1657010
Cholesteryl ester hydrolase in human monocyte/macrophage: cloning, sequencing, and expression of full-length cDNA.
The sensitive technique of RT-PCR was used to identify cholesteryl ester hydrolase (CEH) expressed in human macrophages. This enzyme is thought to regulate the availability of intracellular free cholesterol for efflux. The expected 667-bp product was obtained starting with RNA from human peripheral blood and THP-1 monocytes and macrophages. The cDNA for human macrophage CEH was then cloned by PCR-based screening of a lambda-gt11 cDNA library. The full-length cDNA was sequenced and found to exhibit 76% homology (at the nucleotide and conceptually translated protein level) to hepatic CEH, an enzyme shown to be involved in hepatic cholesterol homeostasis and regulated by cholesterol at the transcription level via sterol response elements in the proximal promoter. Identification of the conserved catalytic triad (Ser(221, His(468), and Glu354)) and the SEDCLY motif places human macrophage CEH in the family of carboxylesterases. A greater than 20-fold increase in CEH activity was observed when COS-1 and COS-7 cells were transiently transfected with an eukaryotic expression vector, pcDNA3.1/V5/His-TOPO, containing the cDNA for human macrophage CEH. Using this full-length cDNA as a probe, a 2.2-kb transcript was identified by Northern blot analysis of total RNA from human peripheral blood and THP -1 macrophages. Overexpression of human macrophage CEH resulted in an impairment of upregulation of low-density lipoprotein (LDL) receptor mRNA in Chinese hamster ovary (CHO-K1) cells grown in cholesterol-deficient environment. These data identify the human macrophage CEH, demonstrate its expression in human peripheral blood macrophage and human macrophage cell line, THP-1, and suggest its role in the intracellular cholesteryl ester metabolism.
25354783
Molecular cloning and expression of rat hepatic neutral cholesteryl ester hydrolase.
The 1923 bp cDNA for rat hepatic cholesteryl ester hydrolase (CEH) was cloned by screening a lambda gt11 expression library with an oligonucleotide containing the consensus active site sequence for cholesteryl esterases. Expression of a fusion protein, cross-reacting with antibody to the purified liver CEH, was demonstrated by Western blot analysis. The cDNA was sequenced and found to have only 44% homology with pancreatic CEH. Although unique, the cDNA sequence exhibited much greater overall homology with liver carboxylesterases, in both coding and 5'/3' non-coding regions. In Northern blot analysis, the cDNA hybridized with a single band from liver mRNA but not with pancreatic mRNA. The 1.7 kb coding sequence, predicting a 62 kDa protein, was cloned into an Escherichia coli expression system with an inducible promoter and into COS-7 cells. Both expression systems produced a protein which comigrated with liver CEH (66 kDa) on SDS-PAGE and immunoreacted with antibodies to liver CEH on Western blots. Whereas the prokaryotic system produced an inactive protein, expression in COS-7 cells was accompanied by a 5-fold increase in CEH activity and a corresponding increase in immunoreactive protein.
46480527
Macrophage cholesterol homeostasis and metabolic diseases: critical role of cholesteryl ester mobilization
Atherogenic dyslipidemia, including low HDL levels, is the major contributor of residual risk of cardiovascular disease that remains even after aggressive statin therapy to reduce LDL-cholesterol. Currently, distinction is not made between HDL-cholesterol and HDL, which is a lipoprotein consisting of several proteins and a core containing cholesteryl esters (CEs). The importance of assessing HDL functionality, specifically its role in facilitating cholesterol efflux from foam cells, is relevant to atherogenesis. Since HDLs can only remove unesterified cholesterol from macrophages while cholesterol is stored as CEs within foam cells, intracellular CE hydrolysis by CE hydrolase is vital. Reduction in macrophage lipid burden not only attenuates atherosclerosis but also reduces inflammation and linked pathologies such as Type 2 diabetes and chronic kidney disease. Targeting reduction in macrophage CE levels and focusing on enhancing cholesterol flux from peripheral tissues to liver for final elimination is proposed.
