TRC8 downregulation contributes to the development of non-alcoholic steatohepatitis by exacerbating hepatic endoplasmic reticulum stress.

Endoplasmic reticulum (ER) stress is implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). TRC8 is an ER-resident E3 ligase with roles in modulating lipid and protein biosynthesis. In this study we showed that TRC8 expression was downregulated in steatotic livers of patients and mice fed with a high fat diet (HFD) or a methionine and choline deficient (MCD) diet. To investigate the impact of TRC8 downregulation on steatosis and the progression to non-alcoholic steatohepatitis (NASH), we placed TRC8 knockout (KO) mice and wild type (WT) controls on a HFD or MCD diet and the severities of steatosis and NASH developed were compared. We found that TRC8 deficiency did not significantly affect diet-induced steatosis. Nevertheless, MCD diet-induced NASH as characterized by hepatocyte death, inflammation and fibrosis were exacerbated in TRC8-KO mice. The hepatic ER stress response, as evidenced by increased eIF2α phosphorylation and expression of ATF4 and CHOP, and the level of activated caspase 3, an apoptosis indicator, were augmented by TRC8 deficiency. The hepatic ER stress and NASH induced in mice could be ameliorated by adenovirus-mediated hepatic TRC8 overexpression. Mechanistically, we found that TRC8 deficiency augmented lipotoxic-stress-induced unfolded protein response in hepatocytes by attenuating the arrest of protein translation and the misfolded protein degradation. These findings disclose a crucial role of TRC8 in the maintenance of ER protein homeostasis and its downregulation in steatotic liver contributes to the progression of NAFLD.

Activator protein-2α mediates carbon monoxide-induced stromal cell-derived factor-1α expression and vascularization in ischemic heart.

OBJECTIVE: Increased cardiac stromal cell-derived factor-1α (SDF-1α) expression promotes neovascularization and myocardial repair after ischemic injury through recruiting stem cells and reducing cardiomyocyte death. Previous studies have shown that heme oxygenase-1 and its reaction byproduct, carbon monoxide (CO), induce SDF-1α expression in ischemic heart. However, the mechanism underlying heme oxygenase-1/CO-induced cardiac SDF-1α expression remains elusive. This study aims to investigate the signaling pathway and the transcriptional factor that mediate CO-induced SDF-1α gene expression and cardioprotection. APPROACH AND RESULTS: CO gas and a CO-releasing compound, tricarbonyldichlororuthenium (II) dimer, dose-dependently induced SDF-1α expression in primary neonatal cardiomyocytes and H9C2 cardiomyoblasts. Promoter luciferase-reporter assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation demonstrated that the activator protein 2α (AP-2α) mediated tricarbonyldichlororuthenium (II) dimer-induced SDF-1α gene transcription. Tricarbonyldichlororuthenium (II) dimer induced AP-2α expression via protein kinase B (AKT)-dependent signaling. AKT inhibition or AP-2α knockdown reduced tricarbonyldichlororuthenium (II) dimer-induced SDF-1α expression. Coronary ligation induced transient increases of cardiac AP-2α and SDF-1α expression, which were declined at 1 week postinfarction in mice. Periodic exposure of coronary-ligated mice to CO (250 ppm for 1 hour/day, 6 days) resumed the induction of AP-2α and SDF-1α gene expression in infarcted hearts. Immunohistochemistry and echocardiography performed at 4 weeks after coronary ligation revealed that CO treatment enhanced neovascularization in the myocardium of peri-infarct region and improved cardiac function. CO-mediated SDF-1α expression and cardioprotection was ablated by intramyocardial injection of lentivirus bearing specific short hairpin RNA targeting AP-2α. CONCLUSIONS: Our data demonstrate that AKT-dependent upregulation of AP-2α is essential for CO-induced SDF-1α expression and myocardial repair after ischemic injury.

Cognitive-exercise dual-task intervention ameliorates cognitive decline in natural aging rats through reducing oxidative stress and enhancing synaptic plasticity.

The incidence of aging-related cognitive decline is increasing with population aging. It is urgent to explore ways to ameliorate aging-related cognitive decline. Cognitive-exercise dual-task intervention has shown beneficial effects on improving cognition in aging cohorts, but the mechanisms of the effects remain unclear. In this study, 18-month-old Sprague Dawley rats served as a model of natural aging. First, the performance in the Morris water maze test and the change in synaptophysin content in the hippocampus were used to investigate the cognitive decline of 18-month-old rats. Then, a batch of 18-month-old rats was treated with cognitive, exercise, or cognitive-exercise dual-task intervention for 12 weeks. The novel object recognition test was used to assess cognitive ability. Enzyme-linked immunosorbent assay and Western blotting were used to detect the levels of oxidative stress molecules and synaptic plasticity-related proteins. We found that cognitive-exercise dual-task intervention improved the discrimination index of natural aging rats. After dual-task intervention, the expression levels of synaptophysin, brain-derived neurotrophic factor, superoxide dismutase, and glutathione peroxidase were increased, and the expression level of lipid peroxide malondialdehyde was decreased. Furthermore, the effect of dual-task intervention on synaptic plasticity-related proteins and oxidative stress indicators was greater than that of single cognitive or exercise intervention. In conclusion, cognitive-exercise dual-task intervention can significantly ameliorate aging-related cognitive decline, and the improvement might be related to the reduction of oxidative stress and the enhancement of synaptic plasticity. The effect of cognitive-exercise dual-task intervention may be better than that of single cognitive or exercise intervention.

Increased activation of the caudate nucleus and parahippocampal gyrus in Parkinson's disease patients with dysphagia after repetitive transcranial magnetic stimulation: a case-control study.

