Acid Dehydrogenase Kinase Research Articles

Bicyclic Inhibitors of Branched-Chain α-Keto Acid Dehydrogenase Kinase (BDK) with In Vivo Activity

Bicyclic Inhibitors of Branched-Chain α-Keto Acid Dehydrogenase Kinase (BDK) with In Vivo Activity

MAZ-mediated up-regulation of BCKDK reprograms glucose metabolism and promotes growth by regulating glucose-6-phosphate dehydrogenase stability in triple-negative breast cancer

Tumour metabolic reprogramming is pivotal for tumour survival and proliferation. Investigating potential molecular mechanisms within the heterogeneous and clinically aggressive triple-negative breast cancer (TNBC) subtype is essential to identifying novel therapeutic targets. Accordingly, we investigated the role of branched-chain α-keto acid dehydrogenase kinase (BCKDK) in promoting tumorigenesis in TNBC. We analysed The Cancer Genome Atlas dataset and immunohistochemically stained surgical specimens to investigate BCKDK expression and its prognostic implications in TNBC. The effects of BCKDK on tumorigenesis were assessed using cell viability, colony formation, apoptosis, and cell cycle assays, and subsequently validated in vivo. Metabolomic screening was performed via isotope tracer studies. The downstream target was confirmed using mass spectrometry and a co-immunoprecipitation experiment coupled with immunofluorescence analysis. Upstream transcription factors were also examined using chromatin immunoprecipitation and luciferase assays. BCKDK was upregulated in TNBC tumour tissues and associated with poor prognosis. BCKDK depletion led to reduced cell proliferation both in vitro and vivo. MYC-associated zinc finger protein (MAZ) was confirmed as the major transcription factor directly regulating BCKDK expression in TNBC. Mechanistically, BCKDK interacted with glucose-6-phosphate dehydrogenase (G6PD), leading to increased flux in the pentose phosphate pathway for macromolecule synthesis and detoxification of reactive oxygen species. Forced expression of G6PD rescued the growth defect in BCKDK-deficient cells. Notably, the small-molecule inhibitor of BCKDK, 3,6-dichlorobenzo(b)thiophene-2-carboxylic acid, exhibited anti-tumour effects in a patient-derived tumour xenograft model. Our findings hold significant promise for developing targeted therapies aimed at disrupting the MAZ/BCKDK/G6PD signalling pathway, offering potential advancements in treating TNBC through metabolic reprogramming.

FYN-mediated phosphorylation of BCKDK at Y151 promotes GBM proliferation by increasing the oncogenic metabolite N-acetyl-L-alanine

Branched chain α-keto acid dehydrogenase kinase (BCKDK) is a key enzyme involved in the metabolism of branched-chain amino acids (BCAAs). Its potential as a therapeutic target and prognostic factor for a variety of cancers has been widely reported. In this study, we investigated the expression of BCKDK in clinical glioma samples and found that BCKDK was significantly overexpressed in glioblastoma (GBM) and was associated with its poor prognosis. We further found that BCKDK is phosphorylated by tyrosine protein kinase Fyn at Y151, which increases its catalytic activity and stability, and demonstrate through in vivo and in vitro experiments that BCKDK phosphorylation promotes GBM cell proliferation. In addition, we found that the levels of the metabolite N-acetyl-L-alanine (NAAL) in GBM cells with high BCKDK were higher than those in the silencing group, and silencing or inhibition of BCKDK promotes the expression of ACY1, an enzyme that catalyzes the hydrolysis of NAAL into acetic acid and alanine. Exogenous addition of NAAL can activate the ERK signaling pathway and promote the proliferation of GBM cells. Taken together, we identified a novel mechanism of BCKDK activation and found NAAL is a novel oncogenic metabolite. Our study confirms the importance of the Fyn-BCKDK-ACY1-NAAL signalling axis in the development of GBM and suggests that p-BCKDK (Y151) and NAAL can serve as potential predictors of GBM progression and prognosis.

Bckdk-Mediated Branch Chain Amino Acid Metabolism Reprogramming Contributes to Muscle Atrophy during Cancer Cachexia.

