Genetic determinants of adiponectin regulation revealed by pregnancy

Mechanisms and Physiological Roles of Polymorphisms in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a significant pregnancy complication linked to perinatal complications and an elevated risk of future metabolic disorders for both mothers and their children. GDM is diagnosed when women without prior diabetes develop chronic hyperglycemia due to β-cell dysfunction during gestation. Global research focuses on the association between GDM and single nucleotide polymorphisms (SNPs) and aims to enhance our understanding of GDM's pathogenesis, predict its risk, and guide patient management. This review offers a summary of various SNPs linked to a heightened risk of GDM and explores their biological mechanisms within the tissues implicated in the development of the condition.

Short-term treatment with risperidone ameliorated 1,2-diacetylbenzene-induced liver dysfunction

1,2-Diacetylbenze (C10H10O2, DAB) is a potential inducer or activator of toxic mechanisms. DAB exerts high absorption by the gastrointestinal tract and high blood-brain barrier penetration. However, only the effects of DAB on the central nervous system were reported, with a dearth of evidence of DAB's effects on the liver, which is more susceptible to toxic substances. Risperidone, an atypical antipsychotic drug, has been shown to protect against DAB-induced cognitive impairment in an animal model. Risperidone was found to have little or no effect on the liver after short-term administration. The question of whether risperidone can protect against DAB-induced liver dysfunction, particularly after short-term administration, is unknown. Thus, this study aimed to assess the hepatoprotective effects of risperidone on DAB-induced liver dysfunction in male C57BL/6 mice treated with DAB 5 mg/kg for 1 week and risperidone 0.125-0.25 mg/kg for 2 weeks. After exposure to DAB 5 mg/kg for 1 week, we found that DAB induced liver damage by increasing liver function biomarkers (GGT, ALT, and AST), reactive oxygen species, nitric oxide, and proinflammatory cytokines (IL-1α, IL-1β, IL-6, IL-12, and TNF- α), activating apoptosis (elevated Caspase-3 and Bax levels and reduced Bcl2 level), TLR4/JNK/NF-κB, Jak2/Stat5 pathways, and suppressing Jak2/Stat3 and IRS1/PI3K/AKT/MDM2 pathways. After a 2-week course of treatment, risperidone was able to lessen these effects; the higher dose (0.25 mg/kg) appeared to be more effective than the lower dose (0.125 mg/kg). To strengthen findings from in vivo analysis, in silico analysis also found three targets (Stat3, Caspase-3, AKT, IL-1β), two miRNAs (miR-26b-5p and miR-34a-5p), two transcription factors (NFKB1 and NFKB2), and numerous pathways ("AGE-RAGE signaling pathway in diabetic complications", "hepatitis B", "alcoholic liver disease", "apoptosis", and "liver cirrhosis") as the key molecular processes involved in the pathogenesis of DAB-induced liver damage and targeted by risperidone. The physicochemical characteristics and pharmacokinetics of DAB and risperidone also support the toxic effects of DAB and the beneficial properties of risperidone in the liver. In conclusion, these findings reflect the therapeutic effects of risperidone on DAB-induced liver dysfunction after 1 week and 2 weeks exposure to DAB and risperidone, respectively.

TCDD-inducible Poly (ADP-ribose) Polymerase Promotes Adipogenesis of Both Brown and White Preadipocytes

Background

TCDD-inducible poly (ADP-ribose) polymerase (TiPARP) is a DNA repair enzyme with functions in energy metabolism, signal transduction, cell differentiation, and other biological processes, which may closely related to lipid metabolism and is highly expressed in adipose tissue. Adipose tissue can be divided into white adipose tissue (WAT) that stores energy and brown adipose tissue (BAT) that releases energy and generates heat. In the present study, we investigated whether TiPARP can affect adipogenesis in adipose tissue and thus participate in the development of obesity.

Methods

BAT primary cells or 3T3-L1 cells infected with adenovirus expressing TiPARP or TiPARP-targeted short hairpin RNA (shTiPARP) were cultured to induce adipogenic differentiation. The expression of TiPARP was detected by real-time PCR and Western blotting. The expression of specific BAT- and WAT-related markers was detected by real-time PCR. The accumulation of lipid droplets in differentiated cells was detected by Oil Red O staining.

Results

TiPARP was highly expressed in both subcutaneous WAT and BAT, and TiPARP mRNA level increased significantly along with adipogenic differentiation. Activation of TiPARP or overexpression of TiPARP upregulated BAT-related markers in primary BAT cells and WAT-related markers in 3T3-L1 cells, together with increased lipid accumulation. On the contrary, knockdown of TiPARP downregulated expression of specific markers in both BAT primary cells and 3T3-L1 cells, together with decreased lipid accumulation.

Conclusion

TiPARP regulates adipogenesis in both BAT primary cells and 3T3-L1 cells and therefore plays an important role in modulating maturity and lipid accumulation in brown and white adipocytes. These findings provide us with a new strategy for combating obesity.

