Population genetic and family studies on aldehyde dehydrogenase deficiency and alcohol sensitivity

Useful method to monitor the physiological effects of alcohol ingestion by combination of micro-integrated laser Doppler blood flow meter and arm-raising test

Alcohol has a variety of effects on the human body, affecting both the sympathetic and parasympathetic nervous system. We examined the peripheral blood flow of alcohol drinkers using a micro-integrated laser Doppler blood flow meter (micro-electromechanical system blood flow sensor). An increased heart rate and blood flow was recorded at the earlobe after alcohol ingestion, and we observed strong correlation between blood flow, heart rate, and breath alcohol content in light drinkers; but not heavy drinkers. We also found that the amplitude of pulse waves measured at the fingertip during an arm-raising test significantly decreased on alcohol consumption, regardless of the individual's alcohol tolerance. Our micro-electromechanical system blood flow sensor successfully detected various physiological changes in peripheral blood circulation induced by alcohol consumption.

A family study of homeland Korean alcohol use

Survey data were obtained from 199 homeland Korean families consisting of 199 sets of parents, and 300 college-age sons (162) and daughters (138). Data were obtained regarding quantity and frequency of alcohol consumption by users and of judgments of what constituted "normal" and "problem" alcohol use, flushing status, symptoms experienced following alcohol use, reasons for drinking given by users, and reasons for abstaining given by abstainers. Fathers and sons differed little in use status, but daughters were abstainers far less often than their mothers. Female users drank a good deal less than males, fathers and sons differed slightly, while daughters drank considerably more than their mothers. Own use was substantially correlated with judgments of the nature of normal use and far less related judgements of problem use. There was a significant difference in fast versus slow skin flushing. with a higher proportion of females being fast flushers. Fast flushers drank less than slow flushers and also judged lower amounts of consumption as being "normal." Fast flushers experienced more physical symptoms than slow flushers; persons who drank more experienced fewer symptoms. Males more than females, slow flushers more than fast flushers, and heavy more than light users of alcohol are more likely to endorse a variety of reasons for drinking. Reasons for not drinking differ little across family membership groups. Contemporary homeland Koreans drink less than would have been expected on the basis of prior research, even though there is a substantial generational difference among females, with daughters being less frequently abstainers and drinking more, and more often than their mothers.

The retinoid X receptor response element in the human aldehyde dehydrogenase 2 promoter is antagonized by the chicken ovalbumin upstream promoter family of orphan receptors

Two tandem sites in the aldehyde dehydrogenase 2 promoter (designated FP330-5' and FP330-3') that bind members of the nuclear receptor superfamily were recently identified. Antibodies against apolipoprotein regulatory protein (ARP-1) altered DNA-protein interactions in electrophoretic mobility shift assays using oligonucleotides representing either promoter site and rat liver or cultured cell nuclear extracts. In vitro-translated chicken ovalbumin upstream promoter transcription factor (COUP-TFI), ARP-1, or ErbA-related protein 2 (Ear2) bound both sites. In addition, ARP-1/RXR, COUP-TFI/RXR, and ARP-1/COUP-TFI heterodimers bound the FP330-3' site. Mutagenesis of the FP330-3' site indicated that a DR-1 element was the preferred binding site for these factors. Transfected expression plasmids for these factors suppressed basal expression of reporter constructs containing the FP330-3' sites and the induction of the reporter by RXRalpha plus retinoic acid. Mutation of the two sites increased activity of a construct driven by 600 bp of the ALDH2 promoter in cell lines expressing COUP-TFs. The ALDH2 FP330-3' site appears to represent a complex nuclear receptor response element that is activated by RXRs and HNF-4 but repressed by members of the COUP-TF family.