Branched chain amino acids (BCAAs) are essential amino acids and important nutrient signals for energy and protein supplementation. The study uses muscle-specific branched-chain α-keto acid dehydrogenase kinase (Bckdk) conditional knockout (cKO) mice to reveal the contribution of BCAA metabolic dysfunction to muscle wasting. Muscle-specific Bckdk-cKO mice are generated through crossbreeding of Bckdkf/f mice with Myf5Cre mice. Lewis lung cancer (LLC) tumor transplantation is used to establish the cancer cachexia model. The occurrence of cancer cachexia is accelerated in the muscle-specific Bckdk-cKO mice after bearing LLC tumor. Wasting skeletal muscle is characterized by increased protein ubiquitination degradation and impaired protein synthesis. The wasting muscle gastrocnemius is mechanized as a distinct BCAA metabolic dysfunction. Based on the atrophy phenotype resulting from BCAA metabolism dysfunction, the optimized BCAA supplementation improves the survival of cancer cachexia in muscle-specific Bckdk-cKO mice bearing LLC tumors, and improves the occurrence of cancer cachexia. The mechanism of BCAA supplementation on muscle mass preservation is based on the promotion of protein synthesis and the inhibition of protein ubiquitination degradation. Dysfunctional BCAA metabolism contributes to the inhibition of protein synthesis and increases protein degradation in the cancer cachexia model of muscle-specific Bckdk-cKO mice bearing LLC tumors. The reprogramming of BCAA catabolism exerts therapeutic effects by stimulating protein synthesis and inhibiting protein degradation in skeletal muscle.

Identification of putative allosteric inhibitors of BCKDK via virtual screening and biological evaluation

Abnormal accumulation of branched-chain amino acids (BCAAs) can lead to metabolic diseases and cancers. Branched-chain α-keto acid dehydrogenase kinase (BCKDK) is a key negative regulator of BCAA catabolism, and targeting BCKDK provides a promising therapeutic approach for diseases caused by BCAA accumulation. Here, we screened PPHN and POAB as novel putative allosteric inhibitors by integrating allosteric binding site prediction, large-scale ligand database virtual screening, and bioactivity evaluation assays. Both of them showed a high binding affinity to BCKDK, with Kd values of 3.9 μM and 1.86 μM, respectively. In vivo experiments, the inhibitors demonstrated superior kinase inhibitory activity and notable antiproliferative and proapoptotic effects on diverse cancer cells. Finally, bulk RNA-seq analysis revealed that PPHN and POAB suppressed cell growth through a range of signalling pathways. Taken together, our findings highlight two novel BCKDK inhibitors as potent therapeutic candidates for metabolic diseases and cancers associated with BCAA dysfunctional metabolism.

Loss of BCAA catabolism enhances Rab1A-mTORC1 signaling activity and promotes tumor proliferation in NSCLC

BackgroundNon-small cell lung cancer (NSCLC) is a leading cause of cancer death. Branched-chain amino acid (BCAA) homeostasis is important for normal physiological metabolism. Branched-chain keto acid dehydrogenase kinase (BCKDK) is a rate-limiting enzyme involved in BCAA degradation. BCAA metabolism has been highlighted in human cancers. The aberrant activation of mTORC1 has been implicated in tumor progression. Rab1A is a small GTPase, an activator of mTORC1, and an oncogene. This study aimed to reveal the specific role of BCKDK-BCAA-Rab1A-mTORC1 signaling in NSCLC. MethodsWe analyzed a cohort of 79 patients with NSCLC and 79 healthy controls. Plasma BCAA assays, immunohistochemistry, and network and pathway analyses were performed. The stable cell lines BCKDK-KD, BCKDK-OV A549, and H1299 were constructed. BCKDK, Rab1A, p-S6 and S6 were detected using western blotting to explore their molecular mechanisms of action in NSCLC. The effects of BCAA and BCKDK on the apoptosis and proliferation of H1299 cells were detected by cell function assays. ResultsWe demonstrated that NSCLC was primarily involved in BCAA degradation. Therefore, combining BCAA, CEA, and Cyfra21-1 is clinically useful for treating NSCLC. We observed a significant increase in BCAA levels, downregulation of BCKDHA expression, and upregulation of BCKDK expression in NSCLC cells. BCKDK promotes proliferation and inhibits apoptosis in NSCLC cells, and we observed that BCKDK affected Rab1A and p-S6 in A549 and H1299 cells via BCAA modulation. Leucine affected Rab1A and p-S6 in A549 and H1299 cells and affected the apoptosis rate of H1299 cells.In conclusion, BCKDK enhances Rab1A-mTORC1 signaling and promotes tumor proliferation by suppressing BCAA catabolism in NSCLC, suggesting a new biomarker for the early diagnosis and identification of metabolism-based targeted approaches for patients with NSCLC.

Toxicological Studies on the Sinai Plant Urginea maritima (Scilla) in Wistar Albino Rats

The varied toxicity of Urginea maritima (a plant that grows in north Sinai) on Wistar albino rats was investigated. Twenty-four rats weighing 100±20 gm. were divided into 4 groups, the first group, which included six male rats, and the second group, which included six female rats, were given di-methyl sulfoxide orally for 45 consecutive days and were regarded as the control groups. The third group included six male rats who received 36 mg/kg B.W (1/20 LD50 from the alcoholic extract of Urginea maritima) for 45 days in succession. The fourth group was made up of six female rats who received a daily dose of 26 mg/kg B.W (1/20 LD50 of the alcoholic Urginea maritima extract) for 45 successive days. Serum samples were taken for biochemical study after the end of the experiment, and sciatic nerve, heart, and brain tissues were also taken for histopathological analysis. The findings demonstrated significant changes in the exposed animals' serum levels of calcium (Ca++), sodium (Na+), and potassium (K+) ions. While serum K+ levels dramatically increased, serum Ca++ and Na+ levels significantly dropped. Lactic acid dehydrogenase (LDH) and serum creatine kinase (CK-MB) activities also significantly increased. In addition, pathological alterations in the heart, brain, and sciatic nerve were discovered when compared to control groups.

Baitouweng decoction alleviates dextran sulfate sodium-induced ulcerative colitis by suppressing leucine-related mTORC1 signaling and reducing oxidative stress

Ethnopharmacological relevanceBaitouweng decoction (BTW) has been used for hundreds of years to treat ulcerative colitis (UC) in China and has produced remarkable clinical results. However, the knowledge in protective mechanism of BTW against UC is still unclear. Aim of the studyThe present study was designed to investigate the anti-UC effects of BTW and the underlying mechanisms involved. Methods3.5% dextran sulfate sodium (DSS)-induced experimental colitis was used to simulate human UC and the mice were treated with BTW (6.83 g/kg), leucine (200 mg/kg, Leu) or rapamycin (2 mg/kg, RAPA) as a positive control for 7 days. The clinical symptoms, serum myeloperoxidase (MPO) and malondialdehyde (MDA) levels were evaluated. Biological samples were collected to detect the effects of BTW on mechanistic target of rapamycin complex 1 (mTORC1) pathway and Leu metabolism. ResultsIn our study, BTW notably improved the clinical symptoms and histopathological tissue damage and reduced the release of proinflammatory cytokines, including IL-6, IL-1β and TNF-α in UC mice. BTW also alleviated oxidative stress by decreasing serum MPO and MDA levels. Additionally, BTW significantly suppressed mTORC1 activity in the colon tissues of UC mice. Serum metabolomics analysis revealed that the mice receiving BTW had lower Leu levels, which was in line with the decreased expression of branched-chain α-keto acid dehydrogenase kinase (BCKDK) in the colon tissues. Furthermore, oral administration of Leu aggravated DSS-induced acute colitis and enhanced mTORC1 activity in the colon. ConclusionThese data strongly demonstrated that BTW could ameliorate DSS-induced UC by regulating the Leu-related mTORC1 pathway and reducing oxidative stress.

Inhibition of branched-chain alpha-keto acid dehydrogenase kinase augments the sensitivity of ovarian and breast cancer cells to paclitaxel

ContextMany cancer patients who initially respond to chemotherapy eventually develop chemoresistance, and to address this, we previously conducted a RNAi screen to identify genes contributing to resistance. One of the hits from the screen was branched-chain α-keto acid dehydrogenase kinase (BCKDK). BCKDK controls the metabolism of branched-chain amino acids (BCAAs) through phosphorylation and inactivation of the branched-chain α-keto acid dehydrogenase complex (BCKDH), thereby inhibiting catabolism of BCAAs.MethodsWe measured the impact on paclitaxel sensitivity of inhibiting BCKDK in ovarian and breast cancer cell lines.ResultsInhibition of BCKDK using siRNA or two chemical inhibitors (BCKDKi) was synergistic with paclitaxel in both breast and ovarian cancer cells. BCKDKi reduced levels of BCAA and the addition of exogenous BCAA suppressed this synergy. BCKDKi inactivated the mTORC1-Aurora pathway, allowing cells to overcame M-phase arrest induced by paclitaxel. In some cases, cells almost completed cytokinesis, then reverted to a single cell, resulting in multinucleate cells.ConclusionBCKDK is an attractive target to augment the sensitivity of cancer cells to paclitaxel.

Evaluation of therapeutic strategies targeting BCAA catabolism using a systems pharmacology model.

Background: Abnormal branched-chained amino acids (BCAA) accumulation in cardiomyocytes is associated with cardiac remodeling in heart failure. Administration of branched-chain α-keto acid dehydrogenase (BCKD) kinase inhibitor BT2 has been shown to reduce cardiac BCAA levels and demonstrated positive effects on cardiac function in a preclinical setting. The current study is focused on evaluating the impact of BT2 on the systemic and cardiac levels of BCAA and their metabolites as well as activities of BCAA catabolic enzymes using a quantitative systems pharmacology model. Methods: The model is composed of an ordinary differential equation system characterizing BCAA consumption with food, disposal in the proteins, reversible branched-chain-amino-acid aminotransferase (BCAT)-mediated transamination to branched-chain keto-acids (BCKA), followed by BCKD-mediated oxidation. Activity of BCKD is regulated by the balance of BCKDK and protein phosphatase 2Cm (PP2Cm) activities, affected by BT2 treatment. Cardiac BCAA levels are assumed to directly affect left ventricular ejection fraction (LVEF). Biochemical characteristics of the enzymes are taken from the public domains, while plasma and cardiac BCAA and BCKA levels in BT2 treated mice are used to inform the model parameters. Results: The model provides adequate reproduction of the experimental data and predicts synchronous BCAA responses in the systemic and cardiac space, dictated by rapid BCAA equilibration between the tissues. The model-based simulations indicate maximum possible effect of BT2 treatment on BCAA reduction to be 40% corresponding to 12% increase in LVEF. Model sensitivity analysis demonstrates strong impact of BCKDK and PP2Cm activities as well as total BCKD and co-substrate levels (glutamate, ketoglutarate and ATP) on BCAA and BCKA levels. Conclusion: Model based simulations confirms using of plasma measurements as a marker of cardiac BCAA changes under BCKDK inhibition. The proposed model can be used for optimization of preclinical study design for novel compounds targeting BCAA catabolism.

Altered branched-chain α-keto acid metabolism is a feature of NAFLD in individuals with severe obesity.

