📋 Browse Articles

Recent research has emphasized the significance of testis-specific serine proteases in regulating various aspects of sperm maturation and function. Among them, serine protease 55 (PRS55) plays an important role in the energy metabolism of sperm and is essential for male fertility in mice. A recent case study further suggests its potential importance to human fertility. However, the underlying molecular mechanism by which PRS55 influences sperm function are still not well understood. The present study aims to investigate these mechanisms further. In this study, we found impaired mitochondrial function in Prss55 Our study demonstrates that PRSS55 interacts with BCKDK and BCKDHA, and regulates BCAA metabolism and energy homeostasis, thereby facilitating sperm migration. Our study provides a biological rationale for PRSS55 as a potential therapeutic target for the treatment of male infertility in clinical. Show less

Rubia cordifolia L. (RCL) is a widely used medicinal with a long history. It exhibits anti-inflammatory and antioxidant properties and prevents apoptosis. While there is growing evidence that exhausted exercise (EE) might cause cardiac damage, RCL has been shown to provide cardioprotective effects. The effects and mechanisms of RCL on exercise-induced myocardial injury remain unclear. In this study, we tested the RCL extract using a rat model of exhausted swimming. We evaluated the therapeutic effect of RCL on exercise-induced myocardial damage using PCR, ELISA, hematoxylin-eosin (H&E) staining, DHE staining, and other methods. UPLC-Q-TOF-MS was employed to identify the components of the RCL extract and its blood-entry components, and network pharmacology was constructed. LC-MS was utilized to investigate left ventricular metabolomics. These two approaches were combined to predict the possible metabolic pathways regulated by RCL. Finally, the targets of the metabolic pathway were verified using molecular docking and western blot analysis. The findings suggest that rubioncolin B, 4-hydroxy-2-carbexyanthraquinone, and 9-Oxo-9H-xanthene-4-carboxylic acid may be the primary active compounds of RCL. RCL promotes the degradation pathway of branched-chain amino acids (BCAA), including valine, leucine, and isoleucine, regulates the proteins BCAT2 and BCKDK, reduces pathological injuries, inflammation, oxidative stress, and collagen deposition, and mitigates the effects of exhaustion-induced myocardial injuries by influencing the key target AKR1C1 and the metabolite L-Valine. This study provides a foundation for the development of RCL as a sports supplement to alleviate EE-induced myocardial injury. Show less

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the selective loss of dopaminergic neurons in the substantia nigra, resulting in motor symptoms such as bradykinesia, tremor, rigidity, and postural instability, as well as a wide variety of non-motor manifestations. Branched-chain amino acids (BCAAs)-leucine, isoleucine, and valine-are essential nutrients involved in neurotransmitter synthesis, energy metabolism, and cellular signaling. Emerging evidence suggests that BCAA metabolism is intricately linked to the pathophysiology of PD. Dysregulation of BCAA levels has been associated with energy metabolism, mitochondrial dysfunction, oxidative stress, neuroinflammation, and altered neurotransmission. Furthermore, the branched-chain ketoacid dehydrogenase kinase (BCKDK), a key regulator of BCAA catabolism, has been implicated in PD through its role in modulating neuronal energetics and redox homeostasis. In this review, we synthesize current molecular, genetic, microbiome, and clinical evidence on BCAA dysregulation in PD to provide an integrative perspective on the BCAA-PD axis and highlight directions for future translational research. We explored the dualistic role of BCAAs as both potential neuroprotective agents and metabolic stressors, and critically examined the therapeutic prospects and limitations of BCAA supplementation and BCKDK targeting. Show less

Maple syrup urine disease (MSUD) is a rare inborn error of metabolism caused by impaired catabolism of branched-chain amino acids (BCAAs). The genes BCKDHA, BCKDHB, DBT, and DLD encode the subunits of the branched-chain α-ketoacid dehydrogenase (BCKDH) complex, which is essential for BCAA metabolism. Catalytic subunits are BCKDHA, BCKDHB, DBT, and DLD, whereas the regulator subunits are PPM1K and BCKDK. PPM1K plays a critical role by dephosphorylating and activating this enzyme complex. Pathogenic variants in the PPM1K gene cause an extremely rare, mild form of MSUD. Here, we report an 8-year-old male patient with a mild form of MSUD putatively caused by a novel homozygous variant in PPM1K. The patient presented with mild dysmorphic features, delayed speech, relative microcephaly, and overweight, all considered familial phenotypic traits. Laboratory findings revealed mildly elevated plasma branched-chain amino acids, mild lactic acidemia, and a slight increase in urinary keto acids. Exome sequencing identified a novel homozygous missense variant, c.925A>G p.(Ile309Val), in the PPM1K gene. This case represents the third reported patient with a mild form of MSUD associated with the first reported missense variant in the PPM1K gene in the literature, further expanding the clinical and genetic spectrum of PPM1K-related disorders. Show less

