MicroRNA-155 is essential for the optimal proliferation and survival of plasmablast B cells.

A fast antibody response can be critical to contain rapidly dividing pathogens. This can be achieved by the expansion of antigen-specific B cells in response to T-cell help followed by differentiation into plasmablasts. MicroRNA-155 (miR-155) is required for optimal T-cell-dependent extrafollicular responses via regulation of PU.1, although the cellular processes underlying this defect are largely unknown. Here, we show that miR-155 regulates the early expansion of B-blasts and later on the survival and proliferation of plasmablasts in a B-cell-intrinsic manner, by tracking antigen-specific B cells in vivo since the onset of antigen stimulation. In agreement, comparative analysis of the transcriptome of miR-155-sufficient and miR-155-deficient plasmablasts at the peak of the response showed that the main processes regulated by miR-155 were DNA metabolic process, DNA replication, and cell cycle. Thus, miR-155 controls the extent of the extrafollicular response by regulating the survival and proliferation of B-blasts, plasmablasts and, consequently, antibody production

EPISPOT: An epigenome-driven approach for detecting and interpreting hotspots in molecular QTL studies.

We present EPISPOT, a fully joint framework which exploits large panels of epigenetic annotations as variant-level information to enhance molecular quantitative trait locus (QTL) mapping. Thanks to a purpose-built Bayesian inferential algorithm, EPISPOT accommodates functional information for both cis and trans actions, including QTL hotspot effects. It effectively couples simultaneous QTL analysis of thousands of genetic variants and molecular traits with hypothesis-free selection of biologically interpretable annotations which directly contribute to the QTL effects. This unified, epigenome-aided learning boosts statistical power and sheds light on the regulatory basis of the uncovered hits; EPISPOT therefore marks an essential step toward improving the challenging detection and functional interpretation of trans-acting genetic variants and hotspots. We illustrate the advantages of EPISPOT in simulations emulating real-data conditions and in a monocyte expression QTL study, which confirms known hotspots and finds other signals, as well as plausible mechanisms of action. In particular, by highlighting the role of monocyte DNase-I sensitivity sites from >150 epigenetic annotations, we clarify the mediation effects and cell-type specificity of major hotspots close to the lysozyme gene. Our approach forgoes the daunting and underpowered task of one-annotation-at-a-time enrichment analyses for prioritizing cis and trans QTL hits and is tailored to any transcriptomic, proteomic, or metabolomic QTL problem. By enabling principled epigenome-driven QTL mapping transcriptome-wide, EPISPOT helps progress toward a better functional understanding of genetic regulation

The polycystic ovary syndrome: an example of obesity-related cardiovascular complication affecting young women

Polycystic ovary syndrome (PCOS) is a good example of obesity-related cardiovascular complication affecting young women. PCOS is not only considered a reproductive problem but rather represents a complex endocrine, multifaceted syndrome with important health implications. Several evidences suggest an increased cardiovascular risk of cardiovascular disease associated with this syndrome, characterized by an impairment of heart structure and function, endothelial dysfunction and lipid abnormalities. All these features, probably linked to insulin-resistance, are often present in obese PCOS patients. Cardiovascular abnormalities represent important long-term sequelae of PCOS that need further investigations

MicroRNA-155 controls affinity-based selection by protecting c-MYC+ B cells from apoptosis.

