The oxidative-stress-induced alteration in paracellular junctional complexes was analysed in Caco-2 cell monolayer. Oxidative stress induced a rapid increase in tyrosine phosphorylation of occludin, zonula occludens (ZO)-1, E-cadherin and beta-catenin. An oxidative-stress-induced decrease in transepithelial electrical resistance was associated with a redistribution of occludin-ZO-1 and E-cadherin-beta-catenin complexes from the intercellular junctions. Genistein, a tyrosine kinase inhibitor, prevented the oxidative-stress-induced decrease in resistance and redistribution of protein complexes. Occludin, ZO-1, E-cadherin and beta-catenin in the Triton-insoluble cytoskeletal fraction were reduced by oxidative stress, which was prevented by genistein. Oxidative stress also reduced the co-immunoprecipitation of ZO-1 with occludin, which was prevented by genistein. Co-immunoprecipitation of beta-catenin with E-cadherin was unaffected by oxidative stress or genistein. ZO-1, E-cadherin and beta-catenin in the plasma membrane or membrane-cytoskeleton were either slightly reduced or unaffected by oxidative stress or genistein. These results show that oxidative stress induces tyrosine phosphorylation and cellular redistribution of occludin-ZO-1 and E-cadherin-beta-catenin complexes by a tyrosine-kinase-dependent mechanism.
Objective. To evaluate associations between lipid levels, inflammation, and rheumatoid arthritis (RA) disease activity, at baseline and during treatment, with the risk of major adverse cardiovascular events (MACE) in tocilizumab-treated patients with RA.Methods. In retrospective post hoc analyses, data were pooled for 3,986 adult patients with moderate to severe RA who received >1 dose of tocilizumab (4 mg/kg or 8 mg/kg) intravenously every 4 weeks in randomized controlled trials and extension studies. Cox proportional hazards modeling was used to evaluate associations between baseline characteristics and posttreatment changes in laboratory and disease characteristics (week 24) and change in disease activity and laboratory values from baseline to week 24 with the risk of future MACE during extended followup.Results. We identified 50 independently adjudicated cases of MACE during 14,683 patient-years of followup (0.34 MACE cases/100 patient-years). At baseline, age, a history of cardiac disorders, the Disease Activity Score in 28 joints (DAS28), and the total cholesterol:high-density lipoprotein cholesterol ratio were independently associated with MACE in multivariable models (P < 0.05 for all). During treatment, a higher DAS28 and higher swollen and tender joint counts at week 24 were associated with future MACE. In separate models, greater reductions in the DAS28 and joint counts from baseline to week 24 were inversely associated with future MACE; changes in lipid parameters were not statistically significantly associated with the risk of MACE.Conclusion. In this population of patients treated with tocilizumab, an association was observed between the baseline total cholesterol:high-density lipoprotein cholesterol ratio and an increased risk of MACE. The risk of MACE while receiving treatment, however, was associated with control of disease activity but not lipid changes. Larger studies are needed to confirm these findings.Patients with rheumatoid arthritis (RA) have approximately double the risk of myocardial infarction (MI) and stroke compared with that in the general population (1,2). Several studies suggest that the increased incidence of cardiovascular disease (CVD) in RA is not completely explained by traditional CV risk factors such as diabetes mellitus, hypertension, smoking, and dyslipidemia (3-5). Indeed, the HLA-DRB1 shared epitope, higher erythrocyte sedimentation rates (ESRs), and RA comorbidities such as vasculitis and pulmonary disease are associated with an increased risk of CVDrelated mortality (4,6). In a population-based incidence cohort of RA patients with high ESRs, those with much lower total cholesterol and low-density lipoprotein
SUMMARYActivation of both mTOR and its downstream target, S6K1 (p70 S6 kinase) have been implicated to affect cardiac hypertrophy. Our earlier work, in a feline model of 1-48 h pressure overload, demonstrated that mTOR/S6K1 activation occurred primarily through a PKC/c-Raf pathway. To further delineate the role of specific PKC isoforms on mTOR/S6K1 activation, we utilized primary cultures of adult feline cardiomyocytes in vitro and stimulated with endothelin-1 (ET-1), phenylephrine (PE), TPA, or insulin. All agonist treatments resulted in S2248 phosphorylation of mTOR and T389 and S421/T424 phosphorylation of S6K1, however only ET-1 and TPA-stimulated mTOR/S6K1 activation was abolished with infection of a dominant negative adenoviral c-Raf (DNRaf) construct. Expression of DN-PKC ε blocked ET-1-stimulated mTOR S2448 and S6K1 S421/ T424 and T389 phosphorylation but had no effect on insulin-stimulated S6K1 phosphorylation. Expression of DN-PKC δ or pretreatment of cardiomyocytes with rottlerin, a PKC δ specific inhibitor, blocked both ET-1 and insulin stimulated mTOR S2448 and S6K1 T389 phosphorylation. However, treatment with Gö6976, a specific classical PKC (cPKC) inhibitor did not affect mTOR/S6K1 activation. These data indicate that: (i) PKC ε is required for ET-1-stimulated T421/S424 phosphorylation of S6K1, (ii) both PKC ε and PKC δ are required for ET-1-stimulated mTOR S2448 and S6K1 T389 phosphorylation, (iii) PKC δ is also required for insulin-stimulated mTOR S2448 and S6K1 T389 phosphorylation. Together, these data delineate both distinct and combinatorial roles of specific PKC isoforms on mTOR and S6K1 activation in adult cardiac myocytes following hypertrophic stimulation.
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