Maple syrup urine disease (MSUD) is a disorder of branched-chain amino acid metabolism caused by a defect in the branched-chain α-ketoacid dehydrogenase (BCKD) complex (OMIM #248600). The hallmark presentation is encephalopathic crisis in neonates, but can also present with metabolic decompensation, developmental delays, and feeding difficulties. Biochemical evidence for MSUD includes elevated branched-chain amino acids (BCAA) and the pathognomonic presence of alloisoleucine. The BCKD complex contains several subunits associated with autosomal recessive MSUD, while its regulatory proteins have less well-defined disease associations. We report on two families with the same Show less

Metabolic reprogramming of vascular smooth muscle cell (VSMC) plays a critical role in the pathogenesis of thoracic aortic dissection (TAD). Previous researches have mainly focused on dysregulation of fatty acid or glucose metabolism, while the impact of amino acids catabolic disorder in VSMCs during the development of TAD remains elusive. Here, we identified branched-chain amino acid (BCAA) catabolic defect as a metabolic hallmark of TAD. The bioinformatics analysis and data from human aorta revealed impaired BCAA catabolism in TAD individuals. This was accompanied by upregulated branched-chain α-ketoacid dehydrogenase kinase (BCKDK) expression and BCKD E1 subunit alpha (BCKDHA) phosphorylation, enhanced vascular inflammation, and hyperactivation of mTOR signaling. Further in vivo experiments demonstrated that inhibition of BCKDK with BT2 (a BCKDK allosteric inhibitor) treatment dephosphorylated BCKDHA and re-activated BCAA catabolism, attenuated VSMCs phenotypic switching, alleviated aortic remodeling, mitochondrial reactive oxygen species (ROS) damage and vascular inflammation. Additionally, the beneficial actions of BT2 were validated in a TNF-α challenged murine VSMC cell line. Meanwhile, rapamycin conferred similar beneficial effects against VSMC phenotypic switching, cellular ROS damage as well as inflammatory response. However, co-treatment with MHY1485 (a classic mTOR activator) reversed the beneficial effects of BT2 by reactivating mTOR signaling. Taken together, the in vivo and in vitro evidence showed that impairment of BCAA catabolism resulted in aortic accumulation of BCAA and further caused VSMC phenotypic switching, mitochondrial ROS damage and inflammatory response via mTOR hyperactivation. BCKDK and mTOR signaling may serve as the potential drug targets for the prevention and treatment of TAD. Show less

Elevated levels of branched chain amino acids (BCAAs) and branched-chain α-ketoacids are associated with cardiovascular and metabolic disease, but the molecular mechanisms underlying a putative causal relationship remain unclear. The branched-chain ketoacid dehydrogenase kinase (BCKDK) inhibitor BT2 (3,6-dichlorobenzo[b]thiophene-2-carboxylic acid) is often used in preclinical models to increase BCAA oxidation and restore steady-state BCAA and branched-chain α-ketoacid levels. BT2 administration is protective in various rodent models of heart failure and metabolic disease, but confoundingly, targeted ablation of Bckdk in specific tissues does not reproduce the beneficial effects conferred by pharmacologic inhibition. Here, we demonstrate that BT2, a lipophilic weak acid, can act as a mitochondrial uncoupler. Measurements of oxygen consumption, mitochondrial membrane potential, and patch-clamp electrophysiology show that BT2 increases proton conductance across the mitochondrial inner membrane independently of its inhibitory effect on BCKDK. BT2 is roughly sixfold less potent than the prototypical uncoupler 2,4-dinitrophenol and phenocopies 2,4-dinitrophenol in lowering de novo lipogenesis and mitochondrial superoxide production. The data suggest that the therapeutic efficacy of BT2 may be attributable to the well-documented effects of mitochondrial uncoupling in alleviating cardiovascular and metabolic disease. Show less

The activation of branched chain amino acid (BCAA) catabolism has garnered interest as a potential therapeutic approach to improve insulin sensitivity, enhance recovery from heart failure, and blunt tumor growth. Evidence for this interest relies in part on BT2, a small molecule that promotes BCAA oxidation and is protective in mouse models of these pathologies. BT2 and other analogs allosterically inhibit branched chain ketoacid dehydrogenase kinase (BCKDK) to promote BCAA oxidation, which is presumed to underlie the salutary effects of BT2. Potential "off-target" effects of BT2 have not been considered, however. We therefore tested for metabolic off-target effects of BT2 in Show less

Lipid metabolism disorders appear to play an important role in the ageing process, thus understanding the cellular and molecular mechanisms underlying the association of ageing with elevated vulnerability to lipid metabolism related diseases is crucial towards promoting quality of life in old age. MicroRNAs (miRNAs) have emerged as crucial regulators of lipid metabolism, and some miRNAs have key roles in ageing. In this study, we investigated changes in liver lipid metabolism of ageing mice and the mechanisms of the altered expression of miRNAs in the ageing liver which contributes to the age-dependent increase in lipid synthesis. Here we found that miR-743b-3p was higher expressed in the liver tissues of ageing mice through the small RNA sequencing and bioinformatics analysis, and its target PPM1K was predicted and confirmed the target relationship of miR-743b-3p with PPM1K in the aged mouse liver tissues and the cultured senescent hepatocytes in vitro. Moreover, using the transfected miR-743b-3p mimics/inhibitors into the senescent hepatocyte AML12. We found that miR-743b-3p inhibition reversed the hepatocyte senescence, and finally decreased the expression of genes involved in lipid synthesis(Chrebp, Fabp4, Acly and Pparγ) through increasing the target gene expression of PPM1K which regulated the expression of branched-chain amino acids (BCAA) metabolism-related genes (Bckdhα, Bckdk, Bcat2, Dbt). These results identify that age-induced expression of miR-743b-3p inhibits its target PPM1K which induces BCAA metabolic disorder and regulates hepatocyte lipid accumulation during ageing. Show less

Branched-chain amino acid transferase 1 (BCAT1) is highly expressed in multiple cancers and is associated with poor prognosis, particularly in glioblastoma (GBM). However, the post-translational modification (PTM) mechanism of BCAT1 is unknown. Here, we investigated the cross-talk mechanisms between phosphorylation and ubiquitination modifications in regulating BCAT1 activity and stability. We found that BCAT1 is phosphorylated by branched chain ketoacid dehydrogenase kinase (BCKDK) at S5, S9, and T312, which increases its catalytic and antioxidant activity and stability. STUB1 (STIP1 homology U-box-containing protein 1), the first we found and reported E3 ubiquitin ligase of BCAT1, can also be phosphorylated by BCKDK at the S19 site, which disrupts the interaction with BCAT1 and inhibits its degradation. In addition, we demonstrate through in vivo and in vitro experiments that BCAT1 phosphorylation inhibiting its ubiquitination at multiple sites is associated with GBM proliferation and that inhibition of the BCKDK-BCAT1 axis enhances the sensitivity to temozolomide (TMZ). Overall, we identified novel mechanisms for the regulation of BCAT1 modification and elucidated the importance of the BCKDK-STUB1-BCAT1 axis in GBM progression. Show less

Altered branched chain amino acids (BCAAs), including leucine, isoleucine, and valine, are frequently observed in patients with advanced cancer. We evaluated the efficacy of chimeric antigen receptor (CAR) T cell-mediated cancer cell lysis potential in the immune microenvironment of BCAA supplementation and deletion. BCAA supplementation increased cancer cell killing percentage, while accelerating BCAA catabolism and decreasing BCAA transporter decreased cancer cell lysis efficacy. We thus designed BCKDK engineering CAR T cells for the reprogramming of BCAA metabolism in the tumor microenvironment based on the genotype and phenotype modification. BCKDK overexpression (OE) in CAR-T cells significantly improved cancer cell lysis, while BCKDK knockout (KO) resulted in inferior lysis potential. In an in vivo experiment, BCKDK-OE CAR-T cell treatment significantly prolonged the survival of mice bearing NALM6-GL cancer cells, with the differentiation of central memory cells and an increasing proportion of CAR-T cells in the peripheral circulation. BCKDK-KO CAR-T cell treatment resulted in shorter survival and a decreasing percentage of CAR-T cells in the peripheral circulation. In conclusion, BCKDK-engineered CAR-T cells exert a distinct phenotype for superior anticancer efficiency. Show less

