Intraparticulate localization and some properties of a clofibrate-induced peroxisomal aldehyde dehydrogenase from rat liver

Abstract

A study was made of the effect of chronic administration of the hypolipidemic drug clofibrate on the activity and intracellular localization of rat liver aldehyde dehydrogenase. The enzyme was assayed using several aliphatic and aromatic aldehydes. Clofibrate treatment caused a 1.5 to 2.3-fold increase in the liver specific aldehyde dehydrogenase activity. The induced enzyme has a high K , for acetaldehyde and was found to be located in peroxisomes and microsomes. Clofibrate did not alter the enzyme activity in the cytoplasmic fraction.The total peroxisomal aldehyde dehydrogenase activity increased 3 to 4-fold under the action of clofibrate. Disruption of the purified peroxisomes by the hypotonic treatment or in the alkaline conditions resulted in the release of catalase from the broken organelles, while aldehyde dehydrogenase as well as nucleoid-bound urate oxidase and the peroxisomal membrane marker NADH : cytochrome c reductase remained in the peroxisomal 'ghosts'. At the same time, treatment by Triton X-100 led to solubilization of the membrane-bound NADH : cytochrome c reductase and aldehyde dehydrogenase from intact peroxisomes and their 'ghosts'. These results indicate that aldehyde dehydrogenase is located in the peroxisomal membrane.The peroxisomal aldehyde dehydrogenase is active with different aliphatic and aromatic aldehydes, except for formaldehyde and glyceraldehyde. The enzyme K, values lie in the millimolar range for acetaldehyde, propionaldehyde, benzaldehyde and phenylacetaldehyde and in the micromolar range for nonanal. Both NAD and NADP serve as coenzymes for the enzyme. Aldehyde dehydrogenase was inhibited by disulfiram, Nethylmaleimide and 5,5'-dithiobis(2-nitrobenzoic)acid. According to its basic kinetic properties peroxisomal aldehyde dehydrogenase seems to be similar to a clofibrate-induced microsomal enzyme. The functional role of both enzymes in the liver cells is discussed.There are two isoenzymes of aldehyde dehydrogenase in rat liver which differ in their subcellular distribution, kinetic and molecular properties. Isoenzyme with a low K, for acetaldehyde was found in the mitochondria1 matrix [I, 21. Another species of aldehyde dehydrogenase has a high K,,, for acetaldehyde. The latter isoenzyme is tightly membranebound and distributed among mitochondria and microsomes [l, 3, 41. Except for these organelles, the activity of aldehyde dehydrogenase was detected in peroxisomes [5, 61. However, its intraparticulate location and properties were not described.Some xenobiotics and chemical carcinogens are able to induce at least two new isoenzymes of aldehyde dehydrogenase which are localized in supernatant fraction and not detectable in normal liver [7-lo]. In rat hepatomas the specific cytosolic isoenzymes which preferentially oxidize aromatic aldehydes using NADP as coenzyme are found [lo -121. All these isoenzymes consistently differ in a number of kinetic and molecular properties from aldehyde dehydrogenase of normal liver.It is known that clofibrate and other hypolipidemic agents with...

Phytanic acid: production from phytol, its breakdown and role in human disease

“…Precise expression studies of the two human variants will have to elucidate the putative role of FALDH in α-oxidation. Some reports in the literature indicate that a distinct aldehyde dehydrogenase inducible by clofibrate is present in rat liver peroxisomes [52]. However, since it is known that FALDH is also induced by clofibrate [53] and since the aldehyde dehydrogenase that was described by Antonenkov et al [52] is also membrane-bound, it cannot be excluded that microsomal contamination is at the basis of these results.…”

Clofibrate pretreatment in mice confers resistance against hepatic lipid peroxidation

“…Perhaps one candidate protein that could be investigated in future studies is aldehyde dehydrogenase, since Antonenkov and other workers have observed a 2-3 induction of this enzyme in the livers of peroxisome proliferator-treated rats [65,66]. Since certain aldehyde dehydrogenase isoforms can metabolize toxic lipid-derived aldehydes, enhanced activity of this pathway could feasibly provide cellular protection during times of oxidative stress.…”

Molecular Mechanisms and Physiological Significance of Organelle Interactions and Cooperation

“…However, it has also been claimed that DHAP is synthesized endogenously from glycerol-3-phosphate (G3P) as catalyzed by the enzyme glycerol-3-phosphate dehydrogenase (G3PDH/GPD1). Interestingly, earlier work from Antonenkov (Antonenkov et al, 1985) has shown that rat liver peroxisomes do contain G3PDH activity although the true identity of this enzyme activity has never been resolved definitively. In this respect it is important to mention the work of Jung et al in yeast which revealed dynamic changes in the subcellular distribution of G3PDH ranging from peroxisomal to cytosolic depending on the metabolic status of the cells (Jung et al, 2010).…”