PRC2 is dispensable for HOTAIR-mediated transcriptional repression

Long non-coding RNAs (lncRNAs) play diverse roles in physiological and pathological processes. Several lncRNAs have been suggested to modulate gene expression by guiding chromatin-modifying complexes to specific sites in the genome. However, besides the example of Xist, clear-cut evidence demonstrating this novel mode of regulation remains sparse. Here, we focus on HOTAIR, a lncRNA that is overexpressed in several tumor types and previously proposed to play a key role in gene silencing through direct recruitment of Polycomb Repressive Complex 2 (PRC2) to defined genomic loci. Using genetic tools and a novel RNA-tethering system, we investigated the interplay between HOTAIR and PRC2 in gene silencing. Surprisingly, we observed that forced overexpression of HOTAIR in breast cancer cells leads to subtle transcriptomic changes that appear to be independent of PRC2. Mechanistically, we found that artificial tethering of HOTAIR to chromatin causes transcriptional repression, but that this effect does not require PRC2. Instead, PRC2 recruitment appears to be a consequence of gene silencing. We propose that PRC2 binding to RNA might serve functions other than chromatin targeting

Antiphospholipid Antibodies Bind ATP: A putative Mechanism for the Pathogenesis of Neuronal Dysfunction

Antiphospholipid antibodies (aPL) generated in experimental animals cross-react with ATP. We therefore examined the possibility that aPL IgG from human subjects bind to ATP by affinity column and an enzyme linked immunosorbent assay (ELISA). Sera with high levels of aPL IgG were collected from 12 patients with the antiphospholipid syndrome (APS). IgG fractions from 10 of 12 APS patients contained aPL that could be affinity-bound to an ATP column and completely eluted with NaCl 0.5 M. A significant (>50%) inhibition of aPL IgG binding by ATP 5 mM was found in the majority. Similar inhibition was obtained with ADP but not with AMP or cAMP. All the affinity purified anti-ATP antibodies also bound β2-glycoprotein-I (β2-GPI, also known as apolipoprotein H) suggesting that, similar to most pathogenic aPL, their binding depends on this serum cofactor. We further investigated this possibility and found that the binding of β2-GPI to the ATP column was similar to that of aPL IgG in that most was reversed by NaCl 0.5 M. Furthermore, addition of β2-GPI to aPL IgG significantly increased the amount of aPL binding to an ATP column. We conclude that aPL IgG bind ATP, probably through β2-GPI. This binding could interfere with the normal extracellular function of ATP and similar neurotransmitters

Metabolomics to unveil and understand phenotypic diversity between pathogen populations

Visceral leishmaniasis is caused by a parasite called Leishmania donovani, which every year infects about half a million people and claims several thousand lives. Existing treatments are now becoming less effective due to the emergence of drug resistance. Improving our understanding of the mechanisms used by the parasite to adapt to drugs and achieve resistance is crucial for developing future treatment strategies. Unfortunately, the biological mechanism whereby Leishmania acquires drug resistance is poorly understood. Recent years have brought new technologies with the potential to increase greatly our understanding of drug resistance mechanisms. The latest mass spectrometry techniques allow the metabolome of parasites to be studied rapidly and in great detail. We have applied this approach to determine the metabolome of drug-sensitive and drug-resistant parasites isolated from patients with leishmaniasis. The data show that there are wholesale differences between the isolates and that the membrane composition has been drastically modified in drug-resistant parasites compared with drug-sensitive parasites. Our findings demonstrate that untargeted metabolomics has great potential to identify major metabolic differences between closely related parasite strains and thus should find many applications in distinguishing parasite phenotypes of clinical relevance

Sex-Chromosome Homomorphy in Palearctic Tree Frogs Results from Both Turnovers and X-Y Recombination.

