ABSTRACT
1 The role of the extraendothelial and constitutive isoforms of cyclo-oxygenase-2 (COX-2) in the contractile effect of angiotensin II (Ang II) was investigated using thoracic and abdominal aortic rings without endothelium from young Wistar rats. 2 Ang II elicited similar contractions in both aortic segments, and the effect was inhibited by pretreatment with NS398 (a selective COX-2 inhibitor) but not SC-560 [selective cyclo-oxygenase-1 (COX-1) inhibitor]. 3 COX-2 mRNA was expressed under basal conditions in both aortic segments. Additionally, Ang II increased COX-2 mRNA expression in the abdominal but not the thoracic segment, while cycloheximide (a protein synthesis inhibitor) did not affect the contractile response to Ang II in either of the two segments; this suggests that the effect is not associated with de novo COX-2 synthesis. 4 In conclusion, the basal amount of COX-2 found in aortic smooth muscle cells is sufficient to explain the production of the prostanoids related to the contractile effect of Ang II. The production of these prostanoids, which are derived from constitutive COX-2, occurs independently of the endothelium vascular system.
Subject(s)
Angiotensin II/metabolism , Aorta/metabolism , Cyclooxygenase 2/metabolism , Endothelium, Vascular/physiology , Gene Expression Regulation, Enzymologic/drug effects , Vasoconstriction/drug effects , Animals , Aorta/drug effects , Aorta, Abdominal/drug effects , Aorta, Abdominal/metabolism , Aorta, Thoracic/drug effects , Aorta, Thoracic/metabolism , Cyclooxygenase 1/metabolism , Cyclooxygenase 2/genetics , Cyclooxygenase 2 Inhibitors/pharmacology , Cyclooxygenase Inhibitors/pharmacology , Endothelium, Vascular/drug effects , In Vitro Techniques , Isoenzymes/genetics , Isoenzymes/metabolism , Male , Organ Specificity , Osmolar Concentration , Protein Biosynthesis , RNA, Messenger/metabolism , Rats , Rats, WistarABSTRACT
AIM: To assess the functional consequence of the hepatocyte nuclear factor 1alpha gene (HNF-1alpha) G574S variant previously proposed as a diabetes susceptibility allele, in a group of Mexican Type 2 diabetic patients with end-stage renal disease (ESRD). METHODS: The transcriptional activity of the HNF-1alpha G574S recombinant protein on the human insulin promoter was assessed by transfection assays in RINm5f and HepG2 cell lines. RESULTS: Two unrelated Mexican diabetic patients with no known African ancestry were found to carry the G574S variant. This substitution was not found among unrelated healthy control subjects. Whereas the G574S HNF-1alpha transcription activation of the human insulin promoter was 40% lower than that of the wild-type protein in RINm5f beta cells, no difference was found in a hepatic cell line (HepG2). CONCLUSIONS: G574S affects the transactivation potential of HNF-1alpha on the insulin promoter in pancreatic beta-cells. Although it has been difficult to prove its role in the development of diabetes in case-control association studies, this variant exhibits functional effects consistent with it being a potential diabetes susceptibility allele.
