Rational design of soluble expressed human aldehyde dehydrogenase 2 with high stability and activity in pepsin and trypsin.

Acetaldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme in alcohol metabolism, and oral administration of ALDH2 is a promising method for alcohol detoxification. However, recombinant ALDH2 is susceptible to hydrolysis by digestive enzymes in the gastrointestinal tract and is expressed as inactive inclusion bodies in E. coli. In this study, we performed three rounds of rational design to address these issues. Specifically, the surface digestive sites of pepsin and trypsin were replaced with other polar amino acids, while hydrophobic amino acids were incorporated to reshape the catalytic cavity of ALDH2. The resulting mutant DE2-852 exhibited a 45-fold increase in soluble expression levels, while its stability against trypsin and pepsin increased by eightfold and twofold, respectively. Its catalytic efficiency (kcat/Km) at pH 7.2 and 3.2 improved by more than four and five times, respectively, with increased Vmax and decreased Km values. The enhanced properties of DE2-852 were attributed to the D457Y mutation, which created a more compact protein structure and facilitated a faster collision between the substrate and catalytic residues. These results laid the foundation for the oral administration and mass preparation of highly active ALDH2 and offered insights into the oral application of other proteins.

Frizzled class receptor 5 contributes to ovarian cancer chemoresistance through aldehyde dehydrogenase 1A1.

BACKGROUND: Chemoresistance is associated with tumor relapse and unfavorable prognosis. Multiple mechanisms underlying chemoresistance have been elucidated, including stemness and DNA damage repair. Here, the involvement of the WNT receptor, FZD5, in ovarian cancer (OC) chemoresistance was investigated. METHODS: OC cells were analyzed using in vitro techniques including cell transfection, western blot, immunofluorescence and phalloidin staining, CCK8 assay, colony formation, flowcytometry, real-time PCR, and tumorisphere formation. Pearson correlation analysis of the expression levels of relevant genes was conducted using data from the CCLE database. Further, the behavior of OC cells in vivo was assessed by generation of a mouse xenograft model. RESULTS: Functional studies in OC cells showed that FZD5 contributes to epithelial phenotype maintenance, growth, stemness, HR repair, and chemoresistance. Mechanistically, FZD5 modulates the expression of ALDH1A1, a functional marker for cancer stem-like cells, in a ß-catenin-dependent manner. ALDH1A1 activates Akt signaling, further upregulating RAD51 and BRCA1, to promote HR repair. CONCLUSIONS: Taken together, these findings demonstrate that the FZD5-ALDH1A1-Akt pathway is responsible for OC cell survival, and targeting this pathway can sensitize OC cells to DNA damage-based therapy.

The aldehyde dehydrogenase 2 rs671 variant enhances amyloid ß pathology.

In the ALDH2 rs671 variant, a guanine changes to an adenine, resulting in a dramatic decrease in the catalytic activity of the enzyme. Population-based data are contradictory about whether this variant increases the risk of Alzheimer's disease. In East Asian populations, the prevalence of the ALDH2 rs671 variant is 30-50%, making the National Human Brain Bank for Development and Function (the largest brain bank in East Asia) an important resource to explore the link between the ALDH2 rs671 polymorphism and Alzheimer's disease pathology. Here, using 469 postmortem brains, we find that while the ALDH2 rs671 variant is associated with increased plaque deposits and a higher Aß40/42 ratio, it is not an independent risk factor for Alzheimer's disease. Mechanistically, we show that lower ALDH2 activity leads to 4-HNE accumulation in the brain. The (R)-4-HNE enantiomer adducts to residue Lys53 of C99, favoring Aß40 generation in the Golgi apparatus. Decreased ALDH2 activity also lowers inflammatory factor secretion, as well as amyloid ß phagocytosis and spread in brains of patients with Alzheimer's disease. We thus define the relationship between the ALDH2 rs671 polymorphism and amyloid ß pathology, and find that ALDH2 rs671 is a key regulator of Aß40 or Aß42 generation.

ALDH1A1 drives prostate cancer metastases and radioresistance by interplay with AR- and RAR-dependent transcription.

