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Molecular Cell Apr 2022The product of hexokinase (HK) enzymes, glucose-6-phosphate, can be metabolized through glycolysis or directed to alternative metabolic routes, such as the pentose...
The product of hexokinase (HK) enzymes, glucose-6-phosphate, can be metabolized through glycolysis or directed to alternative metabolic routes, such as the pentose phosphate pathway (PPP) to generate anabolic intermediates. HK1 contains an N-terminal mitochondrial binding domain (MBD), but its physiologic significance remains unclear. To elucidate the effect of HK1 mitochondrial dissociation on cellular metabolism, we generated mice lacking the HK1 MBD (ΔE1HK1). These mice produced a hyper-inflammatory response when challenged with lipopolysaccharide. Additionally, there was decreased glucose flux below the level of GAPDH and increased upstream flux through the PPP. The glycolytic block below GAPDH is mediated by the binding of cytosolic HK1 with S100A8/A9, resulting in GAPDH nitrosylation through iNOS. Additionally, human and mouse macrophages from conditions of low-grade inflammation, such as aging and diabetes, displayed increased cytosolic HK1 and reduced GAPDH activity. Our data indicate that HK1 mitochondrial binding alters glucose metabolism through regulation of GAPDH.
Topics: Animals; Glucose; Glycolysis; Hexokinase; Mice; Mitochondria; Pentose Phosphate Pathway
PubMed: 35305311
DOI: 10.1016/j.molcel.2022.02.028 -
Autophagy 2015Hexokinases (HKs) catalyze the first step of glucose metabolism, phosphorylating glucose to glucose 6-phosphate (G6P). HK2/hexokinase-II is a predominant isoform in... (Review)
Review
Hexokinases (HKs) catalyze the first step of glucose metabolism, phosphorylating glucose to glucose 6-phosphate (G6P). HK2/hexokinase-II is a predominant isoform in insulin-sensitive tissues such as heart, skeletal muscle, and adipose tissues and is also upregulated in many types of tumors associated with enhanced aerobic glycolysis (the Warburg effect). Accumulating evidence indicates that HK2 plays an important role not only in glycolysis but also in cell survival. Although there is increasing recognition that cellular metabolism and cell survival are closely related, the molecular link between metabolism and autophagic pathways has not been fully elucidated. We recently discovered that HK2 facilitates autophagy in response to glucose deprivation (HK substrate deprivation) to protect cardiomyocytes, and suggest that HK2 functions as a molecular switch from glycolysis to autophagy to ensure cellular energy homeostasis under starvation conditions.
Topics: Animals; Autophagy; Cytoprotection; Glucose; Glycolysis; Hexokinase; Humans; Mechanistic Target of Rapamycin Complex 1; Multiprotein Complexes; TOR Serine-Threonine Kinases
PubMed: 26075878
DOI: 10.1080/15548627.2015.1042195 -
International Journal of Molecular... Apr 2021Hexokinases are a family of ubiquitous exose-phosphorylating enzymes that prime glucose for intracellular utilization. Hexokinase 2 (HK2) is the most active isozyme of... (Review)
Review
Hexokinases are a family of ubiquitous exose-phosphorylating enzymes that prime glucose for intracellular utilization. Hexokinase 2 (HK2) is the most active isozyme of the family, mainly expressed in insulin-sensitive tissues. HK2 induction in most neoplastic cells contributes to their metabolic rewiring towards aerobic glycolysis, and its genetic ablation inhibits malignant growth in mouse models. HK2 can dock to mitochondria, where it performs additional functions in autophagy regulation and cell death inhibition that are independent of its enzymatic activity. The recent definition of HK2 localization to contact points between mitochondria and endoplasmic reticulum called Mitochondria Associated Membranes (MAMs) has unveiled a novel HK2 role in regulating intracellular Ca fluxes. Here, we propose that HK2 localization in MAMs of tumor cells is key in sustaining neoplastic progression, as it acts as an intersection node between metabolic and survival pathways. Disrupting these functions by targeting HK2 subcellular localization can constitute a promising anti-tumor strategy.
Topics: Animals; Antineoplastic Agents; Apoptosis; Autophagy; Calcium Signaling; Cell Hypoxia; Cell-Penetrating Peptides; Enzyme Induction; Gene Expression Regulation, Neoplastic; Glycolysis; Hexokinase; Humans; Intracellular Membranes; Mice; MicroRNAs; Mitochondria; Molecular Targeted Therapy; Neoplasm Proteins; Neoplasms; Neoplasms, Experimental; Phosphorylation; Protein Kinase Inhibitors; Protein Processing, Post-Translational; Rats; Ubiquitination
PubMed: 33946854
DOI: 10.3390/ijms22094716 -
Proceedings of the National Academy of... Feb 2023Microglial phagocytosis is an energetically demanding process that plays a critical role in the removal of toxic protein aggregates in Alzheimer's disease (AD). Recent...
