The minor allele of the CREBRF rs373863828 p.R457Q coding variant is associated with reduced levels of myostatin in males: Implications for body composition

A Polynesian-specific SLC22A3 variant associates with low plasma lipoprotein(a) concentrations independent of apo(a) isoform size in males

Lipoprotein(a) (Lp(a)) is a low-density lipoprotein (LDL)-like particle in which the apolipoprotein B component is covalently linked to apolipoprotein(a) (apo(a)). Lp(a) is a well-established independent risk factor for cardiovascular diseases. Plasma Lp(a) concentrations vary enormously between individuals and ethnic groups. Several nucleotide polymorphisms in the SLC22A3 gene associate with Lp(a) concentration in people of different ethnicities. We investigated the association of a Polynesian-specific (Māori and Pacific peoples) SLC22A3 gene coding variant p.Thr44Met) with the plasma concentration of Lp(a) in a cohort of 302 healthy Polynesian males. An apo(a)-size independent assay assessed plasma Lp(a) concentrations; all other lipid and apolipoprotein concentrations were measured using standard laboratory techniques. Quantitative real-time polymerase chain reaction was used to determine apo(a) isoforms. The range of metabolic (HbA1c, blood pressure, and blood lipids) and blood lipid variables were similar between the non-carriers and carriers in age, ethnicity and BMI adjusted models. However, rs8187715 SLC22A3 variant was significantly associated with lower Lp(a) concentrations. Median Lp(a) concentration was 10.60 nmol/L (IQR: 5.40-41.00) in non-carrier group, and was 7.60 nmol/L (IQR: 5.50-12.10) in variant carrier group (P<0.05). Lp(a) concentration inversely correlated with apo(a) isoform size. After correction for apo(a) isoform size, metabolic parameters and ethnicity, the association between the SLC22A3 variant and plasma Lp(a) concentration remained. The present study is the first to identify the association of this gene variant and low plasma Lp(a) concentrations. This provides evidence for better guidance on ethnic specific cut-offs when defining 'elevated' and 'normal' plasma Lp(a) concentrations in clinical applications.

Cellular Senescence and Extracellular Vesicles in the Pathogenesis and Treatment of Obesity-A Narrative Review

This narrative review explores the pathophysiology of obesity, cellular senescence, and exosome release. When exposed to excessive nutrients, adipocytes develop mitochondrial dysfunction and generate reactive oxygen species with DNA damage. This triggers adipocyte hypertrophy and hypoxia, inhibition of adiponectin secretion and adipogenesis, increased endoplasmic reticulum stress and maladaptive unfolded protein response, metaflammation, and polarization of macrophages. Such feed-forward cycles are not resolved by antioxidant systems, heat shock response pathways, or DNA repair mechanisms, resulting in transmissible cellular senescence via autocrine, paracrine, and endocrine signaling. Senescence can thus affect preadipocytes, mature adipocytes, tissue macrophages and lymphocytes, hepatocytes, vascular endothelium, pancreatic β cells, myocytes, hypothalamic nuclei, and renal podocytes. The senescence-associated secretory phenotype is closely related to visceral adipose tissue expansion and metaflammation; inhibition of SIRT-1, adiponectin, and autophagy; and increased release of exosomes, exosomal micro-RNAs, pro-inflammatory adipokines, and saturated free fatty acids. The resulting hypernefemia, insulin resistance, and diminished fatty acid β-oxidation lead to lipotoxicity and progressive obesity, metabolic syndrome, and physical and cognitive functional decline. Weight cycling is related to continuing immunosenescence and exposure to palmitate. Cellular senescence, exosome release, and the transmissible senescence-associated secretory phenotype contribute to obesity and metabolic syndrome. Targeted therapies have interrelated and synergistic effects on cellular senescence, obesity, and premature aging.

