Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ethanol-inducible form of cytochrome P-450 (IIE1) is expressed and induced by ethanol, predominantly in the centrilobular region. Because this isoenzyme has a particularly high capacity to convert carbon tetrachloride and several other hepatotoxins into reactive intermediates, its role in producing damage was studied by comparing the effect of carbon tetrachloride exposure on hepatocytes isolated from either the periportal or the perivenous region by digitonin-collagenase perfusion. After exposure for 18 hr of primary culture to 600 mumol/L of carbon tetrachloride, periportal cells were only slightly damaged, as estimated from dye exclusion and lactate dehydrogenase leakage. In marked contrast, perivenous cells, which contained a several-fold higher amount of immunoreactive P-450 IIE1 apoprotein, were partly damaged after exposure to 60 to 150 mumol/L of carbon tetrachloride and severely damaged after 600 mumol/L. Similarly, lipid peroxidation after carbon tetrachloride was much more prominent in perivenous cells. The differences between perivenous and periportal cells in carbon tetrachloride-induced injury were larger when cells were isolated from chronically ethanol-treated rats. Isoniazid, an efficient inhibitor of P-450 IIE1, protected against damage by carbon tetrachloride more efficiently than the general P-450 inhibitor cimetidine. Our results suggest that the greater susceptibility of the perivenous hepatocytes to carbon tetrachloride-induced damage is associated with the high expression of P-450 IIE1 in these cells. This enzyme may also be involved in damage elicited by several other typical centrilobular hepatotoxins.
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PMID:Role of ethanol-inducible cytochrome P-450 IIE1 in carbon tetrachloride-induced damage to centrilobular hepatocytes from ethanol-treated rats. 222 5

P-450IIB genes (P-450b and P-450e in rat) are induced following treatment with phenobarbital predominantly in hepatocytes located in zones 2 and 3 of the liver acinus. The previous finding of phenobarbital-mediated induction of P-450IIB mRNAs and apoproteins in the same zonal hepatocytes suggests that this differential induction is most likely due to zonal differences in the activation of gene transcription. To determine whether differential P-450IIB gene transcription was dependent on the type of inducer (i.e., inducer specificity) or on the capacity of hepatocytes located in different acinar zones to respond to inducers (i.e. zonal specificity), the pattern of acinar induction was evaluated following treatment with inducers that have diverse physiochemical properties and inductive capacities. The zonal distribution of P-450b and P-450e mRNAs in liver was determined by in situ hybridization after the administration of either phenobarbital, polychlorinated biphenyls, chlordane, or chlorpromazine. Liver sections were hybridized with 3H-labeled RNA transcripts of a P-450e cDNA that recognizes sequences of both P-450b and P-450e mRNAs and the pattern of zonal mRNA induction was measured by quantitative image analysis. Each inducer increased P-450b,e mRNA levels predominantly in hepatocytes of zones 2 and 3 of the hepatic acinus. The P-450b and P-450e apoproteins were induced in the same zonal hepatocytes as the P-450b,e mRNAs as shown by immunofluorescence studies using monoclonal antibodies. Therefore, differential transcriptional induction of the P-450IIB genes in the liver acinus does not seem to be dependent on a specific chemical inducer, but rather is a characteristic capacity of hepatocytes located in different acinar zones. To determine whether the induction of P-450b and P-450e was dependent on the liver tissue organization, hepatocytes were isolated by collagenase perfusion of the liver and transplanted into the spleens of syngeneic rats. Induction of P-450b and P-450e mRNAs and apoproteins, assessed 1 month after transplantation, was evident with each of the chemical inducers. These data suggest that, once hepatocytes have attained the capacity to respond to inducers, the organization of hepatocytes into acini and the sinusoidal microenvironment of the liver are not required for hepatocytes to maintain the ability to respond to inducers with an increase in transcription of P-450IIB genes. Moreover, the splenic hepatocytes demonstrated a heterogeneous pattern of P-450b,e apoprotein induction; this raises the possibility that the acinar organization is also not required for the heterogenous expression of P-450IIB genes.
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PMID:Induction of P-450IIB genes within the rat liver acinus is not dependent on the chemical inducer or on the acinar organization. 247 Jul 62

We have investigated the production of collagenous proteins by primary cultures of rat lung epithelial cells (type II pneumocytes). Three major bacterial collagenase-sensitive chains were synthesized and secreted into the medium between 12 and 36 h of culture. Two of the chains comigrated on sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis (SDS-PAGE) with radiolabeled type IV procollagen (PC) chains isolated from adult rat lung (Mr = 185,000 and 170,000 after reduction) and were coprecipitated with monospecific antibodies to type IV collagen. Cyanogen bromide (CNBr) peptide maps of the chromatographically purified chains were identical to maps of rat lung type IV PC, and confirmed the identity of these chains as pro alpha 1(IV) and pro alpha 2(IV). Type IV PC was the major high molecular weight collagen in the cell layer, and a fraction of the newly synthesized type IV PC was selectively deposited on the substratum together with newly synthesized fibronectin. Type II cells also secreted a low molecular weight, non-disulfide-bonded, collagenase-sensitive protein (Mr = 19,000, collagen standards; Mr = 26,000, globular standards). The protein coeluted with type IV PC from DEAE-cellulose but was resolved from native type IV on CM-cellulose. The protein was not precipitated with polyclonal antibodies to type IV collagen or rat surfactant apoprotein. These studies further demonstrate the heterogeneity of collagenous macro-molecules synthesized by lung epithelial cells in vitro. We suggest that interactions between pneumocyte-derived fibronectin and type IV procollagen contribute to the formation of the epithelial basement membrane and to the attachment of these cells in normal or injured lung.
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PMID:Synthesis of collagenous proteins by pulmonary type II epithelial cells. 357 11

The uptake and internalization of a triglyceride emulsion by rat hepatocytes in culture less than 24 hr was either inhibited or uninfluenced by apoE. ApoE significantly increased the uptake of these emulsions in later cultures. Specific low density lipoprotein (LDL) binding was similar for hepatocyte monolayers prior to and after 24 hr. Rat hepatocytes in culture for 2 days, which were treated with collagenase, detached and then replated within 1 hr and were apoE-responsive in 2 hr. Heparin inhibited the apoE stimulation in both hepatocytes and hepatoma monolayers. Heparin wash of hepatocytes or hepatoma cells incubated with apoE-[14C]triolein emulsions at 4 degrees C resulted in a considerable loss in radiolabeled cell lipid. A similar wash after 37 degrees C incubations produced little loss suggesting internalization. Hepatocytes had lower affinity but similar apoE-emulsion binding capacity compared to hepatoma cells. Triolein emulsions with apoE were significantly more rapidly metabolized by the hepatocyte than unsupplemented emulsions. The apoE-mediated hepatocyte lipid uptake was inhibited by apoC proteins. High molar ratios of free fatty acid/albumin also suppressed hepatocyte apoE-mediated lipid uptake. Both rat high density lipoprotein (HDL) and LDL inhibited with a potency directly related to their content of apoE. Human LDL and HDL without apoE also inhibited the interaction with less potency than the rat lipoproteins. Human HDL inhibition was diminished after removal of apoC proteins.
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PMID:Effect of apoE on triglyceride emulsion interaction with hepatocyte and hepatoma G2 cells. 362 37

Cultured rat hepatocytes obtained by liver perfusion with collagenase in the presence of soybean trypsin inhibitor were used to examine the role of high density lipoproteins (HDL) in supplying cholesterol to the hepatocyte for bile acid synthesis. Within 6 hr of adding HDL (d 1.07-1.21 g/ml) obtained from rat serum there was a significant stimulation of bile acid synthesis and secretion that reached 2-fold after 24 hr. The stimulation by HDL occurred at normal plasma concentrations (i.e., 500 micrograms/ml) and showed further stimulation in a dose-dependent manner reaching a maximum stimulation of 2- to 2.5-fold. The stimulation of bile acid synthesis was dependent on the cholesteryl ester content of the HDL. Several lines of evidence show that the HDL is taken up by a receptor-mediated process dependent on apoE. These include: 1) at the same concentration (500 micrograms/ml) apoE-poor HDL (not retained by heparin affinity chromatography of HDL isolated from the plasma of rats fasted for 72 hr stimulated bile acid synthesis by 48%, whereas apoE-rich HDL stimulated bile acid synthesis by 110%; 2) reductive methylation totally blocked the stimulation of bile acid synthesis by HDL; 3) HDLC, which contained apoE as its major protein component, also maximally stimulated bile acid synthesis; and 4) human HDL, which contained no detectable apoE, failed to stimulate bile acid synthesis. Additional studies showed that apoE-enriched HDL and HDLC both inhibited cholesterol synthesis (determined by the incorporation of 3H2O) and caused a net accumulation of cholesteryl esters in hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of bile acid synthesis in cultured rat hepatocytes: stimulation by apoE-rich high density lipoproteins. 362 41

Isolation and separation of rat liver cells into endothelial, Kupffer, and parenchymal cell fractions were performed at different times after injection of human 125I-acetyl low density lipoproteins (LDL). In order to minimize degradation and redistribution of the injected lipoprotein during cell isolation, a low temperature (8 degrees C) procedure was applied. Ten min after injection, isolated endothelial cells contained 5 times more acetyl-LDL apoprotein per mg of cell protein than the Kupffer cells and 31 times more than the hepatocytes. A similar relative importance of the different cell types in the uptake of acetyl-LDL was observed 30 min after injection. For studies on the in vitro interaction of endothelial and Kupffer cells with acetyl-LDL, the cells were isolated with a collagenase perfusion at 37 degrees C. Pure endothelial (greater than 95%) and purified Kupffer cells (greater than 70%) were obtained by a two-step elutriation method. It is demonstrated that the rat liver endothelial cell possesses a high affinity receptor specific for the acetyl-LDL because a 35-fold excess of unlabeled acetyl-LDL inhibits association of the labeled compound for 70%, whereas unlabeled native human LDL is ineffective. Binding to the acetyl-LDL receptor is coupled to rapid uptake and degradation of the apolipoprotein. Addition of the lysosomotropic agents chloroquine (50 microM) or NH4Cl (10 mM) resulted in more than 90% inhibition of the high affinity degradation, indicating that this occurs in the lysosomes. With the purified Kupffer cell fraction, the cell association and degradation of acetyl-LDL was at least 4 times less per mg of cell protein than with the pure endothelial cells. Although cells isolated with the cold pronase technique are also still able to bind and degrade acetyl-LDL, it appeared that 40-60% of the receptors are destroyed or inactivated during the isolation procedure. It is concluded that the rat liver endothelial cell is the main cell type responsible for acetyl-LDL uptake.
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PMID:In vivo and in vitro uptake and degradation of acetylated low density lipoprotein by rat liver endothelial, Kupffer, and parenchymal cells. 631 44

We isolated and characterized immunoreactive apolipoprotein B (apoB)-containing lipoproteins from human atherosclerotic plaque and plasma to determine whether very-low-density lipoprotein (VLDL) can enter and become incorporated into the atherosclerotic lesion and how plaque apoB-containing lipoproteins differ from apoB-containing lipoproteins isolated from plasma. Atherosclerotic plaques were obtained during aortic surgery and processed immediately. Lipoproteins were extracted from minced plaque in a buffered saline solution (extract A). In selected cases a second extraction was done after plaque was incubated with collagenase (extract B). Lipoproteins were then isolated from the extracts by anti-apoB immunosorption and separated into VLDL + intermediate-density lipoprotein (IDL) (d < 1.019 g/mL) and low-density lipoprotein (LDL) (1.019 < d < 1.070 g/mL) fractions by ultracentrifugation. The VLDL + IDL fractions from plaque contained more than one third of the total apoB-associated lipoprotein cholesterol in both extracts A and B. The lipid composition of VLDL + IDL in both extracts was related to that of plasma VLDL + IDL. By electron microscopy mean particle diameters of VLDL + IDL from extracts A and B were 9% and 23%, respectively, greater than VLDL + IDL diameters from plasma. Mean diameters of LDL from extracts A and B were 11% and 31% greater than LDL diameters from plasma. The apoE-apoB ratio of extract A VLDL + IDL was nearly twice that of plasma VLDL + IDL and severalfold higher than that of extract A LDL. Immunoblots of both VLDL + IDL and LDL from extract A demonstrated minimal fragmentation of apoB.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Triglyceride-rich lipoproteins isolated by selected-affinity anti-apolipoprotein B immunosorption from human atherosclerotic plaque. 794 2

We have determined the role of cholesteryl ester transfer protein (CETP) in selective uptake of high density lipoprotein (HDL)-derived cholesteryl esters (CE) by human adipose tissue, using organ culture or collagenase-digested adipocytes. Incubation of the fresh tissue fragments with HDL containing [3H]CE or 125I-apoprotein (apo) A-I resulted in significant uptake of HDL-CE-derived label. Addition of recombinant CETP (rCETP) increased CE uptake in a dose-response fashion. In contrast, little association of 125I-apoA-I with adipose tissue was noted, and addition of rCETP did not alter apoA-I uptake or degradation. Incubation of adipose tissue with TP2, an anti-CETP monoclonal antibody, which inhibits neutral lipid transfer, markedly reduced selective uptake of HDL-CE. Studies using human adipocytes isolated by collagenase digestion also demonstrated selective uptake of HDL-CE and enhancement of this process by rCETP. To confirm that the association of HDL-CE-derived radioactivity with adipose tissue was not due to neutral lipid exchange between adipocytes and HDL, we measured changes in HDL composition following incubation of HDL and rCETP with isolated adipocytes. A decrease in HDL-CE concentration in the medium was observed, an effect which was markedly attenuated when incubations were carried out in the presence of monoclonal antibody TP2. Furthermore, the decrease in HDL-CE was accompanied by an increase in HDL free cholesterol, likely representing efflux of adipocyte cholesterol to HDL. There were no significant changes in phospholipid, apoA-I, or apoA-II in the medium following incubation with adipocytes. These data demonstrate a novel and important role for CETP in selective uptake of HDL-cholesteryl esters by human adipocytes and suggest that this pathway may be of quantitative physiological significance in HDL remodeling and adipocyte cholesterol accumulation.
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PMID:Cholesteryl ester transfer protein mediates selective uptake of high density lipoprotein cholesteryl esters by human adipose tissue. 929 95

Previous studies have shown that surfactant apoprotein A (SP-A) and natural or synthetic surfactant can modulate the release of pro-inflammatory cytokines from alveolar mononuclear phagocytes. The aim of this study was to assess whether SP-A or Surfactant (Surf) from patients with pulmonary alveolar proteinosis (PAP) can affect the release of two chemokines (interleukin (IL)-8 and monocyte chemtactic peptide (MCP)-1) from human monocytes and rat lung type-II cells. In addition IL-8 and MCP-1 levels were assessed in the brochoalveolar lavage fluid (BALF) of seven patients with PAP and compared with those in a group of control subjects (n=5). SP-A, tested over a wide range of concentrations, significantly increased IL-8 and MCP-1 release from monocytes. SP-A retained its activity after collagenase digestion, but was not active after heat treatment. The release of IL-8 by monocytes was also stimulated by Surf. Finally, median BALF IL-8 and MCP-1 levels in PAP patients were significantly higher than in controls (9.50 and 9.51 pg x mL(-1) in controls versus 151.95 and 563.70 pg x mL(-1) in PAP, respectively) and significantly correlated with SP-A concentrations in BALF. Overall the results of this study support the view that the high content of alveolar surfactant apoprotein A may contribute to the upregulation of chemokine release in pulmonary alveolar proteinosis, thus contributing to airway inflammation.
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PMID:Surfactant apoprotein A modulates interleukin-8 and monocyte chemotactic peptide-1 production. 1210 68

Black rice and its pigment fraction may have antiatherogenic activity, but the exact component contributing to the beneficial effect remains unclear. The aim of the present study was to investigate the influence of the anthocyanin-rich extract from black rice on the vulnerability of advanced plaques in apolipoprotein (apo) E-deficient mice. Using LC-MS, the anthocyanin-rich extract from black rice was identified as containing cyanidin-3-glucoside and peonidin-3-glucoside. ApoE-deficient mice (n = 30; 30 wk old) were randomly divided into 3 groups: a control group (fed the AIN-93G diet), the simvastin group [simva; fed the AIN-93G diet containing simvastatin, 50 mg/(kg.d)], or the anthocyanin-rich extract group [antho; fed the AIN-93G diet supplemented with anthocyanin-rich extract from black rice, 300 mg/(kg.d)]. After 20 wk of intervention, the plaque area that developed in the brachiocephalic artery of mice in the antho group was smaller than that of the control mice. Both the antho and simva groups had lower frequencies of the large necrotic core and thin fibrous cap in plaques than the control group. Collagen I was increased and matrix metalloproteinase-1 contents were reduced in the brachiocephalic lesion of both the antho and simva groups compared with the control group. Furthermore, mRNA levels of tissue factor and inducible nitric oxide synthase in aortae were decreased in the antho and simva groups. Supplementation of anthocyanin-rich extract improved the lipid profile by decreasing serum triglyceride, total cholesterol, and non-HDL cholesterol. These results suggest that chronic diet intake of anthocyanin-rich extract from black rice may enhance plaque stabilization in old apoE-deficient mice. The underlying mechanism is related mainly to inhibiting proinflammatory factors and improving the serum lipid profile.
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PMID:An anthocyanin-rich extract from black rice enhances atherosclerotic plaque stabilization in apolipoprotein E-deficient mice. 1685 44


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