Contrasting with birds and mammals, poikilothermic vertebrates often have homomorphic sex chromosomes, possibly resulting from high rates of sex-chromosome turnovers and/or occasional X-Y recombination. Strong support for the latter mechanism was provided by four species of European tree frogs, which inherited from a common ancestor (∼ 5 Ma) the same pair of homomorphic sex chromosomes (linkage group 1, LG1), harboring the candidate sex-determining gene Dmrt1. Here, we test sex linkage of LG1 across six additional species of the Eurasian Hyla radiation with divergence times ranging from 6 to 40 Ma. LG1 turns out to be sex linked in six of nine resolved cases. Mapping the patterns of sex linkage to the Hyla phylogeny reveals several transitions in sex-determination systems within the last 10 My, including one switch in heterogamety. Phylogenetic trees of DNA sequences along LG1 are consistent with occasional X-Y recombination in all species where LG1 is sex linked. These patterns argue against one of the main potential causes for turnovers, namely the accumulation of deleterious mutations on nonrecombining chromosomes. Sibship analyses show that LG1 recombination is strongly reduced in males from most species investigated, including some in which it is autosomal. Intrinsically low male recombination might facilitate the evolution of male heterogamety, and the presence of important genes from the sex-determination cascade might predispose LG1 to become a sex chromosome

The Efficacy of Pharmacotherapy for Decreasing the Expansion Rate of Abdominal Aortic Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND: Pharmacotherapy may represent a potential means to limit the expansion rate of abdominal aortic aneurysms (AAAs). Studies evaluating the efficacy of different pharmacological agents to slow down human AAA-expansion rates have been performed, but they have never been systematically reviewed or summarized. METHODS AND FINDINGS: Two independent reviewers identified studies and selected randomized trials and prospective cohort studies comparing the growth rate of AAA in patients with pharmacotherapy vs. no pharmacotherapy. We extracted information on study interventions, baseline characteristics, methodological quality, and AAA growth rate differences (in mm/year). Fourteen prospective studies met eligibility criteria. Five cohort studies raised the possibility of benefit of beta-blockers [pooled growth rate difference: -0.62 mm/year, (95%CI, -1.00 to -0.24)], but this was not confirmed in three beta-blocker RCTs [pooled RCT growth rate difference: -0.05 mm/year (-0.16 to 0.05)]. Statins have been evaluated in two cohort studies that yield a pooled growth rate difference of -2.97 (-5.83 to -0.11). Doxycycline and roxithromycin have been evaluated in two RCTs that suggest possible benefit [pooled RCT growth rate difference: -1.32 mm/year (-2.89 to 0.25)]. Studies assessing NSAIDs, diuretics, calcium channel blockers and ACE inhibitors, meanwhile, did not find statistically significant differences. CONCLUSIONS: Beta-blockers do not appear to significantly reduce the growth rate of AAAs. Statins and other anti-inflammatory agents appear to hold promise for decreasing the expansion rate of AAA, but need further evaluation before definitive recommendations can be made

Fibroma ossificante dei seni paranasali: diagnosi e management

Le lesioni fibro-ossee benigne raramente colpiscono i seni paranasali e sono suddivise in 3 entità: osteoma, displasia fibrosa e fibroma ossificante. Questi presentano simili caratteristiche cliniche, radiologiche e istologiche ma hanno un comportamento diverso. Il fibroma ossificante, in particolare la variante istologica giovanile, può presentare un comportamento aggressivo con un alto rischio di recidiva se rimosso in modo incompleto. Lo scopo dello studio è quello di paragonare il comportamento clinico del fibroma ossificante con quello delle altre lesioni fibro-ossee; di evidenziare un eventuale comportamento differente tra i vari sottotipi istologici; di descrivere i vantaggi, i limiti e i risultati della chirurgia endoscopica endonasale rispetto ai dati presenti in letteratura. Abbiamo analizzato retrospettivamente 11 pazienti affetti da fibroma ossificante naso-sinusale e trattati in un centro ospedaliero di terzo livello. Tutti i pazienti sono stati sottoposti a TC. La RM è stata eseguita in caso di coinvolgimento del basicranio o in caso di recidiva. Una biopsia pre-operatoria è stata effettuata nei casi in cui la massa era raggiungibile per via endoscopica. Un paziente è stato sottoposto a embolizzazione pre-operatoria ed ha riportato una cecità monolaterale al termine della procedure. In base alla localizzazione, l’exeresi del tumore è stata eseguita con un approccio endoscopico (7 pazienti), esterno (3), combinato (1). Istologicamente 5 pazienti hanno riportato un sottotipo convenzionale, 5 la variante giovanile psammomatoide associata in un caso a cisti aneurismatica ossea, e un paziente la variante giovanile trabecolare. Tre pazienti affetti dalla variante istologica giovanile psammomatoide hanno presentato un’invasione del basicranio e sono stati sottoposti ad exeresi subtotale per via endoscopica che ha richiesto in seguito, a causa di un aumento di volume del residuo, un secondo intervento per via transbasale. I reperti clinici, radiologici e istologici dovrebbero essere considerati insieme per una accurata diagnosi differenziale tra le lesioni fibro-ossee. Ulteriori studi sono necessari per concludere se la localizzazione e l’estensione del fibroma ossificante al momento della diagnosi sono più importanti della variante istologica. L’approccio endoscopico è la prima opzione nella maggior parte dei casi anche se in alcuni selezionati pazienti l’approccio esterno risulta ancora necessario

