A functional BH3 domain in an aquaporin from Leishmania infantum.

Despite the absence of sequences showing significant similarity to any of the members of the Bcl-2 family of proteins in protozoa, experiments carried out in yeast or trypanosomatids have demonstrated that ectopic expression of some of these members alters their response to different death stimuli. Because the BH3 domain is the smallest common signature in all the proteins of this family of apoptosis regulators and also because they are essential for molecular interactions between antagonistic members, we looked for sequences with significant similarity to the BH3 motif in the Leishmania infantum genome. Among the top scoring ones, we found the MYLALQNLGDEV amino-acid stretch at the C terminus of a previously described aquaporin, now renamed as Li-BH3AQP. This motif is highly conserved in homologous proteins from other species of the Leishmania genus. The association of Li-BH3AQP with human Bcl-XL was demonstrated by both co-immunoprecipitation and yeast two-hybrid experiments. Ectopic expression of Li-BH3AQP reduced viability of HeLa cells and this deleterious effect was abrogated by the simultaneous overexpression of Bcl-XL. Although we were not able to demonstrate a reduction in parasite viability when the protein was overexpressed in Leishmania promastigotes, a prodeath effect could be observed when the parasites overexpressing Li-BH3AQP were treated with staurosporine or antimycin A. Surprisingly, these parasites were more resistant, compared with wild-type parasites, to hypotonic stress or nutrient deprivation. The prodeath activity was abolished upon replacement of two highly conserved amino acids in this BH3 domain. Taken together, these results point to Li-BH3AQP as the first non-enzymatic protein ever described in trypanosomatids that is involved in cell death

Identification and Functional Characterization of G6PC2 Coding Variants Influencing Glycemic Traits Define an Effector Transcript at the G6PC2-ABCB11 Locus

Genome wide association studies (GWAS) for fasting glucose (FG) and insulin (FI) have identified common variant signals which explain 4.8% and 1.2% of trait variance, respectively. It is hypothesized that low-frequency and rare variants could contribute substantially to unexplained genetic variance. To test this, we analyzed exome-array data from up to 33,231 non-diabetic individuals of European ancestry. We found exome-wide significant (P<5×10-7) evidence for two loci not previously highlighted by common variant GWAS: GLP1R (p.Ala316Thr, minor allele frequency (MAF)=1.5%) influencing FG levels, and URB2 (p.Glu594Val, MAF = 0.1%) influencing FI levels. Coding variant associations can highlight potential effector genes at (non-coding) GWAS signals. At the G6PC2/ABCB11 locus, we identified multiple coding variants in G6PC2 (p.Val219Leu, p.His177Tyr, and p.Tyr207Ser) influencing FG levels, conditionally independent of each other and the non-coding GWAS signal. In vitro assays demonstrate that these associated coding alleles result in reduced protein abundance via proteasomal degradation, establishing G6PC2 as an effector gene at this locus. Reconciliation of single-variant associations and functional effects was only possible when haplotype phase was considered. In contrast to earlier reports suggesting that, paradoxically, glucose-raising alleles at this locus are protective against type 2 diabetes (T2D), the p.Val219Leu G6PC2 variant displayed a modest but directionally consistent association with T2D risk. Coding variant associations for glycemic traits in GWAS signals highlight PCSK1, RREB1, and ZHX3 as likely effector transcripts. These coding variant association signals do not have a major impact on the trait variance explained, but they do provide valuable biological insights

Adenomegalias en niños: Abordaje diagnóstico en el Consultorio de Hemato-oncología de un Hospital de Referencia

Introducción: Las adenopatías constituyen uno de los motivos más frecuentes de consulta al hematólogo pediatra. Si bien la mayoría de los casos corresponde a procesos benignos transitorios autolimitados, en algunas ocasiones pueden ser manifestaciones iniciales de patologías más graves, principalmente relacionadas con enfermedades malignas.Objetivos: Determinar las características clínicas y los métodos diagnósticos utilizados en pacientes que consultaron por adenopatías en el Departamento de Hemato-oncología de la Cátedra y Servicio de Pediatría del CMI-Hospital de Clínicas, de enero de 2000 a julio de 2005.Materiales y Métodos: Estudio descriptivo retrospectivo, de corte transversal, mediante revisión de historias clínicas, de enero de 2000 a julio de 2005.Resultados: Se analizaron 65 pacientes que consultaron por adenopatías; el rango de edad fue de 1 a 16 años con predominio de menores de 5 años (41.5%), siendo en el sexo predominante el masculino en un 68%. El promedio de tiempo transcurrido desde el inicio de los síntomas hasta la consulta fue de 207 días. 81.5% (53/65) de los pacientes presentaron adenomegalias localizadas, de los cuales el 66% correspondió a la región lateral cervical, 18.5% (12/65) presentaron adenomegalias generalizadas. La asociación con esplenomegalia se observó en el 18.5% (12/65), hepatomegalia en el 17% (11/65) y síntomas sistémicos en el 31% (20/65). Se realizaron radiografías de tórax en el 91% (59/65), constatándose ensanchamiento mediastinal en el 34% (20/59). Estudio de ecografía abdominal se realizó en el 55% (36/65), observando hepatomegalia en un 14% (5/36), adenopatías linfáticas en el 5% (2/36). Tomografía Axial Computada (TAC) de abdomen se realizó en el 49% (32/65), la cual reveló adenopatías retroperitoneales y paraaórticas en el 22% (7/32). La TAC de tórax se realizó en el 49%, presentando adenopatías mediastinales y nódulos pulmonares en el 37.5% (12/32). La biopsia ganglionar se indicó en un 66% de los casos, y aspirado de médula ósea en el 48%. Como diagnóstico final se tuvo una leve predominancia de patologías malignas, Adenitis infecciosa en el 37%, Hiperplasia reactiva inespecífica 5% (3/65), pero el porcentaje de enfermedad maligna, en este caso Linfoma de Hodgkin fue alto correspondiendo al 48% de los casos (31/65).Conclusiones: La atención del niño con adenopatía debe seguir un esquema de manejo organizado, orientado a adoptar la conducta más acorde a cada caso, buscando el diagnóstico oportuno y así asegurar el adecuado tratamiento