Rationale: Current therapies for metastatic osseous disease frequently fail to provide a durable treatment response. To date, there are only limited therapeutic options for metastatic prostate cancer, the mechanisms that drive the survival of metastasis-initiating cells are poorly characterized, and reliable prognostic markers are missing. A high aldehyde dehydrogenase (ALDH) activity has been long considered a marker of cancer stem cells (CSC). Our study characterized a differential role of ALDH1A1 and ALDH1A3 genes as regulators of prostate cancer progression and metastatic growth. Methods: By genetic silencing of ALDH1A1 and ALDH1A3 in vitro, in xenografted zebrafish and murine models, and by comparative immunohistochemical analyses of benign, primary tumor, and metastatic specimens from patients with prostate cancer, we demonstrated that ALDH1A1 and ALDH1A3 maintain the CSC phenotype and radioresistance and regulate bone metastasis-initiating cells. We have validated ALDH1A1 and ALDH1A3 as potential biomarkers of clinical outcomes in the independent cohorts of patients with PCa. Furthermore, by RNAseq, chromatin immunoprecipitation (ChIP), and biostatistics analyses, we suggested the molecular mechanisms explaining the role of ALDH1A1 in PCa progression. Results: We found that aldehyde dehydrogenase protein ALDH1A1 positively regulates tumor cell survival in circulation, extravasation, and metastatic dissemination, whereas ALDH1A3 plays the opposite role. ALDH1A1 and ALDH1A3 are differentially expressed in metastatic tumors of patients with prostate cancer, and their expression levels oppositely correlate with clinical outcomes. Prostate cancer progression is associated with the increasing interplay of ALDH1A1 with androgen receptor (AR) and retinoid receptor (RAR) transcriptional programs. Polo-like kinase 3 (PLK3) was identified as a transcriptional target oppositely regulated by ALDH1A1 and ALDH1A3 genes in RAR and AR-dependent manner. PLK3 contributes to the control of prostate cancer cell proliferation, migration, DNA repair, and radioresistance. ALDH1A1 gain in prostate cancer bone metastases is associated with high PLK3 expression. Conclusion: This report provides the first evidence that ALDH1A1 and PLK3 could serve as biomarkers to predict metastatic dissemination and radiotherapy resistance in patients with prostate cancer and could be potential therapeutic targets to eliminate metastasis-initiating and radioresistant tumor cell populations.

Preclinical Evaluation of NTX-301, a Novel DNA Hypomethylating Agent in Ovarian Cancer.

PURPOSE: DNA methylation causes silencing of tumor-suppressor and differentiation-associated genes, being linked to chemoresistance. Previous studies demonstrated that hypomethylating agents (HMA) resensitize ovarian cancer to chemotherapy. NTX-301 is a highly potent and orally bioavailable HMA, in early clinical development. EXPERIMENTAL DESIGN: The antitumor effects of NTX-301 were studied in ovarian cancer models by using cell viability, stemness and ferroptosis assays, RNA sequencing, lipidomic analyses, and stimulated Raman spectroscopy. RESULTS: Ovarian cancer cells (SKOV3, IC50 = 5.08 nmol/L; OVCAR5 IC50 = 3.66 nmol/L) were highly sensitive to NTX-301 compared with fallopian tube epithelial cells. NTX-301 downregulated expression of DNA methyltransferases 1-3 and induced transcriptomic reprogramming with 15,000 differentially expressed genes (DEG, P < 0.05). Among them, Gene Ontology enrichment analysis identified regulation of fatty acid biosynthesis and molecular functions related to aldehyde dehydrogenase (ALDH) and oxidoreductase, known features of cancer stem cells. Low-dose NTX-301 reduced the ALDH(+) cell population and expression of stemness-associated transcription factors. Stearoyl-coenzyme A desaturase 1 (SCD), which regulates production of unsaturated fatty acids (UFA), was among the top DEG downregulated by NTX-301. NTX-301 treatment decreased levels of UFA and increased oxidized lipids, and this was blunted by deferoxamine, indicating cell death via ferroptosis. NTX-301-induced ferroptosis was rescued by oleic acid. In vivo, monotherapy with NTX-301 significantly inhibited ovarian cancer and patient-derived xenograft growth (P < 0.05). Decreased SCD levels and increased oxidized lipids were detected in NTX-301-treated xenografts. CONCLUSIONS: NTX-301 is active in ovarian cancer models. Our findings point to a new mechanism by which epigenetic blockade disrupts lipid homeostasis and promotes cancer cell death.

Effects of Hovenia dulcis fruit and peduncle extract on alcohol metabolism.

