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R L Bell,
M W Kimpel,
Z A Rodd,
W N Strother,
F Bai,
C L Peper,
R D Mayfield,
L Lumeng, D W Crabb,
W J McBride,
F A Witzmann
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ABSTRACT: Chronic ethanol (EtOH) drinking produces neuronal alterations within the limbic system. To investigate changes in protein expression levels associated with EtOH drinking, inbred alcohol-preferring (iP) rats were given one of three EtOH access conditions in their home-cages: continuous ethanol (CE: 24h/day, 7days/week access to EtOH), multiple scheduled access (MSA: four 1-h sessions during the dark cycle/day, 5 days/week) to EtOH, or remained EtOH-naïve. Both MSA and CE groups consumed between 6 and 6.5g of EtOH/kg/day after the 3rd week of access. On the first day of EtOH access for the seventh week, access was terminated at the end of the fourth MSA session for MSA rats and the corresponding time point (2300h) for CE rats. Ten h later, the rats were decapitated, brains extracted, the nucleus accumbens (NAcc) and amygdala (AMYG) microdissected, and protein isolated for 2-dimensional gel electrophoretic analyses. In the NAcc, MSA altered expression levels for 12 of the 14 identified proteins, compared with controls, with six of these proteins altered by CE access, as well. In the AMYG, CE access changed expression levels for 22 of the 27 identified proteins, compared with controls, with 8 of these proteins altered by MSA, as well. The proteins could be grouped into functional categories of chaperones, cytoskeleton, intracellular communication, membrane transport, metabolism, energy production, or neurotransmission. Overall, it appears that EtOH drinking and the conditions under which EtOH is consumed, differentially affect protein expression levels between the NAcc and AMYG. This may reflect differences in neuroanatomical and/or functional characteristics associated with EtOH self-administration and possibly withdrawal, between these two brain structures.
Alcohol 09/2006; 40(1):3-17. · 2.47 Impact Factor
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ABSTRACT: The aldehyde dehydrogenase 2 (ALDH2) promoter contains a nuclear receptor response element (NRRE) that represents an overlapping direct repeat-1 (DR-1) and -5 (DR-5) element. Because DR-1 elements are preferred binding sites for peroxisome proliferator-activated receptors (PPARs), we tested the hypothesis that PPARs regulate ALDH2 expression.
We examined the ability of PPAR isoforms to bind to the ALDH2 NRRE in electrophoretic mobility shift assays, their ability to activate the transcription of promoter-reporter constructs containing this NRRE, the effect of PPAR ligands on ALDH2 expression in liver, and the role of the PPARalpha on the expression of ALDH2 by using PPARalpha-null mice.
In vitro translated PPARs bound the ALDH NRRE with high affinity. Mutation of the NRRE indicated that binding was mediated by the DR-1 element. Cotransfection of PPAR expression plasmids showed that PPARalpha had no effect on expression of heterologous promoter constructs containing the NRRE. PPARgamma slightly induced expression, whereas PPARdelta repressed basal activity of the promoter and blocked induction by hepatocyte nuclear factor 4. Treatment of rats with the PPAR ligand clofibrate repressed expression of ALDH2 in rats fed either stock rodent chow or a low-protein diet. Consistent with the transfection data, expression of ALDH2 protein was not different in PPARalpha-null mice. Treatment of the mice with the PPARalpha agonist WY14643 slightly decreased the level of ALDH2 protein in both wild-type and PPARalpha-null mice, suggesting that the effect of WY14643 was not mediated by the receptor.
These data indicate that ALDH2 is not part of the battery of lipid metabolizing enzymes and proteins regulated by PPARalpha
Alcoholism Clinical and Experimental Research 08/2001; 25(7):945-52. · 3.34 Impact Factor
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ABSTRACT: Research has substantiated the role of several mechanisms responsible for alcohol-induced hepatotoxicity. These mechanisms include: oxidative stress and lipid peroxidation; immunogenic processes initiated by formation of protein adducts of acetaldehyde, other aldehydes and 1-hydroxyethyl radicals; and activation of Kupffer cells by endotoxin and subsequent cascade of events that involved cytokines, chemokines, and adhesion molecules. Increasing evidence implicates enhanced intestinal permeability caused by alcohol ingestion as the culprit that leads to endotoxemia. While oxidative stress is important, the principal source of reactive oxygen species that causes alcohol-induced liver injury is hotly debated. Potential sources may include cytochrome P450IIE1, activated Kupffer cells, and mitochondrial electron transfer chain. Apoptosis is likely an important pathway that culminates in hepatocyte cell death. Abstinence, corticosteroids, and enteral nutrition remain the cornerstones in the treatment of alcoholic hepatitis. The efficacies of medications such as S-adenosylmethionine and pentoxifylline will need further confirmation by additional randomized trials before they can be recommended as standard therapies for alcoholic hepatitis.
Current Opinion in Gastroenterology 06/2001; 17(3):211-20. · 4.19 Impact Factor
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D W Crabb,
J Pinairs,
R Hasanadka,
M Fang,
M A Leo,
C S Lieber,
H Tsukamoto,
K Motomura,
T Miyahara,
M Ohata, [......],
S Sanghani,
N Kedishvili,
H Shiraishi,
H Yokoyama,
M Miyagi,
H Ishii,
I Bergheim,
I Menzl,
A Parlesak,
C Bode
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ABSTRACT: This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Hirokazu Yokoyama and David Crabb. The presentations were (1) Roles of vitamin A, retinoic acid, and retinoid receptors in the expression of liver ALDH2, by J. Pinaire, R. Hasanadka, M. Fang, and David W. Crabb; (2) Alcohol, vitamin A, and beta-carotene: Adverse interactions, by M. A. Leo and Charles S. Lieber; (3) Retinoic acid, hepatic stellate cells, and Kupffer cells, by Hidekazu Tsukamoto, K. Motomura, T. Miyahara, and M. Ohata; (4) Retinoid storage and metabolism in liver, by William Bosron, S. Sanghani, and N. Kedishvili; (5) Characterization of oxidation pathway from retinol to retinoic acid in esophageal mucosa, by Haruko Shiraishi, Hirokazu Yokoyama, Michiko Miyagi, and Hiromasa Ishii; and (6) Ethanol in an inhibitor of the cytosolic oxidation of retinol in the liver and the large intestine of rats as well as in the human colon mucosa, by Ina Bergheim, Ina Menzl, Alexandr Parlesak, and Christiane Bode.
Alcoholism Clinical and Experimental Research 06/2001; 25(5 Suppl ISBRA):207S-217S. · 3.34 Impact Factor
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ABSTRACT: This manuscript represents the proceedings of a symposium at the 2000 RSA Meeting in Denver, Colorado. The organizer/chair was Ting-Kai Li. The presentations were: (1) Introduction to the Symposium, by Ting-Kai Li; (2) ALDH2 polymorphism and alcohol metabolism, by Shih-Jiun Yin; (3) ALDH2 promoter polymorphism and alcohol metabolism, by David W. Crabb; (4) Use of BrAC clamping to estimate alcohol elimination rates: Application to studies of the influence of genetic and environmental determinants, by Sean O'Connor; and (5) Effect of food and food composition on alcohol elimination rates as determined by clamping, by Vijay A. Ramchandani.
Alcoholism Clinical and Experimental Research 02/2001; 25(1):136-44. · 3.34 Impact Factor
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ABSTRACT: Fatty acids are ligands for the peroxisome proliferator-activated receptor alpha (PPAR alpha). Fatty acid levels are increased in liver during the metabolism of ethanol and might be expected to activate PPAR alpha. However, ethanol inhibited PPAR alpha activation of a reporter gene in H4IIEC3 hepatoma cells expressing alcohol-metabolizing enzymes but not in CV-1 cells, which lack these enzymes. Ethanol also reduced the ability of the PPAR alpha ligand WY14,643 to activate reporter constructs in the hepatoma cells or cultured rat hepatocytes. This effect of ethanol was abolished by the alcohol dehydrogenase inhibitor 4-methylpyrazole and augmented by the aldehyde dehydrogenase inhibitor cyanamide, indicating that acetaldehyde was responsible for the action of ethanol. PPAR alpha/retinoid X receptor extracted from hepatoma cells exposed to ethanol or acetaldehyde bound poorly to an oligonucleotide containing peroxisome proliferator response elements. This effect was also blocked by 4-methylpyrazole and augmented by cyanamide. Furthermore, in vitro translated PPAR alpha exposed to acetaldehyde failed to bind DNA. Thus, ethanol metabolism blocks transcriptional activation by PPAR alpha, in part due to impairment of its ability to bind DNA. This effect of ethanol may promote the development of alcoholic fatty liver and other hepatic consequences of alcohol abuse.
Journal of Biological Chemistry 02/2001; 276(1):68-75. · 4.77 Impact Factor
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ABSTRACT: Vitamin A has been suggested to regulate the expression of liver alcohol dehydrogenase (ADH) in humans. There are few studies on the ability of retinoic acid to affect ADH expression in vivo and none on its effects on alcohol metabolic rate.
Male Sprague Dawley rats were used for isolation of hepatocytes or were rendered vitamin A deficient by feeding a deficient diet for 7 weeks. ADH, retinoic acid receptor beta, and retinoid X receptor alpha protein levels were analyzed by Western blotting. Alcohol elimination rate was determined by following blood alcohol levels after administering a 1.5 g/kg dose of ethanol intraperitoneally.
Retinoic acid had no effect on ADH protein in cultured hepatocytes. In the vitamin A deficient rats, retinol was not detectable in serum or liver at the time animals were killed. ADH and retinoid X receptor alpha protein levels were unchanged in the deficient group compared with a vitamin A sufficient control group, whereas retinoic acid receptor beta levels increased 40%. The deficient rats had a reduced volume of distribution of alcohol, but this largely was accounted for by their smaller body size. The alcohol elimination rates were lower in the deficient animals, but this was accounted for by reduced body and liver weights.
Severe vitamin A deficiency did not alter liver ADH protein expression or rates of alcohol elimination when expressed per gram of body or liver weight.
Alcoholism Clinical and Experimental Research 01/2001; 24(12):1759-64. · 3.34 Impact Factor
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Methods in Enzymology 02/2000; 324:218-28. · 2.04 Impact Factor
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D W Crabb
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ABSTRACT: The understanding of how alcohol damages the liver has expanded substantially over the last decade. In particular, the genetics of alcoholism, the genesis of fatty liver, the role of oxidant stress, interactions between endotoxin and the Kupffer cell, and the factors that control activation of the hepatic stellate cell (HSC) have been the focus of a great deal of research. Genetic mechanisms for increasing the risk of alcoholism include alterations in alcohol metabolizing enzymes as well as neurobiological differences between individuals. The development of fatty liver may involve both redox forces, oxidative stress, and alterations in peroxisome proliferator activated receptor function. Oxidative stress is now known to involve both microsomal and mitochondrial systems. Recent studies implicate stimulation of Kupffer cells by portal vein endotoxin as a cause of release of cytokines and chemokines, hepatocyte hyper-metabolism, and activation of HSC. These actions appear to be in part gender-dependent and may explain the susceptibility of women to alcoholic liver disease. Activation of HSC underlies liver fibrosis and cirrhosis of all types; control of this activation might permit control of the progression of fibrosis. These advances suggest a number of new approaches as therapy for alcoholic liver injury.
The Keio Journal of Medicine 01/2000; 48(4):184-8.
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ABSTRACT: The strong protective effect of the ALDH2*2 mutation on risk of alcoholism suggests that other mutations that reduce mitochondrial aldehyde dehydrogenase (ALDH) activity in the liver might also deter drinking. This study describes a polymorphic locus found in the promoter of the ALDH2 gene that affects expression of reporter constructs.
Polymerase chain reaction (PCR)-based sequencing was used to search for polymorphisms. The ability of the promoter variants to bind transcription factors apolipoprotein A regulatory protein 1 (ARP-1) and chicken ovalbumin upstream promoter-transcription factor (COUP-TF) was tested in gel retardation assays using in vitro synthesized transcription factors. The variant promoters were tested for transcriptional activity using a heterologous promoter system and transient transfection assays.
A common polymorphism (A or G) in the human ALDH2 promoter region was found at -361 base pair (bp) from the translation start site. This polymorphism was found at different frequencies in African Americans, Caucasians, and Asians. The polymorphism occurs adjacent to the core binding motif for the transcription factors COUP-TF and ARP-1. Competition and binding affinity determinations did not show differences in the ability of these two sequences to bind the factors. Reporter genes containing these elements upstream of a basal thymidine kinase promoter had similar activity when transfected into a fibroblast (CV-1) cell line. However, the reporter containing the G allele was more active than that containing the A allele in hepatoma (H4IIEC3) cells.
The -361 bp A/G polymorphism is common in all racial groups tested. The G allele was more active than the A allele in a transfection assay. The basis for this difference is not known. If the differences in activity of the promoter constructs were paralleled by differences in ALDH2 enzyme activity in the liver, this polymorphism could affect risk of alcoholism.
Alcoholism Clinical and Experimental Research 07/1999; 23(6):963-8. · 3.34 Impact Factor
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ABSTRACT: Many medications can interact with alcohol, thereby altering the metabolism or effects of alcohol and/or the medication. Some of these interactions can occur even at moderate drinking levels and result in adverse health effects for the drinker. Two types of alcohol-medication interactions exist: (1) pharmacokinetic interactions, in which alcohol interferes with the metabolism of the medication, and (2) pharmacodynamic interactions, in which alcohol enhances the effects of the medication, particularly in the central nervous system (e.g., sedation). Pharmacokinetic interactions generally occur in the liver, where both alcohol and many medications are metabolized, frequently by the same enzymes. Numerous classes of prescription medications can interact with alcohol, including antibiotics, antidepressants, antihistamines, barbiturates, benzodiazepines, histamine H2 receptor antagonists, muscle relaxants, nonnarcotic pain medications and anti-inflammatory agents, opioids, and warfarin. In addition, many over-the-counter and herbal medications can cause negative effects when taken with alcohol.
Alcohol research & health: the journal of the National Institute on Alcohol Abuse and Alcoholism 02/1999; 23(1):40-54. · 0.58 Impact Factor
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ABSTRACT: Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is expressed in a tissue-specific fashion with high levels in liver, heart, kidney, and muscle, and low levels in most other tissues. The ALDH2 promoter was found to bind nuclear proteins at a pair of adjacent sites approximately 300 bp upstream from the translation start site, each of which was contacted at motifs containing the hexamer A/GGGTCA. The 3' site was shown to bind in vitro translated HNF-4. It was also shown by electrophoretic mobility shift assay utilizing antibodies against nuclear factors and rat liver nuclear extracts to be bound by hepatocyte nuclear factor 4 (HNF-4), chicken ovalbumin upstream promoter transcription factor I and II, and retinoid X receptors. A reporter construct containing four copies of this promoter element was activated by co-transfection of an HNF-4 expression plasmid in COS-1 and hepatoma cell lines. These results suggest that the tissue specificity of ALDH2 expression is in part determined by its activation by HNF-4.
Biochimica et Biophysica Acta 09/1998; 1399(2-3):181-6. · 4.66 Impact Factor
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D W Crabb
Hepatology 06/1997; 25(5):1292-4. · 11.66 Impact Factor
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ABSTRACT: The preproenkephalin A gene is regulated by upstream cis-acting elements which respond to various signals, such as cAMP, calcium, and phorbol esters. An additional regulatory element was detected downstream of the transcription start site of the human preproenkephalin A gene in transfection experiments. The element was localized by DNAse I footprinting and methylation interference assays to a direct repeat (DR-1) element in the first (untranslated) exon. Deletion or mutation of this site reduced transcriptional activity of promoter-reporter constructs by over 50%. Antibodies against COUP-TF beta/ARP-1 and RXR transcription factors altered the pattern seen on electrophoretic mobility shift assays using double-stranded oligonucleotide containing the exon 1 protein binding site. This suggests that the factors that bind this site and modulate transcription of the PPE gene include members of the COUP-TF and retinoid X receptor families.
Molecular Brain Research 05/1997; 45(1):50-8. · 2.00 Impact Factor
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Advances in experimental medicine and biology 02/1997; 414:395-402. · 1.09 Impact Factor
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ABSTRACT: Deficiency in mitochondrial aldehyde dehydrogenase (ALDH2), a tetrameric enzyme, results from inheriting one or two ALDH2*2 alleles. This allele encodes a protein subunit with a lysine for glutamate substitution at position 487 and is dominant over the wild-type allele, ALDH2*1. The ALDH2*2-encoded subunit (ALDH2K) reduces the activity of ALDH2 enzyme in cell lines expressing the wild-type subunit (ALDH2E). In addition to this effect on the enzyme activity, we now report that ALDH2*2 heterozygotes had lower levels of ALDH2 immunoreactive protein in autopsy liver samples. The half-lives of ALDH2 protein in HeLa cell lines expressing ALDH2*1, ALDH2*2, or both were determined by the rate of loss of immunoreactive protein after inhibition of protein synthesis with puromycin and by pulse-chase experiments. By either measure, ALDH2E enzyme was very stable, with a half-life of at least 22 h. ALDH2K enzyme had an enzyme half-life of only 14 h. In cells expressing both subunits, most of the subunits assemble as heterotetramers, and these enzymes had a half-life of 13 h. Thus, the effect of ALDH2K on enzyme turnover is dominant. These studies indicate that the ALDH2*2 allele exerts its dominant effect both by interfering with the catalytic activity of the enzyme and by increasing its turnover. This represents the first example of a dominantly acting allele with this effect on a mitochondrial enzyme's turnover.
