leptin and 2-tert-butylhydroquinone

Gestational diabetes mellitus (GDM) is a common disorder characterized by abnormal glucose metabolism during pregnancy, affecting 2% to 5% of pregnant women. Currently, clinical treatment for GDM is very limited. The present study was designed to investigate the effect and underlying molecular mechanism of tertiary butylhydroquinone (TBHQ) in a pregnant C57BL/KsJ-Lep db/+ (referred to as db+) GDM mouse model. The results showed that nonpregnant db/+ mice did not show a diabetic phenotype, and TBHQ had no effect on glucose and insulin tolerance in these mice. Moreover, in db/+ pregnant mice exhibiting typical diabetes symptoms, such as hyperglycemia and hypoinsulinemia, TBHQ could remarkably decrease the blood glucose level, increase insulin level, and improve glucose and insulin intolerance. The results also revealed that TBHQ could inhibit oxidative stress in pregnant db/+ mice. Furthermore, TBHQ greatly improved offspring survival rate, glucose metabolism, and insulin tolerance. In addition, TBHQ inhibited oxidative stress by reducing malondialdehyde (MDA) and reactive oxygen species (ROS) levels and increased superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities. Moreover, we found that TBHQ activated the nuclear factor erythroid 2-related factor 2 (Nrf2), thereby increasing the levels of Nrf2, and ultimately upregulating the expression of heme oxygenase 1 (NO-1) and superoxide dismutase 2 (SOD2). In conclusion, our findings demonstrated that TBHQ alleviated GDM via Nrf2 activation.

Topics: Animals; Antioxidants; Blood Glucose; Diabetes, Gestational; Disease Models, Animal; Female; Hydroquinones; Leptin; Mice; Mice, Inbred C57BL; NF-E2-Related Factor 2; Oxidative Stress; Pregnancy; Reactive Oxygen Species; Up-Regulation

Very little is known regarding molecular mechanism(s) underlying transcriptional regulation of any G-protein gene despite the importance of G-protein expression in modulating cellular processes. Here we show that phorbol myristate acetate (PMA) and tert-butylhydroquinone (tBHQ), which induce oxidative stress in cells, up-regulate transcription of Galpha(i2) in K562 cells. Redox-sensing chemicals abrogated this transcriptional effect. A dominant negative I-kappaB double mutant (S32A/S36A) suppressed PMA-induced transcription by 54-62%, suggesting involvement of nuclear factor-kappaB (NF-kappaB). SN50, a cell-permeable peptide that inhibits nuclear import of stress-responsive transcription factors (such as NF-kappaB), inhibited PMA- and tBHQ-induced transcription. Deletion of an NF-kappaB-binding motif that maps at +10/+19 in the promoter resulted in 55-60% suppression of PMA-induced transcription, and 81% suppression of tBHQ-induced transcription. Mutation of an antioxidant response element (ARE) that maps at -84/-76 in the promoter resulted in 51 and 86% decrease in PMA- and tBHQ-induced transcription, respectively. In electrophoretic mobility shift assays, this element formed complexes with the transcription factors NF-E2p45 and Nrf2 that are prototypic for binding to the ARE, as well as with c-Fos, which can also interact with the ARE. Chromatin immunoprecipitation analysis demonstrated recruitment of these transcription factors to the promoter. Exogenously transfected Nrf2 transactivated the Galpha(i2) gene promoter; the cytoskeleton-associated protein, Keap1, abrogated this effect. Taken together, the present studies reveal that transcription factors that bind NF-kappaB and/or antioxidant response elements play an activating role in the transcription of the human Galpha(i2) gene.

Topics: Amino Acid Motifs; Antioxidants; Binding Sites; Blotting, Western; Cell Line; Cell Nucleus; Chromatin Immunoprecipitation; DNA-Binding Proteins; Dose-Response Relationship, Drug; Enzyme Inhibitors; Gene Deletion; GTP-Binding Protein alpha Subunit, Gi2; GTP-Binding Protein alpha Subunits, Gi-Go; Humans; Hydroquinones; Intracellular Signaling Peptides and Proteins; K562 Cells; Kelch-Like ECH-Associated Protein 1; Leptin; Models, Genetic; Mutagenesis, Site-Directed; Mutation; NF-E2-Related Factor 2; NF-kappa B; Peptides; Polymerase Chain Reaction; Promoter Regions, Genetic; Protein Binding; Proteins; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fos; Response Elements; Tetradecanoylphorbol Acetate; Time Factors; Trans-Activators; Transcription, Genetic; Transcriptional Activation; Transfection; Up-Regulation