Glucose-6-Phosphate Dehydrogenase, Redox Homeostasis and Embryogenesis.

Normal embryogenesis requires complex regulation and precision, which depends on multiple mechanistic details. Defective embryogenesis can occur by various mechanisms. Maintaining redox homeostasis is of importance during embryogenesis. NADPH, as produced from the action of glucose-6-phosphate dehydrogenase (G6PD), has an important role in redox homeostasis, serving as a cofactor for glutathione reductase in the recycling of glutathione from oxidized glutathione and for NADPH oxidases and nitric oxide synthases in the generation of reactive oxygen (ROS) and nitrogen species (RNS). Oxidative stress differentially influences cell fate and embryogenesis. While low levels of stress (eustress) by ROS and RNS promote cell growth and differentiation, supra-physiological concentrations of ROS and RNS can lead to cell demise and embryonic lethality. G6PD-deficient cells and organisms have been used as models in embryogenesis for determining the role of redox signaling in regulating cell proliferation, differentiation and migration. Embryogenesis is also modulated by anti-oxidant enzymes, transcription factors, microRNAs, growth factors and signaling pathways, which are dependent on redox regulation. Crosstalk among transcription factors, microRNAs and redox signaling is essential for embryogenesis.

G6PD deficiency, redox homeostasis, and viral infections: implications for SARS-CoV-2 (COVID-19).

The COVID-19 pandemic has so far affected more than 45 million people and has caused over 1 million deaths worldwide. Infection with SARS-CoV-2, the pathogenic agent, which is associated with an imbalanced redox status, causes hyperinflammation and a cytokine storm, leading to cell death. Glucose-6-phosphate dehydrogenase (G6PD) deficient individuals may experience a hemolytic crisis after being exposed to oxidants or infection. Individuals with G6PD deficiency are more susceptible to coronavirus infection than individuals with normally functioning G6PD. An altered immune response to viral infections is found in individuals with G6PD deficiency. Evidence indicates that G6PD deficiency is a predisposing factor of COVID-19.

tert-Butyl Hydroperoxide (tBHP)-Induced Lipid Peroxidation and Embryonic Defects Resemble Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency in C. elegans.

G6PD is required for embryonic development in animals, as severe G6PD deficiency is lethal to mice, zebrafish and nematode. Lipid peroxidation is linked to membrane-associated embryonic defects in Caenorhabditis elegans (C. elegans). However, the direct link between lipid peroxidation and embryonic lethality has not been established. The aim of this study was to delineate the role of lipid peroxidation in gspd-1-knockdown (ortholog of g6pd) C. elegans during reproduction. tert-butyl hydroperoxide (tBHP) was used as an exogenous inducer. Short-term tBHP administration reduced brood size and enhanced germ cell death in C. elegans. The altered phenotypes caused by tBHP resembled GSPD-1 deficiency in C. elegans. Mechanistically, tBHP-induced malondialdehyde (MDA) production and stimulated calcium-independent phospholipase A2 (iPLA) activity, leading to disturbed oogenesis and embryogenesis. The current study provides strong evidence to support the notion that enhanced lipid peroxidation in G6PD deficiency promotes death of germ cells and impairs embryogenesis in C. elegans.

The role of the RGD motif in CD97/ADGRE5-and EMR2/ADGRE2-modulated tumor angiogenesis.

CD97/ADGRE5, an adhesion G protein-coupled receptor (aGPCR), is highly expressed in several tumor cell types. CD97 has been shown to modulate tumorigenesis in part by promoting HUVEC migration, invasion and angiogenesis through the interaction with integrin α5ß1 via its ectodomain RGD motif. In this study, we show that CD97 could induce angiogenesis via an alternative RGD-independent mechanism. Overexpression of CD97 with the wild-type or mutant RGD motif in HT1080 cells led to up-regulated MMP-9 and induced angiogenesis as revealed by the in vitro endothelial cell tube formation assay and in ovo chick chorioallantoic membrane assay. By contrast, expression of EMR2/ADGRE2, the CD97-homologous aGPCR that contains a corresponding SGD sequence, fails to induce angiogenesis due to lower MMP-9 expression. Interestingly, a single change of the SGD to RGD sequence allowed EMR2 to up-regulate MMP-9 expression, leading to enhanced angiogenesis. MMP-9 was shown to promote the proliferation, migration, and invasion of HUVEC partly by modulating the levels of VEGF, PIGF, and bFGF. Finally, we showed that the MMP-9 expression was in turn modulated by N-cadherin that was up-regulated by CD97 and EMR2/RGD. Our results indicate that two homologous aGPCRs, CD97 and EMR2, modulate angiogenesis and HUVEC proliferation, migration, and invasion through N-cadherin-regulated MMP-9 expression by RGD-independent and -dependent mechanisms, respectively.

The RGD motif is involved in CD97/ADGRE5-promoted cell adhesion and viability of HT1080 cells.

