE: During myocardial infarction (MI), cardiac fibroblasts (CFs) transform into myofibroblast (CMT). This study aimed to investigate the crosstalk of Notch1 and transforming growth factor-ß1 (TGF-ß1)/Smad3 signaling in the regulation of CMT and myocardial fibrosis. METHODS: Primary CFs were isolated from young rats and treated with TGF-ß1 or adenovirus to overexpress or knockdown Notch1 intracellular domain (N1ICD) or Smad3. RESULTS: TGF-ß1 decreased the expression of fibroblast markers but increased the expression of myofibroblast markers in rat CFs. TGF-ß1 increased the proliferation, invasion, and adhesion, and the secretion of collagen I of CFs, and these effects were inhibited by N1ICD overexpression. Moreover, endogenous Smad3 phosphorylation in CFs was enhanced by N1ICD knockdown, whereas TGF-ß1 induced Smad3 phosphorylation was antagonized by the N1ICD overexpression. Conversely, endogenous N1ICD activation in CFs was antagonized by Smad3, whereas TGF-ß1 induced N1ICD inactivation was antagonized by Smad3 knockdown. Coimmunoprecipitation showed that N1ICD interacted with Smad3 and immunostaining revealed the colocalization of N1ICD and Smad3 in the nuclei of CFs. Moreover, we demonstrated the functional antagonism of N1ICD and Smad3 on the phenotypes of CFs. Finally, TGF-ß1/Smad3 signaling promoted whereas Notch signaling inhibited myocardial fibrosis in rat MI model. CONCLUSION: Notch signaling inhibits CMT by antagonizing TGF-ß1/Smad3 signaling. Notch signaling activators and TGF-ß1/Smad3 signaling inhibitors could be exploited for therapeutic intervention to inhibit myocardial fibrosis after MI.

Notch1 provides myocardial protection by improving mitochondrial quality control.

Mitochondrial quality control is a new target for myocardial protection. Notch signaling plays an important role in heart development, maturation, and repair. However, the role of Notch in the myocardial mitochondrial quality control remains elusive. In this study, we isolated myocardial cells from rats and established myocardial ischemia reperfusion injury (IRI) model. We modulated Notch1 expression level in myocardial cells via infection with recombinant adenoviruses Ad-N1ICD and Ad-shN1ICD. We found that IR reduced myocardial cells viability, but Notch1 overexpression increased the viability of myocardial cells exposed to IRI. In addition, Notch1 overexpression improved ATP production, increased mitochondrial fusion and decreased mitochondrial fission, and inhibited mitophagy in myocardial cells exposed to IRI. However, N1ICD knockdown led to opposite effects. The myocardial protection role of Notch1 was related to the inhibition of Pink1 expression and Mfn2 and Parkin phosphorylation. In conclusion, Notch1 exerts myocardial protection and this is correlated with the maintenance of mitochondrial quality control and the inhibition of Pink1/Mfn2/Parkin signaling.

NSD2 silencing alleviates pulmonary arterial hypertension by inhibiting trehalose metabolism and autophagy.

Nuclear receptor binding SET domain 2 (NSD2)-mediated metabolic reprogramming has been demonstrated to regulate oncogenesis via catalyzing the methylation of histones. The present study aimed to investigate the role of NSD2-mediated metabolic abnormality in pulmonary arterial hypertension (PAH). Monocrotaline (MCT)-induced PAH rat model was established and infected with adeno-associated virus carrying short hairpin RNA (shRNA) targeting NSD2. Hemodynamic parameters, ventricular function, and pathology were evaluated by microcatheter, echocardiography, and histological analysis. Metabolomics changes in lung tissue were analyzed by LC-MS. The results showed that silencing of NSD2 effectively ameliorated MCT-induced PAH and right ventricle dysfunction, and partially reversed pathological remodeling of pulmonary artery and right ventricular hypertrophy. In addition, the silencing of NSD2 markedly reduced the di-methylation level of H3K36 (H3K36me2 level) and inhibited autophagy in pulmonary artery. Non-targeted LC-MS based metabolomics analysis indicated that trehalose showed the most significant change in lung tissue. NSD2-regulated trehalose mainly affected ABC transporters, mineral absorption, protein digestion and absorption, metabolic pathways, and aminoacyl-tRNA biosynthesis. In conclusion, we reveal a new role of NSD2 in the pathogenesis of PAH related to the regulation of trehalose metabolism and autophagy via increasing the H3K36me2 level. NSD2 is a promising target for PAH therapy.

miR-21 promotes cardiac fibroblast-to-myofibroblast transformation and myocardial fibrosis by targeting Jagged1.

