IRX3 is a genetic modifier for birth weight, adolescent obesity and transaminase metabolism

Association of common genetic variants with body mass index in Russian population

BACKGROUND

Overweight is the scourge of modern society and a major risk factor for many diseases. For this reason, understanding the genetic component predisposing to high body mass index (BMI) seems to be an important task along with preventive measures aimed at improving eating behavior and increasing physical activity.

METHODS

We analyzed genetic data of a European cohort (n = 21,080, 47.25% women, East Slavs ancestry >80%) for 5 frequently found genes in the context of association with obesity: IPX3 (rs3751723), MC4R (rs17782313), TMEM18 (rs6548238), PPARG (rs1801282) and FTO (rs9939609).

RESULTS

Our study revealed significant associations of FTO (rs9939609) (β = 0.37 (kg/m²)/allele, p = <2 × 10^-16), MC4R (rs17782313) (β = 0.28 (kg/m²)/allele, p = 5.79 × 10^-9), TMEM18 (rs6548238) (β = 0.29 (kg/m²)/allele, p = 2.43 × 10^-8) with BMI and risk of obesity.

CONCLUSIONS

The results confirm the contribution of FTO, M4CR, and TMEM18 genes to the mechanism of body weight regulation and control.

Association between genetic risk score and tri-ponderal mass index growth trajectories among different dietary consumption adolescents in a prospective Taiwanese cohort

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in various genetic loci are associated with childhood obesity; however, their influence on adolescent growth patterns has rarely been explored. This study investigated whether genetic variants could predict tri-ponderal mass index (TMI)-derived growth trajectories and the interaction between genetic and dietary factors.

METHODS

We conducted Taiwan Puberty Longitudinal Study, a prospective cohort that recruited 1,135 children since 2018. Anthropometric measurements were recorded every three months, while dietary nutrition assessment and biological sampling for genotyping were collected during the first visit. TMI growth trajectory groups were identified using growth mixture modeling. A multinomial logistic regression model for different growth trajectories was used to examine the effect of candidate SNPs, and the most related SNPs were used to establish the genetic risk score. We then explored the effect of the genetic risk score in subgroup analysis according to dietary calories and different dietary consumption patterns.

RESULTS

Three TMI-based growth trajectory groups were identified among adolescents. The "increased weight" trajectory group accounted for approximately 9.7% of the participants. FTO/rs7206790 was associated with the increased weight growth trajectory after adjusting for the baseline TMI and other correlated covariates (OR: 2.13, 95% CI: 1.08-4.21). We generated the genetic risk score using 4 SNPs (FTO/rs7206790, ADCY9/rs2531995, TFAP2B/rs4715210, and TMEM18/rs6548238) and selected the threshold of 10 points to define risk categories. There were 11.66% and 3.24% of participants belonged to the increased weight trajectory in high- and low-risk groups, respectively; and the predictive ability of the genetic risk score was notable among low calories intake participants (OR: 1.90, 95% CI: 1.18-3.05 vs. OR: 1.17, 95% CI: 0.78-1.75 in high calories intake group).

CONCLUSION

Our results offer a new perspective on the genetic and dietary basis of changes in adolescent obesity status. Individualized interventions for obesity prevention may be considered among high-risk children.

IRX3 plays an important role in the pathogenesis of metabolic-associated fatty liver disease by regulating hepatic lipid metabolism

Metabolic-associated fatty liver disease (MAFLD) affects approximately a quarter of the global population. Identification of the key genes and pathways involved in hepatic lipid metabolism is of the utmost importance for the diagnosis, treatment, and prevention of MAFLD. In this study, differentially expressed genes were identified through whole-genome transcriptional analysis of liver tissue from MAFLD patients and healthy controls, and a series of lipid metabolism-related molecules and pathways were obtained through pathway analysis. Subsequently, we focused on Iroquois homeobox protein 3 (IRX3), one of 13 transcription factors that were screened from the 331 differentially expressed genes. The transcription factor IRX3 was significantly decreased in the liver tissue of patients with MAFLD when compared with healthy controls. Pearson's correlation analysis showed that the expression levels of IRX3 in liver tissue were negatively correlated with serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, and uric acid levels. The overexpression and interference of IRX3 induced the increased and decreased lipid droplet accumulation in vitro, respectively. Moreover, interference of IRX3 expression increased mitochondrial fragmentation and reduced the activity of the mitochondrial respiratory chain complex IV. In summary, the study demonstrated that IRX3 regulated hepatic lipid metabolism of MAFLD, and also revealed the effect of IRX3 on mitochondria might be an important mechanism by which IRX3 regulated hepatic lipid metabolism of MAFLD.