Expression and localization of human alcohol and aldehyde dehydrogenase enzymes in skin

Alcohol dehydrogenase (ADH; EC 1.1.1.1) and aldehyde dehydrogenase (ALDH; EC 1.2.1.3.) are important enzymes involved in the biotransformation of both alcohols and aldehydes. Today, six classes of ADH and twelve classes of ALDH have been defined in mammals. Here we report the detection and localisation of three classes of ADH and two classes of ALDH in human skin, using Western blot analysis and immunohistochemistry with class-specific antisera. Western blot analysis of human skin cytosol revealed that class I-III ADH and class 1 and class 3 ALDH enzymes are expressed, constitutively, in three different anatomical regions of human skin (foreskin, breast, abdomen). Densitometric analysis of the immunoreactive bands revealed differential constitutive expression of these enzymes in foreskin, breast, and abdomen skin. Immunohistochemistry showed the presence of class I ADH and class III ADH enzymes, predominantly in the epidermis with some localised expression in the dermal appendages of human skin. In comparison, staining for class II ADH was more faint in the epidermis with very little dermal expression. Class 1 ALDH and class 3 ALDH were predominantly localised to the epidermis with minimal, highly localised dermal appendageal expression. These cutaneous ADH and ALDH enzymes may play significant roles in the metabolism of endogenous or xenobiotic alcohols and aldehydes.

Heterotetramers of human liver mitochondrial (class 2) aldehyde dehydrogenase expressed in Escherichia coli. A model to study the heterotetramers expected to be found in Oriental people

About 50% of the Oriental population have less liver mitochondrial aldehyde dehydrogenase (ALDH2) activity than do other people. It was found that they possessed an enzyme with a lysine at position 487 (E487K) instead of glutamate (Glu487). We previously found that the Km for NAD of recombinant human and rat E487K enzymes increased more than 150-fold (Farrés, J., Wang X., Takahashi, K., Cunningham, S. J. , Wang, T.T., and Weiner, H (1994) J. Biol. Chem. 269, 13854-13860). Many aldehyde dehydrogenase-deficient people were found to be heterozygous when genotyped for ALDH2. In this study liver tissue from heterozygous people was analyzed and found to possess mRNAs for both the glutamate and the lysine subunits. Western blot analysis showed that the glutamate subunit was present. The cDNAs for Glu487 and E487K were coexpressed on one plasmid in Escherichia coli, and the enzyme forms were separated from each other by isoelectric focusing to show that heterotetramers were formed. Only one Km value for NAD could be measured with the purified heterotetrameric enzyme that possessed just 16-18% activity of the glutamate homotetrameric enzyme. The E487K homotetramers had 8% specific activity of the Glu487 enzyme. There was no pre-steady state burst of NADH formation with the heterotetramer, a property found with the glutamate enzyme. Similar results were found for the coexpressed rat liver enzyme, except that a higher specific activity, 48%, was obtained. Thus, we conclude that presence of the lysine subunit altered the activity of the glutamate subunit in the heterotetramer to make it function more like an E487K enzyme.

Investigation of the mechanism of alcohol-induced bronchial asthma

BACKGROUND

Many Japanese patients with asthma experience episodes or exacerbation of asthma after alcohol consumption. This phenomenon is not seen in Caucasians and is specific to Asians. This has been thought to be attributable to a difference in alcohol metabolism, in particular the metabolism of acetaldehyde, between Asians and Caucasians.

METHODS

An oral ethanol challenge test, a leukocyte histamine release test, and an ELISA for detection of IgE specific to acetaldehyde-human serum albumin conjugate were carried out in 42 adults with bronchial asthma and nine healthy adults.

RESULTS

Fifty-five percent of the patients with asthma responded to the ethanol challenge and showed a 20% or greater reduction in forced expiratory volume in 1 second. Blood acetaldehyde and plasma histamine levels were significantly higher in responders than in nonresponders. The leukocyte histamine release test revealed no ethanol-induced histamine release. Acetaldehyde, on the other hand, was found to induce histamine release in a volume-dependent manner. The histamine release was significantly higher in the asthma group (both responders and nonresponders) than in the healthy control group. ELISA did not detect any IgE specific to acetaldehyde-human serum albumin conjugate.

CONCLUSION

Alcohol-induced bronchial asthma seems to develop as follows. Alcohol elevates blood acetaldehyde levels, which leads to degranulation of mast cells (or basophils). The resultant release of chemical mediators, such as histamine, induces asthma.