Hepatic de novo lipogenesis is influenced by the branched-chain α-keto acid dehydrogenase (BCKDH) kinase (BCKDK). Here, we aimed to determine whether circulating levels of the immediate substrates of BCKDH, the branched-chain α-keto acids (BCKAs), and hepatic BCKDK expression are associated with the presence and severity of nonalcoholic fatty liver disease (NAFLD). Eighty metabolites (3 BCKAs, 14 amino acids, 43 acylcarnitines, 20 ceramides) were quantified in plasma from 288 patients with bariatric surgery with severe obesity and scored liver biopsy samples. Metabolite principal component analysis factors, BCKAs, branched-chain amino acids (BCAAs), and the BCKA/BCAA ratio were tested for associations with steatosis grade and presence of nonalcoholic steatohepatitis (NASH). Of all analytes tested, only the Val-derived BCKA, α-keto-isovalerate, and the BCKA/BCAA ratio were associated with both steatosis grade and NASH. Gene expression analysis in liver samples from 2 independent bariatric surgery cohorts showed that hepatic BCKDK mRNA expression correlates with steatosis, ballooning, and levels of the lipogenic transcription factor SREBP1. Experiments in AML12 hepatocytes showed that SREBP1 inhibition lowered BCKDK mRNA expression. These findings demonstrate that higher plasma levels of BCKA and hepatic expression of BCKDK are features of human NAFLD/NASH and identify SREBP1 as a transcriptional regulator of BCKDK.

The Role of Branched-Chain Amino Acids and Branched-Chain α-Keto Acid Dehydrogenase Kinase in Metabolic Disorders.

Branched-chain amino acids (BCAAs), composed of leucine, isoleucine, and valine, are important essential amino acids in human physiology. Decades of studies have revealed their roles in protein synthesis, regulating neurotransmitter synthesis, and the mechanistic target of rapamycin (mTOR). BCAAs are found to be related to many metabolic disorders, such as insulin resistance, obesity, and heart failure. Also, many diseases are related to the alteration of the BCAA catabolism enzyme branched-chain α-keto acid dehydrogenase kinase (BCKDK), including maple syrup urine disease, human autism with epilepsy, and so on. In this review, diseases and the corresponding therapies are discussed after the introduction of the catabolism and detection methods of BCAAs and BCKDK. Also, the interaction between microbiota and BCAAs is highlighted.

Comparative metabolomic analysis in horses and functional analysis of branched chain (alpha) keto acid dehydrogenase complex in equine myoblasts under exercise stress.

The integration of metabolomics and transcriptomics may elucidate the correlation between the genotypic and phenotypic patterns in organisms. In equine physiology, various metabolite levels vary during exercise, which may be correlated with a modified gene expression pattern of related genes. Integrated metabolomic and transcriptomic studies in horses have not been conducted to date. The objective of this study was to detect the effect of moderate exercise on the metabolomic and transcriptomic levels in horses. In this study, using nuclear magnetic resonance (NMR) spectroscopy, we analyzed the concentrations of metabolites in muscle and plasma; we also determined the gene expression patterns of branched chain (alpha) keto acid dehydrogenase kinase complex (BCKDK), which encodes the key regulatory enzymes in branched-chain amino acid (BCAA) catabolism, in two breeds of horses, Thoroughbred and Jeju, at different time intervals. The concentrations of metabolites in muscle and plasma were measured by 1H NMR (nuclear magnetic resonance) spectroscopy, and the relative metabolite levels before and after exercise in the two samples were compared. Subsequently, multivariate data analysis based on the metabolic profiles was performed using orthogonal partial least square discriminant analysis (OPLS-DA), and variable important plots and t-test were used for basic statistical analysis. The stress-induced expression patterns of BCKDK genes in horse muscle-derived cells were examined using quantitative reverse transcription polymerase chain reaction (qPCR) to gain insight into the role of transcript in response to exercise stress. In this study, we found higher concentrations of aspartate, leucine, isoleucine, and lysine in the skeletal muscle of Jeju horses than in Thoroughbred horses. In plasma, compared with Jeju horses, Thoroughbred horses had higher levels of alanine and methionine before exercise; whereas post-exercise, lysine levels were increased. Gene expression analysis revealed a decreased expression level of BCKDK in the post-exercise period in Thoroughbred horses.

