Biomaterial Database

Functional differences in cholesterol ester hydrolase and acyl-coenzyme-A/cholesterol acyltransferase between the outer and inner zones of the guinea pig adrenal cortex. 1988

T Nishikawa, and K Mikami, and Y Saito, and Y Tamura, and S Yoshida

Department of Internal Medicine, Chiba University School of Medicine, Japan.

Previous studies clearly demonstrated that cells isolated from the chromatically distinct inner (primarily zona reticularis) and outer (zona fasciculata and zona glomerulosa) zones of the guinea pig adrenal cortex have vastly different steroidogenic capabilities; the outer zone produces far more cortisol than the inner zone, and mitochondrial cholesterol side-chain cleavage activity in the inner zone is not modulated by ACTH. Thus, in this study we have investigated the characteristics and properties of cholesterol ester hydrolase (CEHase) and acyl-coenzyme-A/cholesterol acyltransferase (ACAT) in the outer and inner zones of the guinea pig adrenal to clarify the zonal difference in cholesterol metabolism. CEHase showed two pH optima at around pH 4.5 and pH 7.5 in the outer zone, while optimum activity in the inner zone was found only around pH 4.5, suggesting a lack of neutral CEHase in the inner zone. The acid CEHase was found mainly in the lysosomal fraction, and the neutral CEHase was located mainly in the microsomal fraction. The neutral CEHase activity in the outer zone was significantly enhanced by ether stress, while the acid CEHase activity was not changed in either of the two zones by stress. The basal activity of ACAT was significantly higher in the outer zone than in the inner zone. The present experiments also demonstrated that the inner zone always showed lower ACAT activity than the outer zone even when added cholesterol exogenously. It is suggested that the relatively low activity of ACAT may not always be explained by the reduced content of cholesterol in the microsomal fraction of zona reticularis. ACAT activity in the outer zone was significantly decreased by ether-induced stress, but that in the inner zone was not changed. The content of esterified cholesterol in whole homogenate and the microsomal fraction was significantly decreased in the outer zone, but not in the inner zone, by ether stress. Thus, the decrease in esterified cholesterol after ether stress seems to relate to increased neutral CEHase activity and decreased ACAT activity in the outer zone. The present observation clearly indicates that the lack of neutral CEHase and the lesser activity of ACAT in the inner zone than in the outer zone may contribute to the impaired cholesterol metabolism in the inner zone.

UI	MeSH Term	Description	Entries
D008247	Lysosomes	A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes MEMBRANE FUSION. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed).	Autolysosome,Autolysosomes,Lysosome
D008297	Male		Males
D008861	Microsomes	Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	Microsome
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D002265	Carboxylic Ester Hydrolases	Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.	Carboxylesterases,Ester Hydrolases, Carboxylic,Hydrolases, Carboxylic Ester
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol
D002785	Sterol O-Acyltransferase	An enzyme that catalyzes the formation of cholesterol esters by the direct transfer of the fatty acid group from a fatty acyl CoA derivative. This enzyme has been found in the adrenal gland, gonads, liver, intestinal mucosa, and aorta of many mammalian species. EC 2.3.1.26.	Acyl-CoA-Cholesterol Acyltransferase,Cholesterol Acyltransferase,Cholesterol Esterifying Enzyme,Acyl CoA Cholesterol Acyltransferase,Acyltransferase, Acyl-CoA-Cholesterol,Acyltransferase, Cholesterol,Enzyme, Cholesterol Esterifying,Esterifying Enzyme, Cholesterol,O-Acyltransferase, Sterol,Sterol O Acyltransferase
D002787	Sterol Esterase	An enzyme that catalyzes the hydrolysis of CHOLESTEROL ESTERS and some other sterol esters, to liberate cholesterol plus a fatty acid anion.	Cholesterol Esterase,15-Ketosteryl Oleate Hydrolase,Acylcholesterol Lipase,Cholesterol Ester Hydrolase,Cholesteryl Oleate Hydrolase,Cholesterylester Hydrolase,Hormone-Sensitive Lipase,Lipase A (Lysosomal Acid Cholesterol Esterase),Lipoidal Steroid Esterase,Lysosomal Acid Cholesterol Esterase,Lysosomal Acid Lipase,Steroid Hormone Esterase,Sterol Ester Acylhydrolase,15 Ketosteryl Oleate Hydrolase,Acid Lipase, Lysosomal,Acylhydrolase, Sterol Ester,Esterase, Cholesterol,Esterase, Lipoidal Steroid,Esterase, Steroid Hormone,Esterase, Sterol,Hormone Sensitive Lipase,Hydrolase, 15-Ketosteryl Oleate,Hydrolase, Cholesterol Ester,Hydrolase, Cholesteryl Oleate,Hydrolase, Cholesterylester,Lipase, Acylcholesterol,Lipase, Hormone-Sensitive,Steroid Esterase, Lipoidal
D002788	Cholesterol Esters	Fatty acid esters of cholesterol which constitute about two-thirds of the cholesterol in the plasma. The accumulation of cholesterol esters in the arterial intima is a characteristic feature of atherosclerosis.	Cholesterol Ester,Cholesteryl Ester,Cholesteryl Esters,Ester, Cholesterol,Ester, Cholesteryl,Esters, Cholesterol,Esters, Cholesteryl
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea