The absence of thioredoxin-interacting protein in alveolar cells exacerbates asthma during obesity.

Obesity is associated with an increased incidence of asthma. However, the mechanisms underlying this association are not fully understood. In this study, we investigated the role of thioredoxin-interacting protein (TXNIP) in obesity-induced asthma. Asthma was induced by intranasal injection of a protease from Aspergillus oryzae in normal diet (ND)- or high fat diet (HFD)-fed mice to investigate the symptoms. We measured TXNIP expression in the lungs of patients with asthma and in ND or HFD asthmatic mice. To explore the role of TXNIP in asthma pathogenesis, we induced asthma in the same manner in alveolar type 2 cell-specific TXNIP deficient (TXNIPCre) mice. In addition, the expression levels of pro-inflammatory cytokines were compared based on TXNIP gene expression in A549 cells stimulated with recombinant human tumor necrosis factor alpha. Compared to ND-fed mice, HFD-fed mice had elevated levels of free fatty acids and adipokines, resulting in high reactive oxygen species levels and more severe asthma symptoms. TXNIP expression was increased in both, asthmatic patients and HFD asthmatic mice. However, in experiments using TXNIPCre mice, despite being TXNIP deficient, TXNIPCre mice exhibited exacerbated asthma symptoms. Consistent with this, in vitro studies showed highest expression levels of pro-inflammatory cytokines in TXNIP-silenced cells. Overall, our findings suggest that increased TXNIP levels in obesity-induced asthma is compensatory to protect against inflammatory responses.

Engineering of stable infectious cDNA constructs of a fluorescently tagged tomato chlorosis virus.

Tomato chlorosis virus (ToCV) is an emerging pathogen that cause severe yellow leaf disorder syndrome in tomato plants. In this study, we aimed to generate a recombinant ToCV tagged with green fluorescent protein (GFP) to enable real-time monitoring of viral infection in living plants. Transformation of the full-length cDNA construct of ToCV RNA1 into Escherichia coli resulted in instability issues, which were successfully overcome by inserting a plant intron into RNA1. Subsequently, a GFP tag was engineered into a cDNA construct of ToCV RNA2. The resulting recombinant ToCV-GFP could systemically infect Nicotiana benthamiana plants, and GFP expression was observed along the major veins. Utilizing ToCV-GFP, we also showed that ToCV engages in antagonistic relationships with two different tomato-infecting viruses in mixed infections in N. benthamiana. This study demonstrates the potential of ToCV-GFP as a valuable tool for the visual tracking of infection and movement of criniviruses in living plants.

Progesterone increases hepatic lipid content and plasma lipid levels through PR- B-mediated lipogenesis.

Progesterone (P4) is a crucial reproductive hormone that acts as a precursor for all other endogenous steroids. P4 modulates transcriptional activity during reproduction by binding to progesterone receptors (PR). However, the physiological role of P4 in the liver is understudied. P4-mediated lipid metabolism in the liver was investigated in this study, as P4 facilitates insulin resistance and influences energy metabolism. While exogenous lipids are mainly obtained from food, the liver synthesizes endogenous triglycerides and cholesterol from a carbohydrate diet. Hepatic de novo lipogenesis (DNL) is primarily determined by acetyl-CoA and its biosynthetic pathways, which involve fatty acid and cholesterol synthesis. While P4 increased the hepatic levels of sterol regulatory element-binding protein 1 C (SREBP-1 C), peroxisome proliferator-activated receptor-gamma (PPARγ), acetyl-CoA carboxylase (ACC), and CD36, co-treatment with the P4 receptor antagonist RU486 blocked these proteins and P4-mediated lipogenesis. RNA sequencing was used to assess the role of P4 in lipogenic events, such as fatty liver and fatty acid metabolism, lipoprotein signaling, and cholesterol metabolism. P4 induced hepatic DNL and lipid anabolism were confirmed in the liver of ovarian resection mice fed a high-fat diet or in pregnant mice. P4 increased lipogenesis directly in mice exposed to P4 and indirectly in fetuses exposed to maternal P4. The lipid balance between lipogenesis and lipolysis determines fat build-up and is linked to lipid metabolism dysfunction, which involves the breakdown and storage of fats for energy and the synthesis of structural and functional lipids. Therefore, P4 may impact the lipid metabolism and reproductive development during gestation.

TXNIP in liver sinusoidal endothelial cells ameliorates alcohol-associated liver disease via nitric oxide production.

