Aldehyde Dehydrogenase Activity Research Articles

Empagliflozin Improves Circulating Vascular Regenerative Cell Content in People Not Living With Diabetes But With Cardiovascular Risk Factors.

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-month 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 months, participants randomized to empagliflozin demonstrated increased ALDHhiSSClowCD133+CD34+ pro-angiogenic cells (P=0.048), elevated ALDHhiSSCmidCD163+ regenerative monocyte precursors (P=0.012) and decreased ALDHhiSSCmidCD86+CD163- pro-inflammatory monocyte (P=0.011) polarization compared to placebo. Empagliflozin promoted the recovery of multiple circulating pro-vascular 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.

Discovery of novel small-molecule aldehyde dehydrogenase 2 activators based on drug repurposing

Aldehyde dehydrogenase 2 (ALDH2) plays an important role in the detoxification of reactive aldehydes under oxidative stress. Because an estimated 50% of East Asians carry a common ALDH2 deficient variant with decreased enzyme activity and are more susceptible to toxic aldehydes, more recent findings have highlighted the therapeutic potential of ALDH2 activators in aldehyde-related diseases such as cardiovascular injury. Drug repurposing has unique advantages in providing new lead compounds with good drug-like properties. Herein, we identified Tadalafil from DrugBank as a novel ALDH2 activator using a combination strategy of docking-based and pharmacophore-based virtual screening based on exploring the activation mechanism. Then a hit-based substructure search was completed and has led to the discovery of 5 hits, among which A1 showed better ALDH2 activation activity than Tadalafil. This study provides a good basis for the further research of ALDH2 activators.

Alpha-lipoic Acid Protects Against Chronic Alcohol Consumption-induced Cardiac Damage by the Aldehyde Dehydrogenase 2-associated PINK/Parkin Pathway.

Chronic alcohol intake contributes to high mortality rates due to ethanol-induced cardiac hypertrophy and contractile dysfunction, which are accompanied by increased oxidative stress and disrupted mitophagy. Alpha-lipoic acid (α-LA), a well-known antioxidant, has been shown to protect against cardiac hypertrophy and inflammation. However, little is known about its role and mechanism in the treatment of alcoholic cardiomyopathy. Here, we evaluated the role of α-LA in alcohol-induced cardiac damage by feeding mice a 4.8% (v/v) alcohol diet with or without α-LA for 6 w. Our results suggested that chronic alcohol consumption increased mortality, blood alcohol concentrations, and serum aldehyde levels, but a-LA attenuated the elevations in mortality and aldehydes. Chronic alcohol intake also induced cardiac dysfunction, including enlarged left ventricles, reduced left ventricular ejection fraction, enhanced cardiomyocyte size, and increased serum levels of brain natriuretic peptide, lactate dehydrogenase, and creatine kinase myocardial isoenzyme. Moreover, alcohol intake led to the accumulation of collagen fiber and mitochondrial dysfunction, the effects of which were alleviated by α-LA. In addition, α-LA intake also prevented the increase in reactive oxygen species production and the decrease in mitochondrial number that were observed after alcohol consumption. Chronic alcohol exposure activated PINK1/Parkin-mediated mitophagy. These effects were diminished by α-LA intake by the activation of aldehyde dehydrogenase 2. Our data indicated that α-LA helps protect cardiac cells against the effects of chronic alcohol intake, likely by inhibiting PINK1/Parkin-related mitophagy through the activation of aldehyde dehydrogenase 2.

Implication of the cooking oil-peroxidation product "hydroxynonenal" for Alzheimer's disease.