Adolescent Obesity Modeling: A Framework of Socio-Economic Analysis on Public Health

Bayesian Structural Equation Modeling (SEM-Bayesian) was applied across different research areas to model the correlation between manifest and latent variables. The primary purpose of this study is to introduce a new framework of complexity to adolescent obesity modeling based on adolescent lifestyle through the application of SEM-Bayesian. The introduced model was designed based on the relationships among several factors: household socioeconomic status, healthy food intake, unhealthy food intake, lifestyle, body mass index (BMI) and body fat. One of the main contributions of this study is from considering both BMI and body fat as dependent variables. To demonstrate the reliability of the model, especially in terms of its fitting and accuracy, real-time data were extracted and analyzed across 881 adolescents from secondary schools in Tehran, Iran. The output of this study may be helpful for researchers who are interested in adolescent obesity modeling based on the lifestyle and household socioeconomic status of adolescents.

Prevalence of precocious puberty among Chinese children: a school population-based study

PURPOSE

To investigate the prevalence of precocious puberty in school-based population in Zhongshan, Guangdong, China.

METHODS

We recruited a total of 4058 students in grades 1-3 using a multistage stratified cluster random sampling method in a population-based cross-sectional study. We evaluated height, weight, and development of breast and pubic hair in girls, breast development was evaluated by inspection and palpation combined with ultrasound detection for overweight and obese girls, and testicular volume and development of pubic hair in boys. We estimated overall, sex-, age, and district-specific prevalence of precocious puberty and examined the association between prevalence of precocious puberty and body mass index (BMI).

RESULTS

The unadjusted and adjusted prevalence of precocious puberty by Tanner stage was 4.74% (girls:8.78%, boys:2.58%) and 6.19% (girls:11.47%, boys:3.26%), respectively. In both urban and suburban areas, the prevalence of precocious puberty was higher in the overweight and obese group than in the normal-weight group (p < 0.05). The prevalence of precocious puberty among overweight (27.94%) and obese (48.00%) girls was higher than that of normal-weight girls (8.73%) (p value for trend < 0.05). In boys, the prevalence of precocious puberty in the obese (6.78%) group was higher than that in the normal-weight (2.86%) group (p < 0.05).

CONCLUSIONS

The prevalence of precocious puberty was high in China. Overweight and obesity was related to precocious puberty, but this correlation had gender differences and may be affected by other environmental factors.

The possible mechanisms of the effects of IRX3 gene on body weight: an overview

Introduction

Recent studies reported that FTO exert its effects on body weight through change the expression IRX3. The aim of this study was investigation of the possible mechanisms of the effects of IRX3 gene on obesity.

Material and methods

The present review was carried out using keywords such as polymorphism and/or obesity and/or BMI and/or IRX3 gene and/or Iroquois homeobox protein 3. Databases including PubMed, Science Direct, web of sciences, Scopus, and Cochran databases were used to collect all related articles published from 2000 to 2019.

Results

Based on this review, there are some evidences on the association between the IRX3 polymorphisms and the IRX3 expression level with body weight. In some studies, the up-regulation of IRX3 expression was related to increased body weight, while in some other studies down-regulation of IRX3 expression was related to obesity.

Conclusions

This review investigated the probable mechanisms of the effects of the IRX3 gene on obesity. Studies in this are limited and reported contradictory results. Further studies are required to evaluate the role of IRX3 gene in the associations between genes, diet, and obesity.