Dysregulation of liver sinusoidal endothelial cell (LSEC) differentiation and function has been reported in alcohol-associated liver disease (ALD). Impaired nitric oxide (NO) production stimulates LSEC capillarization and dysfunction; however, the mechanism underlying NO production remains unclear. Here, we investigated the role of thioredoxin-interacting protein (TXNIP), an important regulator of redox homeostasis, in endothelial cell NO production and its subsequent effects on ALD progression. We found that hepatic TXNIP expression was upregulated in patients with ALD and in ethanol diet-fed mice with high expression in LSECs. Endothelial cell-specific Txnip deficiency (TxnipΔEC) in mice exacerbated alcohol-induced liver injury, inflammation, fibrosis, and hepatocellular carcinoma development. Deletion of Txnip in LSECs led to sinusoidal capillarization, downregulation of NO production, and increased release of proinflammatory cytokines and adhesion molecules, whereas TXNIP overexpression had the opposite effects. Mechanistically, TXNIP interacted with transforming growth factor ß-activated kinase 1 (TAK1) and subsequently suppressed the TAK1 pathway. Inhibition of TAK1 activation restored NO production and decreased the levels of proinflammatory cytokines, thereby, blocking liver injury and inflammation in TxnipΔEC mice. Our findings indicate that upregulated TXNIP expression in LSECs serves a protective role in ameliorating ALD. Enhancing TXNIP expression could, therefore, be a potential therapeutic approach for ALD.

Impact of Aging and a High-Fat Diet on Adipose-Tissue-Derived Extracellular Vesicle miRNA Profiles in Mice.

BACKGROUND: Middle-aged adults have the highest obesity rates, leading to significant health complications in later years. Obesity triggers the release of altered molecules, including extracellular vesicles (EVs) from excess adipose tissue (AT), contributing to various health complications. In this study, we assessed the effects of age and a high-fat diet on AT-derived EV miRNA profiles to understand their potential roles in aging and obesity. METHOD: C57BL/6 male mice were subjected to a normal chow diet (NCD) or a high-fat diet (HFD) for either 10-12 weeks (young mice, n = 10) or 50-61 weeks (middle-aged mice, n = 12). After evaluating metabolic characteristics, peri-gonadal white AT was isolated and cultured to obtain EVs. AT-derived EV miRNAs were profiled using a NanoString miRNA panel (n = 599). RESULTS: Middle-aged mice exhibited obesity regardless of diet. Young mice fed an HFD showed similar metabolic traits to middle-aged mice. In the NCD group, 131 differentially expressed miRNAs (DE-miRNAs) emerged in middle-aged mice compared to young mice, including miR-21, miR-148a, and miR-29a, associated with cancer, neuro/psychological disorders, and reproductive diseases. In the HFD group, 55 DE-miRNAs were revealed in middle-aged mice compared to young mice. These miRNAs were associated with significantly suppressed IGF1R activity. CONCLUSION: This study demonstrates the potential significant impact of miRNAs of AT EVs on aging- and obesity-related diseases.

Ellagic Acid Prevented Dextran-Sodium-Sulfate-Induced Colitis, Liver, and Brain Injury through Gut Microbiome Changes.

Inflammatory bowel disease (IBD) affects millions of people worldwide and is considered a significant risk factor for colorectal cancer. Recent in vivo and in vitro studies reported that ellagic acid (EA) exhibits important antioxidant and anti-inflammatory properties. In this study, we investigated the preventive effects of EA against dextran sulfate sodium (DSS)-induced acute colitis, liver, and brain injury in mice through the gut-liver-brain axis. Acute colitis, liver, and brain injury were induced by treatment with 5% (w/v) DSS in the drinking water for 7 days. Freshly prepared EA (60 mg/kg/day) was orally administered, while control (CON) group mice were treated similarly by daily oral administrations with a vehicle (water). All the mice were euthanized 24 h after the final treatment with EA. The blood, liver, colon, and brain samples were collected for further histological and biochemical analyses. Co-treatment with a physiologically relevant dose (60 mg/kg/day) of EA for 7 days significantly reduced the DSS-induced gut barrier dysfunction; endotoxemia; and inflammatory gut, liver, and brain injury in mice by modulating gut microbiota composition and inhibiting the elevated oxidative and nitrative stress marker proteins. Our results further demonstrated that the preventive effect of EA on the DSS-induced IBD mouse model was mediated by blocking the NF-κB and mitogen-activated protein kinase (MAPK) pathway. Therefore, EA co-treatment significantly attenuated the pro-inflammatory and oxidative stress markers by suppressing the activation of NF-κB/MAPK pathways in gut, liver, and brain injury. These results suggest that EA, effective in attenuating IBD in a mouse model, deserves further consideration as a potential therapeutic for the treatment of inflammatory diseases.

Patient-derived glioblastoma cell lines with conserved genome profiles of the original tissue.

Glioblastoma (GBM) is the most lethal intracranial tumor. Sequencing technologies have supported personalized therapy for precise diagnosis and optimal treatment of GBM by revealing clinically actionable molecular characteristics. Although accumulating sequence data from brain tumors and matched normal tissues have facilitated a comprehensive understanding of genomic features of GBM, these in silico evaluations could gain more biological credibility when they are verified with in vitro and in vivo models. From this perspective, GBM cell lines with whole exome sequencing (WES) datasets of matched tumor tissues and normal blood are suitable biological platforms to not only investigate molecular markers of GBM but also validate the applicability of druggable targets. Here, we provide a complete WES dataset of 26 GBM patient-derived cell lines along with their matched tumor tissues and blood to demonstrate that cell lines can mostly recapitulate genomic profiles of original tumors such as mutational signatures and copy number alterations.

Aloe-derived nanovesicles attenuate inflammation and enhance tight junction proteins for acute colitis treatment.

Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease of the digestive tract that causes pain and weight loss and also increases the risk of colon cancer. Inspired by the benefits of plant-derived nanovesicles and aloe, we herein report aloe-derived nanovesicles, including aloe vera-derived nanovesicles (VNVs), aloe arborescens-derived nanovesicles (ANVs), and aloe saponaria-derived nanovesicles (SNVs) and evaluate their therapeutic potential and molecular mechanisms in a dextran sulfate sodium (DSS)-induced acute experimental colitis mouse model. Aloe-derived nanovesicles not only facilitate markedly reduced DSS-induced acute colonic inflammation, but also enable the restoration of tight junction (TJ) and adherent junction (AJ) proteins to prevent gut permeability in DSS-induced acute colonic injury. These therapeutic effects are ascribed to the anti-inflammatory and anti-oxidant effects of aloe-derived nanovesicles. Therefore, aloe-derived nanovesicles are a safe treatment option for IBD.

The Effect of Apple-Derived Nanovesicles on the Osteoblastogenesis of Osteoblastic MC3T3-E1 Cells.

Osteoporosis is characterized by low bone mass and elevated structural deterioration of the bone tissue, resulting in bone weakness with an increased risk of fracture. Considering biological activities of various phytochemicals extracted from apples, we herein demonstrated the potential antiosteoporotic effects of apple-derived nanovesicles (apple NVs) using osteoblastic MC3T3-E1 cells. Apple NVs significantly stimulated the growth of MC3T3-E1 cells. The cellular alkaline phosphatase (ALP) activity was significantly upregulated in the 5 µg/mL apple NVs-treated group. In addition, the concentrarion of mineralized nodules was significantly increased in the apple NVs-treated groups. Furthermore, apple NVs increased the expression of the genes and proteins associated with osteoblast growth and differentiation, such as Runx2, ALP, OPN, and BMP2/4, which further activated ERK- and JNK-related mitogen-activated protein kinase signaling. These results demonstrate that apple NVs have a potential to prevent osteoporosis by promoting osteoblastogenesis in osteoblastic MC3T3-E1 cells through regulating the BMP2/Smad1 pathways.

IL-17A promotes Helicobacter pylori-induced gastric carcinogenesis via interactions with IL-17RC.

BACKGROUND: Gastric cancer (GC) is a common malignancy worldwide, with a major attribution to Helicobacter pylori. Interleukin (IL)-17A has been reported to be up-regulated in serum and tumor of GC patients, but the precise mechanisms underlying its involvement in gastric tumorigenesis are yet to be established. Here, we investigated the roles of IL-17A in the pathogenesis of H. pylori-induced GC. METHODS: GC was induced in IL-17A knockout (KO) and wild-type (WT) mice via N-methyl-N-nitrosourea (MNU) treatment and H. pylori infection. At 50 weeks after treatment, gastric tissues were examined by histopathology, immunohistochemistry, and immunoblot analyses. In vitro experiments on the human GC cell lines were additionally performed to elucidate the underlying mechanisms. RESULTS: Deletion of IL-17A suppressed MNU and H. pylori-induced gastric tumor development accompanied by a decrease in gastric epithelial cell growth, oxidative stress, and expression of gastric epithelial stem cells markers. In AGS cells, recombinant human IL-17A (rhIL-17A) inhibited apoptosis and G1/S phase transition arrest while promoting reactive oxygen species production, sphere formation ability of cancer stem cells (CSC), and expression of stemness-related genes. In addition, rhIL-17A induced expression of IL-17RC, leading to NF-κB activation and increased NADPH oxidase 1 (NOX1) levels. Inhibition of NOX1 with GKT136901 attenuated rhIL-17A-mediated elevation of GC cell growth, ROS generation, and CSC stemness. Clinically, IL-17RC expressions were significantly upregulated in human GC compared with normal gastric tissues. CONCLUSION: Our results suggest that IL-17A promotes gastric carcinogenesis, in part, by regulating IL-17RC/NF-κB/NOX1 pathway, supporting its potential as a target in human GC therapy.