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that reduces cell injuries via detoxification of lipid-peroxidation product, 4-hydroxy-2-nonenal (hydroxynonenal). It is generated exogenously via deep-frying of linoleic acid-rich cooking oils and/or endogenously via oxidation of fatty acids involved in biomembranes. Although its toxicity for human health is widely accepted, the underlying mechanism long remained unknown. In 1998, Yamashima et al. have formulated the "calpain-cathepsin hypothesis" as a molecular mechanism of ischemic neuronal death. Subsequently, they found that calpain cleaves Hsp70.1 which became vulnerable after the hydroxynonenal-induced carbonylation at the key site Arg469. Since it is the pivotal aberration that induces lysosomal membrane rupture, they suggested that neuronal death in Alzheimer's disease similarly occurs by chronic ischemia via the calpain-cathepsin cascade triggered by hydroxynonenal. For nearly three decades, amyloid β (Aβ) peptide was thought to be a root substance of Alzheimer's disease. However, because of both the insignificant correlations between Aβ depositions and occurrence of neuronal death or dementia, and the negative results of anti-Aβ medicines tested so far in the patients with Alzheimer's disease, the strength of the "amyloid cascade hypothesis" has been weakened. Recent works have suggested that hydroxynonenal is a mediator of programmed cell death not only in the brain, but also in the liver, pancreas, heart, etc. Increment of hydroxynonenal was considered an early event in the development of Alzheimer's disease. This review aims at suggesting ways out of the tunnel, focusing on the implication of hydroxynonenal in this disease. Herein, the mechanism of Alzheimer neuronal death is discussed by focusing on Hsp70.1 with a dual function as chaperone protein and lysosomal stabilizer. We suggest that Aβ is not a culprit of Alzheimer's disease, but merely a byproduct of autophagy/lysosomal failure resulting from hydroxynonenal-induced Hsp70.1 disorder. Enhancing ALDH2 activity to detoxify hydroxynonenal emerges as a promising strategy for preventing and treating Alzheimer's disease.

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.

Deubiquitinase OTUD5 as a Novel Protector against 4-HNE-Triggered Ferroptosis in Myocardial Ischemia/Reperfusion Injury.

Despite the development of advanced technologies for interventional coronary reperfusion after myocardial infarction, a substantial number of patients experience high mortality due to myocardial ischemia-reperfusion (MI/R) injury. An in-depth understanding of the mechanisms underlying MI/R injury can provide crucial strategies for mitigating myocardial damage and improving patient survival. Here, it is discovered that the 4-hydroxy-2-nonenal (4-HNE) accumulates during MI/R, accompanied by high rates of myocardial ferroptosis. The loss-of-function of aldehyde dehydrogenase 2 (ALDH2), which dissipates 4-HNE, aggravates myocardial ferroptosis, whereas the activation of ALDH2 mitigates ferroptosis. Mechanistically, 4-HNE targets glutathione peroxidase 4 (GPX4) for K48-linked polyubiquitin-related degradation, which 4-HNE-GPX4 axis commits to myocyte ferroptosis and forms a positive feedback circuit. 4-HNE blocks the interaction between GPX4 and ovarian tumor (OTU) deubiquitinase 5 (OTUD5) by directly carbonylating their cysteine residues at C93 of GPX4 and C247 of OTUD5, identifying OTUD5 as the novel deubiquitinase for GPX4. Consequently, the elevation of OTUD5 deubiquitinates and stabilizes GPX4 to reverse 4-HNE-induced ferroptosis and alleviate MI/R injury. The data unravel the mechanism of 4-HNE in GPX4-dependent ferroptosis and identify OTUD5 as a novel therapeutic target for the treatment of MI/R injury.

Mitochondria in Cancer Stem Cells: From an Innocent Bystander to a Central Player in Therapy Resistance.

Cancer continues to rank among the world's leading causes of mortality despite advancements in treatment. Cancer stem cells, which can self-renew, are present in low abundance and contribute significantly to tumor recurrence, tumorigenicity, and drug resistance to various therapies. The drug resistance observed in cancer stem cells is attributed to several factors, such as cellular quiescence, dormancy, elevated aldehyde dehydrogenase activity, apoptosis evasion mechanisms, high expression of drug efflux pumps, protective vascular niche, enhanced DNA damage response, scavenging of reactive oxygen species, hypoxic stability, and stemness-related signaling pathways. Multiple studies have shown that mitochondria play a pivotal role in conferring drug resistance to cancer stem cells, through mitochondrial biogenesis, metabolism, and dynamics. A better understanding of how mitochondria contribute to tumorigenesis, heterogeneity, and drug resistance could lead to the development of innovative cancer treatments.

