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Human alcohol dehydrogenase (ADH) exists as a heterogeneous group of isozymes capable of oxidizing a wide variety of aliphatic and aromatic alcohols. The five distinct human ADH subunits, each encoded by a separate gene, are differentially expressed during development and are subject to tissue-specific regulation. To analyze the organization and regulation of human ADH genes we first isolated a cDNA clone (pADH12) encoding the 3' portion of the beta ADH gene. In the current study pADH12 was used to screen a human genomic library, and several overlapping and nonoverlapping clones were selected. Hybridization and partial nucleotide sequence analyses of the clones indicated that three full-length human ADH genes encoding the alpha, beta, and gamma subunits were isolated. Human genomic DNA hybridization results indicate that the alpha, beta, and gamma ADH genes form a closely related gene family and suggest that the other known human ADH genes (i.e. those encoding the pi and chi subunits) share a more distant evolutionary relationship. Nucleotide sequence analysis of the beta ADH gene reveals that the coding region is interrupted by eight introns and spans approximately 15 kilobases. A presumptive transcription initiation site for the beta ADH gene was located by S1 nuclease mapping at a position 70 base pairs upstream of the start codon. The 5' flanking region possesses a TATA box promoter element as well as two tandem DNA sequences which display homology to previously examined glucocorticoid-responsive elements.

Human alcohol dehydrogenase (ADH) is encoded by at least five genes that fall into three classes. The class I ADH genes encode the three closely related alpha, beta, and gamma polypeptides. Molecular genetic analysis of class I ADH genes has been initiated by isolating a cDNA clone from a human adult liver cDNA library. A synthetic oligonucleotide mixture encoding a portion of the beta subunit of ADH was used as an in situ hybridization probe for the cDNA library. One positively hybridizing clone, pADH12, which contained an 1100-base-pair cDNA insert, was subjected to DNA sequence analysis. The sequence indicated that the cDNA encoded information for the carboxyl-terminal 91 amino acids of a class I ADH and a 3' untranslated region of 593 nucleotides. Comparisons with the carboxyl terminus of the human ADH beta subunit indicated that the cDNA encoded the beta polypeptide. This probe may facilitate genetic studies of various human alcohol-related syndromes, as well as enable basic molecular studies on human ADH gene expression.

Human alcohol dehydrogenase (ADH) is encoded by at least five genes that fall into three classes. The class I ADH genes encode the three closely related α, β, and γ polypeptides. Molecular genetic analysis of class I ADH genes has been initiated by isolating a cDNA clone from a human adult liver cDNA library. A synthetic oligonucleotide mixture encoding a portion of the β subunit of ADH was used as an in situ hybridization probe for the cDNA library. One positively hybridizing clone, pADH12, which contained an 1100-base-pair cDNA insert, was subjected to DNA sequence analysis. The sequence indicated that the cDNA encoded information for the carboxyl-terminal 91 amino acids of a class I ADH and a 3' untranslated region of 593 nucleotides. Comparisons with the carboxyl terminus of the human ADH β subunit indicated that the cDNA encoded the β polypeptide. This probe may facilitate genetic studies of various human alcohol-related syndromes, as well as enable basic molecular studies on human ADH gene expression.

Human alcohol dehydrogenase (ADH) consists of a complex group of isozymes encoded by at least five non-identical genes, two of which have previously been shown through enzymatic analysis to possess polymorphic variants. Using a cDNA probe the ADH2 gene encoding the beta subunit of human ADH was mapped to human chromosome 4. The cDNA probe for ADH2 was also used to detect a restriction fragment length polymorphism present in human populations. This polymorphism may help establish whether certain ADH allelic variants are linked with certain types of altered alcohol tolerance observed in various individuals. The restriction fragment length polymorphism may also be of use in genetic linkage studies of other genes located near ADH on human chromosome 4.

A cDNA clone for the beta-chain of human alcohol dehydrogenase (ADH) was used to isolate several cross-hybridizing clones from a mouse liver cDNA library. Clones pADHm9 and a portion of pADHm12 were sequenced. pADHm9 coded for a sequence of 151 C-terminal amino acids and some untranslated sequences from the 3' end of its corresponding mRNA. This clone was identified as an Adh-1 cDNA clone. Consistent with the known expression of Adh-1, this gene was expressed constitutively in liver, whereas the Adh-3 gene product was found only in stomach, lung and reproductive tissues. Furthermore, the translated region of the cDNA shared 91% amino acid sequence homology with rat liver ADH. [32P]pADHm9 was used as a hybridization probe to study the mechanism of androgen induction of kidney ADH activity. Induction of A/J female mice by androgen resulted in a dramatic increase in the steady-state level of Adh-1 mRNA content which correlated with the level of enzyme induction. The size of the mRNA obtained from control or induced kidney and liver tissues was indistinguishable by Northern analysis. [32P]pADHm9 was also used to probe restriction fragments of genomic DNA obtained from several inbred mouse strains. The hybridization patterns, considered with the genetic evidence, suggested that pADHm9 recognized sequences which may be present as only a single copy in the genome. No restriction fragment length polymorphisms were observed among the several inbred mouse strains examined.

