Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.1.1.1 (alcohol dehydrogenase)
 9,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biochemical studies indicate that alcohol dehydrogenase (ADH) metabolizes retinol to retinal, and that aldehyde dehydrogenase (ALDH) metabolizes retinal to retinoic acid, a molecule essential for growth and development. Summarized herein are several genetic studies supporting in vivo functions for ADH and ALDH in retinoic acid synthesis. Gene targeting was used to create knockout mice for either Adh1 or Adh4. Both knockout mice were viable and fertile without obvious defects. However, when wild-type and Adh4 knockout mice were subjected to vitamin A deficiency during gestation, the survival rate at birth was 3.3-fold lower for Adh4 knockout mice. When adult mice were examined for production of retinoic acid following retinol administration, Adh1 knockout mice exhibited 10-fold lower retinoic acid levels in liver compared with wild-type, whereas Adh4 knockout mice differed from wild-type by less than 2-fold. Thus, Adh1 plays a major role in the metabolism of a large dose of retinol to retinoic acid in adults, whereas Adh4 plays a role in maintaining sufficient retinol metabolism for development during retinol deficiency. ALDHs were examined by overexpression studies in frog embryos. Injection of mRNAs for either mouse Raldh1 or Raldh2 stimulated retinoic acid synthesis in frog embryos at the blastula stage when retinoic acid is normally undetectable. Overexpression of human ALDH2, human ALDH3, and mouse Aldh-pb did not stimulate retinoic acid production. In addition, Raldh2 knockout mice exhibit embryonic lethality with defects in retinoid-dependent tissues. Overall, these studies provide genetic evidence that Adh1, Adh4, Raldh1, and Raldh2 encode retinoid dehydrogenases involved in retinoic acid synthesis in vivo.
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PMID:Genetic dissection of retinoid dehydrogenases. 1130 68

Multiple forms and gene loci of human alcohol dehydrogenase (ADH EC: 1.2.1.3) and aldehyde dehydrogenase (ALDH, EC: 1.2.1.3) in the major pathway of alcohol metabolism have been found and characterized in the last two decades. With the coenzyme NAD, these enzymes catalyze the reversible conversion of organic alcohols to ketones or aldehydes, and aldehyde to acetic acid. The ADH genes are mapped to chromosome 4p21-25, but the ALDH genes are localized at different chromosomes. The cytochrome P450 2E1 (CYP2E1) gene, which is mapped to chromosome 10q24.3-qter contributes also the conversion of ethanol to acetaldehyde. Genetic polymorphisms have been reported in these alcohol metabolizing enzymes. The metabolisms of alcohol and acetaldehyde in liver and blood after drinking alcohol are thought to be influenced by the interactive action of these enzymes. Amongst the five major classes of the ADH subunits (alpha, beta, gamma, pi, chi, sigma), beta and gamma subunits show genetic polymorphisms. Recently a new nomenclature for ALDH genes has been recommend based on divergent evolution and chromosomal mapping. Two major isoforms designated as cytosolic ALDH1 and mitochondrial ALDH2 can be distinguished by their electrophoretic and kinetic properties as well as by their subcellular localization. Mitochondrial ALDH2 is a major enzyme in the oxidation of acetaldehyde derived from ethanol metabolism. The catalytic deficiency of ALDH2 isozyme is responsible for flushing and other vasomotor symptoms caused by higher acetaldehyde levels after alcohol intake. So far, frequencies of the two alleles of ALDH2 in Mongoloid have been reported in the different population groups. The catalytic deficiency of ALDH2 is caused by a structural point mutation at amino acid position 487, where a substitution of Glu to Lys resulting from a transition of G (C) to A (T) at 1510 nucleotide from the initiation codon has occurred. Individuals deficient in ALDH2 activity refrain from excessive drinking of alcohol due to the aversive reactions, leading to protection against alcoholism. Prevalence of the ALDH2*1 allele is associated with alcoholism, and subsequent studies have confirmed the allelic association with alcoholism in different ethnic groups. The effects of polymorphisms of ADH2 and CYP2E1 remained controversial, even in the same ethnic group. Investigation of mutations for the transacting cis-element in promoter region of the ALDH2 gene will provide important information with respect to regulation of this gene. Transfection assays using the first 600 bp of the upstream nucleotide sequences indicated that a region from -75 to -120 was necessary for the ALDH2 gene expression, and especially NF-Y/CP1 binding site from -92 to -96 (CCAAT box) is important in the expression of the gene. A novel polymorphism due to the nucleotide replacement at -357 G to A was found in all the population groups. Alcoholism is thought to be a multifactorial disease with complex mode of inheritance in addition to psychological and social factors, and many studies of family, adoption and twins concerning alcoholism have revealed that hereditary factor is an important determinant for developing alcoholism. Genetic association studies have contributed to the identification of a number of genetic risk factors for the chronic diseases influenced by genetic disorders and environmental factors.
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PMID:[Classification of alcohol metabolizing enzymes and polymorphisms--specificity in Japanese]. 1139 42