Beneficial effects of WON-21 on the symptoms of a hangover and identification of active compounds: experimental studies on antioxidant, anti-inflammation, and alcohol-metabolizing enzymes

Many hangover cure products containing natural ingredients that are also effective against alcohol-related liver damage or improve liver function have recently become available. In addition to curing liver damage, antioxidants, anti-inflammatory agents, and blood ethanol reduction aids are emerging as relief targets that reduce hangover symptoms. We investigated the ameliorating effect of WON-21 herbal medicinal products by studying the mixing ratio of oriental medicine concept with respect to antioxidant potential, anti-inflammation, and aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) enzyme activities. WON-21 and its components exerted antioxidant and anti-inflammatory effects. Rutin, taxifolin, and quercetin showed superior antioxidant effects compared to the other components. WON-12 effectively reduced iNOS and COX-2 in LPS-stimulated macrophages. Quercetin and apigenin were 2 compounds effective for the inhibition of iNOS and COX-2. WON-21 and quercetin also significantly increased the activities of ALDH and ADH enzymes in a concentration-dependent manner.

Aldehyde Dehydrogenase and Aldo-Keto Reductase Enzymes: Basic Concepts and Emerging Roles in Diabetic Retinopathy.

Diabetic retinopathy (DR) is a complication of diabetes mellitus that can lead to vision loss and blindness. It is driven by various biochemical processes and molecular mechanisms, including lipid peroxidation and disrupted aldehyde metabolism, which contributes to retinal tissue damage and the progression of the disease. The elimination and processing of aldehydes in the retina rely on the crucial role played by aldehyde dehydrogenase (ALDH) and aldo-keto reductase (AKR) enzymes. This review article investigates the impact of oxidative stress, lipid-derived aldehydes, and advanced lipoxidation end products (ALEs) on the advancement of DR. It also provides an overview of the ALDH and AKR enzymes expressed in the retina, emphasizing their growing importance in DR. Understanding the relationship between aldehyde metabolism and DR could guide innovative therapeutic strategies to protect the retina and preserve vision in diabetic patients. This review, therefore, also explores various approaches, such as gene therapy and pharmacological compounds that have the potential to augment the expression and activity of ALDH and AKR enzymes, underscoring their potential as effective treatment options for DR.

Mitochondrial aldehyde dehydrogenase 2 alleviates septic liver injury by inhibiting ferroptosis in mouse model