The impact of CREBRF rs373863828 Pacific-variant on infant body composition

In Māori and Pacific adults, the CREBRF rs373863828 minor (A) allele is associated with increased body mass index (BMI) but reduced incidence of type-2 and gestational diabetes mellitus. In this prospective cohort study of Māori and Pacific infants, nested within a nutritional intervention trial for pregnant women with obesity and without pregestational diabetes, we investigated whether the rs373863828 A allele is associated with differences in growth and body composition from birth to 12-18 months' corrected age. Infants with and without the variant allele were compared using generalised linear models adjusted for potential confounding by gestation length, sex, ethnicity and parity, and in a secondary analysis, additionally adjusted for gestational diabetes. Carriage of the rs373863828 A allele was not associated with altered growth and body composition from birth to 6 months. At 12-18 months, infants with the rs373863828 A allele had lower whole-body fat mass [FM 1.4 (0.7) vs. 1.7 (0.7) kg, aMD -0.4, 95% CI -0.7, 0.0, P = 0.05; FM index 2.2 (1.1) vs. 2.6 (1.0) kg/m2 aMD -0.6, 95% CI -1.2,0.0, P = 0.04]. However, this association was not significant after adjustment for gestational diabetes, suggesting that it may be mediated, at least in part, by the beneficial effect of CREBRF rs373863828 A allele on maternal glycemic status.

Generation of a genetically modified pig model with CREBRFR457Q variant

Obesity is among the strongest risk factors for type 2 diabetes (T2D). The CREBRF missense allele rs373863828 (p. Arg457Gln, p. R457Q) is associated with increased body mass index but reduced risk of T2D in people of Pacific ancestry. To investigate the functional consequences of the CREBRF variant, we introduced the corresponding human mutation R457Q into the porcine genome. The CREBRF^R457Q pigs displayed dramatically increased fat deposition, which was mainly distributed in subcutaneous adipose tissue other than visceral adipose tissue. The CREBRF^R457Q variant promoted preadipocyte differentiation. The increased differentiation capacity of precursor adipocytes conferred pigs the unique histological phenotype that adipocytes had a smaller size but a greater number in subcutaneous adipose tissue (SAT) of CREBRF^R457Q variant pigs. In addition, in SAT of CREBRF^R457Q pigs, the contents of the peroxidative metabolites 4-hydroxy-nonenal and malondialdehyde were significantly decreased, while the activity of antioxidant enzymes, such as glutathione peroxidase, superoxide dismutase, and catalase, was increased, which was in accordance with the declined level of the reactive oxygen species (ROS) in CREBRF^R457Q pigs. Together, these data supported a causal role of the CREBRF^R457Q variant in the pathogenesis of obesity, partly via adipocyte hyperplasia, and further suggested that reduced oxidative stress in adipose tissue may mediate the relative metabolic protection afforded by this variant despite the related obesity.

The PPARGC1A Is the Gene Responsible for Thrifty Metabolism Related Metabolic Diseases: A Scoping Review

The "thrifty genotype" hypothesis has thus far described the relationship between specific genes and the population's resilience to food scarcity circumstances, but its link to the widespread prevalence of genetic diseases and metabolic syndrome has not been adequately mapped. The purpose of the study was to discover genes responsible for thrifty metabolism. A systematic search with keywords was performed for relevant titles. This study used the article's database published by Pubmed, Proquest, and EBSCO from January, 2009 to September, 2022. Out of 418 papers screened for eligibility, the final evaluation determined that five studies should be included in the analysis. Results indicated that PPARGC1A Gly482Ser led to high BMI in the Tongans population but was unrelated to the onset of type 2 diabetes mellitus, but this was not the case in the Maori population. Significantly differing frequencies of PPAR C1431T and Pro12Ala gene polymorphisms were observed in the Iranian population. GWAS identification of additional genes in Asian and European populations did not produce consistent findings. As a summary, PPARGC1A Gly482Ser addresses as the gene responsible for thrifty metabolism in the Pacific population although some studies show inconsistent results.