Low frequency of the ADH2*2 allele among Atayal natives of Taiwan with alcohol use disorders

Genetic variation at two polymorphic alcohol dehydrogenase loci, ADH2 and ADH3, and at the polymorphic mitochondrial aldehyde dehydrogenase locus, ALDH2, may influence the risk of developing alcoholism by modulating the rate of elimination of ethanol and the rate of formation and elimination of acetaldehyde. Populations differ in allele frequencies at these loci. We determined the genotypes at all three of these loci in Atayal natives of Taiwan. The frequencies of ADH2*2, ADH3*1, and ALDH2*1 alleles (0.91, 0.99, and 0.95, respectively) were significantly higher among the Atayal than among a predominantly Han Chinese population from Taiwan. Among the Atayal, the group with alcohol use disorders (alcohol dependence and alcohol abuse) had a significantly lower frequency of the ADH2*2 allele (0.82) than those without alcohol use disorders (0.91). The ADH2*2 allele encodes the beta 2 subunit; isozymes containing beta 2 subunits oxidize alcohol faster in vitro than the beta 1 beta 1 isozyme encoded by ADH2*1. Thus, the simplest explanation for these data is that individuals with a beta 2 isozymes have a higher rate of ethanol oxidation, which is a deterrent to alcohol abuse and dependence in some individuals. The Atayal with alcohol use disorders also had a lower frequency of ALDH2*2 than the controls; this allele is known to be responsible for the alcohol-flush reaction among Asians, and thereby deters drinking.

A non-radioactive method for the detection of a common mutant allele of aldehyde dehydrogenase 2

About 50% of Japanese have been estimated to possess at least one ALDH2*2 allele with a substitution of AAA for GAA at codon 487 of the aldehyde dehydrogenase gene. This mutation is tightly associated with the sensitivity of an individual to alcohol. We developed a method of identifying the ALDH2*2 allele by a non-radioactive technique. DNA from individuals was subjected to polymerase chain reaction in which part of the aldehyde dehydrogenase 2 gene was amplified. After dot-blotting onto nylon membranes, the DNA was hybridized with biotin-labelled allele-specific oligonucleotides. Determination of genotypes on 77 unrelated healthy Japanese individuals, using the conventional method and our new method with gradient hybridization temperature and competitive oligonucleotides, indicated that the latter was superior to the former.

Retinol and retinal metabolism. Relationship to the state of differentiation of cultured human keratinocytes

Cultured keratinocytes offer an attractive model for studying the metabolism of retinol in relation to cell differentiation, since the extent of keratinocyte differentiation can be modulated experimentally. The metabolism of retinol and retinal was studied in cytosol fractions prepared from two distinct keratinocyte populations, differentiating and non-differentiated. The enzymic activities were analysed using physiological concentrations of [3H]retinol and [3H]retinal in the presence of cofactors. The products formed were quantified by h.p.l.c. In the population of differentiating keratinocytes, the formation of retinoic acid from retinol occurred at a rate of 4.49 +/- 0.17 pmol/h per mg of protein, but no such conversion was observed in the population of non-differentiated cells. However, when retinal was used as substrate, retinoic acid was formed in both cell populations, at rates of 14.4 pmol/h per mg of protein in non-differentiated and 51.6 pmol/h per mg of protein in differentiating keratinocytes. Using PAGE/radiobinding assay, we demonstrated that retinoic acid formed from retinol was bound in differentiating keratinocytes to endogenous cellular retinoic acid-binding protein (CRABP). Furthermore, retinal was reduced to retinol in the presence of NADH in both differentiating and non-differentiated keratinocytes at a similar rate (8 pmol/h per mg of protein). Although retinal could not be detected under physiological conditions, it was found in significant amounts at pH 8.5-9, which is optimal for enzymic activity. This indicates that in keratinocytes retinal is an intermediate metabolite in retinoic acid formation from retinol. The enzymes catalysing the conversion of retinol into retinoic acid were found to differ from other alcohol and aldehyde dehydrogenases, since the formation of retinoic acid was not significantly affected by specific inhibitors of alcohol metabolism, such as 4-methylpyrazole and disulfiram. Moreover, the cytosol of non-differentiated keratinocytes did not generate retinoic acid from retinol despite showing alcohol dehydrogenase activity. The results suggest that: (1) retinol metabolism in human keratinocytes is different from that of other alcohols, (2) retinal is an intermediate metabolite in the conversion of retinol into retinoic acid, and (3) differentiating keratinocytes rich in CRABP are probably target cells for retinoic acid action.