Vitamin A (retinol) must be metabolized to an active retinoid ligand in order to fulfill all of its roles in vertebrate development. During retinoid signaling, retinol is first converted to retinal followed by conversion of retinal to the active ligand retinoic acid, which modulates nuclear retinoic acid receptors (RAR). The alcohol dehydrogenase (ADH) enzyme family may function in the metabolism of retinol, the alcohol form of vitamin A, as well as ethanol metabolism. Some members of the ADH family prefer retinol as a substrate over ethanol, and their ability to oxidize retinol is competitively inhibited by intoxicating levels of ethanol. Likewise, there exists an aldehyde dehydrogenase (ALDH) family containing several members preferring retinal as a substrate over acetaldehyde. The spatiotemporal expression patterns of ADH-IV and two forms of ALDH match the spatiotemporal detection of retinoic acid during mouse embryogenesis, i.e., no detection at 6.5 d of embryogenesis (E6.5), followed by detection at E7.5 in the primitive streak, and then detection in numerous tissues later in development. This suggests that certain forms of ADH and ALDH may cooperate to upregulated retinoic acid synthesis during development. Treatment of mouse embryos at E7.5 with an intoxicating amount of ethanol leads to a reduction in retinoic acid levels. At E7.5, two other mouse enzymes known to metabolize ethanol (ADH-I and P450 2E1) are not expressed, indicating that ADH-IV may be the only enzyme available at this stage to metabolize both ethanol and retinol. These findings suggest that ADH-IV participates in the initiation of retinoid signaling by functioning as a retinol dehydrogenase and that this can be inhibited by ethanol intoxication. [ABSTRACT FROM AUTHOR]

Abstract Background Nolz1 is a zinc finger transcription factor whose expression is enriched in the lateral ganglionic eminence (LGE), although its function is still unknown. Results Here we analyze the role of Nolz1 during LGE development. We show that Nolz1 expression is high in proliferating neural progenitor cells (NPCs) of the LGE subventricular zone. In addition, low levels of Nolz1 are detected in the mantle zone, as well as in the adult striatum. Similarly, Nolz1 is highly expressed in proliferating LGE-derived NPC cultures, but its levels rapidly decrease upon cell differentiation, pointing to a role of Nolz1 in the control of NPC proliferation and/or differentiation. In agreement with this hypothesis, we find that Nolz1 over-expression promotes cell cycle exit of NPCs in neurosphere cultures and negatively regulates proliferation in telencephalic organotypic cultures. Within LGE primary cultures, Nolz1 over-expression promotes the acquisition of a neuronal phenotype, since it increases the number of β-III tubulin (Tuj1)- and microtubule-associated protein (MAP)2-positive neurons, and inhibits astrocyte generation and/or differentiation. Retinoic acid (RA) is one of the most important morphogens involved in striatal neurogenesis, and regulates Nolz1 expression in different systems. Here we show that Nolz1 also responds to this morphogen in E12.5 LGE-derived cell cultures. However, Nolz1 expression is not regulated by RA in E14.5 LGE-derived cell cultures, nor is it affected during LGE development in mouse models that present decreased RA levels. Interestingly, we find that Gsx2, which is necessary for normal RA signaling during LGE development, is also required for Nolz1 expression, which is lost in Gsx2 knockout mice. These findings suggest that Nolz1 might act downstream of Gsx2 to regulate RA-induced neurogenesis. Keeping with this hypothesis, we show that Nolz1 induces the selective expression of the RA receptor (RAR)β without altering RARα or RARγ. In addition, Nozl1 over-expression increases RA signaling since it stimulates the RA response element. This RA signaling is essential for Nolz1-induced neurogenesis, which is impaired in a RA-free environment or in the presence of a RAR inverse agonist. It has been proposed that Drosophila Gsx2 and Nolz1 homologues could cooperate with the transcriptional co-repressors Groucho-TLE to regulate cell proliferation. In agreement with this view, we show that Nolz1 could act in collaboration with TLE-4, as they are expressed at the same time in NPC cultures and during mouse development. Conclusions Nolz1 promotes RA signaling in the LGE, contributing to the striatal neurogenesis during development.

