Recent genome-wide association studies have identified a single nucleotide polymorphism within the last intron of MAP2K5 associated with a higher body mass index (BMI) in adults. MAP2K5 is a component of the MAPK-family intracellular signaling pathways, responding to extracellular growth factors such as brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF). In this study, we examined the association of this variant in two cohorts of children from Sweden and Greece. We examine the association of rs2241423 to BMI in a cohort of 474 Swedish children admitted for treatment of childhood obesity and 519 children matched for gender, ethnicity and socioeconomic background from the Stockholm area, as well as a cross-sectional cohort of 2308 Greek school children (Healthy Growth Study). Children were genotyped using a predesigned TaqMan polymorphism assay. Logistic regression was used to test for an association of rs2241423 to obesity in the cohort of Swedish children. Linear regression was used to test for an association of rs2241423 to BMI z-score and phenotypic measurements of body adiposity in the cohort of Greek children. Models were adjusted for age and gender. In the cohort of Greek children the model was also adjusted for stage of pubertal development. The minor allele of rs2241423, allele A, was associated with a protective effect against obesity in the cohort of Swedish children (p = 0.029, OR = 0.79 (95% CI: 0.64-0.98)), and with a lower BMI z-score in the cohort of Greek children (p = 0.028, β = -0.092). No association to phenotypic measurements of body fat distribution could be observed in our study. rs2241423 was associated with BMI and obesity in two independent European cohorts suggesting a role for MAP2K5 in early weight regulation.

Alcaligenes aquatilis strain QD168 (= CCUG 69566) is a marine hydrocarbon-degrading bacterium isolated from crude oil-polluted sediment from Quintero Bay, Central Chile. Here, we present the 4.32-Mb complete genome sequence of strain QD168, with 3,892 coding sequences, 58 tRNAs, and a 56.3% G+C content.

Medulloblastoma (MB), the most frequent malignant childhood brain tumor, can arise from cellular malfunctions during hindbrain development. Here we generate humanized models for Sonic Hedgehog (SHH)-subgroup MB via MYCN overexpression in primary human hindbrain-derived neuroepithelial stem (hbNES) cells or iPSC-derived NES cells, which display a range of aggressive phenotypes upon xenografting. iPSC-derived NES tumors develop quickly with leptomeningeal dissemination, whereas hbNES-derived cells exhibit delayed tumor formation with less dissemination. Methylation and expression profiling show that tumors from both origins recapitulate hallmarks of infant SHH MB and reveal that mTOR activation, as a result of increased Oct4, promotes aggressiveness of human SHH tumors. Targeting mTOR decreases cell viability and prolongs survival, showing the utility of these varied models for dissecting mechanisms mediating tumor aggression and demonstrating the value of humanized models for a better understanding of pediatric cancers.

Psychosocial stress is a key risk factor for substance abuse among adolescents. Recently, epigenetic processes such as DNA methylation have emerged as potential mechanisms that could mediate this relationship. The authors conducted a genome-wide methylation analysis to investigate whether differentially methylated regions are associated with psychosocial stress in an adolescent population. A methylome-wide analysis of differentially methylated regions was used to examine a sample of 1,287 14-year-old adolescents (50.7% of them female) from the European IMAGEN study. The Illumina 450k array was used to assess DNA methylation, pyrosequencing was used for technical replication, and linear regression analyses were used to identify associations with psychosocial stress and substance use (alcohol and tobacco). Findings were replicated by pyrosequencing a test sample of 413 participants from the IMAGEN study. Hypermethylation in the sterile alpha motif/pointed domain containing the ETS transcription factor (SPDEF) gene locus was associated with a greater number of stressful life events in an allele-dependent way. Among individuals with the minor G-allele, SPDEF methylation moderated the association between psychosocial stress and substance abuse. SPDEF methylation interacted with lifetime stress in gray matter volume in the right cuneus, which in turn was associated with the frequency of alcohol and tobacco use. SPDEF was involved in the regulation of trans-genes linked to substance use. Taken together, the study findings describe a novel epigenetic mechanism that helps explain how psychosocial stress exposure influences adolescent substance abuse.

Growth-differentiation factor 15 (GDF-15) is expressed in low to moderate levels in most healthy tissues and increases in response to inflammation. GDF-15 is associated with cardiovascular dysfunction and over-expressed in the myocardium of patients with myocardial infarction (MI). However, little is known about the function of GDF-15 in cardiovascular disease, and the underlying regulatory network of GDF-15 is not known. To investigate a possible association between GDF-15 levels and DNA methylation, we performed a genome-wide DNA methylation study of white blood cells in a population-based study (N = 717). Significant loci where replicated in an independent cohort (N = 963). We also performed a gene ontology (GO) enrichment analysis. We identified and replicated 16 CpG-sites (false discovery rate [FDR] < 0.05), at 11 independent loci including MIR21. MIR21 encodes a microRNA (miR-21) that has previously been shown to be associated with the development of heart disease. Interestingly, GDF15 mRNA contains a binding site for miR-21. Four sites were also differentially methylated in blood from participants previously diagnosed with MI and 14 enriched GO terms (FDR < 0.05, enrichment > 2) were identified, including 'cardiac muscle cell differentiation'. This study shows that GDF-15 levels are associated with differences in DNA methylation in blood cells, and a subset of the loci are also differentially methylated in participants with MI. However, there might be interactions between GDF-15 levels and methylation in other tissues not addressed in this study. These results provide novel links between GDF-15 and cardiovascular disease.

Invasive cervical cancer (ICC) with very low titer of high-risk human papillomavirus (HPV) has worse clinical outcome than cases with high titer, indicating a difference in molecular etiology. Fresh-frozen ICC tumors (n = 49) were classified into high- and low-HPV-titer cases using real-time PCR-based HPV genotyping. The mutation spectra were studied using the AmpliSeq Comprehensive Cancer Panel and the expression profiles using total RNA sequencing, and the results were validated using the AmpliSeq Transcriptome assay. HPV DNA genotyping and RNA sequencing showed that 16.6% of ICC tumors contained very low levels of HPV DNA and HPV transcripts. Tumors with low HPV levels had more mutations with a high allele frequency and fewer mutations with low allele frequency relative to tumors with high HPV titer. A number of genes showed significant expression differences between HPV titer groups, including genes with somatic mutations. Gene ontology and pathway analyses implicated the enrichment of genes involved in DNA replication, cell cycle control and extracellular matrix in tumors with low HPV titer. The results indicate that in low titer tumors, HPVs act as trigger of cancer development whereas somatic mutations are clonally selected and become drivers of the tumor development process. In contrast, in tumors with high HPV titer the expression of HPV oncoproteins plays a major role in tumor development and the many low frequency somatic mutations represent passengers. This putative subdivision of invasive cervical tumors may explain the higher radiosensitivity of ICC tumors with high HPV titer and thereby have consequences for clinical management.