Myocardial fibrosis after myocardial infarction (MI) is a leading cause of heart diseases. MI activates cardiac fibroblasts (CFs) and promotes CF to myofibroblast transformation (CMT). This study aimed to investigate the role of miR-21 in the regulation of CMT and myocardial fibrosis. Primary rat CFs were isolated from young SD rats and treated with TGF-ß1, miR-21 sponge or Jagged1 siRNA. Cell proliferation, invasion and adhesion were detected. MI model was established in male SD rats using LAD ligation method and infected with recombinant adenovirus. The heart function and morphology was evaluated by ultrasonic and histological analysis. We found that TGF-ß1 induced the up-regulation of miR-21 and down-regulation of Jagged1 in rat CFs. Luciferase assay showed that miR-21 targeted 3'-UTR of Jagged1 in rat CFs. miR-21 sponge inhibited the transformation of rat CFs into myofibroblasts, and abolished the inhibition of Jagged1 mRNA and protein expression by TGF-ß1. Furthermore, these effects of miR-21 sponge on rat CFS were reversed by siRNA mediated knockdown of Jagged1. In vivo, heart dysfunction and myocardial fibrosis in MI model rats were partly improved by miR-21 sponge but were aggravated by Jagged1 knockdown. Taken together, these results suggest that miR-21 promotes cardiac fibroblast-to-myofibroblast transformation and myocardial fibrosis by targeting Jagged1. miR-21 and Jagged1 are potential therapeutic targets for myocardial fibrosis.

Notch signaling promotes angiogenesis and improves cardiac function after myocardial infarction.

Currently, the role of Notch signaling during myocardial infarction (MI) remains controversy. In this study we used in vitro and in vivo approaches to investigate the role of Notch signaling in MI. Using cultured human umbilical vein endothelial cells exposed to hypoxia/reoxygenation (H/R), we demonstrated that H/R inhibited the proliferation, VEGF secretion, and tube formation of HUVECs, and these effects were correlated with the inhibition of Notch signaling. Furthermore, these effects were antagonized by overexpression of NICD but aggravated by knockdown of NICD. In addition, in MI model rats we found that heart dysfunction and angiogenesis in model rats was partly improved by NICD overexpression but was aggravated by knockdown of NICD. In conclusion, these data demonstrate that Notch signaling is downregulated in H/R injury in the hearts. Artificial activation of Notch signaling could promote myocardial survival and angiogenesis and improve cardiac function following H/R injury.

[Roles of targeting Ras/Raf/MEK/ERK signaling pathways in the treatment of esophageal carcinoma].

Ras is best known for its ability to regulate cell growth, proliferation and differentiation. Mutations in Ras are associated with the abnormal cell proliferation which can result in incidence of all human cancers. Extracellular signal-regulated kinase (ERK) is a downstream effector of Ras and plays important roles in prognosis of tumors. Recently, evidence has gradually accumulated to demonstrate that there are other effectors between Ras and ERK, these proteins interact each other and constitute the thorough Ras/Raf/MEK/ERK signaling pathway. The pathway has profound effects on incidence of esophageal carcinoma and clinical applications of some chemotherapeutic drugs targeting the pathway. Further understanding of the relevant molecular mechanisms of Ras/Raf/MEK/ERK signaling pathway can be helpful for the development of efficient targeting therapeutic approaches which contribute to the treatment of esophageal cancer. In this article, roles of Ras/Raf/MEK/ERK signaling pathway in esophageal carcinoma as well as pharmacological targeting point in the pathway are reviewed.