A variety of genetically influenced alcohol-related phenotypes relate to risk for alcohol dependence. In Asians, variation in the alcohol dehydrogenase (ADH2) gene relates to alcohol dependence, alcohol consumption, and reported alcohol-related symptoms, even after controlling for variation in the aldehyde dehydrogenase (ALDH2) gene. The association of ADH2 polymorphisms with alcohol-related behavior, however, has not been well characterized in non-Asians. This study evaluated 84 Ashkenazic Jewish American college students to determine the prevalence of the ADH2*2 allele (0.31). Carriers of ADH2*2 reported significantly fewer drinking days per month. ADH2*2, however, was not related to alcohol use disorders, alcohol-induced flushing and associated symptoms, number of binge drinking episodes in the past 90 days, maximum number of drinks ever consumed, or self-reported levels of response to alcohol. Results suggest that Ashkenazic Jewish Americans with ADH2*2 alleles drink less frequently, which might contribute, in part, to the overall lower rates of alcoholism in this population.
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PMID:ADH2 and alcohol-related phenotypes in Ashkenazic Jewish American college students. 1154 39

Alcohol is oxidized to acetaldehyde by alcohol dehydrogenase (ADH) and cytochrome P-4502E1 (CYP2E1), and then to acetate by aldehyde dehydrogenase (ALDH). Polymorphisms of these ethanol-metabolizing enzymes may be associated with inter-individual difference in alcohol metabolism and susceptibility to alcoholic liver disease. We determined genotype and allele frequencies of ALDH2, CYP2E1, ADH2, and ADH3 in male Korean patients with alcoholic cirrhosis (n=56), alcoholics without evidence of liver disease (n=52), and nondrinkers (n=64) by using PCR or PCR-directed mutagenesis followed by restriction enzyme digestion. The prevalences of heterozygous ALDH2*1/*2 plus homozygous ALDH2*2/*2 in patients with alcoholic cirrhosis (7.1%) and alcoholics without evidence of liver disease (3.8%) were significantly lower than that in nondrinkers (45.3%). The c2 allele frequencies of the CYP2E1 in alcoholic cirrhosis, alcoholics without evidence of liver disease, and nondrinkers were 0.21, 0.20, and 0.20, respectively. Allele frequencies of ADH2*2 in the three groups were 0.78, 0.74, and 0.77 and those of ADH3*1 were 0.94, 0.98, and 0.95. Therefore, we confirmed the observation that the ALDH2*2 gene protects against the development of alcoholism. However, the development of cirrhosis in Korean alcoholic patients was not associated with polymorphisms of ethanol-metabolizing enzymes.
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PMID:Association between polymorphisms of ethanol-metabolizing enzymes and susceptibility to alcoholic cirrhosis in a Korean male population. 1174 56

Alcohol dehydrogenase (ADH; EC. 1.1.1.1) and aldehyde dehydrogenase (ALDH; EC 1.2.1.3) play important roles in the metabolism of both endogenous and exogenous alcohols and aldehydes. The expression and localisation patterns of ADH (1-3) and ALDH (1-3) were investigated in the skin and liver of the mouse (BALB/c and CBA/ca), rat (F344) and guinea-pig (Dunkin-Hartley), using Western blot analysis and immunohistochemistry with class-specific antisera. ALDH2 expression and localisation was also determined in human skin, while ethanol oxidation, catalysed by ADH, was investigated in the mouse, guinea-pig and human skin cytosol. Western blot analysis revealed that ADH1, ADH3, ALDH1 and ALDH2 were expressed, constitutively, in the skin and liver of the mouse, rat and guinea-pig. ADH2 was not detected in the skin of any rodent species/strain, but was present in all rodent livers. ALDH3 was expressed, constitutively, in the skin of both strains of mouse and rat, but was not detected in guinea-pig skin and was absent in all livers. Immunohistochemistry showed similar patterns of expression for ADH and ALDH in both strains of mouse, rat, guinea-pig and human skin sections, with localisation predominantly in the epidermis, sebaceous glands and hair follicles. ADH activity (apparent V(max), nmoles/mg protein/min) was higher in liver (6.02-16.67) compared to skin (0.32-1.21) and lower in human skin (0.32-0.41) compared to mouse skin (1.07-1.21). The ADH inhibitor 4-methyl pyrazole (4-MP) reduced ethanol oxidation in the skin and liver in a concentration dependent manner: activity was reduced to approximately 30-40% and approximately 2-10% of the control activity, in the skin and liver, respectively, using 1 mM 4-MP. The class-specific expression of ADH and ALDH enzymes, in the skin and liver and their variation between species, may have toxicological significance, with respect to the metabolism of endogenous and xenobiotic alcohols and aldehydes.
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PMID:Species variations in cutaneous alcohol dehydrogenases and aldehyde dehydrogenases may impact on toxicological assessments of alcohols and aldehydes. 1249 13

