Factors predisposing to obesity: a review of the literature

Comparative Analysis of Genes Associated with Obesity in Humans Using Bioinformatic Data and Tools

Obesity has become a serious global problem that still needs a solution. One of the factors that leads to obesity is genetic predisposition. The identity and characteristics of the genes involved have not yet been fully confirmed. Analyzing the genetic contribution to obesity is a major step towards the solution. In this in silico study, using online bioinformatics tools, we evaluate the role of four genes that are believed to contribute to obesity. Data were collected and analyzed for the sequences of four so-called obesity genes: FTO (fat mass and obesity-associated protein), PPARG (peroxisome proliferator activated receptor γ), ADRB3 (adrenergic receptor β 3) and FABP2 (fatty acid binding protein 2). In the first part of the research, information about the genes was collected and organized and data in FASTA, format are extracted from the National Center for Biotechnology Information (NCBI). In the second part, all genes were analyzed by comparing three species of organisms, Homo sapiens (human), Mus musculus (mouse) and Gallus (chicken). In the third part of this study, phylogenetic trees were constructed for each of the four genes, using blast local alignment search tool (BLAST) and molecular evolutionary genetics analysis (MEGA X) software. Our analysis reveals that the functions of all these genes are associated with overweight and obesity.

Role of estrogen receptors, P450 aromatase, PCNA and p53 in high-fat-induced impairment of spermatogenesis in rats

Obesity and overweight are frequently associated with male subfertility. To address new findings on the players involved in the obesity-induced impairment of spermatogenesis, we used a high-fat diet-induced overweight-rat model. Following four weeks of high-fat diet, the organization of seminiferous epithelium was affected, and tubules lumen showed immature/degenerated cells, typical signs of hormonal imbalance and testicular damage. Real-time PCR analysis allowed us to detect increased levels of ERα and decreased levels of aromatase CYP19 transcripts in testis, suggesting an increase in circulating estrogens derived from the accumulating adipose tissue rather than the induction of testicular estrogen synthesis. Moreover, in situ hybridization analysis showed an increased susceptibility towards estrogens in testis from high-fat fed rats, being ERs expressed not only in spermatogonia, as in control testis, but also in spermatids. Western blot and immunohistochemical analyses revealed an increase in the amount of p53 and PCNA, together with a change in their immunodetection, being the proteins localised on germ cells at different stages of maturation. Differences in p53 and PCNA expression may give evidence and be part of a cellular response to stress conditions and damage caused by the excessive intake of saturated fatty acids.