It is well established that retinoic acid receptors (RARs) function as nuclear receptors that control gene expression in response to binding of the ligand retinoic acid (RA). However, some studies have proposed that RAR-alpha (RARa) controls synaptic plasticity via non-genomic effects outside the nucleus, i.e. effects on mRNA translation of GluA1, a sub-unit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. In order to support this non-genomic mechanism, studies have reported RARa knockout mice or treatment with pharmacological levels of RA and RAR antagonists to propose that RARa is required to control normal synaptic plasticity. A major shortcoming of the non-genomic hypothesis is that there have been no mutational studies showing that RARa can bind the GluA1 mRNA to control GLUA1 protein levels in a non-genomic manner. Also, without a genetic study that removes the endogenous ligand RA, it is impossible to conclude that RARa and its ligand RA control synaptic plasticity through a non-genomic signaling mechanism., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Vitamin A (retinol) is an important nutrient for embryonic development and adult health. Early studies identified retinoic acid (RA) as a metabolite of retinol, however, its importance was not apparent. Later, it was observed that RA treatment of vertebrate embryos had teratogenic effects on limb development. Subsequently, the discovery of nuclear RA receptors (RARs) revealed that RA controls gene expression directly at the transcriptional level through a process referred to as RA signaling. This important discovery led to further studies demonstrating that RA and RARs are required for normal embryonic development. The determination of RA function during normal development has been challenging as RA gain-of-function studies often lead to conclusions about normal development that conflict with RAR or RA loss-of-function studies. However, genetic loss-of-function studies have identified direct target genes of endogenous RA/RAR that are required for normal development of specific tissues. Thus, genetic loss-of-function studies that eliminate RARs or RA-generating enzymes have been instrumental in revealing that RA signaling is required for normal early development of many organs and tissues, including the hindbrain, posterior body axis, somites, spinal cord, forelimbs, heart, and eye.

Retinoic acid (RA) functions as an essential signal for development of the vertebrate eye by controlling the transcriptional regulatory activity of RA receptors (RARs). During eye development, the optic vesicles and later the retina generate RA as a metabolite of vitamin A (retinol). Retinol is first converted to retinaldehyde by retinol dehydrogenase 10 (RDH10) and then to RA by all three retinaldehyde dehydrogenases (ALDH1A1, ALDH1A2, and ALDH1A3). In early mouse embryos, RA diffuses to tissues throughout the optic placode, optic vesicle, and adjacent mesenchyme to stimulate folding of the optic vesicle to form the optic cup. RA later generated by the retina is needed for further morphogenesis of the optic cup and surrounding perioptic mesenchyme; loss of RA at this stage leads to microphthalmia and cornea plus eyelid defects. RA functions by binding to nuclear RARs at RA response elements (RAREs) that either activate or repress transcription of key genes. Binding of RA to RARs regulates recruitment of transcriptional coregulators such as nuclear receptor coactivator (NCOA) or nuclear receptor corepressor (NCOR), which in turn control binding of the generic coactivator p300 or the generic corepressor PRC2. No genes have been identified as direct targets of RA signaling during eye development, so future studies need to focus on identifying such genes and their RAREs. Studies designed to learn how RA normally controls eye development in vivo will provide basic knowledge valuable for determining how developmental eye defects occur and for improving strategies to treat eye defects.

Retinoic acid (RA) is the active form of vitamin A that functions as a ligand for nuclear RA receptors that directly bind genomic control regions to regulate gene expression. However, some studies have suggested that RA may have nongenomic effects outside of the nucleus, particularly with regard to synaptic plasticity. Recent results demonstrate that treatment with pharmacological levels of RA can alter synaptic plasticity which may be useful to treat neurological diseases. However, these results and those reported by others have not shown that endogenous RA is normally required for synaptic plasticity (or any other nongenomic effect) as there are no reports of genetic loss of function studies that remove endogenous RA in adult brain. The implication is that pharmacological levels of RA result in nongenomic effects, some of which may be helpful to treat certain diseases but in other cases this may cause unwanted side effects., Competing Interests: Conflicts of Interest Authors declare that there are no conflicts of interest in this work.