Role of histone lactylation interference RNA m6A modification and immune microenvironment homeostasis in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a severe disease resulting from progressive increases in pulmonary vascular resistance and pulmonary vascular remodeling, ultimately leading to right ventricular failure and even death. Hypoxia, inflammation, immune reactions, and epigenetic modifications all play significant contributory roles in the mechanism of PAH. Increasingly, epigenetic changes and their modifying factors involved in reprogramming through regulation of methylation or the immune microenvironment have been identified. Among them, histone lactylation is a new post-translational modification (PTM), which provides a novel visual angle on the functional mechanism of lactate and provides a promising diagnosis and treatment method for PAH. This review detailed introduces the function of lactate as an important molecule in PAH, and the effects of lactylation on N6-methyladenosine (m6A) and immune cells. It provides a new perspective to further explore the development of lactate regulation of pulmonary hypertension through histone lactylation modification.

SEDT2/METTL14-mediated m6A methylation awakening contributes to hypoxia-induced pulmonary arterial hypertension in mice.

Pulmonary arterial hypertension (PAH) is a fatal disease whose molecular mechanism is unknown. The trimethylation of lysine 36 on histone 3 (H3K36me3) catalyzed by SETD2 and the modification of N6-methyladenine (m6A) mRNA mediated by METTL14 play important roles in a variety of normal and pathological biological processes. However, the role of these epigenetic controls in the pathogenesis of PAH remains unclear. In this study, the expression of SETD2 and METTL14 was elevated in pulmonary artery smooth muscle cells (PASMCs) of hypoxia-induced PAH mice. We further constructed a mouse model with SETD2 specific knockout in smooth muscle cells (SETD2SM22α Cre). Our results suggest that the lack of SETD2 in SMCs protected mice from hypoxia-induced PAH and significantly reduced right ventricular systolic pressure (RVSP), right ventricular/left ventricular plus septum [RV/(LV+S)] weight ratio, and pulmonary median width. In addition, the absence of SETD2 in SMCs alleviates the level of METTL14 expression and the m6A RNA methylation level in PAH SMCs. These results obtained from mice suggest that strategies that target the inhibition of SETD2/METTL14 activity may be a viable treatment for PAH in a clinical setting.

Plasma Lipidomics Identifies Unique Lipid Signatures and Potential Biomarkers for Patients With Aortic Dissection.

Aortic dissection (AD) is a catastrophic cardiovascular emergency with a poor prognosis, and little preceding symptoms. Abnormal lipid metabolism is closely related to the pathogenesis of AD. However, comprehensive lipid alterations related to AD pathogenesis remain unclear. Moreover, there is an urgent need for new or better biomarkers for improved risk assessment and surveillance of AD. Therefore, an untargeted lipidomic approach based on ultra-high-performance liquid chromatograph-mass spectrometry was employed to unveil plasma lipidomic alterations and potential biomarkers for AD patients in this study. We found that 278 of 439 identified lipid species were significantly altered in AD patients (n = 35) compared to normal controls (n = 32). Notably, most lipid species, including fatty acids, acylcarnitines, cholesteryl ester, ceramides, hexosylceramides, sphingomyelins, lysophosphatidylcholines, lysophosphatidylethanolamines, phosphatidylcholines, phosphatidylinositols, diacylglycerols, and triacylglycerols with total acyl chain carbon number ≥54 and/or total double bond number ≥4 were decreased, whereas phosphatidylethanolamines and triacylglycerols with total double bond number <4 accumulated in AD patients. Besides, the length and unsaturation of acyl chains in triacylglycerols and unsaturation of 1-acyl chain in phosphatidylethanolamines were decreased in AD patients. Moreover, lysophosphatidylcholines were the lipids with the largest alterations, at the center of correlation networks of lipid alterations, and had excellent performances in identifying AD patients. The area under the curve of 1.0 and accuracy rate of 100% could be easily obtained by lysophosphatidylcholine (20:0/0:0) or its combination with lysophosphatidylcholine (17:0/0:0) or lysophosphatidylcholine (20:1/0:0). This study provides novel and comprehensive plasma lipidomic signatures of AD patients, identifies lysophosphatidylcholines as excellent potential biomarkers, and would be beneficial to the pathogenetic study, risk assessment and timely diagnosis and treatment of AD.