To observe the ferroptosis triggered by in different pathways during cecal ligation and puncture (CLP)-induced liver injury in septic mice, and to investigate whether mitochondrial aldehyde dehydrogenase 2 (ALDH2) can alleviate sepsis-induced liver injury by inhibiting ferroptosis. Sixty 8-week-old male C57BL/6J mice were randomly divided into sham operation group (Sham group), CLP group, ferroptosis inhibitor ferrostain-1 (Fer-1) group, ALDH2-specific agonist Alda-1 group, iron chelator deferasirox Fe3+ chelate (DXZ) group and dimethyl sulfoxide (DMSO) group, with 10 mice in each group. The septic liver injury was induced by CLP in mice model. In the Sham group, only laparotomy was performed without ligation and puncture of the cecum. 10 mL/kg 5% DMSO, 5 mg/kg Fer-1, 50 mg/kg DXZ and 10 mg/kg Alda-1 were injected intraperitoneally 1 hour before CLP in the DMSO, Fer-1, DXZ and Alda-1 groups respectively. At 24 hours after operation, eyeball blood and liver tissue were collected from anesthetized mice. The hepatic structure and inflammatory infiltration were observed by hematoxylin-eosin (HE) staining. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in serum, the levels of hepatic malondialdehyde (MDA), superoxide dismutase (SOD) and reactive oxygen species (ROS) were detected. Western blotting was used to detect the protein expressions of ALDH2, ferroptosis-related proteins glutathione peroxidase 4 (GPX4), ferroptosis suppressor protein 1 (FSP1) and transferrin receptor 1 (TFR1) in liver tissue. Compared with Sham group, the mice in CLP group showed varying degrees of congestion, disorganized hepatocyte arrangement, inflammatory cell infiltration at 24 hours after operation. Compared with the CLP group, the mice in the Fer-1 group, DXZ group and Alda-1 group liver morphology, liver injury and inflammatory cell infiltration was improved. Compared with Sham group, the serum levels of ALT and AST, the contents of MDA and ROS, and the expression of TFR1 protein in CLP group were significantly increased, while the activity of SOD and the expressions of ALDH2, GPX4 and FSP1 protein in CLP group were significantly decreased. Compared with CLP group, serum ALT and AST levels in Fer-1, DXZ and Alda-1 groups were significantly decreased [ALT (U/L): 45.76±10.81, 37.30±2.98, 36.40±12.75 vs. 73.06±12.20, AST (U/L): 61.57±2.69, 52.41±6.92, 56.05±8.29 vs. 81.59±5.46, all P < 0.05], and the contents of MDA, ROS and TFR1 protein expression in liver tissue were significantly decreased [MDA (μmol/L): 0.60±0.10, 0.57±0.18, 0.83±0.39 vs. 1.61±0.30, ROS (fluorescence intensity): 270.34±9.64, 276.02±62.33, 262.05±18.55 vs. 455.38±36.07, TFR1/GAPDH: 0.90±0.04, 1.01±0.09, 0.55±0.08 vs. 1.18±0.06, all P < 0.05], and the SOD activity and ALDH2, GPX4 and FSP1 protein expressions in liver tissue were significantly increased [SOD (kU/g): 88.77±8.20, 88.37±4.47, 93.43±7.24 vs. 50.27±3.57, ALDH2/GAPDH: 1.10±0.15, 1.02±0.07, 1.14±0.07 vs. 0.70±0.04, GPX4/GAPDH: 1.02±0.12, 0.99±0.08, 1.05±0.19 vs. 0.71±0.10, FSP1/GAPDH: 1.06±0.24, 1.02±0.08, 0.93±0.09 vs. 0.66±0.03, all P < 0.05]. There was no significant difference in the parameters between DMSO group and CLP group. Both GPX4 and FSP1 mediated ferroptosis are involved in liver injury in septic mice. Activation of ALDH2 and inhibition of ferroptosis can alleviatehepatic injury. ALDH2 may play a protective role by regulating FSP1 and GPX4 mediated ferroptosis.

Activation of aldehyde dehydrogenase-2 improves ischemic random skin flap survival in rats.

Random skin flaps have many applications in plastic and reconstructive surgeries. However, distal flap necrosis restricts wider clinical utility. Mitophagy, a vital form of autophagy for damaged mitochondria, is excessively activated in flap ischemia/reperfusion (I/R) injury, thus inducing cell death. Aldehyde dehydrogenase-2 (ALDH2), an allosteric tetrameric enzyme, plays an important role in regulating mitophagy. We explored whether ALDH2 activated by N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1) could reduce the risk of ischemic random skin flap necrosis, and the possible mechanism of action. Modified McFarlane flap models were established in 36 male Sprague-Dawley rats assigned randomly to three groups: a low-dose Alda-1 group (10 mg/kg/day), a high-dose Alda-1 group (20 mg/kg/day) and a control group. The percentage surviving skin flap area, neutrophil density and microvessel density (MVD) were evaluated on day 7. Oxidative stress was quantitated by measuring the superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Blood perfusion and skin flap angiogenesis were assessed via laser Doppler flow imaging and lead oxide-gelatin angiography, respectively. The expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α), vascular endothelial growth factor (VEGF), ALDH2, PTEN-induced kinase 1 (PINK1), and E3 ubiquitin ligase (Parkin) were immunohistochemically detected. Indicators of mitophagy such as Beclin-1, p62, and microtubule-associated protein light chain 3 (LC3) were evaluated by immunofluorescence. Alda-1 significantly enhanced the survival area of random skin flaps. The SOD activity increased and the MDA level decreased, suggesting that Alda-1 reduced oxidative stress. ALDH2 was upregulated, and mitophagy-related proteins (PINK1, Parkin, Beclin-1, p62, and LC3) were downregulated, indicating that ALDH2 inhibited mitophagy through the PINK1/Parkin signaling pathway. Treatment with Alda-1 reduced neutrophil infiltration and expressions of inflammatory cytokines. Alda-1 significantly upregulated VEGF expression, increased the MVD, promoted angiogenesis, and enhanced blood perfusion. ALDH2 activation can effectively enhance random skin flap viability via inhibiting PINK1/Parkin-dependent mitophagy. Moreover, enhancement of ALDH2 activity also exerts anti-inflammatory and angiogenic properties.

