Propofol is a widely used intravenous anesthetic agent with antioxidant properties secondary to its phenol based chemical structure. Treatment with propofol has been found to attenuate oxidative stress and prevent ischemia/reperfusion injury in rat heart. Here, we report that propofol protects cardiac H9c2 cells from hydrogen peroxide (H 2 O 2 )-induced injury by triggering the activation of Akt and a parallel up-regulation of Bcl-2. We show that pretreatment with propofol significantly protects against H 2 O 2 -induced injury. We further demonstrate that propofol activates the PI3K-Akt signaling pathway. The protective effect of propofol on H 2 O 2 -induced injury is reversed by PI3K inhibitor wortmannin, which effectively suppresses propofol-induced activation of Akt, upregulation of Bcl-2, and protection from apoptosis. Collectively, our results reveal a new mechanism by which propofol inhibits H 2 O 2 -induced injury in cardiac H9c2 cells, supporting a potential application of propofol as a preemptive cardioprotectant in clinical settings such as that during coronary bypass surgery.

Coxsackievirus B3 (CVB3) is a small RNA virus associated with diseases such as myocarditis, meningitis, and pancreatitis. We have previously demonstrated that proteasome inhibition reduces CVB3 replication and attenuates virus-induced myocarditis. However, the underlying mechanisms by which the ubiquitin/proteasome system regulates CVB replication remain unclear. In this study, we investigated the role of REG␥, a member of the 11S proteasome activator, in CVB3 replication. We showed that overexpression of REG␥ promoted CVB3 replication but that knockdown of REG␥ led to reduced CVB3 replication. We further demonstrated that REG␥-mediated p53 proteolysis contributes, as least in part, to the proviral function of REG␥. Although total protein levels of REG␥ remained unaltered after CVB3 infection, virus infection induced a redistribution of REG␥ from the nucleus to the cytoplasm, rendering an opportunity for a direct interaction of REG␥ with viral proteins and/or host proteins (e.g., p53), which controls viral growth and thereby enhances viral infectivity. Further analyses suggested a potential modification of REG␥ by SUMO following CVB3 infection, which was verified by both in vitro and in vivo sumoylation assays. Sumoylation of REG␥ may play a role in its nuclear export during CVB3 infection. Taken together, our results present the first evidence that the host REG␥ pathway is utilized and modified during CVB3 infection to promote efficient viral replication.Viruses often adapt to the existing host cellular machinery to complete their own life cycle. The ubiquitin/proteasome system (UPS), a primary intracellular protein degradation system in eukaryotic cells, has emerged as a key modulator in viral infectivity and virus-mediated pathogenesis (6).Coxsackievirus B3 (CVB3) is a small RNA virus associated with diseases such as myocarditis, meningitis, and pancreatitis (36). We have previously studied the function and regulation of the UPS in CVB3 infection and CVB3-induced myocarditis (7,16,17,33). We demonstrated that CVB3 utilizes and manipulates the host UPS to achieve successful replication (17, 33). We provided evidence that proteasome inhibition reduces CVB3 replication and attenuates virus-induced myocarditis (7). However, we recognize the potential toxicity of general inhibition of proteasome function as a therapeutic means. Further investigation to identify specific targets within the UPS utilized during CVB3 infection is urgently needed and will allow for more-precise targeting in drug therapy.The 20S proteasome is a multisubunit protease complex responsible for the degradation of misfolded proteins or shortlived regulatory proteins (16,18). In the absence of proteasome activators, the 20S proteasome is latent and the protein substrates are barred from entering the 20S proteasome (16,18). There are at least two families of proteasome activators, the 19S proteasome (also known as PA700) and the 11S proteasome (also known as REG or PA28) (16, 18). The 19S activator binds to proteasome to form the 26S proteasome...

SummaryObjective-Patients with diabetes experience increased cardiovascular complications after cardiac surgery. Hyperglycaemia predicts increased mortality after myocardial infarction and may influence cardiovascular risk in humans. Impaired prosurvival phosphatase and tensin homologue on chromosome 10 (PTEN)-Akt signaling could be an important feature of the diabetic heart rendering it resistant to preconditioning. This study was designed to evaluate for differences and relationships of myocardial PTEN-Akt-related signaling and baseline glycaemic control marker in type 2 diabetic and non-diabetic patients undergoing coronary artery bypass surgery.Methods-Right atrial biopsies and coronary sinus blood were obtained from 18 type 2 diabetic and 18 non-diabetic patients intraoperatively. Expression and phosphorylation of Akt, eNOS, Bcl-2 and PTEN were evaluated by western blot. Plasma 15-F 2t -isoprostane concentrations were evaluated by liquid chromatography-mass spectrometry.Results-PTEN expression and 15-F 2t -isoprostane concentrations were significantly higher in diabetic patients. Increased fasting blood glucose levels correlated with increased coronary sinus plasma 15-F2t-isoprostane concentrations. Increased cardiac 15-F 2t -isoprostane generation was highly correlated with myocardial PTEN expression. Bcl-2 expression and eNOS phosphorylation were significantly lower in diabetic compared to non-diabetic patients. Akt phosphorylation tended to be lower in diabetic patients, however this tendency failed to reach statistical significance. CIHR Author Manuscript CIHR Author Manuscript CIHR Author ManuscriptConclusion-The current results suggest that prosurvival PTEN-Akt signaling is impaired in the diseased diabetic myocardium. Hyperglycaemia and increased oxidative stress may contribute to this phenomenon. These findings strengthen the understanding of the underlying biologic mechanisms of cardiac injury in diabetic patients, which could facilitate development of new treatments to prevent cardiovascular complications in this high-risk population.

We previously demonstrated that propofol, an intravenous anesthetic with anti-oxidative properties, activated the phosphoinositide 3-kinase (PI3K)/AKT pathway to increase the expression of B cell lymphoma (Bcl)-2 and, therefore the anti-apoptotic potential on cardiomyocytes. Here, we wanted to determine if propofol can also activate the Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 3 pathway, another branch of cardioprotective signaling. The cellular response of nuclear factor kappa B (NFκB) and STAT3 was also evaluated. Cardiac H9c2 cells were treated by propofol alone or in combination with pretreatment by inhibitors for JAK2/STAT3 or PI3K/AKT pathway. STAT3 and AKT phosphorylation, and STAT3 translocation were measured by western blotting and immunofluorescence staining, respectively. Propofol treatment significantly increased STAT3 phosphorylation at both tyrosine 705 and serine 727 residues. Sustained early phosphorylation of STAT3 was observed with 25~75 μM propofol at 10 and 30 min. Nuclear translocation of STAT3 was seen at 4 h after treatment with 50 μM propofol. In cultured H9c2 cells, we further demonstrated that propofol-induced STAT3 phosphorylation was reduced by pretreatment with PI3K/AKT pathway inhibitors wortmannin or API-2. Conversely, pretreatment with JAK2/STAT3 pathway inhibitor AG490 or stattic inhibited propofol-induced AKT phosphorylation. In addition, propofol induced NFκB p65 subunit perinuclear translocation. Inhibition or knockdown of STAT3 was associated with increased levels of the NFκB p65 subunit. Our results suggest that propofol induces an adaptive response by dual activation and crosstalk of cytoprotective PI3K/AKT and JAK2/STAT3 pathways. Rationale to apply propofol clinically as a preemptive cardioprotectant during cardiac surgery is supported by our findings.