[Genetically-induced variability of alcohol metabolism and its effect on drinking behavior and predisposition to alcoholism]

Alcoholism is one of the most challenging current health problems in the Western countries with far-reaching medical, social, and economic consequences. There are a series of factors that interact in predisposing or protecting an individual against alcoholism and alcohol-related disorders. This article surveys the state of our knowledge concerning the biochemical and genetic variations in alcohol metabolism and their implications in alcohol sensitivity, alcohol drinking habits, and alcoholism in different racial/ethnic groups. The major pathway for the degradation of ethanol is its oxidation to hydrogen and acetaldehyde--to which many of the toxic effects of ethanol can be attributed. Variations in alcohol and acetaldehyde metabolism via genetically determined polymorphisms in alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) seem to play an important role in individual and racial differences in acute and chronic reactions to alcohol, alcohol drinking habits, as well as vulnerability to organ damage after chronic alcohol abuse. Alcohol sensitivity and associated discomfort symptoms accompanying alcohol ingestion may be determinental for the significantly low incidence of alcoholism among the Japanese, Chinese and other Orientals of Mongoloid origin. An abnormal ALDH isozyme has been found to be widely prevalent among individuals of the Mongoloid race and is mainly responsible for the acute sensitivity to alcohol commonly observed in this race. Persons sensitive to alcohol by virtue of their genetically controlled ALDH isozyme deficiency may be discouraged from drinking large amounts of alcohol in their daily life due to the initial adverse reaction experienced after drinking alcohol. Indeed, a significantly low incidence of the mitochondrial ALDH isozyme deficiency has been observed in alcoholics as compared to psychiatric patients, drug dependents and healthy controls in Japan. How far any variation in ADH and/or ALDH activity among individuals of Caucasian origin will have similar effects has yet to be studied.

Asians, Asian-Americans and alcohol

The association of flushing (vasodilation, reddening of the skin) with the alcohol use of Asians and Asian-Americans is examined. Historical changes in alcohol use, recent secular changes in alcohol use, and marked differences in consumption among Asian populations and among Asian-Americans of the same national origins, as well as the lack of reduction of sex differences among flushers, indicate that flushing has little influence on alcohol consumption. Social, psychological, and cultural influences seem to be more adequate explanatory devices with regard to Oriental alcohol use.

Inheritance of mitochondrial aldehyde dehydrogenase: genotyping in Chinese, Japanese and South Korean families reveals dominance of the mutant allele

Genotyping of mitochondrial aldehyde dehydrogenase (ALDH I) was performed in enzymatically amplified DNA of 20 Chinese, Japanese and South Korean families (85 individuals) and in 113 unrelated persons by employing allele-specific oligonucleotide probes and dot blot hybridization. Genotyping individuals with phenotypic deficiency of ALDH I activity always showed the presence of at least one mutant allele. The data are compatible with a model assuming dominant inheritance of the mutant allele, which we have previously suggested on the basis of a population study.

Genotype of alcohol dehydrogenase and aldehyde dehydrogenase loci in Japanese alcohol flushers and nonflushers

A much higher incidence of alcohol flushing among Orientals in comparison to Caucasians, i.e., greater than 50% vs 5%-10%, has been attributed to racial differences in alcohol-metabolizing enzymes. A large majority of Orientals are "atypical" in alcohol dehydrogenase-2 locus (ADH2), and their livers exhibit significantly higher ADH activity than the livers of most Caucasians. Approximately 50% of Orientals lack the mitochondrial aldehyde dehydrogenase (ALDH2) activity, and elimination of acetaldehyde might be disturbed. We determined by means of hybridization of genomic DNA samples with allele specific oligonucleotide probes, genotypes of the ADH2 and ALDH2 loci in Japanese alcohol flushers and nonflushers. We found that all individuals with homozygous atypical ALDH2(2)/ALDH2(2) and most of those with heterozygous atypical ALDH1(2)/ALDH2(2) were alcohol flushers, while all subjects with homozygous usual ALDH1(2)/ALDH1(2) were nonflushers. Frequency of the atypical ADH2(2) was found to be higher in alcohol flushers than in nonflushers, but the statistical significance was not established in the sample size examined.