Repetitive transcranial magnetic stimulation (rTMS) has been shown to effectively improve impaired swallowing in Parkinson's disease (PD) patients with dysphagia. However, little is known about how rTMS affects the corresponding brain regions in this patient group. In this case-control study, we examined data from 38 PD patients with dysphagia who received treatment at Beijing Rehabilitation Medicine Academy, Capital Medical University. The patients received high-frequency rTMS of the motor cortex once per day for 10 successive days. Changes in brain activation were compared via functional magnetic resonance imaging in PD patients with dysphagia and healthy controls. The results revealed that before treatment, PD patients with dysphagia showed greater activation in the precentral gyrus, supplementary motor area, and cerebellum compared with healthy controls, and this enhanced activation was weakened after treatment. Furthermore, before treatment, PD patients with dysphagia exhibited decreased activation in the parahippocampal gyrus, caudate nucleus, and left thalamus compared with healthy controls, and this activation increased after treatment. In addition, PD patients with dysphagia reported improved subjective swallowing sensations after rTMS. These findings suggest that swallowing function in PD patients with dysphagia improved after rTMS of the motor cortex. This may have been due to enhanced activation of the caudate nucleus and parahippocampal gyrus. The study protocol was approved by the Ethics Committee of Beijing Rehabilitation Hospital of Capital Medical University (approval No. 2018bkky017) on March 6, 2018 and was registered with Chinese Clinical Trial Registry (registration No. ChiCTR 1800017207) on July 18, 2018.

Areca nut procyanidins ameliorate streptozocin-induced hyperglycemia by regulating gluconeogenesis.

Hepatic gluconeogenesis is a major contributor to blood glucose in diabetes mellitus. Our previous study indicated that areca nut extract enriched with catechin-based procyanidins from oligomers to polymers gave rise to anti-inflammatory effects in vitro and in vivo. Here we have surveyed the molecular features of areca nut procyanidins (ANPs) using quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS) and the resulting mass spectrum accurately described ANP from monomer to hexadecamer. Furthermore, the potential of ANP in terms of blood glucose homeostasis was explored using cyclic adenosine monophosphate (cAMP)/dexamethasone stimulated primary mouse hepatocytes and multiple low dose streptozocin (MLD-STZ) treated mice. With the primary hepatocytes, ANP dose-dependently inhibited gluconeogenesis and reduced the mRNA expression of two gluconeogenic key enzymes, phosphoenol-pyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). Intragastrically feeding of 10mg/kg ANP for 4weeks reduced the levels of fasting blood glucose, PEPCK and G6Pase in MLD-STZ mice. In additional, the level of 5'-AMP-activated protein kinase (AMPK) expression showed a trend towards being restored in the ANP treated MLD-STZ-mice. This study indicated that ANP has the potential to improve hyperglycemia by regulating gluconeogenic related kinases in MLD-STZ-mice.

Effects of Areca catechu L. containing procyanidins on cyclooxygenase-2 expression in vitro and in vivo.

Polyphenols are widely distributed in plants and known for antioxidant and anti-inflammatory properties. Areca nut, rich in polyphenols, is the major component of betel quid and we have previously shown that the extract of areca nut can induce oxidative stress in vitro. In this study, we have further pinpointed that areca nut extract (ANE) contains catechin based procyanidins which range from dimers to decamers and polymers; this was carried out by HPLC and electrospray ionization/mass spectrometry (ESI/MS). To quantify their antioxidant potential, oligomeric and polymeric procyanidins of ANE were separated and evaluated using the Trolox equivalent antioxidant capacity (TEAC) assay. The results clearly demonstrated that the antioxidant capacity of the ANE procyanidins increased with the degree of polymerization. The anti-inflammatory potential of ANE was also tested using 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated human oral cancer SAS cells. ANE inhibited TPA-induced cyclooxygenase-2 (COX-2) protein expression at low doses, which correlated with the inhibition of ERK phosphorylation in the SAS cells. Furthermore, feeding rats with ANE at 1 and 10mg/kg/day for 5days significantly repressed carrageenan-induced inflammatory exudates and PGE(2) formation. In conclusion, ANE, which contains catechins based oligomeric and polymeric procyanidins, regulates COX-2 expression in vitro and possess anti-inflammatory potential in vivo.

Highly oligomeric procyanidins from areca nut induce lymphocyte apoptosis via the depletion of intracellular thiols.

Procyanidins are plant-derived polyphenolic compounds possessing a variety of biological activities, such as immunomodulation, and induction of tumor cell apoptosis. We previously reported that total extract of areca nut exhibited a suppressive effect on the metabolic activity and cytokine expression in normal splenic lymphocytes. As areca nut contains a rich amount of polyphenols, the objective of the present study was to investigate the pro-apoptotic effect of polyphenol-enriched areca nut extract (PANE) and its fractionated oligomeric procyanidins in splenic lymphocytes. Our data showed that PANE markedly induced lymphocyte apoptosis in a concentration- and time-dependent manner. Notably, the fractionated oligomeric procyanidins from pentamers to decamers were active in inducing the apoptosis, whereas monomers to tetramers were inactive. In addition, a marked diminishment in the level of intracellular thiols was revealed in lymphocytes treated with pentamers to decamers. Pretreatment with N-acetyl-L-cysteine, a precursor of glutathione, resulted in significant attenuation of both apoptosis and thiol diminishment induced by areca procyanidins. Taken together, our results indicated that highly oligomeric procyanidins derived from areca nut exhibited a chain length-dependent pro-apoptotic effect in primary lymphocytes, which is mediated, at least in part, by the diminishment of intracellular thiols.