6587208
Macrophage cholesteryl ester mobilization and atherosclerosis.
Accumulation of cholesteryl esters (CE) stored as cytoplasmic lipid droplets is the main characteristic of macrophage foam cells that are central to the development of atherosclerotic plaques. Since only unesterified or free cholesterol (FC) can be effluxed from the cells to extracellular cholesterol acceptors, hydrolysis of CE is the obligatory first step in CE mobilization from macrophages. This reaction, catalyzed by neutral cholesteryl ester hydrolase (CEH), is increasingly being recognized as the rate-limiting step in FC efflux. CEH, therefore, regulates the process of reverse cholesterol transport and ultimate elimination of cholesterol from the body. In this review, we summarize the earlier controversies surrounding the identity of CEH in macrophages, discuss the characteristics of the various candidates recognized to date and examine their role in mobilizing cellular CE and thus regulating atherogenesis. In addition, physiological requirements to hydrolyze lipid droplet-associated substrate and complexities of interfacial catalysis are also discussed to emphasize the importance of evaluating the biochemical characteristics of candidate enzymes that may be targeted in the future to attenuate atherosclerosis.
38585383
Cloning of the human cholesteryl ester hydrolase promoter: identification of functional peroxisomal proliferator-activated receptor responsive elements.
Cholesteryl ester hydrolase (CEH) is responsible for hydrolysis of stored cholesterol esters in macrophage foam cells and release of free cholesterol for high-density lipoprotein-mediated efflux. PCR-based screening of human genomic libraries with human macrophage CEH specific primers resulted in amplification and cloning of 1.7 kb promoter sequence. Analysis of the sequence revealed a lack of consensus TATA-box but presence of a GC-rich proximal sequence, a CAAT box and several binding sites for the transcription factor Sp1. Three putative response elements for peroxisome proliferator-activated receptor (PPRE) were identified at position -176, -779, and -1316. Down-regulation of promoter activity was observed in the presence of either PPARalpha- or PPARgamma-specific ligands and introduction of a 4-point transverse mutation in the PPRE at -176 completely abolished the effect of PPAR ligands on the promoter activity. Analogous to other genes involved in macrophage cholesterol homeostasis, human CEH may also be regulated by PPAR.
29059346
IKKbeta mediates cell shape-induced aromatase expression and estrogen biosynthesis in adipose stromal cells.
Aromatase (Cyp19) is a key enzyme in estrogen biosynthesis and an important target in breast cancer therapy. Within tumor microenvironment, tumor cells stimulate aromatase expression in adipose stromal cells (ASCs), which in turn promotes estrogen-dependent growth of estrogen receptor (ER)-positive tumor cells. However, it is not clear how aromatase transcription and estrogen biosynthesis are regulated in ASCs under a precancerous condition. Here we demonstrate that cell shape change alone is sufficient to induce aromatase expression in primary ASCs from cancer-free individuals. The activation of aromatase transcription is mediated by IkappaB kinase-beta (IKKbeta), a kinase previously known for its cancer-promoting activity in tumor cells. Activation of IKKbeta leads to elevated expression of transcription factor CCAAT/enhancer-binding protein-beta (C/EBPbeta), which binds to and stimulates two breast cancer-associated promoters of the aromatase gene. We also show that shape-induced estrogen production in ASCs can stimulate estrogen-dependent transcription in ER-positive breast tumor cells. We suggest that IKKbeta-dependent aromatase induction due to changes in cellular architecture in adipose tissue may contribute to the breast cancer risks associated with high mammagraphic density and obesity.
11160186
Report of a new syndrome: focus on differential diagnosis and review of Ellis-van Creveld, Curry-Hall, acrofacial dysostosis, and orofacial digital syndromes.