Genotyping of mitochondrial aldehyde dehydrogenase in blood samples using allele-specific oligonucleotides: comparison with phenotyping in hair roots

Deficiency of mitochondrial aldehyde dehydrogenase (ALDH I) is an inborn error of metabolism that is responsible for acute alcohol sensitivity (flushing response) observed only in Orientals of Mongoloid origin. Our previous studies using electrophoretic enzyme detection have shown that this deficiency is prevalent among Japanese, Chinese, and other Orientals. We report here the genotyping of ALDH I locus in blood samples of 218 South Korean individuals by means of hybridization analysis with allele-specific oligonucleotide probes and enzymatically amplified human genomic DNA. The results of genotyping are compared with the phenotype analysis in hair roots of the same individuals. Among 62 apparently deficient phenotypes, 58 heterozygote and 4 homozygote deficient genotypes were observed.

Alcohol and adolescence

Alcohol is the drug of choice for most substance-abusing adolescents and is the drug most often associated with teenage deaths. This article summarizes what is known about the inheritance of alcohol abuse, as well as the physical, developmental, psychosocial, and behavioral factors related to adolescent alcohol use.

Genetic aspects of alcoholism

The importance of genetic factors in alcoholism is supported by family, twin, and adoption studies. The four-fold increased risk for this disorder in adopted-away sons of alcoholics supports the need for studies attempting to identify biologic and genetic factors that influence the future risk for alcoholism. Some methodological issues inherent in the search for markers of a predisposition toward alcoholism are reviewed and the results of studies of children of alcoholics are presented. Two potentially important findings include the decreased intensity of reaction to alcohol challenges in these high-risk young men, and the possibility that they demonstrate small amplitudes of the P300 brain wave. Some clinical and research implications of these findings are discussed.

Aldehyde dehydrogenases, aldehyde oxidase and xanthine oxidase from baboon tissues: phenotypic variability and subcellular distribution in liver and brain

Isoelectric focusing (IEF) and cellulose acetate electrophoresis were used to examine the multiplicity and distribution of aldehyde dehydrogenases (ALDHs), aldehyde oxidase (AOX) and xanthine oxidase (XOX) from tissues of olive and yellow baboons. Five ALDHs were resolved and distinguished on the basis of their differential tissue and subcellular distribution or substrate specificity. Some ALDHs exhibited multiple activity zones. Baboon liver ALDHs were differentially distributed in cytosol (ALDHs II, III and V) and large granular (mitochondrial) fractions (ALDHs I and IV). The major liver ALDHs (I and II) were also broadly distributed in other tissues, as was the major stomach enzyme (ALDH-III). Three brain ALDHs were resolved, which were also differentially distributed between large granular (mitochondrial) (ALDHs I and IV) and cytosolic (ALDH-III) fractions. Electrophoretic variability between individuals was observed for the major liver mitochondrial isozyme (ALDH-I), the major stomach isozyme (ALDH-III) and the minor liver isozymes (ALDHs IV and V). Single forms of AOX and XOX were found in baboon tissue extracts, with the highest activities in liver (AOX) and intestine extracts (XOX). Both oxidases were predominantly localized in the liver soluble fraction.

Detection and partial characterization of a variant form of cytosolic aldehyde dehydrogenase isozyme

A rare case of human liver cytosolic aldehyde dehydrogenase (isozyme II) variation discovered in a Chinese autopsy liver specimen is reported. While the major isozyme band was nearly absent, several additional minor bands were observed on isoelectric focusing gel. Rabbit antibodies to purified human liver ALDH II showed immunological cross-reactivity for the variant enzyme bands. The existence of additional minor bands indicates the presence of tetramer hybrid forms made up of normal and variant monomers. The observed abnormality may represent the heterozygous form of ALDH II variation. A similar variant was also detected in erythrocytes of a male Thai student.