792-P: GLP-1 RA Therapy Increases Circulating Vascular Regenerative Cell Content and Decreases Inflammatory Burden in People with T2D

CV outcome trials have established that long-term use of GLP-1 receptor agonists (GLP-1RAs) yields important CV benefits in people with T2D. Similar to SGLT2i, GLP-1RAs are recommended for people with T2D who have established CVD and heart failure regardless of their A1C. In a randomized trial of people with T2D and coronary artery disease, use of the SGLT2i empagliflozin for 6 months increased the frequency of vascular regenerative (VR) cells in the circulation. To determine if GLP-1RA therapy has a similar impact on the same VR cell populations, we retrospectively analyzed data from an ongoing research program with adults &amp;gt;40 years of age with T2D. Peripheral blood mononuclear cells were isolated and profiled with an established flow cytometry assay that was founded on the activity of the anti-oxidative enzyme aldehyde dehydrogenase (ALDH) that is highly expressed in progenitor (ALDHhi) versus mature (ALDHlow) cells. At baseline, 17 participants were on a GLP-1RA (9 of whom were also on an SGLT2i), 33 were on an SGLT2i but not a GLP-1RA, and 28 were on neither drug class. Mean age, weight, BMI, A1C, and duration of T2D was balanced across the groups. The frequency of ALDHhiSSClow cells (primitive hematopoietic and endothelial progenitor cells that coordinate angiogenesis) was higher in participants who were on a GLP-1RA (0.064%) or an SGLT2i (0.048%) relative to those not on either drug class (0.037%; P&amp;lt;0.05 for both). The frequencies of VR ALDHhiSSCmid monocytes in the three groups were comparable. The frequency of pro-inflammatory ALDHhiSSChi granulocyte precursor cells in participants on a GLP-1RA (2.9%) was lower than that in individuals on an SGLT2i (4.3%; P=0.05) or not on either drug class (5.2%; P&amp;lt;0.01). GLP-1RA therapy in people with T2D was associated with greater VR cell content and lower inflammatory burden. Augmented vessel repair mediated by higher VR cell content may account in part for the CV benefits observed with GLP-1RA in the setting of T2D. Disclosure A.Krishnaraj: None. B.Park: None. E.Bakbak: None. Y.Pan: None. A.Quan: None. H.Teoh: None. S.Verma: Advisory Panel; Amgen Canada, AstraZeneca, Bayer Inc., Boehringer Ingelheim and Eli Lilly Alliance, HLS Therapeutics Inc., Janssen Pharmaceuticals, Inc., Novartis Canada, Novartis, Novo Nordisk, Novo Nordisk Canada Inc., Consultant; AstraZeneca, Other Relationship; Amarin Corporation, AstraZeneca, Bayer Inc., Boehringer Ingelheim and Eli Lilly Alliance, Boehringer Ingelheim International GmbH, Canadian Medical and Surgical Knowledge Translation Research Group, EOCI Pharmacomm, HLS Therapeutics Inc., Janssen Pharmaceuticals, Inc., Novartis Canada, Novo Nordisk, Novo Nordisk Canada Inc., Pfizer Inc., PhaseBio Pharmaceuticals, Inc., S &amp; L Solutions Event Management Inc, Sanofi, Sun Pharmaceutical Industries Ltd., Toronto Knowledge Translation Working Group, Research Support; Amarin Corporation, Amgen Canada, AstraZeneca, Bayer Inc., Boehringer Ingelheim International GmbH, HLS Therapeutics Inc., Novartis, Novo Nordisk, Pfizer Inc., PhaseBio Pharmaceuticals, Inc. D.A.Hess: None.

Identifying the Molecular Drivers of Pathogenic Aldehyde Dehydrogenase Missense Mutations in Cancer and Non-Cancer Diseases.