Branched chain ketoacid dehydrogenase kinase (BCKDK) deficiency is a recently described inherited neurometabolic disorder of branched chain amino acid (BCAA) metabolism implying increased BCAA catabolism. It has been hypothesized that a severe reduction in systemic BCAA levels underlies the disease pathophysiology, and that BCAA supplementation may ameliorate disease phenotypes. To test this hypothesis, we characterized a recent mouse model of BCKDK deficiency and evaluated the efficacy of enteral BCAA supplementation in this model. Surprisingly, BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels. These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology. In support of this conclusion, genetic re-regulation of BCAA catabolism, through Show less

The Maternal-to-Zygotic transition (MZT) is a reprograming process encompassing zygotic genome activation (ZGA) and the clearance of maternally-provided mRNAs. While some factors regulating MZT have been identified, there are thousands of maternal RNAs whose function has not been ascribed yet. Here, we have performed a proof-of-principle CRISPR-RfxCas13d maternal screening targeting mRNAs encoding protein kinases and phosphatases in zebrafish and identified Bckdk as a novel post-translational regulator of MZT. Show less

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. Show less

Muscle wasting can be caused by nutrition deficiency and inefficient metabolism of amino acids, including Branched Chain Amino Acids (BCAAs). Branched Chain Amino Acids are a major contributor to the metabolic needs of healthy muscle and account for over a tenth of lean muscle mass. Branched chain alpha-ketoacid dehydrogenase (BCKD) is the rate limiting enzyme of BCAA metabolism. Inhibition of BCKD is achieved through a reversible phosphorylation event by Branched Chain a-ketoacid dehydrogenase kinase (BCKDK). Our study set out to determine the importance of BCKDK in the maintenance of skeletal muscle. We used the Gene Expression Omnibus Database to understand the role of BCKDK in skeletal muscle pathogenesis, including aging, muscular disease, and interrupted muscle metabolism. We found BCKDK expression levels were consistently decreased in pathologic conditions. These results were most consistent when exploring muscular disease followed by aging. Based on our findings, we hypothesize that decreased BCKDK expression alters BCAA catabolism and impacts loss of normal muscle integrity and function. Further research could offer valuable insights into potential therapeutic strategies for addressing muscle-related disorders. Show less

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 Show less

Elevated circulating branched-chain amino acids (BCAA) have been linked with the severity of insulin resistance across numerous populations, implicating heightened BCAA metabolism as a potential therapy for insulin resistance. Recently, the angiotensin II type 1 receptor (AT1R) inhibitor Valsartan (VAL) was identified as a potent inhibitor of branched-chain alpha-keto acid dehydrogenase kinase (BCKDK), a negative regulator of BCAA metabolism. This work investigated the effect of VAL on myotube metabolism and insulin sensitivity under both insulin sensitive and insulin resistant conditions. C2C12 myotubes were treated with or without VAL at 8 µM for 24 h, both with and without hyperinsulinemic-induced insulin resistance. Oxygen consumption and extracellular acidification were used to measure mitochondrial and glycolytic metabolism, respectively. Gene expression was assessed via qRT-PCR, and insulin sensitivity was assessed via Western blot. Insulin resistance significantly reduced both basal and peak mitochondrial function which were rescued to control levels by concurrent VAL. Changes in mitochondrial function occurred without substantial changes in mitochondrial content or related gene expression. Insulin sensitivity and glycolytic metabolism were unaffected by VAL, as was lipogenic signaling and lipid content. Additionally, both VAL and insulin resistance depressed Bckdha expression. Interestingly, an interaction effect was observed for extracellular isoleucine, valine, and total BCAA (but not leucine), suggesting VAL may alter BCAA utilization in an insulin sensitivity-dependent manner. Insulin resistance appears to suppress mitochondrial function in a myotube model which can be rescued by VAL. Further research will be required to explore the implications of these findings in more complex models. Show less

This study aims to clinically and genetically assess 30 unrelated consanguineous Pakistani families from various ethnic backgrounds, all exhibiting features of neurodevelopmental disorders (NDDs). We conducted clinical, genetic, biochemical, and molecular analyses on 30 consanguineous families with NDDs enrolled from various regions of Pakistan. The likely molecular causes of primary microcephaly and NDDs were identified. Detailed clinical investigations and molecular diagnoses were performed using whole exome sequencing (WES) of the proband, followed by Sanger sequencing for validation and segregation in the available family members of the affected families. WES identified likely disease-causing homozygous variants in 30 unrelated consanguineous families. Six families presented newly described variants in known NDD-related genes: In the present study, we observed a high frequency of Show less

