Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Properties and partial purification of the bovine adrenal cholesterol esterase from the 100000 X g supernatant fraction were investigated. Variations of the enzyme activity with time-dependent (enzymatic) and time-dependent (non enzymatic) effects have been demonstrated. Mg2 has been proved to inhibit the enzyme activity by a non-enzymatic effect in 50mM Tris/HCl buffer, pH 7.4. A time-dependent inactivation of the cholesterol esterase has been observed in the same buffer. The enzyme could be protected from this enzymatic inactivation by its substrate, cholesterol oleate. cAMP, ATP and Mg2 cuase a time-dependent stimulation of the enzyme in 50mM Tris/HCl buffer, pH 7.4. This result suggests that corticotropin activates the soluble cholesterol esterase from bovine adrenals via cAMP-dependent protein kinase. This view is strengthened by the incorporation of 32P radioactivity from [gamma-32P] ATP into the protein fraction of the 100,000 X g supernatant. The protein-bound 32P radioactivity could be co-purified with the enzyme activity during the partial purification of the soluble cholesterol esterase.
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PMID:In vitro activation of a soluble cholesterol esterase from bovine adrenals by a cAMP-dependent protein kinase. 18 77

Rat adrenal cortical cells have been prepared by collagenase dissociation of trypsin-treated adrenal tissue. The content and compositions of cholesteryl ester, phospholipid, and triglyceride fatty acids compare favorably with those of undissociated rat adrenal tissue. During 2-hour control incubations of adrenal cortical cells, steroidogenesis was not detected, and the levels of sterol ester, phospholipid, and triglyceride fatty acids were not significantly altered. Incubations with adrenocorticotropic hormone (ACTH) resulted in coricosterone production and significant depletions of sterol ester and triglyceride fatty acids, but not of phospholipid fatty acids. Although all fatty acid esters of cholesterol were hydrolyzed under these conditions, the greatest contributions to the net decrease in sterol esters were by oleate, arachidonate, and adrenate. Incubations with dibutyryl cyclic adenosine monophosphate (0.5 mM) resulted in significantly greater levels of corticosterone production than did ACTH (250 muunits), but the effects on cellular lipids were comparable to those seen with the tropic hormone. This study represents the first demonstration of hormone-induced hydrolysis of sterol esters in an in vitro cell suspension system. The results are discussed with respect to hormone-sensitive sterol ester hydrolase of adrenal cortex, and to the role of endogenous cholesteryl esters in the steroidogenic pathway.
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PMID:ACTH-induced hydrolysis of cholesteryl esters in rat adrenal cells. 20 12

The effects of corticotropin (ACTH) and tetradecanoyl phorbol acetate (TPA) on cholesterol ester hydrolase, intracellular cholesteryl ester concentration and steroid hormone formation were studied in mouse adrenal tumor cells (Y-1) in monolayer culture. Cholesterol ester hydrolase activity increased about 2-fold during 7 min incubation with ACTH, dibutyryl 3',5'-cyclic AMP (dbcAMP) and TPA at maximally effective concentrations; whereas, incubation with phorbol monoacetate had no effect. Long-term exposure to ACTH and dbcAMP markedly lowered intracellular cholesteryl [3H]-oleate concentration and highly increased steroid hormone output, while TPA treatment resulted in lowering cholesteryl [3H]-oleate content without affecting steroid hormone formation. Calcium activated phospholipid-dependent protein kinase C was detected in Y-1 cell cytosol. It is concluded that the mouse adrenal tumor cells in monolayer culture respond to ACTH in a fashion similar to normal adrenocortical cells; whereas, the response to the phorbol ester TPA (possibly mediated through protein kinase C) involves activation of cholesterol ester hydrolase and cholesteryl ester depletion, however, without affecting steroid hormone secretion.
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PMID:Hormone-sensitive cholesterol ester hydrolase in adrenal tumor cells: activation by corticotropin and tetradecanoyl phorbol acetate. 216 Aug 87