Testing the role of predicted gene knockouts in human anthropometric trait variation.

Although the role of complete gene inactivation by two loss-of-function mutations inherited in trans is well-established in recessive Mendelian diseases, we have not yet explored how such gene knockouts (KOs) could influence complex human phenotypes. Here, we developed a statistical framework to test the association between gene KOs and quantitative human traits. Our method is flexible, publicly available, and compatible with common genotype format files (e.g. PLINK and vcf). We characterized gene KOs in 4,498 participants from the NHLBI Exome Sequence Project (ESP) sequenced at high coverage (>100X), 1,976 French Canadians from the Montreal Heart Institute Biobank sequenced at low coverage (5.7X), and >100,000 participants from the GIANT Consortium genotyped on an exome array. We tested associations between gene KOs and three anthropometric traits: body mass index (BMI), height and BMI-adjusted waist-to-hip ratio (WHR). Despite our large sample size and multiple datasets available, we could not detect robust associations between specific gene KOs and quantitative anthropometric traits. Our results highlight several limitations and challenges for future gene KO studies in humans, in particular when there is no prior knowledge on the phenotypes that might be affected by the tested gene KOs. They also suggest that gene KOs identified with current DNA sequencing methodologies probably do not strongly influence normal variation in BMI, height, and WHR in the general human population

The arginine methyltransferase PRMT7 promotes extravasation of monocytes resulting in tissue injury in COPD.

Extravasation of monocytes into tissue and to the site of injury is a fundamental immunological process, which requires rapid responses via post translational modifications (PTM) of proteins. Protein arginine methyltransferase 7 (PRMT7) is an epigenetic factor that has the capacity to mono-methylate histones on arginine residues. Here we show that in chronic obstructive pulmonary disease (COPD) patients, PRMT7 expression is elevated in the lung tissue and localized to the macrophages. In mouse models of COPD, lung fibrosis and skin injury, reduced expression of PRMT7 associates with decreased recruitment of monocytes to the site of injury and hence less severe symptoms. Mechanistically, activation of NF-κB/RelA in monocytes induces PRMT7 transcription and consequential mono-methylation of histones at the regulatory elements of RAP1A, which leads to increased transcription of this gene that is responsible for adhesion and migration of monocytes. Persistent monocyte-derived macrophage accumulation leads to ALOX5 over-expression and accumulation of its metabolite LTB4, which triggers expression of ACSL4 a ferroptosis promoting gene in lung epithelial cells. Conclusively, inhibition of arginine mono-methylation might offer targeted intervention in monocyte-driven inflammatory conditions that lead to extensive tissue damage if left untreated

Loss-of-function mutations in <em>SLC30A8</em> protect against type 2 diabetes.

Loss-of-function mutations protective against human disease provide in vivo validation of therapeutic targets, but none have yet been described for type 2 diabetes (T2D). Through sequencing or genotyping of ~150,000 individuals across 5 ancestry groups, we identified 12 rare protein-truncating variants in SLC30A8, which encodes an islet zinc transporter (ZnT8) and harbors a common variant (p.Trp325Arg) associated with T2D risk and glucose and proinsulin levels. Collectively, carriers of protein-truncating variants had 65% reduced T2D risk (P = 1.7 &times; 10(-6)), and non-diabetic Icelandic carriers of a frameshift variant (p.Lys34Serfs*50) demonstrated reduced glucose levels (-0.17 s.d., P = 4.6 &times; 10(-4)). The two most common protein-truncating variants (p.Arg138* and p.Lys34Serfs*50) individually associate with T2D protection and encode unstable ZnT8 proteins. Previous functional study of SLC30A8 suggested that reduced zinc transport increases T2D risk, and phenotypic heterogeneity was observed in mouse Slc30a8 knockouts. In contrast, loss-of-function mutations in humans provide strong evidence that SLC30A8 haploinsufficiency protects against T2D, suggesting ZnT8 inhibition as a therapeutic strategy in T2D prevention