CD97/ADGRE5 is an adhesion G protein-coupled receptor (aGPCR) involved in tumor cell adhesion, migration, angiogenesis, and apoptosis. CD97 has been shown previously to stimulate angiogenesis by interacting with integrins on endothelial cells via an Arginine-Glycine-Aspartic acid (RGD) motif. In this report, the role of the RGD motif in tumor cell adhesion and apoptosis was investigated using a previously-established HT1080 cell-based system. We found that the RGD motif is critical in CD97-promoted cell adhesion, in part due to the up-regulation of αvß5 and α2ß1 integrins, and that CD97 mediates its anti-apoptotic effect in extrinsic apoptosis via RGD-dependent cell adhesion. In contrast, CD97-modulated anti-apoptotic effect in intrinsic apoptosis is mediated by RGD-independent, N-cadherin-induced homotypic cell aggregation. Hence, CD97 promotes tumorigenesis via RGD-dependent and -independent mechanisms.

Genetic factors associated with patient-specific warfarin dose in ethnic Indonesians.

BACKGROUND: CYP2C9 and VKORC1 are two major genetic factors associated with inter-individual variability in warfarin dose. Additionally, genes in the warfarin metabolism pathway have also been associated with dose variance. We analyzed Single Nucleotide Polymorphisms (SNPs) in these genes to identify genetic factors that might confer warfarin sensitivity in Indonesian patients. METHODS: Direct sequencing method was used to identify SNPs in CYP2C9, VKORC1, CYP4F2, EPHX1, PROC and GGCX genes in warfarin-treated patients. Multiple linear regressions were performed to model the relationship warfarin daily dose requirement with genetic and non-genetic variables measured and used to develop a novel algorithm for warfarin dosing. RESULTS: From the 40 SNPs analyzed, CYP2C9 rs17847036 and VKORC1 rs9923231 showed significant association with warfarin sensitivity. In our study population, no significant correlation could be detected between CYP2C9*3, CYP2C9C-65 (rs9332127), CYP4F2 rs2108622, GGCX rs12714145, EPHX1 rs4653436 and PROC rs1799809 with warfarin sensitivity. CONCLUSIONS: VKORC1 rs9923231 AA and CYP2C9 rs17847036 GG genotypes were associated with low dosage requirements of most patients (2.05 ± 0.77 mg/day and 2.09 ± 0.70 mg/day, respectively). CYP2C9 and VKORC1 genetic variants as well as non-genetic factors such as age, body weight and body height account for 15.4% of variance in warfarin dose among our study population. Additional analysis of this combination could allow for personalized warfarin treatment in ethnic Indonesians.

Alpha-fetoprotein gene polymorphisms and risk of HCC and cirrhosis.

BACKGROUND: Elevated level of alpha fetoprotein (AFP) is found in approximately 60% of hepatocellular carcinoma (HCC) cases. Other liver diseases including cirrhosis and chronic hepatitis are related with an increased level of AFP. The regulation of AFP gene expression has been relatively less studied although the gene has been suggested to play a role in HCC development. This study aimed at identifying genetic variations in AFP that might be associated with the presence of HCC and cirrhosis among ethnic Indonesians. METHODS: Direct DNA sequencing was carried out to sequence AFP promoter, exons, and 3' untranslated region (UTR) in DNA samples isolated from 119 HCC, 119 cirrhosis and 105 control subjects. For each sample serum AFP level was determined and association studies with single nucleotide polymorphisms (SNPs) and haplotypes were performed. RESULTS: In this study we identified 47 SNPs in the AFP gene. Statistically significant associations with HCC and cirrhosis were detected for six individual SNPs in the AFP promoter, AFP intron 1 and intron 2 (rs6834059, rs3796678, rs3796677, rs3796676, rs28532518 and rs4646038). Furthermore, we identified two SNPs in AFP intron 7 and 3'UTR, rs2298839 and rs10020432, which are associated with increased risk of cirrhosis. CONCLUSION: Genetic variants in the AFP gene may be associated with HCC and cirrhosis risk for ethnic Indonesians.

Genetic factors contribute to patient-specific warfarin dose for Han Chinese.

BACKGROUND: Warfarin is a commonly prescribed anticoagulant drug for the prevention of thromboses. To address the association of genetic factors and warfarin dosage for ethnic Han Chinese, we genotyped six candidate genes involved in the warfarin interactive pathway with focus on SNPs with reported association with warfarin dose. METHODS: We recruited a study population consisted of 318 patients receiving warfarin treatment and 995 healthy controls. PCR and direct sequencing were used to identify the sequence polymorphisms. RESULTS: In our study population, SNP rs1799853 of CYP2C9, rs1687390 of ORM1-2, and rs2069919 of PROC showed no variation. SNPs rs12714145 of GGCX and rs1799809 of PROC showed no significant correlation with warfarin dose. The associations of SNPs rs9934438 and rs9923231 of VKORC1, the 3 (rs1057910) and C(-65) (rs9332127) alleles of CYP2C9, and SNP rs4653436 of EPHXI with the dose of warfarin were significant. CONCLUSION: A multiple regression model based on the genetic polymorphisms of VKORC1, CYP2C9, EPHX1 and the non-genetic factors of age and body weight can explain 40.2% of the variance in warfarin dose in Han Chinese patients. Translation of this knowledge into clinical guidelines for warfarin prescription may improve the safety and efficacy of warfarin treatment among Han Chinese.