The relationship between adiposity and metabolic health is well established. However, very little is known about the fat depot, known as paracardial fat (pCF), located superior to and surrounding the heart. Here, we show that pCF remodels with aging and a high-fat diet and that the size and function of this depot are controlled by alcohol dehydrogenase 1 (ADH1), an enzyme that oxidizes retinol into retinaldehyde. Elderly individuals and individuals with obesity have low ADH1 expression in pCF, and in mice, genetic ablation of Adh1 is sufficient to drive pCF accumulation, dysfunction, and global impairments in metabolic flexibility. Metabolomics analysis revealed that pCF controlled the levels of circulating metabolites affecting fatty acid biosynthesis. Also, surgical removal of the pCF depot was sufficient to rescue the impairments in cardiometabolic flexibility and fitness observed in Adh1-deficient mice. Furthermore, treatment with retinaldehyde prevented pCF remodeling in these animals. Mechanistically, we found that the ADH1/retinaldehyde pathway works by driving PGC-1α nuclear translocation and promoting mitochondrial fusion and biogenesis in the pCF depot. Together, these data demonstrate that pCF is a critical regulator of cardiometabolic fitness and that retinaldehyde and its generating enzyme ADH1 act as critical regulators of adipocyte remodeling in the pCF depot.

The function of retinoic acid (RA) during limb development is still debated, as loss and gain of function studies led to opposite conclusions. With regard to limb initiation, genetic studies demonstrated that activation of FGF10 signaling is required for the emergence of limb buds from the trunk, with Tbx5 and RA signaling acting upstream in the forelimb field, whereas Tbx4 and Pitx1 act upstream in the hindlimb field. Early studies in chick embryos suggested that RA as well as Meis1 and Meis2 ( Meis1/2 ) are required for subsequent proximodistal patterning of both forelimbs and hindlimbs, with RA diffusing from the trunk, functioning to activate Meis1/2 specifically in the proximal limb bud mesoderm. However, genetic loss of RA signaling does not result in loss of limb Meis1/2 expression and limb patterning is normal, although Meis1/2 expression is reduced in trunk somitic mesoderm. More recent studies demonstrated that global genetic loss of Meis1/2 results in a somite defect and failure of limb bud initiation. Other new studies reported that conditional genetic loss of Meis1/2 in the limb results in proximodistal patterning defects, and distal FGF8 signaling represses Meis1/2 to constrain its expression to the proximal limb. In this review, we hypothesize that RA and Meis1/2 both function in the trunk to initiate forelimb bud initiation, but that limb Meis1/2 expression is activated proximally by a factor other than RA and repressed distally by FGF8 to generate proximodistal patterning.

Identification of target genes that mediate required functions downstream of transcription factors is hampered by the large number of genes whose expression changes when the factor is removed from a specific tissue and the numerous binding sites for the factor in the genome. Retinoic acid (RA) regulates transcription via RA receptors bound to RA response elements (RAREs) of which there are thousands in vertebrate genomes. Here, we combined chromatin immunoprecipitation sequencing (ChIP-seq) for epigenetic marks and RNA-seq on trunk tissue from wild-type and Aldh1a2-/- embryos lacking RA synthesis that exhibit body axis and forelimb defects. We identified a relatively small number of genes with altered expression when RA is missing that also have nearby RA-regulated deposition of histone H3 K27 acetylation (H3K27ac) (gene activation mark) or histone H3 K27 trimethylation (H3K27me3) (gene repression mark) associated with conserved RAREs, suggesting these genes function downstream of RA. RA-regulated epigenetic marks were identified near RA target genes already known to be required for body axis and limb formation, thus validating our approach; plus, many other candidate RA target genes were found. Nuclear receptor 2f1 (Nr2f1) and nuclear receptor 2f2 (Nr2f2) in addition to Meis homeobox 1 (Meis1) and Meis homeobox 2 (Meis2) gene family members were identified by our approach, and double knockouts of each family demonstrated previously unknown requirements for body axis and/or limb formation. A similar epigenetic approach can be used to determine the target genes for any transcriptional regulator for which a knockout is available., Competing Interests: The authors have declared that no competing interests exist.