Pro-gamma-melanotropins (pro-gamma-MSH) are implicated in the control of aldosterone secretion by the normal adrenal cortex and in idiopathic hyperaldosteronism. In contrast with other melanotropins (alpha- and beta-MSH), the pro-gamma-MSH increase aldosterone secretion by normal adrenals only in the presence of adrenocorticotrophic hormone (ACTH). However, in aldosteronoma cells this stimulatory effect of the pro-gamma-MSH is not ACTH-dependent. The mechanism of pro-gamma-MSH action on aldosterone biosynthesis may involve activation of cholesteryl ester hydrolase in zona glomerulosa, resulting in an increased provision of cholesterol for steroidogenesis.
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PMID:Control of aldosterone secretion by pituitary hormones. 355 89

Five peptides derived from pro-corticotropin/endorphin (pro-ACTH/endorphin), the pituitary corticotroph cell prohormone, were bioassayed with isolated rat adrenocortical cells: alpha- and beta-melanotropin, beta-lipotropin, beta-endorphin, and the amino-terminal region of pro-ACTH/endorphin known as "16k fragment." The effect of each on steroidogenesis was measured at potentially physiological concentrations (0.01-1 nM) in both the absence and presence of varying concentrations of ACTH-(1-24). Of the peptides tested, only 16k fragment, the amino-terminal region of pro-ACTH/endorphin, has a slight but significant potentiating effect on ACTH-(1-24) action. Prior treatment of 16k fragment with trypsin for 30 sec dramatically increases this dose-dependent synergism. Experiments performed in vivo with hypophysectomized female rats indicate that the trypsin digest of 16k fragment stimulates cholesterol ester hydrolase (cholesterol esterase; sterol-ester acylhydrolase, EC 3.1.1.13) activity in the adrenal cortex but fails to activate cholesterol side-chain cleavage. The effect of the trypsinized material can therefore be qualitatively distinguished from that of ACTH-(1-24). When both ACTH-(1-24) and the digest are administered together, a synergistic increase in serum corticosterone concentration results. We propose that a portion of 16k fragment molecule may play a hormonal role in the control of adrenocortical steroidogenesis.
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PMID:Adrenocortical response to corticotropin is potentiated by part of the amino-terminal region of pro-corticotropin/endorphin. 624 28

A synthetic peptide, representing a portion of the 16K (16,000 dalton)-fragment sequence within the pro-adrenocorticotropin/endorphin precursor molecule, potentiates the steroidogenic action of the 1 to 24 portion of adrenocorticotropin [ACTH(1-24)] on the rat adrenal cortex. The peptide has 27 amino acid residues and consists of gamma-melanotropin with a carboxyl terminal extension. It affects both the inner and outer adrenocortical zones of hypophysectomized animals, as evidenced by a synergistic augmentation of corticosterone and aldosterone production, respectively. The peptide can be distinguished from adrenocorticotropin by its activation of cholesterol ester hydrolase and its failure to stimulate cholesterol side-chain cleavage.
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PMID:Pro-adrenocorticotropin/endorphin-derived peptides: coordinate action on adrenal steroidogenesis. 624 78

The activities of neutral cholesterol esterase and acyl-CoA : cholesterol acyltransferase in rat adrenal gland were measured at various time intervals over 24 h. The activity of cholesterol esterase displayed diurnal rhythm, with a major peak at the onset of darkness coinciding with the peak in the diurnal rhythm of plasma corticosterone concentration. The activity of acyl-CoA : cholesterol acyltransferase also exhibited a characteristic diurnal rhythm, with the minimum activity occurring 3 h after the onset of darkness. The profile of the rhythm exhibited by the activity of the esterifying enzyme was similar to the mirror image of the pattern of diurnal rhythm in the activity of 3-hydroxy-3-methylglutaryl-CoA reductase. Microsomal non-esterified cholesterol showed a gradual decline with a significant decrease in concentration at the onset of darkness, thus suggesting that diurnal removal of cholesterol in the environment of the esterifying enzyme and hydroxymethylglutaryl-CoA reductase leads to such diurnal decrease or increase in the activities of these two enzymes. Acute administration of corticotropin led to a 3-fold increase in the activity of cholesterol esterase, a 50% decrease in the activity of acyl-CoA : cholesterol acyltransferase and a 2-fold increase in the activity of hydroxymethylglutaryl-CoA reductase. Corticotropin administration also resulted in a significant decrease in microsomal non-esterified cholesterol and increase in plasma corticosterone concentration. These observations suggest that corticotropin plays an important part in generating the diurnal rhythm in the activities of the three enzymes.
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PMID:Regulation of neutral cholesterol esterase and acyl-CoA : cholesterol acyltransferase in the rat adrenal gland. 628 34

