A Conserved GPG-Motif in the HIV-1 Nef Core Is required for principal nef-activities

© 2015 Martínez-Bonet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedTo find out new determinants required for Nef activity we performed a functional alanine scanning analysis along a discrete but highly conserved region at the core of HIV-1 Nef. We identified the GPG-motif, located at the 121–137 region of HIV-1 NL4.3 Nef, as a novel protein signature strictly required for the p56Lck dependent Nef-induced CD4-downregulation in T-cells. Since the Nef-GPG motif was dispensable for CD4-downregulation in HeLa-CD4 cells, Nef/AP-1 interaction and Nef-dependent effects on Tf-R trafficking, the observed effects on CD4 downregulation cannot be attributed to structure constraints or to alterations on general protein trafficking. Besides, we found that the GPG-motif was also required for Nef-dependent inhibition of ring actin re-organization upon TCR triggering and MHCI downregulation, suggesting that the GPG-motif could actively cooperate with the Nef PxxP motif for these HIV-1 Nef-related effects. Finally, we observed that the Nef-GPG motif was required for optimal infectivity of those viruses produced in T-cells. According to these findings, we propose the conserved GPG-motif in HIV-1 Nef as functional region required for HIV-1 infectivity and therefore with a potential interest for the interference of Nef activity during HIV-1 infection.This work was supported by the Ramon y Cajal research program (MICIIN-RYC-2005-002174; http://www.mineco.gob.es/portal/site/mineco/idi), Fondo de Investigación Sanitaria en España (FIS-PS09/01386; http://www.isciii.es/) to RM, and Comunidad de Madrid (S-2010/BMD-2332; http://www.madrimasd.org/) to MAM-F, and the Deutsche Forschungsgemeinschaft (TRR83, project 15 to OTF). MM-B, CP and VB hold a fellowship from the Fondo de Investigación Sanitaria en España (FIS, http://www.isciii.es/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio

A Conserved GPG-Motif in the HIV-1 Nef Core Is Required for Principal Nef-Activities.

To find out new determinants required for Nef activity we performed a functional alanine scanning analysis along a discrete but highly conserved region at the core of HIV-1 Nef. We identified the GPG-motif, located at the 121-137 region of HIV-1 NL4.3 Nef, as a novel protein signature strictly required for the p56Lck dependent Nef-induced CD4-downregulation in T-cells. Since the Nef-GPG motif was dispensable for CD4-downregulation in HeLa-CD4 cells, Nef/AP-1 interaction and Nef-dependent effects on Tf-R trafficking, the observed effects on CD4 downregulation cannot be attributed to structure constraints or to alterations on general protein trafficking. Besides, we found that the GPG-motif was also required for Nef-dependent inhibition of ring actin re-organization upon TCR triggering and MHCI downregulation, suggesting that the GPG-motif could actively cooperate with the Nef PxxP motif for these HIV-1 Nef-related effects. Finally, we observed that the Nef-GPG motif was required for optimal infectivity of those viruses produced in T-cells. According to these findings, we propose the conserved GPG-motif in HIV-1 Nef as functional region required for HIV-1 infectivity and therefore with a potential interest for the interference of Nef activity during HIV-1 infection.This work was supported by the Ramon y Cajal research program (MICIIN-RYC-2005-002174; http://www.mineco.gob.es/portal/site/mineco/idi), Fondo de Investigación Sanitaria en España (FIS-PS09/01386; http://www.isciii.es/) to RM, and Comunidad de Madrid (S-2010/BMD-2332; http://www.madrimasd.org/) to MAM-F, and the Deutsche Forschungsgemeinschaft (TRR83, project 15 to OTF). MM-B, CP and VB hold a fellowship from the Fondo de Investigación Sanitaria en España (FIS, http://www.isciii.es/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S

An anti-ICAM-2 (CD102) monoclonal antibody induces immune-mediated regressions of transplanted ICAM-2-negative colon carcinomas

Monoclonal antibodies (mAbs) can mediate antitumor effects by indirect mechanisms involving antiangiogenesis and up-regulation of the cellular immune response rather than by direct tumor cell destruction. From mAbs raised by immunization of rats with transformed murine endothelial cells, a mAb (EOL4G8) was selected for its ability to eradicate a fraction of established colon carcinomas that did not express the EOL4G8-recognized antigen. The antigen was found to be ICAM-2 (CD102). Antitumor effects of EOL4G8, which required a functional T-cell compartment, were abrogated by depletion of CD8(+) cells and correlated with antitumor CTL activity, whereas only a mild inhibition of angiogenesis was observed. Interestingly, we found that EOL4G8 acting on endothelial ICAM-2 markedly enhances leukotactic factor activity-1-independent adhesion of immature dendritic cells to endothelium-an effect that is at least in part mediated by DC-SIGN (CD209)

Blood DNA methylation and liver cancer in American Indians: evidence from the Strong Heart Study

Purpose: Liver cancer incidence among American Indians/Alaska Natives has risen over the past 20 years. Peripheral blood DNA methylation may be associated with liver cancer and could be used as a biomarker for cancer risk. We evaluated the association of blood DNA methylation with risk of liver cancer. Methods: We conducted a prospective cohort study in 2324 American Indians, between age 45 and 75 years, from Arizona, Oklahoma, North Dakota and South Dakota who participated in the Strong Heart Study between 1989 and 1991. Liver cancer deaths (n = 21) were ascertained using death certificates obtained through 2017. The mean follow-up duration (SD) for non-cases was 25.1 (5.6) years and for cases, 11.0 (8.8) years. DNA methylation was assessed from blood samples collected at baseline using MethylationEPIC BeadChip 850 K arrays. We used Cox regression models adjusted for age, sex, center, body mass index, low-density lipoprotein cholesterol, smoking, alcohol consumption, and immune cell proportions to examine the associations. Results: We identified 9 CpG sites associated with liver cancer. cg16057201 annotated to MRFAP1) was hypermethylated among cases vs. non-cases (hazard ratio (HR) for one standard deviation increase in methylation was 1.25 (95% CI 1.14, 1.37). The other eight CpGs were hypomethylated and the corresponding HRs (95% CI) ranged from 0.58 (0.44, 0.75) for cg04967787 (annotated to PPRC1) to 0.77 (0.67, 0.88) for cg08550308. We also assessed 7 differentially methylated CpG sites associated with liver cancer in previous studies. The adjusted HR for cg15079934 (annotated to LPS1) was 1.93 (95% CI 1.10, 3.39). Conclusions: Blood DNA methylation may be associated with liver cancer mortality and may be altered during the development of liver cancer.This work was supported by grants from the National Heart, Lung, and Blood Institute (NHLBI) (Contract Numbers 75N92019D00027, 75N92019D00028, 75N92019D00029 and 75N92019D00030) and previous Grants (R01HL090863, R01HL109315, R01HL109301, R01HL109284, R01HL109282, and R01HL109319 and Cooperative Agreements: U01HL41642, U01HL41652, U01HL41654, U01HL65520 and U01HL65521); by the National Institute of Environmental Health Sciences (Grant Numbers R25ES025505, R01ES032638, R01ES021367, R01ES025216, P42ES033719, P30ES009089); by the Chilean CONICYT/FONDECYT-POSTDOCTORADO Nº 3180486 and by a fellowship from “la Caixa” Foundation (ID 100010434) (fellowship code “LCF/BQ/DR19/11740016”). The funders had no role in the planning, conducting, analysis, interpretation, or writing of this study. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the ofcial views of the National Institutes of Health (United States) or the National Health Institute Carlos III (Spain).S

Cadmium, Smoking, and Human Blood DNA Methylation Profiles in Adults from the Strong Heart Study.