Journal of Clinical Investigation 12/1996; 98(9):2027-32. · 15.39 Impact Factor
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Alcoholism Clinical and Experimental Research 12/1996; 20(8 Suppl):113A-116A. · 3.34 Impact Factor
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ABSTRACT: CV-1 cells were stably transfected with a preproenkephalin A (PPE) promoter-chloramphenicol acetyltransferase (CAT) reporter plasmid containing -176 to +171 bp of the human PPE gene. Low levels of CAT were expressed constitutively. The reporter enzyme activity was induced by treatment of the cells for 6 h with drugs that increased intracellular cAMP (forskolin and 8-bromo-cAMP), intracellular calcium (A23187), or protein kinase C activity (tetradecanoyl phorbol-4-acetate, TPA) in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine. Co-administration of dexamethasone reduced the magnitude of phorbol ester-stimulated CAT activity by about 50%, while there were smaller but not significant effects on forskolin- or A23187-stimulated expression of this reporter construct. In transient transfections which included the PPE-CAT reporter gene and a glucocorticoid receptor expression plasmid, dexamethasone significantly reduced stimulated expression of the reporter by TPA, forskolin, and A23187. The effect was observed with 10(-8)-10(-6) M dexamethasone and was blocked by the presence of the glucocorticoid antagonist RU486, suggesting that the effect of dexamethasone was mediated by the glucocorticoid receptor. The promoter region contained in this construct lacks a classical glucocorticoid response element or known negative elements; thus, dexamethasone may reduce stimulated expression of the PPE promoter via indirect effects.
Molecular Brain Research 12/1996; 42(1):103-8. · 2.00 Impact Factor
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ABSTRACT: Mitochondrial aldehyde dehydrogenase (ALDH2) activity is produced at low levels in many tissues, with highest production in liver. Transfection assays using the first 600 bp of upstream DNA provided evidence for both positive and negative regulatory elements in the proximal promoter. A region from -79 to -116 bp was protected in DNase I footprinting assays and bound in electrophoretic mobility shift assays (EMSA) by a nuclear factor found in all cell lines and tissues tested. This region, denoted FP160, contained the consensus recognition sites for Sp1 and AP2, and a CCAAT box. The CCAAT box was specifically protected by a nuclear factor in methylation interference assays. Mutagenesis of specific bp within the CCAAT box eliminated protein binding in vitro and decreased transcriptional activity from the ALDH2 promoter approximately 50% in reporter gene assays. Competition experiments showed that the nuclear factor binding to the FP160 oligodeoxyribonucleotide (oligo) was competed by oligos corresponding to an NY-Y/CP1-binding site to a greater extent than by those containing sites for CTF/NF1, C/EPB or CP2. The heat stability, resistance to proteinase K digestion, sensitivity to inhibition of DNA binding by o-phenanthroline, and immunological properties of the liver factor binding to FP160 were very similar to the corresponding properties of NF-Y/CP1. Thus, the proximal ALDH2 promoter was bound by NF-Y/CP1 and this transcription factor may be responsible for the basal expression of the gene observed in most tissues. The NFY-CP1 present in rat liver has similar properties to that previously characterized in M12 B-lymphoma cells and LMTK mouse fibroblasts.
Gene 10/1996; 173(2):155-61. · 2.34 Impact Factor
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ABSTRACT: Rat 3-hydroxyisobutyrate dehydrogenase exhibits significant amino acid sequence homology with 6-phosphogluconate dehydrogenase, D-phenylserine dehydrogenase from Pseudomonas syringae, and a number of hypothetical proteins encoded by genes of microbial origin. Key residues previously proposed to have roles in substrate binding and catalysis in sheep 6-phosphogluconate dehydrogenase are highly conserved in this entire family of enzymes. Site-directed mutagenesis, chemical modification, and substrate specificity studies were used to compare possible mechanistic similarities of 3-hydroxyisobutyrate dehydrogenase with 6-phosphogluconate dehydrogenase. The data suggest that 3-hydroxyisobutyrate and 6-phosphogluconate dehydrogenases may comprise, in part, a previously unrecognized family of 3-hydroxyacid dehydrogenases.
FEBS Letters 08/1996; 389(3):263-7. · 3.54 Impact Factor