Aims: It is still unclear which enzymes contribute to the adaptive enhancement of alcohol metabolism by chronic alcohol consumption (CAC). ADH1 (Class I) has the lowest Km for ethanol and the highest sensitivity for 4-methylpyrazole (4MP) among ADH isozymes, while ADH3 (Class III) has the highest Km and the lowest sensitivity. We investigated how these two major ADHs relate to the adaptive enhancement of alcohol metabolism., Methods: Male mice with different ADH genotypes (WT, Adh1-/- and Adh3-/-) were subjected to CAC experiment using a 10% ethanol solution for 1 month. Alcohol elimination rate (AER) was measured after ethanol injection at a 4.0 g/kg dose. 4MP-sensitive and -insensitive AERs were measured by the simultaneous administration of 4MP at a dose of 0.5 mmol/kg in order to estimate ADH1 and non-ADH1 pathways., Results: AER was enhanced by CAC in all ADH genotypes, especially more than twofold in Adh1-/- mice, with increasing ADH1 and/or ADH3 liver contents, but not CYP2E1 content. 4MP-sensitive AER was also increased by CAC in WT and Adh3-/- strains, which was greater in Adh3-/- than in WT mice. The sensitive AER was increased even in Adh1-/- mice probably due to the increase in ADH3, which is semi-sensitive for 4MP. 4MP-insensitive AER was also increased in WT and Adh1-/- by CAC, but not in Adh3-/- mice., Conclusion: ADH1 contributes to the enhancement of alcohol metabolism by CAC, particularly in the absence of ADH3. ADH3 also contributes to the enhancement as a non-ADH1 pathway, especially in the absence of ADH1., (© The Author(s) 2019. Medical Council on Alcohol and Oxford University Press. All rights reserved.)

Each vestibular sensory epithelium in the inner ear is divided morphologically and physiologically into two zones, called the striola and extrastriola in otolith organ maculae, and the central and peripheral zones in semicircular canal cristae. We found that formation of striolar/central zones during embryogenesis requires Cytochrome P450 26b1 (Cyp26b1)-mediated degradation of retinoic acid (RA). In Cyp26b1 conditional knockout mice, formation of striolar/central zones is compromised, such that they resemble extrastriolar/peripheral zones in multiple features. Mutants have deficient vestibular evoked potential (VsEP) responses to jerk stimuli, head tremor and deficits in balance beam tests that are consistent with abnormal vestibular input, but normal vestibulo-ocular reflexes and apparently normal motor performance during swimming. Thus, degradation of RA during embryogenesis is required for formation of highly specialized regions of the vestibular sensory epithelia with specific functions in detecting head motions.

Retinoic acid (RA), a metabolite of retinol (vitamin A), functions as a ligand for nuclear RA receptors (RARs) that regulate development of chordate animals. RA-RARs can activate or repress transcription of key developmental genes. Genetic studies in mouse and zebrafish embryos that are deficient in RA-generating enzymes or RARs have been instrumental in identifying RA functions, revealing that RA signaling regulates development of many organs and tissues, including the body axis, spinal cord, forelimbs, heart, eye and reproductive tract. An understanding of the normal functions of RA signaling during development will guide efforts for use of RA as a therapeutic agent to improve human health. Here, we provide an overview of RA signaling and highlight its key functions during development., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

Metabolic reprogramming is an active regulator of stem cell fate choices, and successful stem cell differentiation in different compartments requires the induction of oxidative phosphorylation. However, the mechanisms that promote mitochondrial respiration during stem cell differentiation are poorly understood. Here we demonstrate that Stat3 promotes muscle stem cell myogenic lineage progression by stimulating mitochondrial respiration in mice. We identify Fam3a, a cytokine-like protein, as a major Stat3 downstream effector in muscle stem cells. We demonstrate that Fam3a is required for muscle stem cell commitment and skeletal muscle development. We show that myogenic cells secrete Fam3a, and exposure of Stat3-ablated muscle stem cells to recombinant Fam3a in vitro and in vivo rescues their defects in mitochondrial respiration and myogenic commitment. Together, these findings indicate that Fam3a is a Stat3-regulated secreted factor that promotes muscle stem cell oxidative metabolism and differentiation, and suggests that Fam3a is a potential tool to modulate cell fate choices.

In mouse, retinoic acid (RA) is required for the early phase of body axis extension controlled by a population of neuromesodermal progenitors (NMPs) in the trunk called expanding-NMPs, but not for the later phase of body axis extension controlled by a population of NMPs in the tail called depleting-NMPs. Recent observations suggest that zebrafish utilize depleting-NMPs but not expanding-NMPs for body axis extension. In zebrafish, a role for RA in body axis extension was not supported by previous studies on aldh1a2 (raldh2) mutants lacking RA synthesis. Here, by treating zebrafish embryos with an RA synthesis inhibitor, we also found that body axis extension and somitogenesis was not perturbed, although loss of pectoral fin and cardiac edema were observed consistent with previous studies. The conclusion that zebrafish diverges from mouse in not requiring RA for body axis extension is consistent with zebrafish lacking early expanding-NMPs to generate the trunk. We suggest that RA control of body axis extension was added to higher vertebrates during evolution of expanding-NMPs., (Copyright © 2018 Elsevier Inc. All rights reserved.)