ETHNOPHARMACOLOGICAL RELEVANCE: The dried fruit and peduncle of Hovenia dulcis Thunberg (Rhamnaceae) (HD) has been used as a folk medicine to treat liver disease, detoxify alcoholism, and prevent and cure hangovers. AIM OF THE STUDY: We investigated the pharmacology of HD on the kinetics of EtOH and on the enzymes related to alcohol metabolism to seek the scientific evidence of HD to prevent hangover, the effectiveness as a folk medicine. MATERIALS AND METHODS: EtOH was orally administered 30 min after oral administration of HD boiling water extract in rats. Then, the profiles of blood EtOH concentrations were measured. Mice were reared with food containing powdered HD for 7 days, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were measured. Hepa1c1c7 cells were cultured with the medium containing HD extract, and the activities of ADH and ALDH were measured. RESULTS: HD extract reduced the blood EtOH concentrations in rats and induced the activities of ADH and ALDH and mRNA and protein expressions of ADH1B, ALDH1A1, and ALDH2 in the liver of mice and Hepa1c1c7 cells. Dihydromyricetin, one of the ingredients of HD, significantly induced the activities of ADH and ALDH in Hepa1c1c7 cells, however, the fractions containing hydrophilic organic compounds with small molecular weight contributed the most of the activities of HD extract. CONCLUSIONS: We clarified the experimental pharmacological evidences of HD as a folk medicine to detoxify alcoholism and prevent hangovers.

ALDH2 dysfunction and alcohol cooperate in cancer stem cell enrichment.

The alcohol metabolite acetaldehyde is a potent human carcinogen linked to esophageal squamous cell carcinoma (ESCC) initiation and development. Aldehyde dehydrogenase 2 (ALDH2) is the primary enzyme that detoxifies acetaldehyde in the mitochondria. Acetaldehyde accumulation causes genotoxic stress in cells expressing the dysfunctional ALDH2E487K dominant negative mutant protein linked to ALDH2*2, the single nucleotide polymorphism highly prevalent among East Asians. Heterozygous ALDH2*2 increases the risk for the development of ESCC and other alcohol-related cancers. Despite its prevalence and link to malignant transformation, how ALDH2 dysfunction influences ESCC pathobiology is incompletely understood. Herein, we characterize how ESCC and preneoplastic cells respond to alcohol exposure using cell lines, three-dimensional organoids and xenograft models. We find that alcohol exposure and ALDH2*2 cooperate to increase putative ESCC cancer stem cells with high CD44 expression (CD44H cells) linked to tumor initiation, repopulation and therapy resistance. Concurrently, ALHD2*2 augmented alcohol-induced reactive oxygen species and DNA damage to promote apoptosis in the non-CD44H cell population. Pharmacological activation of ALDH2 by Alda-1 inhibits this phenotype, suggesting that acetaldehyde is the primary driver of these changes. Additionally, we find that Aldh2 dysfunction affects the response to cisplatin, a chemotherapeutic commonly used for the treatment of ESCC. Aldh2 dysfunction facilitated enrichment of CD44H cells following cisplatin-induced oxidative stress and cell death in murine organoids, highlighting a potential mechanism driving cisplatin resistance. Together, these data provide evidence that ALDH2 dysfunction accelerates ESCC pathogenesis through enrichment of CD44H cells in response to genotoxic stressors such as environmental carcinogens and chemotherapeutic agents.

An idea to explore: Determination of single nucleotide polymorphisms in alcohol metabolism-related genes using PCR-based assays to understand the link between an individual's genotype and phenotype.

Here, we propose a laboratory exercise to quickly determine single nucleotide polymorphisms (SNPs) in human alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) genes involved in alcohol metabolism. In this exercise, two different genotyping methods based on polymerase chain reaction (PCR), namely allele-specific (AS) PCR and a PCR-restriction fragment polymorphism (RFLP) analysis, can be performed under the same PCR program (2-step × 35 cycles, 35 min total) in parallel using a hair root lysate as a template. In AS-PCR, the target regions of the G- or A-alleles of both genes are allele-specifically amplified in a single PCR tube. In the PCR-RFLP analysis, the two genes are amplified simultaneously in a single tube, and then a portion of the PCR product is double-digested with restriction enzymes MslI and Eam1104I for 5 min. The resulting reaction products of each method are electrophoresed side by side, and the genotypes are determined from the DNA band patterns. With the optimized protocol, the whole process from template preparation to genotyping can be completed in about 75 min. During PCR, students also perform an ethanol patch test to estimate their ability to metabolize alcohol. This series of experiments can help students learn the principles and applications of PCR/SNP analyses. By comparing the genotypes revealed by PCR and the phenotypes revealed by the patch tests, students can gain a better understanding of the clinical value of genetic testing.

