Characterization of peroxisomal 3-hydroxy-3-methylglutaryl coenzyme A reductase in UT2 cells: sterol biosynthesis, phosphorylation, degradation, and statin inhibition.
We have previously identified a CHO cell line (UT2 cells) that expresses only one 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase protein which is localized exclusively in peroxisomes [Engfelt, H.W., Shackelford, J.E., Aboushadi, N., Jessani, N., Masuda, K., Paton, V.G., Keller, G.A., and Krisans, S.K. (1997) J. Biol. Chem. 272, 24579-24587]. In this study, we utilized the UT2 cells to determine the properties of the peroxisomal reductase independent of the endoplasmic reticulum (ER) HMG-CoA reductase. We demonstrated major differences between the two proteins. The peroxisomal reductase is not the rate-limiting enzyme for cholesterol biosynthesis in UT2 cells. The peroxisomal reductase protein is not phosphorylated, and its activity is not altered in the presence of inhibitors of cellular phosphatases. Its rate of degradation is not accelerated in response to mevalonate. Finally, the degradation process is not blocked by N-acetyl-Leu-Leu-norleucinal (ALLN). Furthermore, the peroxisomal HMG-CoA reductase is significantly more resistant to inhibition by statins. Taken together, the data support the conclusion that the peroxisomal reductase is functionally and structurally different from the ER HMG-CoA reductase.
Aboushadi
N
N
Department of Biology, San Diego State University, California 92182, USA.
Shackelford
J E
JE
Jessani
N
N
Gentile
A
A
Krisans
S K
SK
D019342:Acetic Acid / Q000378:metabolism; D000101:Acetyl-CoA C-Acetyltransferase / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016466:CHO Cells / Q000187:drug effects / Q000201:enzymology; D002250:Carbon Radioisotopes; D002453:Cell Cycle; D002470:Cell Survival; D002784:Cholesterol / Q000096:biosynthesis*; D002999:Clone Cells / Q000187:drug effects / Q000201:enzymology; D006224:Cricetinae; D017666:Deuterium Oxide / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006903:Hydroxymethylglutaryl CoA Reductases / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism; D007783:Lactones / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008148:Lovastatin / Q000494:pharmacology*; D008798:Mevalonic Acid / Q000378:metabolism; D020675:Peroxisomes / Q000201:enzymology*; D010766:Phosphorylation; D019821:Simvastatin / Q000494:pharmacology; D014316:Tritium
D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007783:Lactones; D007976:Leupeptins; D014316:Tritium; C063261:acetylleucyl-leucyl-norleucinal; C054282:antibiotic 1233A; D000255:Adenosine Triphosphate; D002784:Cholesterol; D008148:Lovastatin; D019821:Simvastatin; D006903:Hydroxymethylglutaryl CoA Reductases; D000101:Acetyl-CoA C-Acetyltransferase; D006904:Hydroxymethylglutaryl-CoA Synthase; D017666:Deuterium Oxide; D019342:Acetic Acid; D008798:Mevalonic Acid