Alcoholic beverages are causally related to cancer of the oral cavity, pharynx, larynx and esophagus. Ethanol is oxidized to acetaldehyde and then to acetate by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), both of which have genetic polymorphisms. A review of case-control studies of the effects of ALDH2, ADH2 and ADH3 genotypes shows consistently positive associations between inactive heterozygous ALDH2 and the less-active ADH2 genotypes and the risk for esophageal cancer in East Asian heavy drinkers and this enzyme-related vulnerability may extend to light-to-moderate drinkers. Some studies suggest similar associations with the risk for head and neck cancer in moderate-to-heavy-drinking Japanese. An established carcinogen in experimental animals, acetaldehyde can interact with human DNA. ALDH2-associated cancer susceptibility fits into a scenario in which acetaldehyde plays a critical role in the development of human cancer. Alcohol flushing and drinking behavior may partly explain this carcinogenic effect in carriers of less-active ADH2 genotypes. Whether the ADH3 genotype influences head and neck cancer risk in Western nations is controversial. Professional and public education about risky conditions connected to the ALDH2 and ADH2 genotypes and environmental factors is important in a new strategic approach to the prevention of alcohol-related cancers in East Asians. The use of simple tests to identify inactive ALDH2 on the basis of alcohol flushing responses could benefit many people, by helping them to identify their own cancer risks. Such testing could also help clinicians diagnose esophageal cancer earlier, through the use of endoscopic screening in the high-risk population.
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PMID:Genetic polymorphisms of alcohol and aldehyde dehydrogenases and risk for esophageal and head and neck cancers. 1267 87

High alcohol sensitivity among Asians is mainly due to a genetic polymorphism in the low Km aldehyde dehydrogenase (ALDH2) gene. Strong correlations between the ALDH2 genotype and alcohol sensitivity or alcohol drinking habits have been reported. Another prevalent polymorphism in the alcohol dehydrogenase beta-subunit (ADH2 gene) among Asians appears to modify skin flushing reactions after exposure to ethanol but does not influence alcohol drinking behavior. Both the ADH2 and ALDH2 genotypes have been significantly correlated with the risk of alcoholism. In a Japanese occupational population, a gene-environment interaction of the ALDH2 genotype and daily hassles scores for development of problem drinking behavior was observed. Habitual drinkers with the ALDH2*1/*2 genotype had higher frequencies of sister-chromatid exchange in cultured lymphocytes and higher 8-OHdG levels in polymorphonuclear leukocytes than those with the ALDH2*1/*1 genotype. Alcoholics and heavy drinkers with the ALDH2*1/*2 genotype have been shown to have significantly elevated risks for esophageal and multiple cancers in upper digestive organs than those with the ALDH2*1/*1 genotype. In Japan, bronchial asthma patients with the ALDH2*1/*2 genotype have been shown to have a significantly elevated risk for experiencing alcohol-induced asthma compared with the ALDH2*1/*1 genotype. Providing services to determine these genotypes would be of great help for each individual to make a plan for tailor-made health promotion.
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PMID:[Gene-environmental interactions in alcohol-related health problems--contributions of molecular biology to behavior modifications]. 1280 63

Enzymes encoded by two gene families, alcohol dehydrogenase ( ADH) and aldehyde dehydrogenase ( ALDH), mediate alcohol metabolism in humans. Allelic variants have been identified that alter metabolic rates and influence risk for alcoholism. Specifically, ADH1B*47His (previously ADH2-2) and ALDH2-2 have been shown to confer protection against alcoholism, presumably through accumulation of acetaldehyde in the blood and a resultant 'flushing response' to alcohol consumption. In the current study, variants at ADH1B (previously ADH2), ADH1C (previously ADH3), and ALDH2 were assayed in DNA extracts from participants belonging to a Southwest American Indian tribe ( n=490) with a high prevalence of alcoholism. Each subject underwent a clinical interview for diagnosis of alcohol dependence, as well as evaluation of intermediate phenotypes such as binge drinking and flushing response to alcohol consumption. Detailed haplotypes were constructed and tested against alcohol dependence and related intermediate phenotypes using both association and linkage analysis. ADH and ALDH variants were also assayed in three Asian and one African population (no clinical data) in order to provide an evolutionary context for the haplotype data. Both linkage and association analysis identified several ADH1C alleles and a neighboring microsatellite marker that affected risk of alcohol dependence and were also related to binge drinking. These data strengthen the support for ADH as a candidate locus for alcohol dependence and suggest further productive study.
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PMID:Allelic variation at alcohol metabolism genes ( ADH1B, ADH1C, ALDH2) and alcohol dependence in an American Indian population. 1288

