Correlation of peroxisome proliferator-activated receptor (PPAR-γ) mRNA expression with Pro12Ala polymorphism in obesity

LncRNA H19 promotes adipogenic differentiation disorder by sponging miR-130b-3p to upregulate PPARγ in steroid-induced osteonecrosis of the femoral head

Steroid-induced osteonecrosis of the femoral head (SONFH) is a debilitating condition linked to glucocorticoid-induced adipogenic dysregulation of bone marrow mesenchymal stem cells (BMSCs). While long noncoding RNA H19 has been implicated in differentiation disorders across pathologies, its role in SONFH remains undefined. This study investigated H19's regulatory mechanism in SONFH progression. We observed significant upregulation of H19 in both femoral head lesions and BMSCs from SONFH patients compared to controls. Knockdown of H19 in SONFH-derived BMSCs suppressed peroxisome proliferator-activated receptor γ (PPARγ) expression, attenuated adipogenic differentiation, and reduced lipid accumulation, as evidenced by decreased Oil Red O staining and FABP4 levels. Mechanistically, H19 acted as a competitive endogenous RNA (ceRNA) by sponging miR-130b-3p, thereby alleviating miR-130b-3p-mediated repression of PPARγ. Luciferase assays confirmed direct binding between miR-130b-3p and H19/PPARγ, while rescue experiments demonstrated that miR-130b-3p inhibition reversed PPARγ downregulation induced by H19 silencing. Our findings reveal a novel H19/miR-130b-3p/PPARγ axis driving adipogenic differentiation of BMSCs in SONFH, positioning H19 as a potential therapeutic target. This study provides critical insights into the epigenetic regulation of BMSC lineage commitment in SONFH pathogenesis, offering new avenues for intervention.

PPAR-γ Gene Expression in Human Adipose Tissue Is Associated with Weight Loss After Sleeve Gastrectomy

BACKGROUND

The peroxisome proliferator-activated receptor (PPAR)-γ plays a key role in adipose tissue differentiation and fat metabolism. However, it is unclear which factors may regulate its expression and whether obese patients have changes in adipose tissue expression of PPAR-γor potential regulators such as miR-27. Thus, our aims were to analyze PPAR-γ and miR-27 expression in adipose tissue of obese patients, and to correlate their levels with clinical variables.

SUBJECTS AND METHODS

We included 43 morbidly obese subjects who underwent sleeve gastrectomy (31 of them completed 1-year follow-up) and 19 non-obese subjects. mRNA expression of PPAR-γ1 and PPAR-γ2, miR-27a, and miR-27b was measured by qPCR in visceral and subcutaneous adipose tissue. Clinical variables and serum adipokine and hormone levels were correlated with PPAR-γ and miR-27 expression. In addition, a systematic review of the literature regarding PPAR-γ expression in adipose tissue of obese patients was performed.

RESULTS

We found no differences in the expression of PPAR-γ and miR-27 in adipose tissue of obese patients vs. controls. The literature review revealed discrepant results regarding PPAR-γ expression in adipose tissue of obese patients. Of note, we described a significant negative correlation between pre-operative PPAR-γ1 expression in adipose tissue of obese patients and post-operative weight loss, potentially linked with insulin resistance markers.

CONCLUSION

PPAR-γ1 expression in adipose tissue is associated with weight loss after sleeve gastrectomy and may be used as a biomarker for response to surgery.

Genetic polymorphisms associated with obesity in the Arab world: a systematic review

BACKGROUND

Obesity, one of the most common chronic health conditions worldwide, is a multifactorial disease caused by complex genetic and environmental interactions. Several association studies have revealed a considerable number of candidate loci for obesity; however, the genotype-phenotype correlations remain unclear. To date, no comprehensive systematic review has been conducted to investigate the genetic risk factors for obesity among Arabs.

OBJECTIVES

This study aimed to systematically review the genetic polymorphisms that are significantly associated with obesity in Arabs.

METHODS

We searched four literature databases (PubMed, Science Direct, Scopus, and Google Scholar) from inception until May 2020 to obtain all reported genetic data related to obesity in Arab populations. Quality assessment and data extraction were performed individually by three investigators.

RESULTS

In total, 59 studies comprising a total of 15,488 cases and 9,760 controls were included in the systematic review. A total of 76 variants located within or near 49 genes were reported to be significantly associated with obesity. Among the 76 variants, two were described as unique to Arabs, as they have not been previously reported in other populations, and 19 were reported to be distinctively associated with obesity in Arabs but not in non-Arab populations.

CONCLUSIONS

There appears to be a unique genetic and clinical susceptibility profile of obesity in Arab patients.

Expression of the gene coading for PGC-1α in peripheral blood leukocytes and related gene variants in patients with Parkinson's disease

INTRODUCTION

Peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α) plays an important role in Parkinson's disease (PD). The aim of the study was to evaluate PGC-1α gene expression in the peripheral blood of PD patients. We also investigated PGC-1α-related gene variants and identified whether they are associated with PGC-1α gene expression.