Ellis-van Creveld (EvC) and Curry-Hall (CH) syndromes are rare syndromes that occur due to mutations of genes mapped to the chromosome 4p16 region. Hence, they both have few features that are common. The dental literature describing the oral manifestations and etiology of both syndromes is scarce. We report a case of a 7-year-old girl who appeared with features that are common to both syndromes, as well as with other features such as reduced cranial base flexure and toes of equal length with skeletal changes that have not been mentioned or described in earlier reports. The patient possibly represents a new syndromic entity that has not been reported until now. Further, we present a review of various other similar syndromes, such as various types of orofacial digital (OFD) syndrome and acrofacial dysostosis.
45939646
Full genomic analysis of a simian SA11-like G3P[2] rotavirus strain isolated from an asymptomatic infant: identification of novel VP1, VP6 and NSP4 genotypes.
We report here the full genomic analysis of a simian SA11-like G3P[2] group A rotavirus (GAR) strain, B10, isolated from an asymptomatic infant in Kenya in 1987. By nucleotide sequence identities and phylogenetic analyses, the VP7-VP4-VP2-VP3-NSP1-NSP2-NSP3-NSP5 genes of strain B10 exhibited maximum genetic relatedness to those of the different isolates of simian strain SA11, and were assigned to the G3-P[2]-C5-M5-A5-N5-T5-H5 genotypes, respectively. On the other hand, the VP1, VP6 and NSP4 genes of strain B10 did not belong to any of the established GAR genotypes, and therefore, were assigned to new genotype numbers R8, I16 and E13, respectively, by the Rotavirus Classification Working Group. These observations suggested that strain B10 might have originated from reassortment event/s involving simian SA11-like strains and GAR strains from unknown animal host species (possibly other wild animals) preceding transmission to humans. Alternatively, considering the lack of data on simian GARs, it might be also possible that the VP1, VP6 and NSP4 genes of strain B10 are those of unknown simian strains, and that strain B10 might be a typical simian strain that was directly transmitted to humans. Therefore, either hypothesis pointed towards a rare instance of possible direct transmission of GARs from an animal host (possibly a monkey or some other wild animal) to humans. This was corroborated by the presence of different species of wild animals including non-human primates, and unhygienic conditions at the sampling site. To our knowledge, the present study is the first report on the detection of a simian SA11-like G3P[2] GAR strain in humans.
44599964
Airway obstruction in lungs obtained from an asthmatic donor complicating heart-lung transplantation.
6513668
A Role of CREB in BRCA1 Constitutive Promoter Activity and Aromatase Basal Expression
Aromatase is the rate-limiting enzyme in estrogen biosynthesis and a key target in breast cancer treatment. Its ovary-specific promoter, pII, is induced in response to protein kinase A (PKA) activation. It has been proposed that breast cancer susceptibility gene 1, BRCA1, is involved in negative regulation of aromatase pII activity. Surprisingly, inhibition of PKA pathway by inhibitor H89 elevates basal aromatase expression while abolishes cAMP-mediated aromatase induction in an ovarian granulosa cell line, KGN. In this report, we decipher the mechanism by which the PKA pathway negatively regulates aromatase basal expression. We show that PKA pathway plays a positive role in the expression of BRCA1. H89 effectively reduces endogenous BRCA1 mRNA levels as well as reporter gene expression from a BRCA1 promoter. Mutation of a cAMP-responsive element (CRE) in the BRCA1 promoter reduces BRCA1 expression. Chromatin immunoprecipitation (ChIP) shows that CRE-binding protein, CREB, binds to the BRCA1 promoter. Furthermore, knockdown of CREB in KGN cells leads to decreased BRCA1 level as well as elevated basal aromatase mRNA expression. These data demonstrate that both the CRE site in the BRCA1 promoter and CREB are required for BRCA1 constitutive expression. Our study suggests that PKA pathway exerts its negative impact on basal aromatase expression indirectly by contributing to the constitutive expression of BRCA1.