Adrenal secretory rates of cortisol and arterial concentrations of adrenocorticotropin (ACTH) were measured in conscious trained dogs subjected to intravenous infusion of ACTH. To investigate the causal relation of ACTH to the secretion of cortisol, a mechanistic mathematical model based on current hypotheses of adrenocortical function was constructed and tested. It is widely believed that ACTH stimulates cortisol secretion through adenosine 3',5'-cyclic monophosphate (cAMP), which provides substrate cholesterol by activating cholesterol ester hydrolase and facilitating transport of cholesterol to the side-chain cleavage enzyme. In addition, cholesterol modulates its own synthesis by inhibiting beta-hydroxy-beta-methylglutaryl (HMG)-CoA reductase in the adrenocortical cell. These and other steps in the biosynthetic reaction sequence were described using differential equations subject to the additional constraints imposed by available measurements of intracellular quantities. The resulting model is consistent with many of the known characteristics of the canine adrenal response to ACTH. In this model, steady-state nonlinearities arise from cooperative binding of cAMP to its receptor protein and saturation of mitochondrial pregnenolone transport. The transient response is dominated by a depletable pool of intracellular free cholesterol. Other inferences based on the model are presented, and a quantifiable cellular basis for increased adrenal sensitivity to ACTH is proposed.
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PMID:A mechanistic model of ACTH-stimulated cortisol secretion. 632 2

We have used a monoclonal antibody, A2, to study the structure and function on the lipid droplet capsule in steroidogenic adrenal cells. This antibody reacts with a 160-kD protein found in the rat adrenal cortex. Immunofluorescence microscopy shows a dominant rim pattern, which surrounds individual lipid droplets and is distinct from the filamentous vimentin staining. The boundary of lipid droplets in steroidgenic Leydig cells and 3T3 adipocytes is also immunostained by this antibody. The strong association of the 160-kD protein with the lipid droplet is demonstrated by its resistance to Triton X-100 extraction. Stimulation of steroid secretion by adrenocorticotropin results in the detachment of this protein from the lipid droplet and its movement to the cytosol. These findings suggest that the translocation of this 160-kD protein from lipid droplet surface to cytosol on stimulation might be important in facilitating the binding of cholesterol ester hydrolase to the surface of lipid droplets, as proposed for adipocytes, during lipolytic stimulation.
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PMID:A lipid droplet-specific capsule is present in rat adrenal cells: evidence from a monoclonal antibody. 852 43

Acyl-CoA synthetase 4 (ACS4) is an arachidonate-preferring enzyme abundant in steroidogenic tissues. We demonstrate that ACS4 expression in steroidogenic tissues in vivo is induced by adrenocorticotropic hormone (ACTH) and suppressed by glucocorticoid. ACTH also induced ACS4 protein but not its mRNA in Y1 adrenocortical tumor cells, whereas both ACS4 mRNA and protein were increased by dibutyryl cAMP (db-cAMP) and forskolin. Furthermore, the levels of ACS4 mRNA and protein in Y1 cells were induced by arachidonate. These data suggest that ACS4 expression in steroidogenic cells is regulated in coordination with induced steroidogenesis and arachidonate released by cholesterol ester hydrolase.
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PMID:Regulation by adrenocorticotropic hormone and arachidonate of the expression of acyl-CoA synthetase 4, an arachidonate-preferring enzyme expressed in steroidogenic tissues. 1092 47


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