METHODS

259 PD patients and 253 healthy controls were included in this study. PPARGC1A (the gene encoding PGC-1α) expression levels were tested using real-time PCR. Single nucleotide polymorphisms (SNPs) of the PGC-1α-related genes (PPARGC1A, PPARG and SIRT1) were genotyped by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

RESULTS

PPARGC1A levels were significantly decreased in PD patients (P = 0.000) and negatively correlated with the patients' H&Y stage (r = -0.212, P = 0.039) and UPDRS-III score (r = -0.208, P = 0.044), after correcting, these correlations disappeared. The genotype frequencies of PGC-1α-related gene variants were not associated with the risk of PD. PPARGC1A rs2970870 variant was associated with the NMS score (P = 0.026), SIRT1 rs7895833 variant was associated with HAMA score (P = 0.029). PPARG rs4684847 variant was associated with MMSE score (P = 0.031). PPARG rs1801282, rs4684847, rs3856806 variants were associated with MoCA score. After correcting, only the association between PPARG rs4684847 and MoCA score remained significant (FDR = 0.048). PGC-1α-related gene variants had no effect on PGC-1α gene expression.

CONCLUSION

The decreased expression of PGC-1α may not be due to its related gene variants. PGC-1α could become a candidate blood-based biomarker for diagnosis and monitoring disease progression.

Genetic association studies of obesity in Africa: a systematic review

Obesity is increasing in Africa, but the underlying genetic background largely remains unknown. We assessed existing evidence on genetic determinants of obesity among populations within Africa. MEDLINE and EMBASE were searched and the bibliographies of retrieved articles were examined. Included studies had to report on the association of a genetic marker with obesity indices and the presence/occurrence of obesity/obesity trait. Data were extracted on study design and characteristics, genetic determinants and effect estimates of associations with obesity indices. According to this data, over 300 polymorphisms in 42 genes have been studied in various population groups within Africa mostly through the candidate gene approach. Polymorphisms in genes such as ACE, ADIPOQ, ADRB2, AGRP, AR, CAPN10, CD36, C7orf31, DRD4, FTO, MC3R, MC4R, SGIP1 and LEP were found to be associated with various measures of obesity. Of the 36 polymorphisms previously validated by genome-wide association studies (GWAS) elsewhere, only FTO and MC4R polymorphisms showed significant associations with obesity in black South Africans, Nigerians and Ghanaians. However, these data are insufficient to establish the true nature of genetic susceptibility to obesity in populations within Africa. There has been recent progress in describing the genetic architecture of obesity among populations within Africa. This effort needs to be sustained via GWAS studies.

Relationship between expression and methylation of obesity-related genes in children

Epigenetic control of gene expression in children remains poorly understood, but new technologies can help elucidate the relationship between expression and DNA methylation. Here, we utilized the nCounter Analysis System to characterise the expression of 60 genes in 69 9-year-old children from a cohort with a high prevalence of obesity. nCounter expression levels ranged broadly (from 3 to over 10000 messenger RNA counts) and were divided into four categories: high (>2000 counts), moderate (200-1000 counts), low (100-200 counts) and marginal (<100 counts). For a subset of five genes (ADIPOR1, PPARG1, GSTM1, PON1 and ACACA) from different expression level categories, we validated nCounter data using reverse transcription-polymerase chain reaction (RT-PCR), and expanded RT-PCR analysis of ADIPOR1 to include 180 children. Expression data from the two methodologies were correlated for all five genes included in the validation experiment, with estimates ranging from r s = 0.26 (P = 0.02) to r s = 0.88 (P < 5×10(-6)). ADIPOR1 and PPARG1 nCounter expression levels were negatively correlated (r = -0.60, P < 5×10(-5)), and this relationship was stronger in overweight children (r = -0.73, P < 5×10(-5)) than in normal weight children (r = -0.42, P = 0.016). Using methylation data from the Infinium HumanMethylation450 BeadChip (n = 180), we found eight CpG sites in ADIPOR1 and PPARG where methylation level was associated with expression by RT-PCR (P < 0.05). Hypomethylation of PPARG gene body site cg10499651 was associated with increased expression as measured by both RT-PCR and nCounter (P < 0.05). We found no statistically significant relationships between either expression or methylation of ADIPOR1 and PPARG and body mass index or waist circumference. In addition to demonstrating the validity of expression data derived from nCounter, our results illustrate the use of new technologies in assessing epigenetic effects on expression in children.

Genetics of oxidative stress in obesity

Obesity is a multifactorial disease characterized by the excessive accumulation of fat in adipose tissue and peripheral organs. Its derived metabolic complications are mediated by the associated oxidative stress, inflammation and hypoxia. Oxidative stress is due to the excessive production of reactive oxygen species or diminished antioxidant defenses. Genetic variants, such as single nucleotide polymorphisms in antioxidant defense system genes, could alter the efficacy of these enzymes and, ultimately, the risk of obesity; thus, studies investigating the role of genetic variations in genes related to oxidative stress could be useful for better understanding the etiology of obesity and its metabolic complications. The lack of existing literature reviews in this field encouraged us to gather the findings from studies focusing on the impact of single nucleotide polymorphisms in antioxidant enzymes, oxidative stress-producing systems and transcription factor genes concerning their association with obesity risk and its phenotypes. In the future, the characterization of these single nucleotide polymorphisms (SNPs) in obese patients could contribute to the development of controlled antioxidant therapies potentially beneficial for the treatment of obesity-derived metabolic complications.