The epigenetic effects of individual environmental toxicants in tobacco remain largely unexplored. Cadmium (Cd) has been associated with smoking-related health effects, and its concentration in tobacco smoke is higher in comparison with other metals. We studied the association of Cd and smoking exposures with human blood DNA methylation (DNAm) profiles. We also evaluated the implication of findings to relevant methylation pathways and the potential contribution of Cd exposure from smoking to explain the association between smoking and site-specific DNAm. We conducted an epigenome-wide association study of urine Cd and self-reported smoking (current and former vs. never, and cumulative smoking dose) with blood DNAm in 790,026 CpGs (methylation sites) measured with the Illumina Infinium Human MethylationEPIC (Illumina Inc.) platform in 2,325 adults 45-74 years of age who participated in the Strong Heart Study in 1989-1991. In a mediation analysis, we estimated the amount of change in DNAm associated with smoking that can be independently attributed to increases in urine Cd concentrations from smoking. We also conducted enrichment analyses and in silico protein-protein interaction networks to explore the biological relevance of the findings. At a false discovery rate (FDR)-corrected level of 0.05, we found 6 differentially methylated positions (DMPs) for Cd; 288 and 17, respectively, for current and former smoking status; and 77 for cigarette pack-years. Enrichment analyses of these DMPs displayed enrichment of 58 and 6 Gene Ontology and Kyoto Encyclopedia of Genes and Genomes gene sets, respectively, including biological pathways for cancer and cardiovascular disease. In in silico protein-to-protein networks, we observed key proteins in DNAm pathways directly and indirectly connected to Cd- and smoking-DMPs. Among DMPs that were significant for both Cd and current smoking (annotated to PRSS23, AHRR, F2RL3, RARA, and 2q37.1), we found statistically significant contributions of Cd to smoking-related DNAm. Beyond replicating well-known smoking epigenetic signatures, we found novel DMPs related to smoking. Moreover, increases in smoking-related Cd exposure were associated with differential DNAm. Our integrative analysis supports a biological link for Cd and smoking-associated health effects, including the possibility that Cd is partly responsible for smoking toxicity through epigenetic changes. https://doi.org/10.1289/EHP6345.This work was supported by grants by the National Heart, Lung, and Blood Institute (NHLBI) (under contract numbers 75N92019D00027, 75N92019D00028, 75N92019D00029, & 75N92019D00030) and previous grants (R01HL090863, R01HL109315, R01HL109301, R01HL109284, R01HL109282, and R01HL109319 and cooperative agreements U01HL41642, U01HL41652, U01HL41654, U01HL65520, and U01HL65521), by the National Institute of Health Sciences (R01ES021367, R01ES025216, P42ES010349, P30ES009089), by the Spanish Funds for Research In Health Sciences, Carlos III Health Institute, co-funded by European Regional Development Fund (CP12/03080 and PI15/00071), by Chilean CONICYT/FONDECYT-POSTDOCTORADO Nº3180486 (A.L.R.-C) and a fellowship from “La Caixa” Foundation (ID 100010434). The fellowship code is “LCF/BQ/DR19/11740016.”S

Combined Inactivation of the Candida albicans GPR1 and TPS2 Genes Results in Avirulence in a Mouse Model for Systemic Infection▿

Inhibition of the biosynthesis of trehalose, a well-known stress protectant in pathogens, is an interesting approach for antifungal or antibacterial therapy. Deletion of TPS2, encoding trehalose-6-phosphate (T6P) phosphatase, results in strongly reduced virulence of Candida albicans due to accumulation of T6P instead of trehalose in response to stress. To further aggravate the deregulation in the pathogen, we have additionally deleted the GPR1 gene, encoding the nutrient receptor that activates the cyclic AMP-protein kinase A signaling pathway, which negatively regulates trehalose accumulation in yeasts. A gpr1 mutant is strongly affected in morphogenesis on solid media as well as in vivo in a mouse model but has only a slightly decreased virulence. The gpr1 tps2 double mutant, on the other hand, is completely avirulent in a mouse model for systemic infection. This strain accumulates very high T6P levels under stress conditions and has a growth defect at higher temperatures. We also show that a tps2 mutant is more sensitive to being killed by macrophages than the wild type or the gpr1 mutant. A double mutant has susceptibility similar to that of the single tps2 mutant. For morphogenesis on solid media, on the other hand, the gpr1 tps2 mutant shows a phenotype similar to that of the single gpr1 mutant. Taken together these results show that there is synergism between Gpr1 and Tps2 and that their combined inactivation results in complete avirulence. Combination therapy targeting both proteins may prove highly effective against pathogenic fungi with increased resistance to the currently used antifungal drugs