The N-Terminal Domain and Glycosomal Localization of Leishmania Initial Acyltransferase LmDAT Are Important for Lipophosphoglycan Synthesis

Ether glycerolipids of Leishmania major are important membrane components as well as building blocks of various virulence factors. In L. major, the first enzyme of the ether glycerolipid biosynthetic pathway, LmDAT, is an unusual, glycosomal dihydroxyacetonephosphate acyltransferase important for parasite's growth and survival during the stationary phase, synthesis of ether lipids, and virulence. The present work extends our knowledge of this important biosynthetic enzyme in parasite biology. Site-directed mutagenesis of LmDAT demonstrated that an active enzyme was critical for normal growth and survival during the stationary phase. Deletion analyses showed that the large N-terminal extension of this initial acyltransferase may be important for its stability or activity. Further, abrogation of the C-terminal glycosomal targeting signal sequence of LmDAT led to extraglycosomal localization, did not impair its enzymatic activity but affected synthesis of the ether glycerolipid-based virulence factor lipophosphoglycan. In addition, expression of this recombinant form of LmDAT in a null mutant of LmDAT did not restore normal growth and survival during the stationary phase. These results emphasize the importance of this enzyme's compartmentalization in the glycosome for the generation of lipophosphoglycan and parasite's biology

Proteasome inhibition reduces plasma cell and antibody secretion, but not angiotensin II-induced hypertension

IntroductionDepletion of mature B cells affords protection against experimental hypertension. However, whether B cell-mediated hypertension is dependent on differentiation into antibody-secreting cells (ASCs) remains unclear. Using the proteasome inhibitor, bortezomib, the present study tested the effect of ASC reduction on angiotensin II-induced hypertension.MethodsMale C57BL6/J mice were infused with angiotensin II (0.7 mg/kg/day; s.c.) for 28 days via osmotic minipump to induce hypertension. Normotensive control mice received saline infusion. Bortezomib (750 μg/kg) or vehicle (0.1% DMSO) was administered (i.v.) 3 days prior to minipump implantation, and twice weekly thereafter. Systolic blood pressure was measured weekly using tail-cuff plethysmography. Spleen and bone marrow B1 (CD19+B220−), B2 (B220+CD19+) and ASCs (CD138hiSca-1+Blimp-1+) were enumerated by flow cytometry. Serum immunoglobulins were quantified using a bead-based immunoassay.ResultsBortezomib treatment reduced splenic ASCs by ∼68% and ∼64% compared to vehicle treatment in normotensive (2.00 ± 0.30 vs. 0.64 ± 0.15 × 105 cells; n = 10–11) and hypertensive mice (0.52 ± 0.11 vs. 0.14 ± 0.02 × 105 cells; n = 9–11), respectively. Bone marrow ASCs were also reduced by bortezomib in both normotensive (4.75 ± 1.53 vs. 1.71 ± 0.41 × 103 cells; n = 9–11) and hypertensive mice (4.12 ± 0.82 vs. 0.89 ± 0.18 × 103 cells; n = 9–11). Consistent with ASC reductions, bortezomib reduced serum IgM and IgG2a in all mice. Despite these reductions in ASCs and antibody levels, bortezomib did not affect angiotensin II-induced hypertension over 28 days (vehicle: 182 ± 4 mmHg vs. bortezomib: 177 ± 7 mmHg; n = 9–11).ConclusionReductions in ASCs and circulating IgG2a and IgM did not ameliorate experimental hypertension, suggesting other immunoglobulin isotypes or B cell effector functions may promote angiotensin II-induced hypertension