Placental epigenetic marks related to gestational weight gain reveal potential genes associated with offspring obesity parameters.

OBJECTIVE: Offspring exposed to gestational obesity have an increased risk for chronic diseases. Increasing evidence suggests that epigenetics may play a mechanistic role in metabolic programming. This study aimed to identify placental DNA methylation marks associated with gestational weight gain (GWG) and to study their association with offspring obesity parameters at school age. METHODS: A global methylation array was performed in 24 placentas from mothers with different degrees of GWG (screening sample). The methylation percentage of four cytosine-guanine (CpG) sites and the relative expression of the respective annotated genes were studied in 90 additional placentas (validation sample). Associations of these epigenetic marks with clinical parameters in the offspring at 6 years of age were examined. RESULTS: The screening analysis identified 104 CpG sites (97 genes) associated with GWG. The validation analysis of four selected CpG sites (annotating for FRAT1, SNX5, and KCNK3 genes) showed that the upregulation of SNX5 methylation, the downregulation of FRAT1 methylation, and KCNK3 underexpression associated with an adverse metabolic phenotype in children of women with increased GWG. CONCLUSIONS: These results suggest that placental regulation of FRAT1, SNX5, and KCNK3 relates to obesity parameters in offspring exposed to excessive GWG and thereby could condition the risk for future metabolic disorders.

Iron status and cardiometabolic risk in children.

AIM: We aimed to evaluate associations between serum ferritin and transferrin and variables related to the metabolic syndrome (MetS) in children. METHODS: Cross-sectional and longitudinal study in prepubertal children (n = 832) aged 3-14 years. A subset (n = 203) were re-examined after a mean follow-up of 3.7 ± 0.8 years[range 2-6]. Outcomes were MetS and MetS components scores, glycosylated haemoglobin (HbA1c), and their follow-up change. RESULTS: Children with low ferritin had increased HbA1c Z scores (ANCOVA, P = 0.003). Ferritin was inversely associated with glycaemia [fully adjusted ß (95% confidence interval): -2.35(-4.36 to -0.34)]. Transferrin was associated with diastolic blood pressure [ß: 0.02(0.01-0.04)] and log-HOMA-IR [ß:0.001(0.0005-0.002)]. MetS risk score worsened during follow-up in children with the lowest baseline ferritin levels. In contrast, at baseline ferritin was positively associated with all (except glycaemia) the MetS-related variables but adjustments for inflammatory, hepatic function, and body mass markers attenuated those associations (P > 0.05). CONCLUSIONS: Lower iron status was independently associated with glycaemic markers and MetS in children, whereas higher ferritin levels were related to other cardiometabolic risk markers under the influence of inflammation, hepatic injury and body mass. Research is required to study whether this mixed pattern is part of an early risk or would be explained by a normal transition during growth and development.

Traction forces at the cytokinetic ring regulate cell division and polyploidy in the migrating zebrafish epicardium.

Epithelial repair and regeneration are driven by collective cell migration and division. Both cellular functions involve tightly controlled mechanical events, but how physical forces regulate cell division in migrating epithelia is largely unknown. Here we show that cells dividing in the migrating zebrafish epicardium exert large cell-extracellular matrix (ECM) forces during cytokinesis. These forces point towards the division axis and are exerted through focal adhesions that connect the cytokinetic ring to the underlying ECM. When subjected to high loading rates, these cytokinetic focal adhesions prevent closure of the contractile ring, leading to multi-nucleation through cytokinetic failure. By combining a clutch model with experiments on substrates of different rigidity, ECM composition and ligand density, we show that failed cytokinesis is triggered by adhesion reinforcement downstream of increased myosin density. The mechanical interaction between the cytokinetic ring and the ECM thus provides a mechanism for the regulation of cell division and polyploidy that may have implications in regeneration and cancer.

Iron Status and Metabolically Unhealthy Obesity in Prepubertal Children.

OBJECTIVE: This study aimed to evaluate the association of metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) with iron status markers in prepubertal children. METHODS: Three hundred twelve prepubertal children with overweight and obesity from a pediatric general Spanish population were evaluated. MHO and MUO were defined as obesity with the absence or presence of metabolic syndrome components. Phenotypes of metabolically healthy overweight including obesity (MHOV) and metabolically unhealthy overweight including obesity (MUOV) were also studied and defined using the same criteria. Serum ferritin, transferrin, and blood hemoglobin levels were evaluated. RESULTS: Prevalence rates of MHOV and MHO were 35% (n = 111/312) and 27.1% (n = 42/155), respectively. Ferritin and hemoglobin levels were higher in children with MUOV versus MHOV (P < 0.05). MUO was positively associated with ferritin (beta [95% CI] = 0.43 [0.05 to 0.81]) and hemoglobin levels (0.43 [0.05 to 0.81]). These associations remained significant independently of age, sex, C-reactive protein, physical activity, and BMI/waist z scores in bivariate linear regression models. In multivariable models, transaminase levels attenuated the association of MUO with ferritin and hemoglobin levels (P > 0.05). CONCLUSIONS: MUOV and MUO are associated with higher ferritin and hemoglobin levels in prepubertal children affected by overweight and obesity. Increased circulating ferritin in MUO might be influenced by liver injury.