Mitochondrial aldehyde dehydrogenase-2 coordinates the hydrogen sulfide - AMPK axis to attenuate high glucose-induced pancreatic ß-cell dysfunction by glutathione antioxidant system.

Progression of ß-cell loss in diabetes mellitus is significantly influenced by persistent hyperglycemia. At the cellular level, a number of signaling cascades affect the expression of apoptotic genes, ultimately resulting in ß-cell failure; these cascades have not been elucidated. Mitochondrial aldehyde dehydrogenase-2 (ALDH2) plays a central role in the detoxification of reactive aldehydes generated from endogenous and exogenous sources and protects against mitochondrial deterioration in cells. Here we report that under diabetogenic conditions, ALDH2 is strongly inactivated in ß-cells through CDK5-dependent glutathione antioxidant imbalance by glucose-6-phosphate dehydrogenase (G6PD) degradation. Intriguingly, CDK5 inhibition strengthens mitochondrial antioxidant defense through ALDH2 activation. Mitochondrial ALDH2 activation selectively preserves ß-cells against high-glucose-induced dysfunction by activating AMPK and Hydrogen Sulfide (H2S) signaling. This is associated with the stabilization and enhancement of the activity of G6PD by SIRT2, a cytoplasmic NAD+-dependent deacetylase, and is thereby linked to an elevation in the GSH/GSSG ratio, which leads to the inhibition of mitochondrial dysfunction under high-glucose conditions. Furthermore, treatment with NaHS, an H2S donor, selectively preserves ß-cell function by promoting ALDH2 activity, leading to the inhibition of lipid peroxidation by high-glucose concentrations. Collectively, our results provide the first direct evidence that ALDH2 activation enhances H2S-AMPK-G6PD signaling, leading to improved ß-cell function and survival under high-glucose conditions via the glutathione redox balance.

A patent review on aldehyde dehydrogenase inhibitors: an overview of small molecule inhibitors from the last decade.

INTRODUCTION: Physiological and pathophysiological effects arising from detoxification of aldehydes in humans implicate the enzyme aldehyde dehydrogenase (ALDH) gene family comprising of 19 isoforms. The main function of this enzyme family is to metabolize reactive aldehydes to carboxylic acids. Dysregulation of ALDH activity has been associated with various diseases. Extensive research has since gone into studying ALHD isozymes, their structural biology and developing small-molecule inhibitors. Novel chemical strategies to enhance the selectivity of ALDH inhibitors have now appeared. AREAS COVERED: A comprehensive review of patent literature related to aldehyde dehydrogenase inhibitors in the last decade and half (2007-2022) is provided. EXPERT OPINION: Aldehyde dehydrogenase (ALDH) is an important enzyme that metabolizes reactive exogenous and endogenous aldehydes in the body through NAD(P)±dependent oxidation. Hence this family of enzymes possess important physiological as well as toxicological roles in human body. Significant efforts in the field have led to potent inhibitors with approved clinical agents for alcohol use disorder therapy. Further clinical translation of novel compounds targeting ALDH inhibition will validate the promised therapeutic potential in treating many human diseases.The scientific/patent literature has been searched on SciFinder-n, Reaxys, PubMed, Espacenet and Google Patents. The search terms used were 'ALDH inhibitors', 'Aldehyde Dehydrogenase Inhibitors'.

Identification of genetic variants in two families with Keratoconus.

BACKGROUND: This research investigated the genetic characteristic of two Chinese families with keratoconus (KC). METHODS: For all people in the two families with KC, their history, clinical data, and peripheral blood were collected. One hundred healthy participants without KC and 112 sporadic KC patients were recruited as the controls. Whole exome sequencing of the genomic DNA and polymerase chain reaction were conducted for all the controls and family members to verify the variants. Functional analyses of the variants was performed using the software programs. RESULTS: A missense tuberous sclerosis 1 (TSC1) variant g.135797247A > G (c.622A > G, p.Ser208Gly) was detected in family 1. A single nucleotide polymorphism (SNP) rs761232139 (p.Gly235Arg) in aldehyde dehydrogenase 3 family member A1 (ALDH3A1) gene was detected in family 2. The variant c.622A > G in TSC1 and the SNP rs761232139 in ALDH3A1 were predicted as being probably damaging. CONCLUSIONS: Novel variant c.622A > G in TSC1 and SNP rs761232139 in ALDH3A1 have been detected in families with KC. These two findings may play a role in the pathogenesis of KC.

