Biomedical subjects

Stephanie Harris

Publications and source records attributed to Stephanie Harris.

2 recordsLinked to original sources

PubMed2004

Relationship between carbamoyl-phosphate synthetase genotype and systemic vascular function.

Endothelial cells can convert l-citrulline to l-arginine, the precursor of nitric oxide. The present study tests the hypothesis that a C-to-A nucleotide transversion (T1405N) in the gene-encoding carbamoyl-phosphate synthetase 1, the enzyme catalyzing the rate-limiting step in l-citrulline formation, influences nitric oxide metabolite concentrations or nitric oxide-mediated vasodilation in humans. Bradykinin (100, 200, and 400 ng/min) was infused via brachial artery in 106 (CC:AC:AA=40:54:12) healthy subjects. Sodium nitroprusside (1.6, 3.2, and 6.4 microg/min) was also infused in 87 (CC:AC:AA=31:46:10) subjects. Forearm blood flow was measured by plethysmography and blood samples were collected for tissue-type plasminogen activator antigen, nitric oxide metabolites, and cyclic GMP. There was a significant relationship between carbamoyl-phosphate synthetase 1 genotype and nitric oxide metabolites, such that nitric oxide metabolite concentrations were highest in individuals homozygous for the C allele (mean+/-SD, 14.0+/-8.5 micromol/L), lowest in individuals homozygous for the A allele (9.1+/-3.1 micromol/L), and intermediate (11.8+/-6.6 micromol/L) in heterozygotes (P=0.036). There was a significant effect of carbamoyl-phosphate synthetase 1 genotype on forearm blood flow during bradykinin (P=0.028), such that the vasodilator response was greatest in C allele homozygotes (22.2+/-9.1 mL/min/100 mL at 400 ng/min), least in A allele homozygotes (13.6+/-6.2 mL/min/100 mL), and intermediate (19.4+/-10.7 mL/min/100 mL) in heterozygotes. Similarly, carbamoyl-phosphate synthetase 1 genotype influenced forearm blood flow during nitroprusside (maximal flow 19.2+/-8.3, 18.1+/-8.3, and 11.5+/-4.9 mL/min/100 mL in the CC:AC:AA groups, respectively; P=0.022). In contrast, there was no effect of carbamoyl-phosphate synthetase 1 genotype on the nitric oxide-independent tissue-type plasminogen activator response to bradykinin (P=0.943). These data indicate that a polymorphism in the gene encoding carbamoyl-phosphate synthetase 1 influences nitric oxide production as well as vascular smooth muscle reactivity.

Adult↗

PubMed2002

Redox-sensitive interaction between KIAA0132 and Nrf2 mediates indomethacin-induced expression of gamma-glutamylcysteine synthetase.

Exposure of HepG2 cells to nonsteroidal anti-inflammatory drugs (i.e., indomethacin and ibuprofen; NSAIDs) as well as resveratrol, caused increased expression of the mRNAs coding for the catalytic (Gclc) and modifier (Gclm) subunits of the glutathione synthetic enzyme, gamma-glutamylcysteine synthetase. In addition, indomethacin exposure increased intracellular glutathione content as well as inhibited glutathione depletion and cytotoxicity caused by diethyl maleate. Indomethacin-induced increases in the expression of gamma-glutamylcysteine synthetase mRNA were preceded by increases in steady state levels of intracellular pro-oxidants and glutathione disulfide accumulation. Simultaneous incubation with the thiol antioxidant N-acetylcysteine (NAC) inhibited indomethacin-mediated increases in GCLC mRNA, suggesting that increases in GCLC message were triggered by changes in intracellular oxidation/reduction (redox) reactions. Indirect immunofluorescence using intact cells demonstrated that indomethacin induced the nuclear translocation of Nrf2, a transcription factor believed to regulate GCLC expression. Immunoprecipitation studies showed that indomethacin treatment also inhibited Nrf2 tethering to KIAA0132 (the human homolog of Keap1 accession #D50922), which is believed to be a negative regulator of Nrf2. Consistent with this idea, over-expression of Nrf2 increased GCLC reporter gene expression and over-expression of KIAA0132 inhibited GCLC reporter gene activity as well as inhibited indomethacin-induced increases in the expression of GCLC. Finally, simultaneous treatment with NAC inhibited both indomethacin-induced release of Nrf2 from KIAA0132 and indomethacin-induced nuclear translocation of Nrf2. These results demonstrate that NSAIDs and resveratrol cause increases in the expression of gamma-glutamylcysteine synthetase mRNA and identify these agents as being capable of stimulating glutathione metabolism. These results also support the hypothesis that indomethacin-induced transcriptional activation of GCLC involves the redox-dependent release of KIAA0132 from Nrf2 followed by the nuclear translocation of Nrf2.

Anti-Inflammatory Agents, Non-Steroidal↗