Elevated circulating branched-chain amino acids (BCAAs) are tightly linked to an increased risk in the development of type 2 diabetes mellitus. The rate limiting enzyme of BCAA catabolism branched-chain α-ketoacid dehydrogenase (BCKDH) is phosphorylated at E1α subunit (BCKDHA) by its kinase (BCKDK) and inactivated. Here, the liver-specific BCKDK or BCKDHA knockout mice displayed normal glucose tolerance and insulin sensitivity. However, knockout of BCKDK in the liver inhibited hepatic glucose production as well as the expression of key gluconeogenic enzymes. No abnormal gluconeogenesis was found in mice lacking hepatic BCKDHA. Consistent with the vivo results, BT2-mediated inhibition or genetic knockdown of BCKDK decreased hepatic glucose production and gluconeogenic gene expressions in primary mouse hepatocytes while BCKDK overexpression exhibited an opposite effect. Whereas, gluconeogenic gene expressions were not altered in BCKDHA-silenced hepatocytes. Mechanistically, BT2 treatment attenuated the interaction of cAMP response element binding protein (CREB) with CREB-binding protein and promoted FOXO1 protein degradation by increasing its ubiquitination. Our findings suggest that BCKDK regulates hepatic gluconeogenesis through CREB and FOXO1 signalings, independent of BCKDHA-mediated BCAA catabolism. Show less

Elevated levels of the branched chain α-amino acids valine, leucine, and isoleucine are associated with heart disease and metabolic disorders. The kinase BDK, also known as branched-chain ketoacid dehydrogenase kinase (BCKDK), is a negative regulator of branched-chain α-amino acid metabolism through deactivation of BCKDC, the branched-chain α-ketoacid dehydrogenase complex. Inhibitors of BDK increase the activity of BCKDC and could be useful therapeutic leads for cardiometabolic diseases. We describe a novel bicyclic carboxy amide as an inhibitor of BDK with in vivo activity. Show less

Mitochondrial dysfunction and α-synuclein (αSyn) aggregation are key contributors to Parkinson's Disease (PD). While genetic and environmental risk factors, including mutations in mitochondrial-associated genes, are implicated in PD, the precise mechanisms linking mitochondrial defects to αSyn pathology remain incompletely understood, hindering the development of effective therapeutic interventions. Here, we identify the loss of branched chain ketoacid dehydrogenase kinase (BCKDK) as a mitochondrial risk factor that exacerbates αSyn pathology by disrupting Complex I function. Our findings reveal a consistent downregulation of BCKDK in dopaminergic (DA) neurons from A53T-αSyn mouse models, PD patient-derived induced pluripotent stem (iPS) cells, and postmortem brain tissues. BCKDK deficiency leads to mitochondrial dysfunction, including reduced membrane potential and increased reactive oxygen species (ROS) production upon administration of a stressor, which in turn promotes αSyn oligomerization. Mechanistically, BCKDK interacts with the NDUFS1 subunit of Complex I to stabilize its function. Loss of BCKDK disrupts this interaction, leading to Complex I destabilization and enhanced αSyn aggregation. Notably, restoring BCKDK expression in neuron-like cells rescues mitochondrial integrity and restores Complex I activity. Similarly, in patient-derived iPS cells differentiated to form dopaminergic neurons, NDUFS1 and phosphorylated aSyn levels are partially restored upon BCKDK expression. These findings establish a mechanistic link between BCKDK deficiency, mitochondrial dysfunction, and αSyn pathology in PD, positioning BCKDK as a potential therapeutic target to mitigate mitochondrial impairment and neurodegeneration in PD. Show less

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 K Show less

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 Bckdk 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. Show less

Branched-chain keto-acid dehydrogenase kinase (BCKDK) is the rate-limiting enzyme of branched-chain amino acid (BCAA) metabolism. In the last six years, BCKDK has been used as a kinase to promote tumor proliferation and metastasis. Renal cell carcinoma (RCC) is a highly vascularized tumor. A high degree of vascularization promotes tumor metastasis. Our objective is to explore the relationship between BCKDK and RCC metastasis and its specific mechanism. In our study, BCKDK is highly expressed in renal clear cell carcinoma and promotes the migration of clear cell renal cell carcinoma (ccRCC). Exosomes from ccRCC cells can promote vascular permeability and angiogenesis, especially when BCKDK is overexpressed in ccRCC cells. BCKDK can also augment the miR-125a-5p expression in ccRCC cells and derived exosomes, thereby decreasing the downstream target protein VE-cadherin level, weakening adhesion junction expression, increasing vascular permeability, and promoting angiogenesis in HUVECs. The novel BCKDK/Exosome-miR-125a-5p/VE-cadherin axis regulates intercellular communication between ccRCC cells and HUVECs. BCKDK plays a critical role in renal cancer metastasis, may be used as a molecular marker of metastatic ccRCC, and even may become a potential target of clinical anti-vascular therapy for ccRCC. Show less