Allele balance bias identifies systematic genotyping errors and false disease associations.

In recent years, next-generation sequencing (NGS) has become a cornerstone of clinical genetics and diagnostics. Many clinical applications require high precision, especially if rare events such as somatic mutations in cancer or genetic variants causing rare diseases need to be identified. Although random sequencing errors can be modeled statistically and deep sequencing minimizes their impact, systematic errors remain a problem even at high depth of coverage. Understanding their source is crucial to increase precision of clinical NGS applications. In this work, we studied the relation between recurrent biases in allele balance (AB), systematic errors, and false positive variant calls across a large cohort of human samples analyzed by whole exome sequencing (WES). We have modeled the AB distribution for biallelic genotypes in 987 WES samples in order to identify positions recurrently deviating significantly from the expectation, a phenomenon we termed allele balance bias (ABB). Furthermore, we have developed a genotype callability score based on ABB for all positions of the human exome, which detects false positive variant calls that passed state-of-the-art filters. Finally, we demonstrate the use of ABB for detection of false associations proposed by rare variant association studies. Availability: https://github.com/Francesc-Muyas/ABB.

Identification of Gene Mutations and Fusion Genes in Patients with Sézary Syndrome.

Sézary syndrome is a leukemic form of cutaneous T-cell lymphoma with an aggressive clinical course. The genetic etiology of the disease is poorly understood, with chromosomal abnormalities and mutations in some genes being involved in the disease. The goal of our study was to understand the genetic basis of the disease by looking for driver gene mutations and fusion genes in 15 erythrodermic patients with circulating Sézary cells, 14 of them fulfilling the diagnostic criteria of Sézary syndrome. We have discovered genes that could be involved in the pathogenesis of Sézary syndrome. Some of the genes that are affected by somatic point mutations include ITPR1, ITPR2, DSC1, RIPK2, IL6, and RAG2, with some of them mutated in more than one patient. We observed several somatic copy number variations shared between patients, including deletions and duplications of large segments of chromosome 17. Genes with potential function in the T-cell receptor signaling pathway and tumorigenesis were disrupted in Sézary syndrome patients, for example, CBLB, RASA2, BCL7C, RAMP3, TBRG4, and DAD1. Furthermore, we discovered several fusion events of interest involving RASA2, NFKB2, BCR, FASN, ZEB1, TYK2, and SGMS1. Our work has implications for the development of potential therapeutic approaches for this aggressive disease.

Soluble CRTC3: A Newly Identified Protein Released by Adipose Tissue That Is Associated with Childhood Obesity.

BACKGROUND: CREB-regulated transcription coactivator 3 (CRTC3) is found in adipocytes, where it may promote obesity through disruption of catecholamine signaling. We wished to assess whether CRTC3 is a soluble protein secreted by adipose tissue, explore whether CRTC3 is detectable and quantifiable in the circulation, and ascertain whether CRTC3 serum concentrations are related to metabolic markers in children. METHODS: Explants of adipose tissue from 12 children were cultured to study adipocyte cell size and the secretion of CRTC3 (immunoblot and ELISA). We also performed a cross-sectional and longitudinal study in 211 asymptomatic prepubertal white children at age 7 years, 115 of whom were followed up at age approximately 10 years. We measured circulating concentrations of CRTC3 and studied associations between serum CRTC3 and metabolic markers. RESULTS: Measurable concentrations of CRTC3 were found in conditioned media of adipose tissue explants and in serum samples. CRTC3 concentrations in visceral adipose tissue were negatively associated with adipocyte cell size and positively related to adipocyte cell number (P < 0.05). In the cross-sectional study, higher CRTC3 concentrations were associated with higher body mass index (P = 0.001), waist circumference (P = 0.003), and systolic blood pressure (P = 0.007) and lower high molecular weight adiponectin (P = 0.003). In the longitudinal study, serum concentrations of CRTC3 at age approximately 7 years were associated with changes in waist circumference (ß = 0.254; P = 0.004; r = 0.145) and high molecular weight adiponectin (ß=-0.271; P = 0.014; r = 0.101), respectively, at age approximately 10 years. CONCLUSIONS: CRTC3, a newly identified protein that is related to childhood obesity, is present in the circulation, partly as a result of adipose tissue secretion. Higher serum CRTC3 concentrations are related to and predict a poorer metabolic profile in children.

