ISSN:
0199-9885
Source:
Annual Reviews Electronic Back Volume Collection 1932-2001ff
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract beta-Oxidation occurs in both mitochondria and peroxisomes. Mitochondria catalyze the beta-oxidation of the bulk of short-, medium-, and long-chain fatty acids derived from diet, and this pathway constitutes the major process by which fatty acids are oxidized to generate energy. Peroxisomes are involved in the beta-oxidation chain shortening of long-chain and very-long-chain fatty acyl-coenzyme (CoAs), long-chain dicarboxylyl-CoAs, the CoA esters of eicosanoids, 2-methyl-branched fatty acyl-CoAs, and the CoA esters of the bile acid intermediates di- and trihydroxycoprostanoic acids, and in the process they generate H2O2. Long-chain and very-long-chain fatty acids (VLCFAs) are also metabolized by the cytochrome P450 CYP4A omega-oxidation system to dicarboxylic acids that serve as substrates for peroxisomal beta-oxidation. The peroxisomal beta-oxidation system consists of (a) a classical peroxisome proliferator-inducible pathway capable of catalyzing straight-chain acyl-CoAs by fatty acyl-CoA oxidase, L-bifunctional protein, and thiolase, and (b) a second noninducible pathway catalyzing the oxidation of 2-methyl-branched fatty acyl-CoAs by branched-chain acyl-CoA oxidase (pristanoyl-CoA oxidase/trihydroxycoprostanoyl-CoA oxidase), D-bifunctional protein, and sterol carrier protein (SCP)x. The genes encoding the classical beta-oxidation pathway in liver are transcriptionally regulated by peroxisome proliferator-activated receptor alpha (PPARalpha). Evidence derived from mice deficient in PPARalpha, peroxisomal fatty acyl-CoA oxidase, and some of the other enzymes of the two peroxisomal beta-oxidation pathways points to the critical importance of PPARalpha and of the classical peroxisomal fatty acyl-CoA oxidase in energy metabolism, and in the development of hepatic steatosis, steatohepatitis, and liver cancer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1146/annurev.nutr.21.1.193
Permalink