Human aldehyde dehydrogenases (ALDHs) comprising 19 isoenzymes play a vital role on both endogenous and exogenous aldehyde metabolism. This NAD(P)-dependent catalytic process relies on the intact structural and functional activity of the cofactor binding, substrate interaction, and the oligomerization of ALDHs. Disruptions on the activity of ALDHs, however, could result in the accumulation of cytotoxic aldehydes, which have been linked with a wide range of diseases, including both cancers as well as neurological and developmental disorders. In our previous works, we have successfully characterised the structure-function relationships of the missense variants of other proteins. We, therefore, applied a similar analysis pipeline to identify potential molecular drivers of pathogenic ALDH missense mutations. Variants data were first carefully curated and labelled as cancer-risk, non-cancer diseases, and benign. We then leveraged various computational biophysical methods to describe the changes caused by missense mutations, informing a bias of detrimental mutations with destabilising effects. Cooperating with these insights, several machine learning approaches were further utilised to investigate the combination of features, revealing the necessity of the conservation of ALDHs. Our work aims to provide important biological perspectives on pathogenic consequences of missense mutations of ALDHs, which could be invaluable resources in the development of cancer treatment.

Changes of neurofilament light chain in patients with alcohol dependence following withdrawal and the genetic effect from ALDH2 Polymorphism.

Neurofilament light chain (NFL), as a measure of neuroaxonal injury, has recently gained attention in alcohol dependence (AD). Aldehyde dehydrogenase 2 (ALDH2) is the major enzyme which metabolizes the alcohol breakdown product acetaldehyde. An ALDH2 single nucleotide polymorphism (rs671) is associated with less ALDH2 enzyme activity and increased neurotoxicity. We examined the blood NFL levels in 147 patients with AD and 114 healthy controls using enzyme-linked immunosorbent assay and genotyped rs671. We also followed NFL level, alcohol craving and psychological symptoms in patients with AD after 1 and 2weeks of detoxification. We found the baseline NFL level was significantly higher in patients with AD than in controls (mean ± SD: 264.2 ± 261.8 vs. 72.1 ± 35.6pg/mL, p < 0.001). The receiver operating characteristic curve revealed that NFL concentration could discriminate patients with AD from controls (area under the curve: 0.85; p < 0.001). The NFL levels were significantly reduced following 1 and 2weeks of detoxification, with the extent of reduction correlated with the improvement of craving, depression, and anxiety (p < 0.001). Carriers with the rs671 GA genotype, which is associated with less ALDH2 activity, had higher NLF levels either at baseline or after detoxification compared with GG carriers. In conclusion, plasma NFL level was increased in patients with AD and reduced after early abstinence. Reduction in NFL level corroborated well with the improvement of clinical symptoms. The ALDH2 rs671 polymorphism may play a role in modulating the extent of neuroaxonal injury and its recovery.

Structural basis of a bi-functional malonyl-CoA reductase (MCR) from the photosynthetic green non-sulfur bacterium Roseiflexus castenholzii.

Malonyl-CoA reductase (MCR) is a NADPH-dependent bi-functional enzyme that performs alcohol dehydrogenase and aldehyde dehydrogenase (CoA-acylating) activities in the N- and C-terminal fragments, respectively. It catalyzes the two-step reduction of malonyl-CoA to 3-hydroxypropionate (3-HP), a key reaction in the autotrophic CO2 fixation cycles of Chloroflexaceae green non-sulfur bacteria and the archaea Crenarchaeota. However, the structural basis underlying substrate selection, coordination, and the subsequent catalytic reactions of full-length MCR is largely unknown. For the first time, we here determined the structure of full-length MCR from the photosynthetic green non-sulfur bacterium Roseiflexus castenholzii (RfxMCR) at 3.35 Å resolution. Furthermore, we determined the crystal structures of the N- and C-terminal fragments bound with reaction intermediates NADP+ and malonate semialdehyde (MSA) at 2.0 Å and 2.3 Å, respectively, and elucidated the catalytic mechanisms using a combination of molecular dynamics simulations and enzymatic analyses. Full-length RfxMCR was a homodimer of two cross-interlocked subunits, each containing four tandemly arranged short-chain dehydrogenase/reductase (SDR) domains. Only the catalytic domains SDR1 and SDR3 incorporated additional secondary structures that changed with NADP+-MSA binding. The substrate, malonyl-CoA, was immobilized in the substrate-binding pocket of SDR3 through coordination with Arg1164 and Arg799 of SDR4 and the extra domain, respectively. Malonyl-CoA was successively reduced through protonation by the Tyr743-Arg746 pair in SDR3 and the catalytic triad (Thr165-Tyr178-Lys182) in SDR1 after nucleophilic attack from NADPH hydrides. IMPORTANCE The bi-functional MCR catalyzes NADPH-dependent reduction of malonyl-CoA to 3-HP, an important metabolic intermediate and platform chemical, from biomass. The individual MCR-N and MCR-C fragments, which contain the alcohol dehydrogenase and aldehyde dehydrogenase (CoA-acylating) activities, respectively, have previously been structurally investigated and reconstructed into a malonyl-CoA pathway for the biosynthetic production of 3-HP. However, no structural information for full-length MCR has been available to illustrate the catalytic mechanism of this enzyme, which greatly limits our capacity to increase the 3-HP yield of recombinant strains. Here, we report the cryo-electron microscopy structure of full-length MCR for the first time and elucidate the mechanisms underlying substrate selection, coordination, and catalysis in the bi-functional MCR. These findings provide a structural and mechanistic basis for enzyme engineering and biosynthetic applications of the 3-HP carbon fixation pathways.