The production of high-affinity antibodies by B cells is essential for pathogen clearance. Antibody affinity for antigen is increased through the affinity maturation in germinal centers (GCs). This is an iterative process in which B cells cycle between proliferation coupled with the acquisition of mutations and antigen-based positive selection, resulting in retention of the highest-affinity B cell clones. The posttranscriptional regulator microRNA-155 (miR-155) is critical for efficient affinity maturation and the maintenance of the GCs; however, the cellular and molecular mechanism by which miR-155 regulates GC responses is not well understood. Here, we utilized a miR-155 reporter mouse strain and showed that miR-155 is coexpressed with the proto-oncogene encoding c-MYC in positively selected B cells. Functionally, miR-155 protected positively selected c-MYC+ B cells from apoptosis, allowing clonal expansion of this population, providing an explanation as to why Mir155 deletion impairs affinity maturation and promotes the premature collapse of GCs. We determined that miR-155 directly inhibits the Jumonji family member JARID2, which enhances B cell apoptosis when overexpressed, and thereby promotes GC B cell survival. Our findings also suggest that there is cooperation between c-MYC and miR-155 during the normal GC response, a cooperation that may explain how c-MYC and miR-155 can collaboratively function as oncogenes.R. Nakagawa was supported by a Marie Curie Incoming Fellowship from the European Union’s Seventh Framework Programme for research, technological development, and demonstration. E. Vigorito was supported by the Medical Research Council grants G1001781 and G0700287 and by the Biotechnology and Biological Sciences Research Council. M. Meyer-Hermann was supported by the German Federal Ministry of Education and Research within the Measures for the Establishment of Systems Medicine, project SYSIMIT (BMBF eMed project SYSIMIT, FKZ: 01ZX1308B) and by the Human Frontier Science Program (RGP0033/2015)

Efficient inhibition of miR-155 function in vivo by peptide nucleic acids.

MicroRNAs (miRNAs) play an important role in diverse physiological processes and are potential therapeutic agents. Synthetic oligonucleotides (ONs) of different chemistries have proven successful for blocking miRNA expression. However, their specificity and efficiency have not been fully evaluated. Here, we show that peptide nucleic acids (PNAs) efficiently block a key inducible miRNA expressed in the haematopoietic system, miR-155, in cultured B cells as well as in mice. Remarkably, miR-155 inhibition by PNA in primary B cells was achieved in the absence of any transfection agent. In mice, the high efficiency of the treatment was demonstrated by a strong overlap in global gene expression between B cells isolated from anti-miR-155 PNA-treated and miR-155-deficient mice. Interestingly, PNA also induced additional changes in gene expression. Our analysis provides a useful platform to aid the design of efficient and specific anti-miRNA ONs for in vivo use

MiR-25 regulates Wwp2 and Fbxw7 and promotes reprogramming of mouse fibroblast cells to iPSCs.

BACKGROUND: miRNAs are a class of small non-coding RNAs that regulate gene expression and have critical functions in various biological processes. Hundreds of miRNAs have been identified in mammalian genomes but only a small number of them have been functionally characterized. Recent studies also demonstrate that some miRNAs have important roles in reprogramming somatic cells to induced pluripotent stem cells (iPSCs). METHODS: We screened 52 miRNAs cloned in a piggybac (PB) vector for their roles in reprogramming of mouse embryonic fibroblast cells to iPSCs. To identify targets of miRNAs, we made Dgcr8-deficient embryonic stem (ES) cells and introduced miRNA mimics to these cells, which lack miRNA biogenesis. The direct target genes of miRNA were identified through global gene expression analysis and target validation. RESULTS AND CONCLUSION: We found that over-expressing miR-25 or introducing miR-25 mimics enhanced production of iPSCs. We identified a number of miR-25 candidate gene targets. Of particular interest were two ubiquitin ligases, Wwp2 and Fbxw7, which have been proposed to regulate Oct4, c-Myc and Klf5, respectively. Our findings thus highlight the complex interplay between miRNAs and transcription factors involved in reprogramming, stem cell self-renewal and maintenance of pluripotency

The miR-155-PU.1 axis acts on Pax5 to enable efficient terminal B cell differentiation.

A single microRNA (miRNA) can regulate the expression of many genes, though the level of repression imparted on any given target is generally low. How then is the selective pressure for a single miRNA/target interaction maintained across long evolutionary distances? We addressed this problem by disrupting in vivo the interaction between miR-155 and PU.1 in mice. Remarkably, this interaction proved to be key to promoting optimal T cell-dependent B cell responses, a previously unrecognized role for PU.1. Mechanistically, miR-155 inhibits PU.1 expression, leading to Pax5 down-regulation and the initiation of the plasma cell differentiation pathway. Additional PU.1 targets include a network of genes whose products are involved in adhesion, with direct links to B-T cell interactions. We conclude that the evolutionary adaptive selection of the miR-155-PU.1 interaction is exercised through the effectiveness of terminal B cell differentiation

Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register

Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations

Fine-Scale Mapping at 9p22.2 Identifies Candidate Causal Variants That Modify Ovarian Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

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