The rice peroxisomal receptor PEX5 negatively regulates resistance to rice blast fungus Magnaporthe oryzae.

The receptor protein PEX5, an important component of peroxisomes, regulates growth, development, and immunity in yeast and mammals. PEX5 also influences growth and development in plants, but whether it participates in plant immunity has remained unclear. Here, we report that knockdown of OsPEX5 enhances resistance to the rice blast fungus Magnaporthe oryzae. We demonstrate that OsPEX5 interacts with the E3 ubiquitin ligase APIP6, a positive regulator of plant immunity. APIP6 ubiquitinates OsPEX5 in vitro and promotes its degradation in vivo via the 26S proteasome pathway. In addition, OsPEX5 interacts with the aldehyde dehydrogenase OsALDH2B1, which functions in growth-defense trade-offs in rice. OsPEX5 stabilizes OsALDH2B1 to enhance its repression of the defense-related gene OsAOS2. Our study thus uncovers a previously unrecognized hierarchical regulatory mechanism in which an E3 ubiquitin ligase targets a peroxisome receptor protein that negatively regulates immunity in rice by stabilizing an aldehyde dehydrogenase that suppresses defense gene expression.

Multi-omics profiling reveals cellular pathways and functions regulated by ALDH1B1 in colon cancer cells.

Colon cancer is the third leading cause of cancer death globally. Although early screenings and advances in treatments have reduced mortality since 1970, identification of novel targets for therapeutic intervention is needed to address tumor heterogeneity and recurrence. Previous work identified aldehyde dehydrogenase 1B1 (ALDH1B1) as a critical factor in colon tumorigenesis. To investigate further, we utilized a human colon adenocarcinoma cell line (SW480) in which the ALDH1B1 protein expression has been knocked down by 80% via shRNA. Through multi-omics (transcriptomics, proteomics, and untargeted metabolomics) analysis, we identified the impact of ALDH1B1 knocking down (KD) on molecular signatures in colon cancer cells. Suppression of ALDH1B1 expression resulted in 357 differentially expressed genes (DEGs), 191 differentially expressed proteins (DEPs) and 891 differentially altered metabolites (DAMs). Functional annotation and enrichment analyses revealed that: (1) DEGs were enriched in integrin-linked kinase (ILK) signaling and growth and development pathways; (2) DEPs were mainly involved in apoptosis signaling and cellular stress response pathways; and (3) DAMs were associated with biosynthesis, intercellular and second messenger signaling. Collectively, the present study provides new molecular information associated with the cellular functions of ALDH1B1, which helps to direct future investigation of colon cancer.

Robust assembly of the aldehyde dehydrogenase Ald4p in Saccharomyces cerevisiae.

As part of our studies of yeast aldehyde dehydrogenase (Ald4p) assembly, we identified a population of transformants (SWORD strain) that show more robust filament formation of GFP-tagged Ald4p (Ald4p-GFP) than that of a wild type ALD4::GFP strain. Sequencing of the ALD4 gene in the SWORD strain showed that the increased assembly was not due to changes to the ALD4 coding sequence, suggesting that a second mutation site was altering Ald4p assembly. Using short-read whole-genome sequencing, we identified spontaneous mutations in FLO9. Introduction of the SWORD allele of FLO9 into a wild-type ALD4::GFP yeast strain revealed that the changes to FLO9 were a contributor to the increased length of Ald4p-GFP filaments we observe in the SWORD strain and that this effect was not due to an increase in Ald4p protein levels. However, the expression of the FLO9 (SWORD) allele in wild-type yeast did not fully recapitulate the length control defect we observed in SWORD strains, arguing that there are additional genes contributing to the filament length phenotype. For our future work, this FLO9 from SWORD will be tested whether it could show global effect, promoting the assembly of some other filament-forming enzymes.

Empagliflozin improves circulating vascular regenerative cell content in people without diabetes with risk factors for adverse cardiac remodeling.