191-OR: Hepatic Expression of the Branched-Chain Keto Acid Dehydrogenase Kinase Is Sufficient to Cause Glucose Intolerance in Lean Mice

Perturbed branched-chain amino acid homeostasis is a feature of obesity, insulin-resistance and type 2 diabetes. Induction of the branched-chain keto acid dehydrogenase kinase (BDK) in liver is one mechanism that is thought to contribute to elevated BCAA levels in these conditions. Whether higher levels of BDK in liver are sufficient to disturb systemic BCAA homeostasis and promote glucose intolerance in the absence of obesity or insulin resistance has never been directly tested. We treated 12 week-old C57BL6/J mice with adeno-associated virus, serotype 8 (AAV8) -BDK or control AAV8-GFP to promote long term expression of BDK specifically in liver of lean mice. Mice were then maintained on a standard low-fat chow diet for 8 weeks (n= 9 AAV8-GFP and n=AAV8-BDK) . AAV8-BDK significantly raised BDK protein and mRNA expression in liver but not adipose, skeletal muscle, or cardiac tissue compared to AAV8-GFP control mice. The higher expression of BDK in liver was associated with robust inhibitory phosphorylation of the branched-chain keto acid dehydrogenase (BCKDH) on ser293. AAV8-mediated induction of BDK expression in liver in our study was sufficient to promote significant elevations in circulating levels of the direct substrate of BCKDH, the branched chain α-keto acids as well as their cognate BCAA. There was no effect of AAV8-BDK to alter food intake, weight gain or adiposity. However, glucose tolerance measured by a 1g/kg intraperitoneal glucose tolerance test at week 7 was significantly impaired in mice receiving AAV8-BDK compared to AAV8-GFP control. These data demonstrate for the first time that induction of BDK in liver, as occurs with obesity, is sufficient to disturb systemic BCAA and glucose homeostasis in lean mice. Disclosure J.Walejko: None. R.W.Mcgarrah: None. P.J.White: None. Funding American Diabetes Association (1-16-INI-17)

BCKDK Promotes Ovarian Cancer Proliferation and Migration by Activating the MEK/ERK Signaling Pathway.

Background Ovarian cancer (OC) is the most fatal gynecologic cancer. The branched-chain α-keto acid dehydrogenase kinase (BCKDK) plays an important role in many serious human diseases, including cancers. Its function in promoting cell proliferation and migration has been reported in various cancers. However, the biological role of BCKDK and its molecular mechanisms underlying OC initiation and progression are unclear. Methods First, the expression level of BCKDK in OC cell lines or tissues was determined using tissue microarray- (TMA-) based immunohistochemistry or western blotting. Then, growth curve analysis, anchorage-independent cell transformation assays, wound healing assays, cell migration assays, and tumor xenografts were used to test whether BCKDK could promote cell transformation or metastasis. Finally, the signaling pathways involved in this process were investigated by western blotting or immunoprecipitation. Results We found that the expression of BCKDK was upregulated in OC tissues and the high expression of BCKDK was correlated with an advanced pathological grade in patients. The ectopic overexpression of BCKDK promoted the proliferation and migration of OC cells, and the knockdown of BCKDK with shRNAs inhibited the proliferation and migration of OC ex vivo and in vivo. Moreover, BCKDK promoted OC proliferation and migration by activating MEK. Conclusions Our results demonstrate that BCKDK promotes OC proliferation and migration by activating the MEK/ERK signaling pathway. Targeting the BCKDK-MEK axis may provide a new therapeutic strategy for treating patients with OC.

BDK knockout skeletal muscle satellite cells exhibit enhanced protein translation initiation signal in response to BCAA in vitro

We examined the effects of branched-chain amino acids (BCAAs) and electrical pulse stimulation (EPS) on the mTORC1 pathway in muscle satellite cells (MSCs) isolated from branched-chain α-keto acid dehydrogenase kinase (BDK) knockout (KO) mice in vitro. MSCs were isolated from BDK KO and wild-type (WT) mice, proliferated, and differentiated into myotubes. BCAA stimulation increased the phosphorylation of p70 S6 kinase (p70S6K), a marker of protein translation initiation, in MSCs from WT and BDK KO mice, but the rate of the increase was higher in MSCs isolated from BDK KO mice. Contrarily, there was no difference in the increase in p70S6K phosphorylation by EPS. Acute BDK knockdown in MSCs from WT mice using shRNA decreased p70S6K phosphorylation in response to BCAA stimulation. Collectively, the susceptibility of mTORC1 to BCAA stimulation was elevated by chronic, but not acute, enhancement of BCAA catabolism.

