Melatonin attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism.

Myocardial dysfunction is an important manifestation of sepsis. Previous studies suggest that melatonin is protective against sepsis. In addition, activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been reported to be beneficial in sepsis. However, the role of PI3K/Akt signaling in the protective effect of melatonin against sepsis-induced myocardial dysfunction remains unclear. Here, LY294002, a PI3K inhibitor, was used to investigate the role of PI3K/Akt signaling in mediating the effects of melatonin on sepsis-induced myocardial injury. Cecal ligation and puncture (CLP) surgery was used to establish a rat model of sepsis. Melatonin was administrated to rats intraperitoneally (30 mg/kg). The survival rate, measures of myocardial injury and cardiac performance, serum lactate dehydrogenase level, inflammatory cytokine levels, oxidative stress level, and the extent of myocardial apoptosis were assessed. The results suggest that melatonin administration after CLP surgery improved survival rates and cardiac function, attenuated myocardial injury and apoptosis, and decreased the serum lactate dehydrogenase level. Melatonin decreased the production of the inflammatory cytokines TNF-α, IL-1ß, and HMGB1, increased anti-oxidant enzyme activity, and decreased the expression of markers of oxidative damage. Levels of phosphorylated Akt (p-Akt), unphosphorylated Akt (Akt), Bcl-2, and Bax were measured by Western blot. Melatonin increased p-Akt levels, which suggests Akt pathway activation. Melatonin induced higher Bcl-2 expression and lower Bax expression, suggesting inhibition of apoptosis. All protective effects of melatonin were abolished by LY294002, the PI3K inhibitor. In conclusion, our results demonstrate that melatonin mitigates myocardial injury in sepsis via PI3K/Akt signaling activation.

Adenosine Downregulates the Activities of Glutamatergic Neurons in the Paraventricular Hypothalamic Nucleus Required for Sleep.

Adenosine is an endogenous substance that regulates sleep homeostasis. It plays an important role in sleep induction under physiological condition. So far, the neural mechanisms underlying sleep-promoting effects of adenosine are not completely clear. Recent studies have shown that glutamatergic neurons in the paraventricular hypothalamic nucleus (PVH) play an important role in wakefulness. Using whole-cell patch-clamp, we found that adenosine can inhibit glutamatergic neurons in PVH. This inhibition is mainly achieved by activating adenosine type 1 receptors, thereby reducing hyperpolarization-activated cyclic nucleotide-gated cation channels. By recording electroencephalogram (EEG) and electromyography (EMG), it was found that local administration of adenosine type 1 receptor blocker in PVH could significantly reduce the NREM sleep. On the contrary, if adenosine was given, it could increase the NREM sleep. These results suggest that adenosine can promote sleep by reducing the excitability of PVH neurons. This findings reveal a novel mechanism of adenosine regulating sleep homeostasis.

MicroRNA-103a-3p Promotes Cell Proliferation and Invasion in Non-Small-Cell Lung Cancer Cells through Akt Pathway by Targeting PTEN.

BACKGROUND: Increasing evidence has suggested that microRNA- (miR-) 103a-3p is crucial for cancer progression. However, the specific mechanism of miR-103a-3p in non-small-cell lung cancer (NSCLC) remains unclear until now. So, it is particularly urgent to clarify the mechanism between them. METHODS: qRT-PCR and western blot were used to measure the expression of miR-103a-3p, PTEN, Akt, and p-Akt. Cell biology experiment was applied to detect the biological function of miR-103a-3p in NSCLC cell lines. Moreover, bioinformatics analysis, luciferase reporter assay, and functional complementation analysis were carried out to investigate the target gene. RESULTS: miR-103a-3p was highly expressed in primary NSCLC samples and cell lines. miR-103a-3p mimics promoted the proliferation and invasion of NSCLC cells; miR-103a-3p inhibitor had the opposite effect. A double luciferase reporter gene experiment revealed that miR-103a-3p directly targets the PTEN mRNA 3'UTR region. siPTEN inhibited the proliferation and invasion of NSCLC cells. Further mechanistic studies showed that both overexpression of miR-103a-3p and PTEN knockdown reduced the expression of the p-Akt protein. Overexpression of PTEN partially reversed the cancer-promoting effect of miR-103a-3p. CONCLUSION: miR-103a-3p promotes the progression of NSCLC via Akt signaling by targeting PTEN, highlighting the role of miR-103a-3p/PTEN/Akt signaling and suggesting miR-103a-3p as a novel therapeutic target for NSCLC.