Branched chain ketoacid dehydrogenase kinase (BCKDK) deficiency is a recently described inherited neurometabolic disorder of branched chain amino acid (BCAA) metabolism implying increased BCAA catabolism. It has been hypothesized that a severe reduction in systemic BCAA levels underlies the disease pathophysiology, and that BCAA supplementation may ameliorate disease phenotypes. To test this hypothesis, we characterized a recent mouse model of BCKDK deficiency and evaluated the efficacy of enteral BCAA supplementation in this model. Surprisingly, BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels. These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology. In support of this conclusion, genetic re-regulation of BCAA catabolism, through Show less

Mitochondrial dysfunction in astrocytes has been implicated in the development of various neurological disorders. Mitophagy, mitochondrial autophagy, is required for proper mitochondrial function by preventing the accumulation of damaged mitochondria. The importance of mitophagy, specifically in the astrocytes of the optic nerve (ON), has been little studied. We introduce an animal model in which two separate mutations act synergistically to produce severe ON degeneration. The first mutation is in Show less

In this study, to screen for candidate markers of temozolomide (TMZ) resistance in glioblastoma, we artificially established TMZ drug-resistant glioblastoma (GBM) cell lines, U251-TMZ and U87-TMZ. In the U251-TMZ and U87-TMZ cell lines, we screened and analyzed differentially expressed proteins using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) differential proteomics. Compared with the U251 and U87 control cell lines, 95 differential proteins were screened in the U251-TMZ and U87-TMZ cell lines, of which 28 proteins were upregulated and 67 proteins were down-regulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the co-upregulated proteins showed that most of the differentially expressed proteins were located in the cytoplasm and were significantly upregulated in the biological processes related to vesicular transport in the intimal system and inflammatory response mediated by myeloid leukocytes. Seven candidates were identified as potential GBM markers of TMZ resistance. Combined with existing research findings, our study supports that UAP1L1 and BCKDK are promising potential markers of TMZ resistance in GBM. This is important for further understanding the molecular mechanisms that drive the development and enhancement of TMZ resistance. Show less

Elevated levels of branched chain amino acids (BCAAs) and branched-chain α-ketoacids (BCKAs) are associated with cardiovascular and metabolic disease, but the molecular mechanisms underlying a putative causal relationship remain unclear. The branched-chain ketoacid dehydrogenase kinase (BCKDK) inhibitor BT2 is often used in preclinical models to increase BCAA oxidation and restore steady-state BCAA and BCKA levels. BT2 administration is protective in various rodent models of heart failure and metabolic disease, but confoundingly, targeted ablation of Show less

Breast cancer is the most common malignant cancer in women worldwide. Cancer metastasis is the major cause of cancer-related deaths. BCKDK is associated with various diseases, including proliferation, migration, and invasion in multiple types of human cancers. However, the relevance of BCKDK to the development and progression of breast cancers and its function is unclear. This study found that BCKDK was overexpressed in breast cancer, associated with poor prognosis, and implicated in tumor metastasis. The downregulation of BCKDK expression inhibited the migration of human breast cancer cells in vitro and diminished lung metastasis in vivo. BCKDK perturbed the cadherin-catenin complex at the adherens junctions (AJs) and assembled focal adhesions (FAs) onto the extracellular matrix, thereby promoting the directed migration of breast cancer cells. We observed that BCKDK acted as a conserved regulator of the ubiquitination of cytoskeletal protein talin1 and the activation of the FAK/MAPK pathway. Further studies revealed that BCKDK inhibited the binding of talin1 to E3 ubiquitin ligase-TRIM21, leading to the decreased ubiquitination/degradation of talin1. In conclusion, identifying BCKDK as a biomarker for breast cancer metastasis facilitated further research on diagnostic biomarkers. Elucidating the mechanism by which BCKDK exerted its biological effect could provide a new theoretical basis for developing new markers for breast cancer metastasis and contribute to developing new therapies for the clinical treatment of breast cancer patients. Show less