Aldehyde Dehydrogenase, a Marker of Normal and Malignant Stem Cells, Typifies Mesenchymal Progenitors in Perivascular Niches.

Innate mesenchymal stem cells exhibiting multilineage differentiation and tissue (re)generative-or pathogenic-properties reside in perivascular niches. Subsets of these progenitors are committed to either osteo-, adipo-, or fibrogenesis, suggesting the existence of a developmental organization in blood vessel walls. We evaluated herein the activity of aldehyde dehydrogenase, a family of enzymes catalyzing the oxidation of aldehydes into carboxylic acids and a reported biomarker of normal and malignant stem cells, within human adipose tissue perivascular areas. A progression of ALDHLow to ALDHHigh CD34+ cells was identified in the tunica adventitia. Mesenchymal stem cell potential was confined to ALDHHigh cells, as assessed by proliferation and multilineage differentiation in vitro of cells sorted by flow cytometry with a fluorescent ALDH substrate. RNA sequencing confirmed and validated that ALDHHigh cells have a progenitor cell phenotype and provided evidence that the main isoform in this fraction is ALDH1A1, which was confirmed by immunohistochemistry. This demonstrates that ALDH activity, which marks hematopoietic progenitors and stem cells in diverse malignant tumors, also typifies native, blood vessel resident mesenchymal stem cells.

The Molecular Context of Oxidant Stress Response in Cancer Establishes ALDH1A1 as a Critical Target: What This Means for Acute Myeloid Leukemia.

The protein family of aldehyde dehydrogenases (ALDH) encompasses nineteen members. The ALDH1 subfamily consists of enzymes with similar activity, having the capacity to neutralize lipid peroxidation products and to generate retinoic acid; however, only ALDH1A1 emerges as a significant risk factor in acute myeloid leukemia. Not only is the gene ALDH1A1 on average significantly overexpressed in the poor prognosis group at the RNA level, but its protein product, ALDH1A1 protects acute myeloid leukemia cells from lipid peroxidation byproducts. This capacity to protect cells can be ascribed to the stability of the enzyme under conditions of oxidant stress. The capacity to protect cells is evident both in vitro, as well as in mouse xenografts of those cells, shielding cells effectively from a number of potent antineoplastic agents. However, the role of ALDH1A1 in acute myeloid leukemia has been unclear in the past due to evidence that normal cells often have higher aldehyde dehydrogenase activity than leukemic cells. This being true, ALDH1A1 RNA expression is significantly associated with poor prognosis. It is hence imperative that ALDH1A1 is methodically targeted, particularly for the acute myeloid leukemia patients of the poor prognosis risk group that overexpress ALDH1A1 RNA.

Advancing Cancer Therapy with Copper/Disulfiram Nanomedicines and Drug Delivery Systems.

