SIRT1 is a regulator of autophagy: Implications for the progression and treatment of myocardial ischemia-reperfusion

Epigenetic regulation of diverse regulated cell death modalities in cardiovascular disease: Insights into necroptosis, pyroptosis, ferroptosis, and cuproptosis

Cell death constitutes a critical component of the pathophysiology of cardiovascular diseases. A growing array of non-apoptotic forms of regulated cell death (RCD)-such as necroptosis, ferroptosis, pyroptosis, and cuproptosis-has been identified and is intimately linked to various cardiovascular conditions. These forms of RCD are governed by genetically programmed mechanisms within the cell, with epigenetic modifications being a common and crucial regulatory method. Such modifications include DNA methylation, RNA methylation, histone methylation, histone acetylation, and non-coding RNAs. This review recaps the roles of DNA methylation, RNA methylation, histone modifications, and non-coding RNAs in cardiovascular diseases, as well as the mechanisms by which epigenetic modifications regulate key proteins involved in cell death. Furthermore, we systematically catalog the existing epigenetic pharmacological agents targeting novel forms of RCD and their mechanisms of action in cardiovascular diseases. This article aims to underscore the pivotal role of epigenetic modifications in precisely regulating specific pathways of novel RCD in cardiovascular diseases, thus offering potential new therapeutic avenues that may prove more effective and safer than traditional treatments.

Isoliquiritigenin attenuates myocardial ischemia reperfusion through autophagy activation mediated by AMPK/mTOR/ULK1 signaling

BACKGROUND

Ischemia reperfusion (IR) causes impaired myocardial function, and autophagy activation ameliorates myocardial IR injury. Isoliquiritigenin (ISO) has been found to protect myocardial tissues via AMPK, with exerting anti-tumor property through autophagy activation. This study aims to investigate ISO capacity to attenuate myocardial IR through autophagy activation mediated by AMPK/mTOR/ULK1 signaling.

METHODS

ISO effects were explored by SD rats and H9c2 cells. IR rats and IR-induced H9c2 cell models were established by ligating left anterior descending (LAD) coronary artery and hypoxia/re-oxygenation, respectively, followed by low, medium and high dosages of ISO intervention (Rats: 10, 20, and 40 mg/kg; H9c2 cells: 1, 10, and 100 μmol/L). Myocardial tissue injury in rats was assessed by myocardial function-related index, HE staining, Masson trichrome staining, TTC staining, and ELISA. Autophagy of H9c2 cells was detected by transmission electron microscopy (TEM) and immunofluorescence. Autophagy-related and AMPK/mTOR/ULK1 pathway-related protein expressions were detected with western blot.

RESULTS

ISO treatment caused myocardial function improvement, and inhibition of myocardial inflammatory infiltration, fibrosis, infarct area, oxidative stress, CK-MB, cTnI, and cTnT expression in IR rats. In IR-modeled H9c2 cells, ISO treatment lowered apoptosis rate and activated autophagy and LC3 fluorescence expression. In vivo and in vitro, ISO intervention exhibited enhanced Beclin1, LC3II/LC3I, and p-AMPK/AMPK levels, whereas inhibited P62, p-mTOR/mTOR and p-ULK1(S757)/ULK1 protein expression, activating autophagy and protecting myocardial tissues from IR injury.

CONCLUSION

ISO treatment may induce autophagy by regulating AMPK/mTOR/ULK1 signaling, thereby improving myocardial IR injury, as a potential candidate for treatment of myocardial IR injury.

The function and therapeutic potential of transfer RNA-derived small RNAs in cardiovascular diseases: A review

Transfer RNA-derived small RNAs (tsRNAs) are a class of small non-coding RNA (sncRNA) molecules derived from tRNA, including tRNA derived fragments (tRFs) and tRNA halfs (tiRNAs). tsRNAs can affect cell functions by participating in gene expression regulation, translation regulation, intercellular signal transduction, and immune response. They have been shown to play an important role in various human diseases, including cardiovascular diseases (CVDs). Targeted regulation of tsRNAs expression can affect the progression of CVDs. The tsRNAs induced by pathological conditions can be detected when released into the extracellular, giving them enormous potential as disease biomarkers. Here, we review the biogenesis, degradation process and related functional mechanisms of tsRNAs, and discuss the research progress and application prospects of tsRNAs in different CVDs, to provide a new perspective on the treatment of CVDs.

The role of quercetin in ameliorating bleomycin-induced pulmonary fibrosis: insights into autophagy and the SIRT1/AMPK signaling pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology characterized by a constant incidence rate. Unfortunately, effective pharmacological treatments for this condition are lacking and the identification of novel therapeutic approaches and underlying pathological mechanisms are required. This study investigated the potential of quercetin in alleviating pulmonary fibrosis by promoting autophagy and activation of the SIRT1/AMPK pathway.

METHODS

Mouse models of IPF were divided into four treatment groups: control, bleomycin (BLM), quercetin (Q), and quercetin + EX-527 (Q + E) treatment. Pulmonary fibrosis was induced in the mouse models through intratracheal instillation of BLM. Various indexes were identified through histological staining, Western blotting analysis, enzyme-linked immunosorbent assay, immunohistochemistry, and transmission electron microscopy.

RESULTS

Quercetin treatment ameliorated the pathology of BLM-induced pulmonary fibrosis of mice by reducing α-smooth muscle actin (α-SMA), collagen I (Col I), and collagen III (Col III) levels, and also improved the level of E-cadherin in lung tissue. Furthermore, Quercetin significantly enhanced LC3II/LC3I levels, decreased P62 expression, and increased the number of autophagosomes in lung tissue. These effects were accompanied by the activation of the SIRT1/AMPK pathway. Treatment with EX-527, an inhibitor for SIRT1, reversed all effects induced by quercetin.

CONCLUSION

This study showed that quercetin could alleviate pulmonary fibrosis and improve epithelial-mesenchymal transition by acting on the SIRT1/AMPK signaling pathway, which may be achieved by regulating the level of autophagy.

Caffeic acid phenethyl ester inhibits neuro-inflammation and oxidative stress following spinal cord injury by mitigating mitochondrial dysfunction via the SIRT1/PGC1α/DRP1 signaling pathway

BACKGROUND

The treatment of spinal cord injury (SCI) has always been a significant research focus of clinical neuroscience, with inhibition of microglia-mediated neuro-inflammation as well as oxidative stress key to successful SCI patient treatment. Caffeic acid phenethyl ester (CAPE), a compound extracted from propolis, has both anti-inflammatory and anti-oxidative effects, but its SCI therapeutic effects have rarely been reported.

METHODS

We constructed a mouse spinal cord contusion model and administered CAPE intraperitoneally for 7 consecutive days after injury, and methylprednisolone (MP) was used as a positive control. Hematoxylin-eosin, Nissl, and Luxol Fast Blue staining were used to assess the effect of CAPE on the structures of nervous tissue after SCI. Basso Mouse Scale scores and footprint analysis were used to explore the effect of CAPE on the recovery of motor function by SCI mice. Western blot analysis and immunofluorescence staining assessed levels of inflammatory mediators and oxidative stress-related proteins both in vivo and in vitro after CAPE treatment. Further, reactive oxygen species (ROS) within the cytoplasm were detected using an ROS kit. Changes in mitochondrial membrane potential after CAPE treatment were detected with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide. Mechanistically, western blot analysis and immunofluorescence staining were used to examine the effect of CAPE on the SIRT1/PGC1α/DRP1 signaling pathway.

RESULTS

CAPE-treated SCI mice showed less neuronal tissue loss, more neuronal survival, and reduced demyelination. Interestingly, SCI mice treated with CAPE showed better recovery of motor function. CAPE treatment reduced the expression of inflammatory and oxidative mediators, including iNOS, COX-2, TNF-α, IL-1β, 1L-6, NOX-2, and NOX-4, as well as the positive control MP both in vitro and in vivo. In addition, molecular docking experiments showed that CAPE had a high affinity for SIRT1, and that CAPE treatment significantly activated SIRT1 and PGC1α, with down-regulation of DRP1. Further, CAPE treatment significantly reduced the level of ROS in cellular cytoplasm and increased the mitochondrial membrane potential, which improved normal mitochondrial function. After administering the SIRT1 inhibitor nicotinamide, the effect of CAPE on neuro-inflammation and oxidative stress was reversed.On the contrary, SIRT1 agonist SRT2183 further enhanced the anti-inflammatory and antioxidant effects of CAPE, indicating that the anti-inflammatory and anti-oxidative stress effects of CAPE after SCI were dependent on SIRT1.

CONCLUSION

CAPE inhibits microglia-mediated neuro-inflammation and oxidative stress and supports mitochondrial function by regulating the SIRT1/PGC1α/DRP1 signaling pathway after SCI. These effects demonstrate that CAPE reduces nerve tissue damage. Therefore, CAPE is a potential drug for the treatment of SCI through production of anti-inflammatory and anti-oxidative stress effects.

Angiotensin-converting enzyme inhibitors provide a protective effect on hypoxia-induced injury in human coronary artery endothelial cells via Nrf2 signaling and PLVAP

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) were reported to protect from hypoxia-induced oxidative stress in coronary endothelial cells (CECs) after acute myocardial infarction (AMI). Nrf2 shows a protective effect in hypoxia-induced CECs after AMI. Plasmalemma vesicle-associated protein (PLVAP) plays a pivotal role in angiogenesis after AMI.

AIM

To explore the protective effect of ACEIs and the involved mechanisms under hypoxia challenge.

METHODS

Human coronary endothelial cells (HCAECs) were used to establish hypoxia-induced oxidative stress injury in vitro. Flow cytometry was used to evaluate the protective effect of ACEI on hypoxia conditions.ET-1, NO, ROS, and VEGF were detected by ELISA. HO-1, Nrf2, and Keap-1, the pivotal member in the Nrf2 signaling pathway, eNOS and PLVAP were detected in HEAECs treated with ACEI by immunofluorescence, qPCR, and western blotting.

RESULTS

The hypoxia ACEI or Nrf2 agonist groups showed higher cell viability compared with the hypoxia control group at 24 (61.75±1.16 or 61.23±0.59 vs. 44.24±0.58, both P < 0.05) and 48 h (41.85±1.19 or 59.64±1.13 vs. 22.98±0.25, both P < 0.05). ACEI decreased the levels of ET-1 and ROS under hypoxia challenge at 24 and 48 h (all P < 0.05); ACEI increased the VEGF and NO levels (all P < 0.05). ACEI promoted the expression level of eNOS, HO-1, Nrf2 and PLVAP but inhibited Keap-1 expression at the mRNA and protein levels (all P < 0.05). Blockade of the Nrf2 signaling pathway significantly decreased the expression level of PLVAP.

CONCLUSION

ACEI protects hypoxia-treated HEAECs by activating the Nrf2 signaling pathway and upregulating the expression of PLVAP.