Locoregional Lymphatic Delivery Systems Using Nanoparticles and Hydrogels for Anticancer Immunotherapy.

The lymphatic system has gained significant interest as a target tissue to control cancer progress, which highlights its central role in adaptive immune response. Numerous mechanistic studies have revealed the benefits of nano-sized materials in the transport of various cargos to lymph nodes, overcoming barriers associated with lymphatic physiology. The potential of sustained drug delivery systems in improving the therapeutic index of various immune modulating agents is also being actively discussed. Herein, we aim to discuss design rationales and principles of locoregional lymphatic drug delivery systems for invigorating adaptive immune response for efficient antitumor immunotherapy and provide examples of various advanced nanoparticle- and hydrogel-based formulations.

Extracellular vesicle miRNAs in breast milk of obese mothers.

Background: Breast milk has abundant extracellular vesicles (EVs) containing various biological molecules (cargo), including miRNAs. EVs are not degraded in the gastrointestinal system and circulation; thus, breast milk EVs (bEVs) are expected to interact with other organs in breastfed infants and modify the gene expression of recipient cells using miRNAs. Maternal pre-pregnancy BMI is a critical factor influencing the composition of breast milk. Thus, in mothers with obesity, miRNAs in bEVs can be altered, which might be associated with adverse health outcomes in infants. In this study, we examined 798 miRNAs to determine which miRNAs are altered in the bEVs of mothers with obesity and their potential impact on breastfed infants. Methods: We recruited healthy nursing mothers who were either of normal weight (BMI < 25) or with obesity (BMI ≥ 30) based on their pre-pregnancy BMI, and delivered a singleton baby in the prior 6 months. EVs were isolated from breast milk with ultracentrifugation. bEV characteristics were examined by flow cytometry and fluorescence imaging of EV markers. A total of 798 miRNAs were screened using a NanoString human miRNA panel to find differentially expressed miRNAs in bEVs of mothers with obesity compared to mothers of normal weight. Results: We included 65 nursing mothers: 47 of normal weight and 18 with obesity based on pre-pregnancy BMI. After bEV isolation, we confirmed the expression of various EV markers. Out of 37 EV markers, CD326 (EpCaM) was the most highly expressed in bEVs. The most abundant miRNAs in bEVs include miR-30b-5p, miR-4454, miR-494-3p, and let-7 miRNAs. Target genes of the top 10 miRNAs were associated with cancer, prolactin pathway, EGFR, ErbB, and FoxO signaling pathway. In bEVs of mothers with obesity, 19 miRNAs were differentially expressed (adjusted p < 0.05 cut-off), which include miR-575, miR-630, miR-642a-3p, and miR-652-5p. These miRNAs and their target genes were associated with neurological diseases and psychological disorders. Conclusion: In this study, we characterized bEVs and demonstrated altered miRNAs in bEVs of mothers with obesity and identified the pathways of their potential target genes. Our findings will provide insight for future studies investigating the role of bEVs in breastfed infants.

Role of the WNT/ß-catenin/ZKSCAN3 Pathway in Regulating Chromosomal Instability in Colon Cancer Cell lines and Tissues.