Sodium glucose-cotransporter 2 (SGLT2) inhibitors have been reported to reduce cardiovascular events and heart failure in people with and without diabetes. These medications have been shown to counter regenerative cell exhaustion in the context of prevalent diabetes. This study sought to determine if empagliflozin attenuates regenerative cell exhaustion in people without diabetes. Peripheral blood mononuclear cells were collected at the baseline and 6-mo visits from individuals randomized to receive empagliflozin (10 mg/day) or placebo who were participating in the EMPA-HEART 2 CardioLink-7 trial. Precursor cell phenotypes were characterized by flow cytometry for cell-surface markers combined with high aldehyde dehydrogenase activity to identify precursor cell subsets with progenitor (ALDHhi) versus mature effector (ALDHlow) cell attributes. Samples from individuals assigned to empagliflozin (n = 25) and placebo (n = 21) were analyzed. At baseline, overall frequencies of primitive progenitor cells (ALDHhiSSClow), monocyte (ALDHhiSSCmid), and granulocyte (ALDHhiSSChi) precursor cells in both groups were similar. At 6 mo, participants randomized to empagliflozin demonstrated increased ALDHhiSSClowCD133+CD34+ proangiogenic cells (P = 0.048), elevated ALDHhiSSCmidCD163+ regenerative monocyte precursors (P = 0.012), and decreased ALDHhiSSCmidCD86 + CD163- proinflammatory monocyte (P = 0.011) polarization compared with placebo. Empagliflozin promoted the recovery of multiple circulating provascular cell subsets in people without diabetes suggesting that the cardiovascular benefits of SGLT2 inhibitors may be attributed in part to the attenuation of vascular regenerative cell exhaustion that is independent of diabetes status.NEW & NOTEWORTHY Using an aldehyde dehydrogenase (ALDH) activity-based flow cytometry assay, we found that empagliflozin treatment for 6 mo was associated with parallel increases in circulating vascular regenerative ALDHhi-CD34/CD133-coexpressing progenitors and decreased proinflammatory ALDHhi-CD14/CD86-coexpressing monocyte precursors in individuals without diabetes but with cardiovascular risk factors. The rejuvenation of the vascular regenerative cell reservoir may represent a mechanism via which sodium glucose-cotransporter 2 (SGLT2) inhibitors limit maladaptive repair and delay the development and progression of cardiovascular diseases.

Hypoxia-induced ALDH3A1 promotes the proliferation of non-small-cell lung cancer by regulating energy metabolism reprogramming.

Aldehyde dehydrogenase 3A1 (ALDH3A1) is an NAD+-dependent enzyme that is closely related to tumor development. However, its role in non-small-cell lung cancer (NSCLC) has not been elucidated. This study aimed to clarify the mechanism of ALDH3A1 and identify potential therapeutic targets for NSCLC. Here, for the first time, we found that ALDH3A1 expression could be induced by a hypoxic environment in NSCLC. ALDH3A1 was highly expressed in NSCLC tissue, especially in some late-stage patients, and was associated with a poor prognosis. In mechanistic terms, ALDH3A1 enhances glycolysis and suppresses oxidative phosphorylation (OXPHOS) to promote cell proliferation by activating the HIF-1α/LDHA pathway in NSCLC. In addition, the results showed that ALDH3A1 was a target of ß-elemene. ALDH3A1 can be downregulated by ß-elemene to inhibit glycolysis and enhance OXPHOS, thus suppressing NSCLC proliferation in vitro and in vivo. In conclusion, hypoxia-induced ALDH3A1 is related to the energy metabolic status of tumors and the efficacy of ß-elemene, providing a new theoretical basis for better clinical applications in NSCLC.

A common East-Asian ALDH2 mutation causes metabolic disorders and the therapeutic effect of ALDH2 activators.