Early esophageal squamous cell carcinoma detected by esophageal iodine staining can be easily treated by endoscopic mucosectomy, and identifying its predictors is important in better selecting candidates to screen for this high-mortality cancer. The common etiologies of elevated mean corpuscular volume (MCV) and esophageal cancer, including folate deficiency, smoking, drinking and high acetaldehyde exposure, suggest testing MCV as such a predictor. Japanese alcoholic men with (n = 65) and without (n = 206) esophageal squamous cell carcinomas, excluding those with liver cirrhosis, were assessed for MCV within 7 days of their last drink, alone or in combination with findings from either the alcohol flushing questionnaire or genotyping to identify inactive aldehyde dehydrogenase-2 (ALDH2*1/2*2) and the less-active form of alcohol dehydrogenase-2 (ADH2*1/2*1), which pose risks for esophageal squamous cell carcinoma. MCV was higher in cancer patients than in the control group. MCV was higher in both groups in those who were heavier smokers, had lower body mass index (BMI), experienced alcohol flushing, and had ALDH2*1/2*2. After adjusting for age, drinking and smoking habits, BMI and ALDH2/ADH2 genotypes, macrocytosis of MCV > or =106 fl was associated with increased risk for esophageal cancer (OR = 2.75). Men with both MCV > or =106 fl and alcohol flushing had an even higher cancer risk (OR = 5.51). The combinations of MCV > or =106 fl with ALDH2*1/2*2 or ADH2*1/2*1 alone, and both ALDH2*1/2*2 and ADH2*1/2*1 (ORs = 11.44, 21.22 and 319.7, respectively) showed consistently higher risk than the corresponding group with MCV <106 fl (ORs = 7.24, 4.71 and 27.01, respectively). In conclusion, MCV measurement, alone or in combination with the markers of alcohol sensitivity, provides a new means of predicting risk for esophageal squamous cell carcinoma in Japanese alcoholic men.
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PMID:Macrocytosis, a new predictor for esophageal squamous cell carcinoma in Japanese alcoholic men. 1294 54

The high-affinity (K(M)<1 microM) mitochondrial class 2 aldehyde dehydrogenase (ALDH2) metabolizes most of the acetaldehyde generated in the hepatic oxidation of ethanol. H4-II-E-C3 rat hepatoma cells have been found to express ALDH2. We report a method to assess ALDH2 activity in intact hepatoma cells that does not require mitochondrial isolation. To determine only the high-affinity ALDH2 activity it is necessary to keep constant low concentrations of acetaldehyde in the cells to minimize its metabolism by high-K(M) aldehyde dehydrogenases. To maintain both low and constant concentrations of acetaldehyde we used an "acetaldehyde clamp," which keeps acetaldehyde at a concentration of 4.2+/-0.4 microM. The clamp is attained by addition of excess yeast alcohol dehydrogenase, 14C-ethanol, and oxidized form of nicotinamide adenine dinucleotide (NAD(+)) to the hepatoma cell culture medium. The concentration of 14C-acetaldehyde attained follows the equilibrium constant of the alcohol dehydrogenase reaction. Thus, 14C-acetate is generated virtually by the low-K(M) aldehyde dehydrogenase activity. 14C-acetate is separated from the culture medium by an anionic resin and its radioactivity is determined. We showed that (1) acetate production is linear for 120 min, (2) addition of 160 microM cyanamide to the culture medium leads to a 75%-80% reduction of acetate generated, and (3) ALDH2 activity is dependent on cell-to-cell contact and increases after cells reach confluence. The clamp system allows the determination of ALDH2 activity in less than one million H4-II-E-C3 rat hepatoma cells. The specificity and sensitivity of the "acetaldehyde clamp" assay should be of value in evaluation of the effects of new agents that modify Aldh2 gene expression, as well as in the study of ALDH2 regulation in intact cells.
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PMID:Use of an "acetaldehyde clamp" in the determination of low-KM aldehyde dehydrogenase activity in H4-II-E-C3 rat hepatoma cells. 1461 7


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