Protein kinase C phosphorylates AMP-activated protein kinase α1 Ser487

The key metabolic regulator, AMP-activated protein kinase (AMPK) is reported to be downregulated in metabolic disorders, but the mechanisms are poorly characterised. Recent studies have identified phosphorylation of the AMPKα1/α2 catalytic subunit isoforms at Ser487/491 respectively as an inhibitory regulation mechanism. Vascular endothelial growth factor (VEGF) stimulates AMPK and protein kinase B (Akt) in cultured human endothelial cells. As Akt has been demonstrated to be an AMPKα1 Ser487 kinase, the effect of VEGF on inhibitory AMPK phosphorylation in cultured primary human endothelial cells was examined. Stimulation of endothelial cells with VEGF rapidly increased AMPKα1 Ser487 phosphorylation in an Akt-independent manner, without altering AMPKα2 Ser491 phosphorylation. In contrast, VEGF-stimulated AMPKα1 Ser487 phosphorylation was sensitive to inhibitors of protein kinase C (PKC) and PKC activation using phorbol esters or overexpression of PKC stimulated AMPKα1 Ser487 phosphorylation. Purified PKC and Akt both phosphorylated AMPKα1 Ser487 in vitro with similar efficiency. PKC activation was associated with reduced AMPK activity, as inhibition of PKC increased AMPK activity and phorbol esters inhibited AMPK, an effect lost in cells expressing mutant AMPKα1 Ser487Ala. Consistent with a pathophysiological role for this modification, AMPKα1 Ser487 phosphorylation was inversely correlated with insulin sensitivity in human muscle. These data indicate a novel regulatory role of PKC to inhibit AMPKα1 in human cells. As PKC activation is associated with insulin resistance and obesity, PKC may underlie the reduced AMPK activity reported in response to overnutrition in insulin-resistant metabolic and vascular tissues

Predictors of Visceral Leishmaniasis Relapse in HIV-Infected Patients: A Systematic Review

Visceral leishmaniasis (VL) is the most serious form of an insect-transmitted parasitic disease prevalent in 70 countries. The disease is caused by species of the L. donovani complex found in different geographical regions. These parasites have substantially different clinical, drug susceptibility and epidemiological characteristics. According to data from the World Health Organization, the areas where HIV-Leishmania co-infection is distributed are extensive. HIV infection increases the risk of developing VL, reduces the likelihood of a therapeutic response, and greatly increases the probability of relapse. A better understanding of the factors promoting relapses is essential; therefore we performed a systematic review of articles involving all articles assessing the predictors of VL relapse in HIV-infected individuals older than 14 years of age. Out of 178 relevant articles, 18 met the inclusion criteria and in total, data from 1017 patients were analyzed. We identified previous episodes of VL relapse, CD4+ lymphocyte count fewer than 100 cells/mL at VL diagnosis, and the absence of an increase in CD4+ counts at follow-up as major factors associated with VL relapse. Knowledge of relapse predictors can help to identify patients with different degrees of risk, facilitate and direct prophylaxis choices, and aid in patient counseling

Immunological synapse formation induces mitochondrial clustering and mitophagy in dendritic cells

9 p.-8 fig.The immunological synapse (IS) is a superstructure formed during T cell activation at the zone of contact between T cells and dendritic cells (DCs). The IS includes specific molecular components in the T cell and DCs sides that may result in different functionality. Most of the studies on the IS have focused on the T cell side of this structure and, in contrast, the information available on the IS of DCs is sparse. Autophagy is a cellular process involved in the clearance of damaged proteins and organelles via lysosomal degradation. Mitophagy is the selective autophagy of damaged mitochondria. In this study, it is shown that IS formation induces clustering of mitochondria in the IS of DCs and partial depolarization of these organelles. At the IS of the DCs also accumulate autophagy and mitophagy markers, even when the kinase complex mTORC1, an inhibitor of the autophagy, is active. Together the results presented indicate that IS formation induces local clustering of mitochondria and mitophagy, which could be a homeostatic mechanism to control the quality of mitochondria in this region. The data underline the complexity of the regulatory mechanisms operating in the IS of DCs.This work was supported by Grants SAF-2014-53151-R (Ministerio de Economía y Competitividad), SAF2017-83306-R (Ministerio de Ciencia, Innovación y Universidades), RD08/0075 (Red de Inflamación y Enfermedades Reumáticas [Redes Temáticas de Investigación Cooperativa en Salud Program/Instituto de Salud Carlos III]), and S2010/BMD-2350 (Consejería de Educación y Empleo from Comunidad de Madrid [Raphyme]) (to J.L.R.-F.). L.G.-C. and P.L.-C were supported by fellowships Formación del Profesorado Universitario and Formación de Personal Investigador, conferred by the Ministerio de Educación y Ciencia and Ministerio de Economía y Competitividad, respectively. M.P.M. was supported by the Medical Research Council UK (MC_U105663142) and a Wellcome Trust Investigator Award (110159/Z/15/Z).Peer reviewe

Immunological Synapse Formation Induces Mitochondrial Clustering and Mitophagy in Dendritic Cells.