Disulfiram (DSF) is a thiocarbamate based drug that has been approved for treating alcoholism for over 60 years. Preclinical studies have shown that DSF has anticancer efficacy, and its supplementation with copper (CuII) significantly potentiates the efficacy of DSF. However, the results of clinical trials have not yielded promising results. The elucidation of the anticancer mechanisms of DSF/Cu (II) will be beneficial in repurposing DSF as a new treatment for certain types of cancer. DSF's anticancer mechanism is primarily due to its generating reactive oxygen species, inhibiting aldehyde dehydrogenase (ALDH) activity inhibition, and decreasing the levels of transcriptional proteins. DSF also shows inhibitory effects in cancer cell proliferation, the self-renewal of cancer stem cells (CSCs), angiogenesis, drug resistance, and suppresses cancer cell metastasis. This review also discusses current drug delivery strategies for DSF alone diethyldithocarbamate (DDC), Cu (II) and DSF/Cu (II), and the efficacious component Diethyldithiocarbamate-copper complex (CuET).

ALDH2 ameliorates ethanol-induced gastric ulcer through suppressing NLPR3 inflammasome activation and ferroptosis

Gastric ulcer (GU) is a prevalent and life-threating gastrointestinal disorder. Aldehyde dehydrogenase 2 (ALDH2) is a pivotal component of alcohol metabolism which has been supported to suppress oxidative stress-elicited DNA damage in gastric mucosa cells. Nonetheless, whether ALDH2 is also involved in GU remains indistinct. Firstly, HCl/ethanol-induced experimental rat GU model was successfully established. RT-qPCR and Western blot tested ALDH2 expression in rat tissues. Following the addition of ALDH2 activator Alda-1, gastric lesion area and index were measured. H&E staining detected the histopathology of gastric tissues. ELISA examined the levels of inflammatory mediators. Alcian blue staining evaluated mucus production of gastric mucosa. Oxidative stress levels were estimated by corresponding kits and Western blot. Western blot examined the expression of NLRP3 inflammasome- and ferroptosis-related proteins. Prussian blue staining and corresponding assay kits measured ferroptosis. In ethanol-treated GES-1 cells, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, iron content, ferroptosis, inflammation and oxidative stress were detected as aforementioned above. In addition to that, DCFH-DA staining examined ROS generation. The experimental data corroborated that ALDH2 expression was declined in the tissues of HCl/ethanol-treated rats. Alda-1 ameliorated HCl/ethanol-stimulated gastric mucosal damage, inflammatory response, oxidative stress, NLRP3 inflammasome activation and ferroptosis in rats. Also, the suppressive role of ALDH2 in inflammatory response and oxidative stress was reversed by ferroptosis activator erastin or NLRP3 activator nigericin in HCl/ethanol-challenged GES-1 cells. To be summarized, ALDH2 might play the protective role in the process of GU.

FGF-trapping hampers cancer stem-like cells in uveal melanoma

BackgroundCancer stem-like cells (CSCs) are a subpopulation of tumor cells responsible for tumor initiation, metastasis, chemoresistance, and relapse. Recently, CSCs have been identified in Uveal Melanoma (UM), which represents the most common primary tumor of the eye. UM is highly resistant to systemic chemotherapy and effective therapies aimed at improving overall survival of patients are eagerly required.MethodsHerein, taking advantage from a pan Fibroblast Growth Factor (FGF)-trap molecule, we singled out and analyzed a UM-CSC subset with marked stem-like properties. A hierarchical clustering of gene expression data publicly available on The Cancer Genome Atlas (TCGA) was performed to identify patients’ clusters.ResultsBy disrupting the FGF/FGF receptor (FGFR)-mediated signaling, we unmasked an FGF-sensitive UM population characterized by increased expression of numerous stemness-related transcription factors, enhanced aldehyde dehydrogenase (ALDH) activity, and tumor-sphere formation capacity. Moreover, FGF inhibition deeply affected UM-CSC survival in vivo in a chorioallantoic membrane (CAM) tumor graft assay, resulting in the reduction of tumor growth. At clinical level, hierarchical clustering of TCGA gene expression data revealed a strong correlation between FGFs/FGFRs and stemness-related genes, allowing the identification of three distinct clusters characterized by different clinical outcomes.ConclusionsOur findings support the evidence that the FGF/FGFR axis represents a master regulator of cancer stemness in primary UM tumors and point to anti-FGF treatments as a novel therapeutic strategy to hit the CSC component in UM.