Placental DNA methylation signatures of maternal smoking during pregnancy and potential impacts on fetal growth

Maternal smoking during pregnancy (MSDP) contributes to poor birth outcomes, in part through disrupted placental functions, which may be reflected in the placental epigenome. Here we present a meta-analysis of the associations between MSDP and placental DNA methylation (DNAm) and between DNAm and birth outcomes within the Pregnancy And Childhood Epigenetics (PACE) consortium (N = 1700, 344 with MSDP). We identify 443 CpGs that are associated with MSDP, of which 142 associated with birth outcomes, 40 associated with gene expression, and 13 CpGs are associated with all three. Only two CpGs have consistent associations from a prior meta-analysis of cord blood DNAm, demonstrating substantial tissue-specific responses to MSDP. The placental MSDP-associated CpGs are enriched for environmental response genes, growth-factor signaling, and inflammation, which play important roles in placental function. We demonstrate links between placental DNAm, MSDP and poor birth outcomes, which may better inform the mechanisms through which MSDP impacts placental function and fetal growth.

Heterogeneous impact of type 2 diabetes mellitus-related genetic variants on gestational glycemic traits: review and future research needs

Gestational glucose homeostasis influences mother's metabolic health, pregnancy outcomes, fetal development and offspring growth. To understand the genetic roles in pregnant glucose metabolism and genetic predisposition for gestational diabetes (GDM), we reviewed the recent literature up to Jan, 2018 and evaluated the influence of T2DM-related genetic variants on gestational glycemic traits and glucose tolerance. A total of 140 variants of 89 genes were integrated. Their associations with glycemic traits in and outside pregnancy were compared. The genetic circumstances underlying glucose metabolism exhibit a similarity between pregnant and non-pregnant populations. While, not all of the T2DM-associated genetic variants are related to pregnant glucose tolerance, such as genes involved in fasting insulin/C-peptide regulation. Some genetic variants may have distinct effects on gestational glucose homeostasis. And certain genes may be particularly involved in this process via specific mechanisms, such as HKDC1, MTNR1B, BACE2, genes encoding cell cycle regulators, adipocyte regulators, inflammatory factors and hepatic factors related to gestational glucose sensing and insulin signaling. However, it is currently difficult to evaluate these associations with quantitative synthesis due to inadequate data, different analytical methods, varied measurements for glycemic traits, controversies in diagnosis of GDM, and unknown ethnicity- and/or sex-related influences on pregnant maternal metabolism. In conclusion, different genetic associations with glycemic traits may exist between pregnant and non-pregnant conditions. Comprehensive research on specific genetic regulation in gestation is necessary.

Identifying loci affecting trait variability and detecting interactions in genome-wide association studies

Identification of genetic variants with effects on trait variability can provide insights into the biological mechanisms that control variation and can identify potential interactions. We propose a two-degree-of-freedom test for jointly testing mean and variance effects to identify such variants. We implement the test in a linear mixed model, for which we provide an efficient algorithm and software. To focus on biologically interesting settings, we develop a test for dispersion effects, that is, variance effects not driven solely by mean effects when the trait distribution is non-normal. We apply our approach to body mass index in the subsample of the UK Biobank population with British ancestry (n ~408,000) and show that our approach can increase the power to detect associated loci. We identify and replicate novel associations with significant variance effects that cannot be explained by the non-normality of body mass index, and we provide suggestive evidence for a connection between leptin levels and body mass index variability.

Association of adiponectin gene variants with idiopathic recurrent miscarriage according to obesity status: a case-control study

BACKGROUND

This study addresses whether the association of adiponectin gene (ADIPOQ) variants with idiopathic recurrent pregnancy loss (RPL) is influenced by obesity.

METHODS

Retrospective case-control study performed in outpatient obstetrics/gynecology clinics. Study subjects comprised 308 women with RPL, defined as ≥ 3 consecutive miscarriages of unknown etiology, and 310 control women. ADIPOQ genotyping was done by allele exclusion method on real-time PCR.

RESULTS

Of the 14 ADIPOQ variants tested, the minor allele frequency (MAF) of rs4632532, rs17300539, rs266729, rs182052, rs16861209, and rs7649121 were significantly higher, while rs2241767, and rs1063539 MAF were lower in RPL cases, hence assigning RPL-susceptibility and protection to these variants, respectively. Higher frequencies of heterozygous rs17300539 and rs16861209, and homozygous rs4632532, rs266729, and rs182052 genotypes, and reduced frequencies of heterozygous rs1063539 and rs2241767, homozygous rs2241766 genotypes were seen in RPL cases. ADIPOQ rs4632532, and rs2241766 were associated with RPL in obese, while rs1063539 and rs16861209 were associated with RPL in non-obese women; rs182052 and rs7649121 associated with RPL independently of BMI changes. Based on LD pattern, two haplotype blocks were identified. Within Block 1 containing rs4632532, rs16861194, rs17300539, rs266729, rs182052, rs16861209, rs822396, and rs7649121, increased frequency of CAGGACAT and TAACGAAA, and reduced frequency of TAGCGCAA haplotypes were seen in RPL cases when compared to controls, thereby assigning RPL susceptibility and protection, respectively.

CONCLUSION

This is the first study to document contribution of ADIPOQ variants and haplotypes with RPL, and also to underscore the contribution of obesity to genetic association studies.