Female sex hormones regulate the Th17 immune response to sperm and Candida albicans

9 p.-5 fig.STUDY QUESTION What role do female sex hormones play in the antisperm immune response?SUMMARY ANSWER We found that sperm induce a Th17 immune response and that estradiol down-regulates the antisperm Th17 response by dendritic cells.WHAT IS KNOWN ALREADY Estradiol down-regulates the immune response to several pathogens and impairs the triggering of dendritic cell maturation by microbial products.STUDY DESIGN, SIZE, DURATION Ex vivo and in vivo murine models of vaginal infection with sperm and Candida albicans were used to study the induction of Th17 and its hormonal regulation.PARTICIPANTS/MATERIALS, SETTING, METHODS We analyzed the induction of Th17 cytokines and T cells in splenocytes obtained from BALB/c mice challenged with sperm and C. albicans. For the in vivo vaginal infection models, we used ovariectomized mice treated with vehicle, estradiol or progesterone, and we assessed the effect of these hormones on the immune response in the lymph nodes.MAIN RESULTS AND THE ROLE OF CHANCE Th17 cytokines and T cells were induced by sperm antigens in both ex vivo and in vivo experiments. Estrus levels of estradiol down-regulated the Th17 response to sperm and C. albicans in vivo.LIMITATIONS, REASONS FOR CAUTION This study was conducted using murine models; whether or not the results are applicable to humans is not known.WIDER IMPLICATIONS OF THE FINDINGS Our results describe an adaptive mechanism that reconciles immunity and reproduction and further explains why unregulated Th17 could be linked to infertility and recurrent infections.This work was supported by research grants from the Instituto de Salud Carlos III (ISCIII) (PI10/00897) and Fundación Mutua Madrileña to M.R. M.R. holds a Miguel Servet contract from the ISCIII (CP08/00228). M.A.M.-F. was supported by (ISCIII) INTRASALUD PI09/02029.Peer reviewe

Estradiol impairs the Th17 immune response against Candida albicans

Candida albicans is a commensal opportunistic pathogen that is also a member of gastrointestinal and reproductive tract microbiota. Exogenous factors, such as oral contraceptives, hormone replacement therapy, and estradiol, may affect susceptibility to Candida infection, although the mechanisms involved in this process have not been elucidated. We used a systemic candidiasis model to investigate how estradiol confers susceptibility to infection. We report that estradiol increases mouse susceptibility to systemic candidiasis, as in vivo and ex vivo estradiol-treated DCs were less efficient at up-regulating antigen-presenting machinery, pathogen killing, migration, IL-23 production, and triggering of the Th17 immune response. Based on these results, we propose that estradiol impairs DC function, thus explaining the increased susceptibility to infection during estrus

Mutations on the GPG-loop abrogate HIV-1 Nef-induced CD4 down-regulation.

<p>A-B) CEM cells were transfected with either wild type or the indicated Nef mutants as GFP-fusion proteins. Nef-induced surface CD4 down-regulation was analysed by two-colour flow cytometry in Nef-GFP expressing cells. The mean CD4 (PE) fluorescence intensity (MFI) of the GFP-positive cells was used to calculate the Nef activity on surface CD4 expression (A). Histograms represent the percentage of activity relative to wild-type Nef as the arithmetic mean ± SD of at least three independent experiments. Dot plots and the corresponding MFI are representative of three independent assays (B). ***, p< 0.001. C) The expression of wild type and the indicated Nef-GPG mutants in CEM cells was analysed by western blotting using an anti-GFP antibody. <b>γ</b>-adaptin levels were used as loading control staining.</p