Vascular endothelin converting enzyme-1 expression and activity is upregulated in clinical diabetes.
Circulating and vascular endothelin-1 (ET-1) levels are elevated in diabetes, but the molecular components of the enzymatic activation of ET-1 in the vasculature remains unknown. Furthermore, the distribution of ET receptors favors a contractile phenotype in African Americans with diabetes. Whether there is any difference in local ET-1 activation in this population is unknown. This study examined the expression and activity of ET converting enzyme-1 subisoforms (ECE-1) in the internal mammary artery specimens obtained from patients undergoing coronary artery bypass grafting. The study groups included African-American (AA) and Caucasian (CA), nondiabetic (ND) and diabetic (D) patients: AAND N = 10, CAND N = 9, AAD N = 9, and CAD N = 11. The expression of ECE-1 a, ECE-1 b and ECE-1c subisoforms was studied by RT-PCR. ECE-1 a was upregulated 2- and 4-fold in the CAD and MD groups, respectively (P < .05). In African-American patient groups, ECE-1 activity (fmol/ mg protein.h) was augmented from 2,804 +/- 185 in nondiabetic tissue samples to 6,857 +/- 393 in the diabetic tissue (P < .05). There was a similar increase in the CAD group, which did not significantly differ from AA diabetics. ECE-1 inhibitors, phosphoramidon and FR-901533, inhibited vascular ECE-1 activity by more than 80%. While neutral endopeptidase (NEP) and matrix metalloproteinase-2 (MMP-2) are able to process big ET-1, inhibitors of NEP (thiorphan) and MMP (batimistat) did not affect ECE-1 activity. In conclusion, the enzymatic pathway essential for generating vascular ET-1 is activated in the vasculature of both AA and CA diabetic patients and this activation is highly specific for ECE-1.
Anstadt
Mark P
MP
Department of Surgery, Medical College of Georgia, Augusta, Georgia 30912, USA.
Hutchinson
Jimmie
J
Portik-Dobos
Vera
V
Jafri
Farahdiba
F
Bannan
Mary
M
Mawulawde
Kwabena
K
Ergul
Adviye
A
D001741:Black or African American; D016282:Aspartic Acid Endopeptidases / Q000235:genetics* / Q000378:metabolism; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology* / Q000208:ethnology; D000072396:Endothelin-Converting Enzymes; D004730:Endothelium, Vascular / Q000201:enzymology*; D005260:Female; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D012333:RNA, Messenger; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes