Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both temperature-stable and temperature-labile testicular cholesteryl ester hydrolases are shown to be regulated by an endogenous cAMP-dependent protein kinase activity. The temperature-stable form (Mr = 28,000) was activated 3-fold by the endogenous kinase. This activation was completely blocked by protein kinase inhibitor. Following purification by high performance gel permeation chromatography, the temperature-stable form could also be activated 2-fold by bovine heart protein kinase, type I. The partially purified endogenous protein kinase, type I, which was completely separated from hydrolase activity by ion exchange chromatography, increased hydrolase activity 2-fold in the presence of optimal concentrations of cAMP, ATP, and Mg2+. Cholesteryl ester hydrolase activity could be stabilized indefinitely at -10 degrees C with the addition of 0.1 mM thioglycolate, but not by other thiol reagents. In contrast, the endogenous protein kinase activity was lost from 104,000 X g supernatants after 14 days. However, the property of activation could be restored by addition of bovine heart protein kinase. The temperature-labile hydrolase (Mr = 72,000) could be totally inactivated by a Mg2+-dependent, fluoride-sensitive cytosolic factor and reactivated by cAMP-dependent protein kinase. These observations strongly suggest that the inactivating factor is a phosphoprotein phosphatase.
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PMID:Protein kinase-mediated activation of temperature-labile and temperature-stable cholesteryl ester hydrolases in the rat testis. 308 16

Cholesterol esterase with optimal activity at pH 6.8 was found in the 40,000 X g supernatant fraction prepared from rabbit alveolar macrophages, thioglycolate-elicited mouse peritoneal macrophages, and the J774 macrophage cell line. The neutral cholesterol esterase activity in these three types of macrophages was of the same order of magnitude as that in the 40,000 X g supernatant fraction of adrenal, heart, and liver but considerably lower than that in adipose tissue. The enzyme prepared from J774 cells was activated about 60% by preincubation with cAMP and Mg-ATP; half-maximal activation was obtained at 2.5 X 10(-7) M cAmP. The activation was completely blocked by a specific protein inhibitor of cAMP-dependent protein kinase. These findings suggest that cytoplasmic cholesterol esters stored in macrophages can be mobilized for release by action of the neutral enzyme described and, further, that this process may be regulated by factors that affect intracellular cAMP levels.
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PMID:Neutral cholesterol esterase activity in macrophages and its enhancement by cAMP-dependent protein kinase. 627 1

Macrophages contain a neutral cholesteryl ester hydrolase that can be activated by cAMP-dependent protein kinase. Immunological studies strongly suggest that hormone-sensitive lipase (HSL) is probably responsible for the cholesteryl ester hydrolase activity in macrophages; however, due to the very low level of expression in macrophages, it has been difficult to determine whether the macrophage cholesteryl ester hydrolase and adipose HSL are, in fact, products of the same gene. We have used the sensitive polymerase chain reaction (PCR) technique to demonstrate expression of HSL mRNA in resident and thioglycollate-elicited mouse peritoneal macrophages, as well as in the P388D1 mouse macrophage cell line. PCR was performed using oligonucleotide primer sequences present on adjacent exons of the mouse HSL gene to allow discrimination between products derived from HSL mRNA or genomic DNA sequences; specificity of the PCR was demonstrated by the absence of a product in liver, which does not express HSL mRNA. Northern blot analysis of poly (A)+ RNA from peritoneal macrophages with a mouse adipose HSL cDNA probe demonstrated a low abundance of mRNA of 3.2 kb, identical in size to HSL mRNA in adipose tissue. These findings, together with the results of previous studies demonstrating similarities between HSL and macrophage neutral cholesteryl ester hydrolase, strongly support the conclusion that both are products of a single gene. The development of a PCR assay for HSL mRNA may allow further study of the regulation of neutral cholesteryl ester hydrolase expression in macrophages and foam cells, and its potential role in atherogenesis.
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PMID:Expression of hormone-sensitive lipase mRNA in macrophages. 826 20