Regulatory role of arginase I and II in nitric oxide, polyamine, and proline syntheses in endothelial cells.
Endothelial cells (EC) metabolize L-arginine mainly by arginase, which exists as two distinct isoforms, arginase I and II. To understand the roles of arginase isoforms in EC arginine metabolism, bovine coronary venular EC were stably transfected with the Escherichia coli lacZ gene (lacZ-EC, control), rat arginase I cDNA (AI-EC), or mouse arginase II cDNA (AII-EC). Western blots and enzymatic assays confirmed high-level expression of arginase I in the cytosol of AI-EC and of arginase II in mitochondria of AII-EC. For determining arginine catabolism, EC were cultured for 24 h in DMEM containing 0.4 mM L-arginine plus [1-(14)C]arginine. Urea formation, which accounted for nearly all arginine consumption by these cells, was enhanced by 616 and 157% in AI-EC and AII-EC, respectively, compared with lacZ-EC. Arginine uptake was 31-33% greater in AI-EC and AII-EC than in lacZ-EC. Intracellular arginine content was 25 and 11% lower in AI-EC and AII-EC, respectively, compared with lacZ-EC. Basal nitric oxide (NO) production was reduced by 60% in AI-EC and by 47% in AII-EC. Glutamate and proline production from arginine increased by 164 and 928% in AI-EC and by 79 and 295% in AII-EC, respectively, compared with lacZ-EC. Intracellular content of putrescine and spermidine was increased by 275 and 53% in AI-EC and by 158 and 43% in AII-EC, respectively, compared with lacZ-EC. Our results indicate that arginase expression can modulate NO synthesis in bovine venular EC and that basal levels of arginase I and II are limiting for endothelial syntheses of polyamines, proline, and glutamate and may have important implications for wound healing, angiogenesis, and cardiovascular function.
Li
H
H
Department of Animal Science, Texas A&M University, College Station, Texas 77843, USA.
Meininger
C J
CJ
Hawker
J R
JR
Haynes
T E
TE
Kepka-Lenhart
D
D
Mistry
S K
SK
Morris
S M
SM
Wu
G
G
D000818:Animals; D001119:Arginase / Q000235:genetics / Q000378:metabolism*; D001120:Arginine / Q000493:pharmacokinetics; D002250:Carbon Radioisotopes; D002417:Cattle; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D018698:Glutamic Acid / Q000096:biosynthesis; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007763:Lac Operon; D008833:Microcirculation / Q000502:physiology; D008928:Mitochondria / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D009952:Ornithine / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D011392:Proline / Q000096:biosynthesis*; D051381:Rats; D014162:Transfection
D002250:Carbon Radioisotopes; D007527:Isoenzymes; D011073:Polyamines; D009569:Nitric Oxide; D018698:Glutamic Acid; D001120:Arginine; D011392:Proline; D009952:Ornithine; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D001119:Arginase