PHLDA3 inhibition attenuates endoplasmic reticulum stress-induced apoptosis in myocardial hypoxia/reoxygenation injury by activating the PI3K/AKT signaling pathway

The role of PI3K/AKT signaling pathway in myocardial ischemia-reperfusion injury

Myocardial ischemia has a high incidence and mortality rate, and reperfusion is currently the standard intervention. However, reperfusion may lead to further myocardial damage, known as myocardial ischemia/reperfusion injury (MIRI). There are currently no effective clinical treatments for MIRI. The PI3K/Akt signaling pathway is involved in cardiovascular health and disease and plays an important role in reducing myocardial infarct size and restoring cardiac function after MIRI. Activation of the PI3K/Akt pathway provides myocardial protection through synergistic upregulation of antioxidant, anti-inflammatory, and autophagy activities and inhibition of mitochondrial dysfunction and cardiomyocyte apoptosis. Many studies have shown that PI3K/Akt has a significant protective effect against MIRI. Here, we reviewed the molecular regulation of PI3K/Akt in MIRI and summarized the molecular mechanism by which PI3K/Akt affects MIRI, the effects of ischemic preconditioning and ischemic postconditioning, and the role of related drugs or activators targeting PI3K/Akt in MIRI, providing novel insights for the formulation of myocardial protection strategies. This review provides evidence of the role of PI3K/Akt activation in MIRI and supports its use as a therapeutic target.

Ginsenoside Rk1 inhibits HeLa cell proliferation through an endoplasmic reticulum signaling pathway

Background

Changes to work-life balance has increased the incidence of cervical cancer among younger people. A minor ginseng saponin known as ginsenoside Rk1 can inhibit the growth and survival of human cancer cells; however, whether ginsenoside Rk1 inhibits HeLa cell proliferation is unknown.

Methods and results

Ginsenoside Rk1 blocked HeLa cells in the G0/G1 phase in a dose-dependent manner and inhibited cell division and proliferation. Ginsenoside Rk1 markedly also activated the apoptotic signaling pathway via caspase 3, PARP, and caspase 6. In addition, ginsenoside Rk1 increased LC3B protein expression, indicating the promotion of the autophagy signaling pathway. Protein processing in the endoplasmic reticulum signaling pathway was downregulated in Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, consistent with teal-time quantitative PCR and western blotting that showed YOD1, HSPA4L, DNAJC3, and HSP90AA1 expression levels were dramatically decreased in HeLa cells treated with ginsenoside Rk1, with YOD1 was the most significantly inhibited by ginsenoside Rk1 treatment.

Conclusion

These findings indicate that the toxicity of ginsenoside Rk1 in HeLa cells can be explained by the inhibition of protein synthesis in the endoplasmic reticulum and enhanced apoptosis, with YOD1 acting as a potential target for cervical cancer treatment.

Paeoniflorin Protects H9c2 Cardiomyocytes against Hypoxia/Reoxygenation Induced Injury via Regulating the AMPK/Nrf2 Signaling Pathway

Myocardial ischemia/reperfusion (MIR) injury contributes to the exacerbation of heart disease by causing cardiac arrhythmias, myocardial infarction, and even sudden death. Studies have found that paeoniflorin (PF) has a protective effect on coronary artery disease (CAD). However, the mechanism of PF in MIR has not been fully investigated. The purpose of this study was to investigate the functional role of PF in H9c2 cells subjected to hypoxia/reoxygenation (H/R). Here, PF treatment enhanced cell viability in H/R-stimulated H9c2 cells. In H9c2 cells, PF treatment reduced the formation of reactive oxygen species (ROS) induced by H/R. In H/R-stimulated H9c2 cells, PF also increased the activity of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase. Furthermore, PF protected H9c2 cells against H/R-induced apoptosis, as demonstrated by increased Bcl-2 expression, decreased Bax expression, and decreased caspase-3 activity. Furthermore, PF increased the levels of p-AMPK and nuclear Nrf2 expression in response to H/R stimulation. AMPK inhibition, on the other hand, abolished the PF-mediated increase in Nrf2 signaling and the cardiac-protective effect in H9c2 cells exposed to H/R. These data suggest that PF protected H9c2 cells against H/R-induced oxidative stress and apoptosis through modulating the AMPK/Nrf2 signaling pathway. Our findings support the therapeutic potential of PF in myocardial I/R damage.

PHLDA3 inhibition protects against myocardial ischemia/reperfusion injury by alleviating oxidative stress and inflammatory response via the Akt/Nrf2 axis

Pleckstrin homology-like domain family A, member 3 (PHLDA3) has a particularly critical role in regulating cell survival under stress conditions. However, whether PHLDA3 plays a role in myocardial ischemia/reperfusion injury has not been studied. We aimed to assess the possible role of PHLDA3 in myocardial ischemia/reperfusion (I/R) injury. PHLDA3 expression was increased in myocardial tissue from rats with myocardial I/R injury and rat cardiomyocytes with hypoxia/reoxygenation (H/R) injury. PHLDA3 knockdown protected against myocardial I/R injury in vivo and H/R injury in vitro. Inhibition of PHLDA3 increased the activation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) associated with regulation of the Akt/glycogen synthase kinase-3β (GSK-3β) axis. Repression of Nrf2 reversed PHLDA3-inhibition-mediated cardioprotective effects. Taken together, our work demonstrates that PHLDA3 inhibition exerts a protective role in myocardial I/R injury via regulation of the Akt/GSK-3β/Nrf2 axis. We suggest PHLDA3 as an attractive target for developing treatments against myocardial I/R injury.