Zinc finger protein with KRAB and SCAN domains 3 (ZKSCAN3) acts as an oncogenic transcription factor in human malignant tumors, including colon and prostate cancer. However, most of the ZKSCAN3-induced carcinogenic mechanisms remain unknown. In this study, we identified ZKSCAN3 as a downstream effector of the oncogenic Wnt/ß-catenin signaling pathway, using RNA sequencing and ChIP analyses. Activation of the Wnt pathway by recombinant Wnt gene family proteins or the GSK inhibitor, CHIR 99021 upregulated ZKSCAN3 expression in a ß-catenin-dependent manner. Furthermore, ZKSCAN3 upregulation suppressed the expression of the mitotic spindle checkpoint protein, Mitotic Arrest Deficient 2 Like 2 (MAD2L2) by inhibiting its promoter activity and eventually inducing chromosomal instability in colon cancer cells. Conversely, deletion or knockdown of ZKSCAN3 increased MAD2L2 expression and delayed cell cycle progression. In addition, ZKSCAN3 upregulation by oncogenic WNT/ß-catenin signaling is an early event of the adenoma-carcinoma sequence in colon cancer development. Specifically, immunohistochemical studies (IHC) were performed using normal (NM), hyperplastic polyps (HPP), adenomas (AD), and adenocarcinomas (AC). Their IHC scores were considerably different (61.4 in NM; 88.4 in HPP; 189.6 in AD; 246.9 in AC). In conclusion, ZKSCAN3 could be responsible for WNT/ß-catenin-induced chromosomal instability in colon cancer cells through the suppression of MAD2L2 expression.

Plum Prevents Intestinal and Hepatic Inflammation in the Acute and Chronic Models of Dextran Sulfate Sodium-Induced Mouse Colitis.

SCOPE: Inflammatory bowel disease (IBD), including ulcerative colitis (UC), is a chronic recurrent inflammatory disease of the digestive tract and increases the risk of colon cancer. METHOD AND RESULTS: This study evaluates the effects of dietary intervention with freeze-dried plum (FDP), a natural antioxidant and anti-inflammatory fruit with no toxicity on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in a mouse model and studies the molecular mechanisms of protection through the gut-liver axis. The results show that FDP decreases the levels of inflammatory mediators, which is a nitrative stress biomarker in both acute and chronic models. FDP markedly reduces DSS-induced injury to the colonic epithelium in both acute and chronic models. In addition, FDP significantly decreases the levels of pro-oxidant markers such as CYP2E1, iNOS, and nitrated proteins (detected by anti-3-NT antibody) in DSS-induced acute and chronic colonic injury models. Furthermore, FDP markedly reduces markers of liver injury such as serum ALT/AST, antioxidant markers, and inflammatory mediators in DSS-induced acute and chronic colonic injury. CONCLUSION: These results demonstrate that the FDP exhibits a protective effect on DSS-induced acute and chronic colonic and liver injury through the gut-liver axis via antioxidant and anti-inflammatory properties.

NOP53 Suppresses Autophagy through ZKSCAN3-Dependent and -Independent Pathways.

Autophagy is an evolutionally conserved process that recycles aged or damaged intracellular components through a lysosome-dependent pathway. Although this multistep process is propagated in the cytoplasm by the orchestrated activity of the mTOR complex, phosphatidylinositol 3-kinase, and a set of autophagy-related proteins (ATGs), recent investigations have suggested that autophagy is tightly regulated by nuclear events. Thus, it is conceivable that the nucleolus, as a stress-sensing and -responding intranuclear organelle, plays a role in autophagy regulation, but much is unknown concerning the nucleolar controls in autophagy. In this report, we show a novel nucleolar-cytoplasmic axis that regulates the cytoplasmic autophagy process: nucleolar protein NOP53 regulates the autophagic flux through two divergent pathways, the ZKSCAN3-dependent and -independent pathways. In the ZKSCAN3-dependent pathway, NOP53 transcriptionally activates a master autophagy suppressor ZKSCAN3, thereby inhibiting MAP1LC3B/LC3B induction and autophagy propagation. In the ZKSCAN3-independent pathway, NOP53 physically interacts with histone H3 to dephosphorylate S10 of H3, which, in turn, transcriptionally downregulates the ATG7 and ATG12 expressions. Our results identify nucleolar protein NOP53 as an upstream regulator of the autophagy process.

Mastocytosis-derived extracellular vesicles deliver miR-23a and miR-30a into pre-osteoblasts and prevent osteoblastogenesis and bone formation.