Obesity and type 2 diabetes have reached pandemic proportion. ALDH2 (acetaldehyde dehydrogenase 2, mitochondrial) is the key metabolizing enzyme of acetaldehyde and other toxic aldehydes, such as 4-hydroxynonenal. A missense Glu504Lys mutation of the ALDH2 gene is prevalent in 560 million East Asians, resulting in reduced ALDH2 enzymatic activity. We find that male Aldh2 knock-in mice mimicking human Glu504Lys mutation were prone to develop diet-induced obesity, glucose intolerance, insulin resistance, and fatty liver due to reduced adaptive thermogenesis and energy expenditure. We find reduced activity of ALDH2 of the brown adipose tissue from the male Aldh2 homozygous knock-in mice. Proteomic analyses of the brown adipose tissue from the male Aldh2 knock-in mice identifies increased 4-hydroxynonenal-adducted proteins involved in mitochondrial fatty acid oxidation and electron transport chain, leading to markedly decreased fatty acid oxidation rate and mitochondrial respiration of brown adipose tissue, which is essential for adaptive thermogenesis and energy expenditure. AD-9308 is a water-soluble, potent, and highly selective ALDH2 activator. AD-9308 treatment ameliorates diet-induced obesity and fatty liver, and improves glucose homeostasis in both male Aldh2 wild-type and knock-in mice. Our data highlight the therapeutic potential of reducing toxic aldehyde levels by activating ALDH2 for metabolic diseases.

Aldehyde Dehydrogenase Genes as Prospective Actionable Targets in Acute Myeloid Leukemia.

It has been previously shown that the aldehyde dehydrogenase (ALDH) family member ALDH1A1 has a significant association with acute myeloid leukemia (AML) patient risk group classification and that AML cells lacking ALDH1A1 expression can be readily killed via chemotherapy. In the past, however, a redundancy between the activities of subgroup members of the ALDH family has hampered the search for conclusive evidence to address the role of specific ALDH genes. Here, we describe the bioinformatics evaluation of all nineteen member genes of the ALDH family as prospective actionable targets for the development of methods aimed to improve AML treatment. We implicate ALDH1A1 in the development of recurrent AML, and we show that from the nineteen members of the ALDH family, ALDH1A1 and ALDH2 have the strongest association with AML patient risk group classification. Furthermore, we discover that the sum of the expression values for RNA from the genes, ALDH1A1 and ALDH2, has a stronger association with AML patient risk group classification and survival than either one gene alone does. In conclusion, we identify ALDH1A1 and ALDH2 as prospective actionable targets for the treatment of AML in high-risk patients. Substances that inhibit both enzymatic activities constitute potentially effective pharmaceutics.

Pearls & Oy-sters: Delayed Response to Pyridoxine in Pyridoxine-Dependent Epilepsy.

Inborn errors of metabolism are a diverse group of genetic disorders including many that cause neonatal-onset epilepsy such as pyridoxine-dependent epilepsy (PDE). PDE occurs secondary to biallelic pathogenic variants in ALDH7A1 and can present with refractory neonatal seizures and status epilepticus. Neonatal seizures and encephalopathy are modifiable with pyridoxine (vitamin B6) supplementation. However, the clinical response to pyridoxine supplementation can be delayed. We present the case of a full-term neonate with PDE in which seizure cessation was seen a few hours after intravenous pyridoxine load, but the improvement in EEG background and level of clinical encephalopathy occurred 5 days later. We share this case to provide an example in which clinical improvement in PDE was gradual and required continuation of treatment for several days illustrating the necessity of continuing vitamin B6 supplementation in suspected cases until confirmatory genetic testing is obtained or an alternate cause is found.

Genome-wide characterization and gene expression analyses of ALDH gene family in response to drought stress in moso bamboo (Phyllostachys edulis).

Aldehyde dehydrogenase (ALDH) superfamily, comprising enzymes dependent on NAD+ or NADP+, plays an important role in controlling plant growth and development, as well as in responsing to phytohormone and environmental stress. These enzymes possess the ability to prevent toxic effects of aldehydes by converting them into their corresponding carboxylic acids. However, the potential function of ALDH genes in moso bamboo (Phyllostachys edulis) remains largely unknown. In this study, the ALDH gene superfamily in moso bamboo was analyzed through genome-wide screening, the evolutionary relationship of expansion genes was conducted. Tissue-specific expression patterns of ALDH genes were observed in 26 different tissues. Plant hormone and environmental stress responsive cis-elements were identified in the promoter of ALDH genes, which were supported by public databases data on the expression patterns under various abiotic stresses and hormone treatments. ALDH activity was increased in moso bamboo seedlings exposed to drought, compared to control condition. Furthermore, PeALDH2B2 was found to physically interact with PeGPB1 in response to drought. Overall, the study provides a comprehensive analysis of the ALDH family in moso bamboo and contributes to our understanding of the function of ALDH genes in growth, development, and adaptation to drought stresses.