BCKDK alters the metabolism of non-small cell lung cancer.

BackgroundMetabolic reprogramming is a major feature of many tumors including non-small cell lung cancer (NSCLC). Branched-chain α-keto acid dehydrogenase kinase (BCKDK) plays an important role in diabetes, obesity, and other diseases. However, the function of BCKDK in NSCLC is unclear. This study aimed to explore the function of BCKDK in NSCLC.MethodsMetabolites in the serum of patients with NSCLC and the supernatant of NSCLC cell cultures were detected using nuclear magnetic resonance (NMR) spectroscopy. Colony formation, cell proliferation, and cell apoptosis were assessed to investigate the function of BCKDK in the progression of NSCLC. Glucose uptake, lactate production, cellular oxygen consumption rate, extracellular acidification rate, and reactive oxygen species (ROS) were measured to examine the function of BCKDK in glucose metabolism. The expression of BCKDK was measured using reverse transcriptase-polymerase chain reaction, western blot, and immunohistochemical assay.ResultsCompared with healthy controls and postoperative NSCLC patients, increased branched-chain amino acid (BCAA) and decreased citrate were identified in the serum of preoperative NSCLC patients. Upregulation of BCKDK affected the metabolism of BCAAs and citrate in NSCLC cells. Knockout of BCKDK decreased the proliferation and exacerbated apoptosis of NSCLC cells ex vivo, while increased oxidative phosphorylation and, ROS levels, and inhibited glycolysis.ConclusionsBCKDK may influence glycolysis and oxidative phosphorylation by regulating the degradation of BCAA and citrate, thereby affecting the progression of NSCLC.

Branched-Chain Amino Acid Supplementation Alters the Abundance of Mechanistic Target of Rapamycin and Insulin Signaling Proteins in Subcutaneous Adipose Explants from Lactating Holstein Cows.

Simple SummaryBranched-chain amino acids (BCAAs) are import regulators of mechanistic target of rapamycin (mTOR). In humans and rodents, increased circulating BCAA levels are positively associated with changes in protein abundance of insulin and amino acid (AA) signaling pathways in organs such as skeletal muscle and adipose. Unlike aspects of fatty acid metabolism (e.g., lipolysis, lipogenesis), it is unknown if BCAA directly affect subcutaneous adipose tissue (SAT) AA metabolism and insulin signaling. We propose that BCAA availability within SAT could enhance aspects of AA and insulin function by promoting increases in the abundance of key proteins.The objective of this study was to investigate changes in protein abundance of mTOR and insulin signaling pathway components along with amino acid (AA) transporters in bovine s.c. adipose (SAT) explants in response to increased supply of Leu, Ile, or Val. Explants of SAT from four lactating Holstein cows were incubated with high-glucose serum-free DMEM, to which the 10 essential AAs were added to create the following treatments: ideal mix of essential AA (IPAA; Lys:Met 2.9:1; Lys:Thr 1.8:1; Lys:His 2.38:1; Lys:Val 1.23:1; Lys:Ile 1.45:1; Lys:Leu 0.85:1; Lys:Arg 2.08:1) or IPAA supplemented with Ile, Val, or Leu to achieve a Lys:Ile of 1.29:1 (incIle), Lys:Val 1.12:1 (incVal), or Lys:Leu (incLeu) 0.78:1 for 4 h. Compared with IPAA, incLeu or incIle led to greater activation of protein kinase B (AKT; p-AKT/total AKT) and mTOR (p-mTOR/total mTOR). Total EAA in media averaged 7.8 ± 0.06 mmol/L across treatments. Incubation with incLeu, incIle, or incVal led to greater protein abundance of solute carrier family 38 member 1 (SLC38A1), a Gln transporter, and the BCAA catabolism enzyme branched-chain α-keto acid dehydrogenase kinase (BCKDK) compared with IPAA. Activation of eukaryotic elongation factor 2 (eEF2; p-eEF2/total eEF2) was also greater in response to incLeu, incIle, or incVal. Furthermore, compared with incLeu or incIle, incVal supplementation led to greater abundance of SLC38A1 and BCKDK. BCKDK is a rate-limiting enzyme regulating BCAA catabolism via inactivation and phosphorylation of the BCKD complex. Overall, data suggested that enhanced individual supplementation of BCAA activates mTOR and insulin signaling in SAT. Increased AA transport into tissue and lower BCAA catabolism could be part of the mechanism driving these responses. The potential practical applications for enhancing post-ruminal supply of BCAA via feeding in rumen-protected form support in vivo studies to ascertain the role of these AAs on adipose tissue biology.