Balanced duo of anti-inflammatory SFRP5 and proinflammatory WNT5A in children.

BACKGROUND: Secreted frizzled-related protein 5 (SFRP5) is an adipokine protecting against obesity-related insulin resistance and diabetes. SFRP5 binds to wingless type mouse mammary tumor virus (MMTV) integration site family member 5A (WNT5A) to improve insulin sensitivity. We performed the first study of SFRP5 and WNT5A simultaneously in children. METHODS: Prepubertal children (n = 342) were assessed for circulating SFRP5 (all subjects) and circulating WNT5A (210 subjects), and associations were sought with metabolic markers. In conditioned media of adipose tissue explants from 12 additional children, SFRP5 and WNT5A were studied further. RESULTS: The concentrations of SFRP5 and WNT5A correlated positively in serum and in conditioned media (all P < 0.001). Lower level of circulating SFRP5 (lowest quartile) was associated with higher BMI (15% increase, P < 0.0001) and lower level of high-molecular-weight adiponectin (26% decrease, P = 0.002). Circulating WNT5A related closely with insulin resistance assessed by the homeostasis model assessment for insulin resistance and hepatic markers (alanine transaminase and gamma glutamyl transpeptidase), particularly in children with lower circulating SFRP5 levels (all P < 0.004). CONCLUSION: SFRP5 and WNT5A comprise a balanced duo that may regulate metabolic homeostasis in prepubertal children.

Genome-wide analysis of single nucleotide polymorphisms and copy number variants in fibromyalgia suggest a role for the central nervous system.

Fibromyalgia (FM) is a highly disabling syndrome defined by a low pain threshold and a permanent state of pain. The mechanisms explaining this complex disorder remain unclear, and its genetic factors have not yet been identified. With the aim of elucidating FM genetic susceptibility factors, we selected 313 FM cases having low comorbidities, and we genotyped them on the Illumina 1 million duo array. Genotypic data from 220 control women (Illumina 610k array) was obtained for genome-wide association scan (GWAS) analysis. Copy number variants in FM susceptibility were analyzed by array comparative genomic hybridization (aCGH) experiments on pooled samples using the Agilent 2×400K platform. No single nucleotide polymorphism (SNP) reached GWAS association threshold, but 21 of the most associated SNPs were chosen for replication in 952 cases and 644 controls. Four of the SNPs selected for replication showed a nominal association in the joint analysis, and rs11127292 (MYT1L) was found to be associated to FM with low comorbidities (P=4.28×10(-5), odds ratio [95% confidence interval]=0.58 [0.44-0.75]). aCGH detected 5 differentially hybridized regions. They were followed up, and an intronic deletion in NRXN3 was demonstrated to be associated to female cases of FM with low levels of comorbidities (P=.021, odds ratio [95% confidence interval]=1.46 [1.05-2.04]). Both GWAS and aCGH results point to a role for the central nervous system in FM genetic susceptibility. If the proposed FM candidate genes were further validated in replication studies, this would highlight a neurocognitive involvement in agreement with latest reports.

Association of NTRK3 and its interaction with NGF suggest an altered cross-regulation of the neurotrophin signaling pathway in eating disorders.

Eating disorders (EDs) are complex psychiatric diseases that include anorexia nervosa and bulimia nervosa, and have higher than 50% heritability. Previous studies have found association of BDNF and NTRK2 to ED, while animal models suggest that other neurotrophin genes might also be involved in eating behavior. We have performed a family-based association study with 151 TagSNPs covering 10 neurotrophin signaling genes: NGFB, BDNF, NTRK1, NGFR/p75, NTF4/5, NTRK2, NTF3, NTRK3, CNTF and CNTFR in 371 ED trios of Spanish, French and German origin. Besides several nominal associations, we found a strong significant association after correcting for multiple testing (P = 1.04 x 10(-4)) between ED and rs7180942, located in the NTRK3 gene, which followed an overdominant model of inheritance. Interestingly, HapMap unrelated individuals carrying the rs7180942 risk genotypes for ED showed higher levels of expression of NTRK3 in lymphoblastoid cell lines. Furthermore, higher expression of the orthologous murine Ntrk3 gene was also detected in the hypothalamus of the anx/anx mouse model of anorexia. Finally, variants in NGFB gene appear to modify the risk conferred by the NTRK3 rs7180942 risk genotypes (P = 4.0 x 10(-5)) showing a synergistic epistatic interaction. The reported data, in addition to the previous reported findings for BDNF and NTRK2, point neurotrophin signaling genes as key regulators of eating behavior and their altered cross-regulation as susceptibility factors for EDs.