FTO and IRX3 Genes are Not Promising Markers for Obesity in Labrador Retriever Dogs

Obesity is a serious problem in numerous dog breeds, but knowledge of its hereditary background is scarce. On the contrary, numerous DNA polymorphisms associated with human obesity have been identified, with the strongest effect being demonstrated for FTO gene. We used targeted next-generation sequencing (tNGS) to search for polymorphisms in the region harboring FTO and IRX3 in 32 Labrador dogs. Moreover, we investigated the selected regions of FTO and IRX3, orthologous to the human regions associated with obesity, in 165 Labradors. For all dogs, the following information was available: age, sex, gonadal status, body weight, and body conformation score (BCS). The use of tNGS revealed 12,217 polymorphisms, but none of these obtained significance when lean and obese dogs were compared. Study of two SNPs in the 5’-flanking region of FTO in 165 dogs – creating two upstream reading frames (uORFs) – also showed no association with body weight and BCS but suggested the need for improvement in FTO annotation. No polymorphism was found in the 5’UTR of IRX3. Additionally, no differences of CpG islands methylation status between lean and obese dogs were found. Our study suggests that FTO and IRX3 are not useful markers of obesity in Labrador dogs.

The role of the genetic variants IRX3 rs3751723 and FTO rs9939609 in the obesity phenotypes of children and adolescents

OBJECTIVE

We investigated the association of IRX3 SNP rs3751723 with anthropometric characteristics related to adiposity and potential relationships with FTO SNP rs9939609 in a population of Brazilian children and adolescents.

METHODS

A total of 871 children and adolescents between 7 and 17 years of age were recruited. Adiposity measurements and biochemical parameters were assessed. The variants were genotyped by real-time PCR. Analysis of multiple linear regression, multiple logistic regression, and generalised multifactor dimensionality reduction (GMDR) adjusted for sex, age and ethnicity were applied to test the polymorphisms association with obesity-related phenotypes and the interaction between them.

RESULTS

The analyses showed that IRX3 was associated with obesity and fat percentage (BF%). An association of FTO rs9939609 with body mass index (BMI) Z-Score and with waist circumference (WC) was detected. The odds ratios (OR) showed that IRX3 rs3751723 was associated with risk of obesity in additive model (p=0.017), recessive model (p=0.016) and with high BF% in all models. FTO rs9939609 was associated with risk of obesity in additive model (p=0.031), recessive (p=0.033) and with altered WC in all models. GMDR-based predictive models for the risk of obesity, altered WC and high BF% adjusted by age, ethnicity and sex suggested no interaction of the two loci.

CONCLUSIONS

The genetic variants rs3751723 and rs9939609 have an influence on the characteristics of adiposity; however, the effects of IRX3 and FTO investigated polymorphisms are independent in relation to adiposity parameters.

Gestational diabetes mellitus alters DNA methylation profiles in pancreas of the offspring mice

Gestational diabetes mellitus (GDM), which has an increasing global prevalence, contributes to the susceptibility to metabolic dysregulation and obesity in the offspring via epigenetic modifications. However, the underlying mechanism remains largely obscure. The current study established a GDM mice model to investigate the alternations in the metabolic phenotypes and genomic DNA methylation in the pancreas of the offspring. We found that in the GDM offspring, intrauterine hyperglycemia induced dyslipidemia, insulin resistance, and glucose intolerance. Meanwhile, altered DNA methylation patterns were exhibited in the pancreas and many differentially methylated regions (DMRs)-related genes were involved in glycolipids metabolism and related signaling pathways, including Agap2, Plcbr, Hnf1b, Gnas, Fbp2, Cdh13, Wnt2, Kcnq1, Lhcgr, Irx3, etc. Additionally, the overall hypermethylation of Agap2, verified by bisulfite sequencing PCR (BSP), was negatively correlated with its mRNA expression level. In conclusion, these findings suggest that the DNA methylation changes in the pancreatic genome of the GDM offspring may be associated with the glycolipid metabolism abnormalities, T2DM susceptibility, and obesity in the adult GDM offspring.