Resveratrol alleviates sepsis­induced myocardial injury in rats by suppressing neutrophil accumulation, the induction of TNF­α and myocardial apoptosis via activation of Sirt1.

Sepsis is a severe inflammatory response to systemic infection that frequently affects the myocardium. Previous studies have suggested that resveratrol (RESV) is protective in sepsis. The present study aimed to investigate the role of sirtuin 1 (Sirt1) signaling in the protective effect of intraperitoneally administered RESV against sepsis­induced myocardial injury. Cecal ligation and puncture, or a sham operation, were performed in male Sprague­Dawley rats, and the levels of tumor necrosis factor (TNF)­α and myeloperoxidase (MPO) were assessed by ELISA and an MPO activity kit, respectively. The extent of myocardial apoptosis was assessed by TUNEL staining. The protein expression levels of Sirt1, acetylated (Ac)­Forkhead box O1 (FoxO1), B cell lymphoma 2 apoptosis regulator (Bcl­2) and Bcl­2 associated protein X apoptosis regulator (Bax) were detected by western blot analysis. RESV was demonstrated to attenuate myocardial apoptosis and decrease the production of TNF­α and MPO. Additionally, RESV upregulated the expression of Sirt1 and Bcl­2, and downregulated the expression of Ac­FoxO1 and Bax. The protective effects of RESV were abolished by EX527, a Sirt1 inhibitor. RESV has therefore been demonstrated to attenuate myocardial injury in sepsis by decreasing neutrophil accumulation, TNF­α expression, and myocardial apoptosis via activation of Sirt1 signaling. These results suggest a novel therapeutic strategy for the clinical treatment of sepsis.

Overexpression of Rcan1-1L inhibits hypoxia-induced cell apoptosis through induction of mitophagy.

Mitophagy, a cellular process that selectively targets dysfunctional mitochondria for degradation, is currently a hot topic in research into the pathogenesis and treatment of many human diseases. Considering that hypoxia causes mitochondrial dysfunction, which results in cell death, we speculated that selective activation of mitophagy might promote cell survival under hypoxic conditions. In the present study, we introduced the Regulator of calcineurin 1-1L (Rcan1-1L) to initiate the mitophagy pathway and aimed to evaluate the effect of Rcan1-1L-induced mitophagy on cell survival under hypoxic conditions. Recombinant adenovirus vectors carrying Rcan1-1L were transfected into human umbilical vein endothelial cells and human adult cardiac myocytes. Using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide MTT assay and Trypan blue exclusion assay, Rcan1-1L overexpression was found to markedly reverse cell growth inhibition induced by hypoxia. Additionally, Rcan1-1L overexpression inhibited cell apoptosis under hypoxic conditions, as detected by annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) apoptosis assay. Meanwhile, the mitochondria-mediated cell apoptotic pathway was inhibited by Rcan1-1L. In contrast, knockdown of Rcan1-1L accelerated hypoxia-induced cell apoptosis. Moreover, Rcan1-1L overexpression significantly reduced mitochondrial mass, decreased depolarized mitochondria, and downregulated ATP and reactive oxygen species production. We further delineated that the loss of mitochondrial mass was due to the activation of mitophagy induced by Rcan1-1L. Rcan1-1L overexpression activated autophagy flux and promoted translocation of the specific mitophagy receptor Parkin into mitochondria from the cytosol, whereas inhibition of autophagy flux resulted in the accumulation of Parkin-loaded mitochondria. Finally, we demonstrated that mitochondrial permeability transition pore opening was significantly increased by Rcan1-1L overexpression, which suggested that Rcan1-1L might evoke mitophagy through regulating mitochondrial permeability transition pores. Taken together, we provide evidence that Rcan1-1L overexpression induces mitophagy, which in turn contributes to cell survival under hypoxic conditions, revealing for the first time that Rcan1-1L-induced mitophagy may be used for cardioprotection.