Branched-chain amino acids regulate hyaluronan synthesis and PPARα expression in the skin.

We examined the effects of deletion of branched-chain α-keto acid dehydrogenase kinase (BDK), a key enzyme in branched-chain amino acid catabolism, on hyaluronan synthesis in mice. The skin levels of hyaluronan and the gene expression levels of hyaluronan synthase (Has)2, Has3, and peroxisome proliferator-activated receptor-α were significantly lower in the BDK-knockout group than in the wild-type group.

Dichloroacetate and Pyruvate Metabolism: Pyruvate Dehydrogenase Kinases as Targets Worth Investigating for Effective Therapy of Toxoplasmosis.

Toxoplasmosis, a protozoan infection caused by Toxoplasma gondii, is estimated to affect around 2.5 billion people worldwide. Nevertheless, the side effects of drugs combined with the long period of therapy usually result in discontinuation of the treatment. New therapies should be developed by exploring peculiarities of the parasite's metabolic pathways, similarly to what has been well described in cancer cell metabolism. An example is the switch in the metabolism of cancer that blocks the conversion of pyruvate into acetyl coenzyme A in mitochondria. In this context, dichloroacetate (DCA) is an anticancer drug that reverts the tumor proliferation by inhibiting the enzymes responsible for this switch: the pyruvate dehydrogenase kinases (PDKs). DCA has also been used in the treatment of certain symptoms of malaria; however, there is no evidence of how this drug affects apicomplexan species. In this paper, we studied the metabolism of T. gondii and demonstrate that DCA also inhibits T. gondii's in vitro infection with no toxic effects on host cells. DCA caused an increase in the activity of pyruvate dehydrogenase followed by an unbalanced mitochondrial activity. We also observed morphological alterations frequently in mitochondria and in a few apicoplasts, essential organelles for parasite survival. To date, the kinases that potentially regulate the activity of pyruvate metabolism in both organelles have never been described. Here, we confirmed the presence in the genome of two putative kinases (T. gondii PDK [TgPDK] and T. gondii branched-chain α-keto acid dehydrogenase kinase [TgBCKDK]), verified their cellular localization in the mitochondrion, and provided in silico data suggesting that they are potential targets of DCA.IMPORTANCE Currently, the drugs used for toxoplasmosis have severe toxicity to human cells, and the treatment still lacks effective and safer alternatives. The search for novel drug targets is timely. We report here that the treatment of T. gondii with an anticancer drug, dichloroacetate (DCA), was effective in decreasing in vitro infection without toxicity to human cells. It is known that PDK is the main target of DCA in mammals, and this inactivation increases the conversion of pyruvate into acetyl coenzyme A and reverts the proliferation of tumor cells. Moreover, we verified the mitochondrial localization of two kinases that possibly regulate the activity of pyruvate metabolism in T. gondii, which has never been studied. DCA increased pyruvate dehydrogenase (PDH) activity in T. gondii, followed by an unbalanced mitochondrial activity, in a manner similar to what was previously observed in cancer cells. Thus, we propose the conserved kinases as potential regulators of pyruvate metabolism and interesting targets for new therapies.