The immunological synapse (IS) is a superstructure formed during T cell activation at the zone of contact between T cells and dendritic cells (DCs). The IS includes specific molecular components in the T cell and DCs sides that may result in different functionality. Most of the studies on the IS have focused on the T cell side of this structure and, in contrast, the information available on the IS of DCs is sparse. Autophagy is a cellular process involved in the clearance of damaged proteins and organelles via lysosomal degradation. Mitophagy is the selective autophagy of damaged mitochondria. In this study, it is shown that IS formation induces clustering of mitochondria in the IS of DCs and partial depolarization of these organelles. At the IS of the DCs also accumulate autophagy and mitophagy markers, even when the kinase complex mTORC1, an inhibitor of the autophagy, is active. Together the results presented indicate that IS formation induces local clustering of mitochondria and mitophagy, which could be a homeostatic mechanism to control the quality of mitochondria in this region. The data underline the complexity of the regulatory mechanisms operating in the IS of DCs.This work was supported by Grants SAF-2014-53151-R (Ministerio de Economı´a y Competitividad), SAF2017-83306-R (Ministerio de Ciencia, Innovacio´n y Universidades), RD08/0075 (Red de Inflamacio´n y Enfermedades Reuma´ticas [Redes Tema´ticas de Investigacio´n Cooperativa en Salud Program/Instituto de Salud Carlos III]), and S2010/BMD-2350 (Consejerı´a de Educacio´n y Empleo from Comunidad de Madrid [Raphyme]) (to J.L.R.-F.). L.G.-C. and P.L.-C were supported by fellowships Formacio´n del Profesorado Universitario and Formacio´n de Personal Investigador, conferred by the Ministerio de Educacio´n y Ciencia and Ministerio de Economı´a y Competitividad, respectively. M.P.M. was supported by the Medical Research Council UK (MC_U105663142) and a Wellcome Trust Investigator Award (110159/Z/15/Z)

Effect of accompanying antiretroviral drugs on virological response to pegylated interferon and ribavirin in patients co-infected with HIV and hepatitis C virus

The effects of antiretroviral drugs on the response to pegylated interferon plus ribavirin remain uncertain. We evaluated whether antiretroviral drugs affected the response to pegylated interferon plus ribavirin in patients co-infected with HIV and hepatitis C virus (HCV). We conducted a retrospective analysis of two cohorts of HIV/HCV-co-infected patients treated with pegylated interferon plus ribavirin between 2001 and 2007 in Spain. The outcome measure was sustained virological response (SVR). Logistic regression models were used to test possible associations between non-response and pre-treatment characteristics, including accompanying antiretroviral drugs. The study sample comprised 1701 patients: 63% were infected with HCV genotype (G) 1 or 4 and 88% were taking highly active antiretroviral therapy (HAART). Factors independently associated with increased odds of SVR were G2 or 3, HVC RNA <500,000 IU/mL and CDC clinical category A or B. When we adjusted for these prognostic factors and dose of ribavirin/kg, the adjusted odds ratio (AOR) of SVR for patients without HAART was 1.31 [95% confidence interval (CI) 0.91-1.88; P = 0.144]. Taking the backbone of tenofovir and lamivudine/emtricitabine as a reference, we found that, with the exception of regimens including zidovudine, the effect of other nucleoside reverse transcriptase inhibitor backbones had little effect on SVR. The AOR of SVR for zidovudine and lamivudine was 0.65 (95% CI 0.46-0.93, P = 0.017). We carried out several sensitivity analyses, the results of which were consistent with the findings of the primary analysis. In conclusion, our results suggest that, with the exception of regimens including zidovudine, accompanying antiretroviral drugs have little effect on the virological response to pegylated interferon plus ribavirin in HIV/HCV-co-infected patients.5.068 JCR (2011) Q1, 7/70 Infectious diseases, 18/114 Microbiology, 20/261 Pharmacology & pharmac