Osteoporosis and other manifestations of bone disease are frequent in patients with systemic mastocytosis (SM) in association with the presence of mast cell infiltrates in bone marrow, although the mechanisms behind bone disease remain poorly understood. We find that extracellular vesicles (EVs) released by neoplastic mast cells and present in the serum of patients with SM (SM-EVs) block osteoblast differentiation and mineralization in culture, and when injected into mice diminish the expression of osteoblast markers, and trabecular bone volume and microarchitecture. We demonstrate that miRNA-30a and miRNA-23a, increased in SM-EVs and neoplastic mast cell-derived EVs, attenuate osteoblast maturation by suppressing expression of RUNX2 and SMAD1/5, essential drivers of osteogenesis. Thus, SM-EVs carry and deliver miRNAs that epigenetically interfere with bone formation and can contribute to bone mass reduction in SM. These findings also suggest possibilities for novel approaches to the management of bone disease in mast cell proliferative disorders.

The Possible Influence of Mediterranean Diet on Extracellular Vesicle miRNA Expression in Breast Cancer Survivors.

The Mediterranean diet (MD) has been reported to have beneficial effects on breast cancer and cardiovascular diseases. Recently, microRNAs (miRNAs) have been suggested as biomarkers for the diagnosis and disease prognosis in cancer and cardiovascular diseases. We evaluated the influence of the MD on the plasma-derived extracellular vesicle miRNA signature of overweight breast cancer survivors. Sixteen participants instructed to adhere to the MD for eight weeks were included in this study. To curate differentially expressed miRNAs after MD intervention, we employed two methods: significance analysis of microarrays and DESeq2. The selected miRNAs were analyzed using ingenuity pathway analysis. After an eight-week intervention, body mass index, waist circumference, fasting glucose, fasting insulin, and homeostatic model assessment for insulin resistance were significantly improved. Expression levels of 798 miRNAs were comprehensively analyzed, and 42 extracellular vesicle miRNAs were significantly differentially regulated after the eight-week MD (36 were up and 6 were down-regulated). We also identified enriched pathways in genes regulated by differentially expressed 42 miRNAs, which include signaling associated with breast cancer, energy metabolism, glucose metabolism, and insulin. Our study indicates that extracellular vesicle miRNAs differentially expressed as a result of the MD might be involved in the mechanisms that relate to cardiometabolic risk factors in overweight breast cancer survivors.

Downregulation of NOP53 Ribosome Biogenesis Factor Leads to Abnormal Nuclear Division and Chromosomal Instability in Human Cervical Cancer Cells.

NOP53 ribosome biogenesis factor (NOP53) is a nucleolar protein involved in oncogenesis/tumor suppression, cell cycle regulation, and cell death. Here, we investigated the role of NOP53 in the maintenance of normal nuclear shape and chromosomal stability. Depletion of NOP53 by shRNA caused abnormal nuclear morphology, including large nucleus, irregular nucleus, and multinucleated cells, and chromosomal instability resulting in micronucleus or nuclear bud formation. The abnormal nuclear shape and chromosomal instability were restored by re-expression of NOP53. We further showed that NOP53 was involved in chromosome congression in metaphase. Downregulation of NOP53 induced aberrant chromosome congression and spindle checkpoint activation, resulting in delayed mitosis and mitotic arrest. Thus, our findings demonstrated that the nucleolar protein NOP53 participated in mitotic progression and that dysregulated NOP53 expression caused chromosomal instability in cancer cells.

Aldh2 Attenuates Stem Cell Factor/Kit-Dependent Signaling and Activation in Mast Cells.

Mitochondrial aldehyde dehydrogenase (ALDH2) metabolizes endogenous and exogenous aldehydes and protects cells against oxidative injury. Inactivating genetic polymorphisms in humans are common and associate with alcohol flush reactions. However, whether mast cell Aldh2 activity impacts normal mast cell responses is unknown. Using bone marrow-derived mast cells from Aldh2 knockout mice, we found evidence for a role of mast cell Aldh2 in Kit-mediated responses. Aldh2-deficient mast cells showed enhanced Kit tyrosine kinase phosphorylation and activity after stimulation with its ligand (stem cell factor) and augmentation of downstream signaling pathways, including Stat4, MAPKs, and Akt. The activity of the phosphatase Shp-1, which attenuates Kit activity, was reduced in Aldh2-/- mast cells, along with an increase in reactive oxygen species, known to regulate Shp-1. Reduced Shp-1 activity concomitant with sustained Kit signaling resulted in greater proliferation following Kit engagement, and increased mediator and cytokine release when Aldh2-/- mast cells were co-stimulated via Kit and FcεRI. However, FcεRI-mediated signaling and responses were unaffected. Therefore, our findings reveal a functional role for mast cell intrinsic Aldh2 in the control of Kit activation and Kit-mediated responses, which may lead to a better understanding of mast cell reactivity in conditions related to ALDH2 polymorphisms.