Microglial phagocytosis is an energetically demanding process that plays a critical role in the removal of toxic protein aggregates in Alzheimer's disease (AD). Recent evidence indicates that a switch in energy production from mitochondrial respiration to glycolysis disrupts this important protective microglial function and may provide therapeutic targets for AD. Here, we demonstrate that the translocator protein (TSPO) and a member of its mitochondrial complex, hexokinase-2 (HK), play critical roles in microglial respiratory-glycolytic metabolism and phagocytosis. Pharmacological and genetic loss-of-function experiments showed that TSPO is critical for microglial respiratory metabolism and energy supply for phagocytosis, and its expression is enriched in phagocytic microglia of AD mice. Meanwhile, HK controlled glycolytic metabolism and phagocytosis via mitochondrial binding or displacement. In cultured microglia, TSPO deletion impaired mitochondrial respiration and increased mitochondrial recruitment of HK, inducing a switch to glycolysis and reducing phagocytosis. To determine the functional significance of mitochondrial HK recruitment, we developed an optogenetic tool for reversible control of HK localization. Displacement of mitochondrial HK inhibited glycolysis and improved phagocytosis in TSPO-knockout microglia. Mitochondrial HK recruitment also coordinated the inflammatory switch to glycolysis that occurs in response to lipopolysaccharide in normal microglia. Interestingly, cytosolic HK increased phagocytosis independent of its metabolic activity, indicating an immune signaling function. Alzheimer's beta amyloid drastically stimulated mitochondrial HK recruitment in cultured microglia, which may contribute to microglial dysfunction in AD. Thus, targeting mitochondrial HK may offer an immunotherapeutic approach to promote phagocytic microglial function in AD.
Topics: Animals; Mice; Alzheimer Disease; Amyloid beta-Peptides; Hexokinase; Microglia; Phagocytosis; Mitochondria
PubMed: 36787364
DOI: 10.1073/pnas.2209177120 -
Cell Metabolism Dec 2021Hexokinases (HK) catalyze the first step of glycolysis limiting its pace. HK2 is highly expressed in gut epithelium, contributes to immune responses, and is upregulated...
Hexokinases (HK) catalyze the first step of glycolysis limiting its pace. HK2 is highly expressed in gut epithelium, contributes to immune responses, and is upregulated during inflammation. We examined the microbial regulation of HK2 and its impact on inflammation using mice lacking HK2 in intestinal epithelial cells (Hk2). Hk2 mice were less susceptible to acute colitis. Analyzing the epithelial transcriptome from Hk2 mice during colitis and using HK2-deficient intestinal organoids and Caco-2 cells revealed reduced mitochondrial respiration and epithelial cell death in the absence of HK2. The microbiota strongly regulated HK2 expression and activity. The microbially derived short-chain fatty acid (SCFA) butyrate repressed HK2 expression via histone deacetylase 8 (HDAC8) and reduced mitochondrial respiration in wild-type but not in HK2-deficient Caco-2 cells. Butyrate supplementation protected wild-type but not Hk2 mice from colitis. Our findings define a mechanism how butyrate promotes intestinal homeostasis and suggest targeted HK2-inhibition as therapeutic avenue for inflammation.
Topics: Animals; Caco-2 Cells; Cell Death; Colitis; Epithelial Cells; Hexokinase; Histone Deacetylases; Humans; Mice; Mitochondria; Repressor Proteins
PubMed: 34847376
DOI: 10.1016/j.cmet.2021.11.004 -
Advanced Science (Weinheim,... Jul 2022Metabolic reprogramming is often observed in carcinogenesis, but little is known about the aberrant metabolic genes involved in the tumorigenicity and maintenance of...
Metabolic reprogramming is often observed in carcinogenesis, but little is known about the aberrant metabolic genes involved in the tumorigenicity and maintenance of stemness in cancer cells. Sixty-seven oncogenic metabolism-related genes in liver cancer by in vivo CRISPR/Cas9 screening are identified. Among them, acetyl-CoA carboxylase 1 (ACC1), aldolase fructose-bisphosphate A (ALDOA), fatty acid binding protein 5 (FABP5), and hexokinase 2 (HK2) are strongly associated with stem cell properties. HK2 further facilitates the maintenance and self-renewal of liver cancer stem cells. Moreover, HK2 enhances the accumulation of acetyl-CoA and epigenetically activates the transcription of acyl-CoA synthetase long-chain family member 4 (ACSL4), leading to an increase in fatty acid β-oxidation activity. Blocking HK2 or ACSL4 effectively inhibits liver cancer growth, and GalNac-siHK2 administration specifically targets the growth of orthotopic tumor xenografts. These results suggest a promising therapeutic strategy for the treatment of liver cancer.
Topics: CRISPR-Cas Systems; Coenzyme A Ligases; Fatty Acid-Binding Proteins; Fatty Acids; Hexokinase; Humans; Liver Neoplasms; Neoplastic Stem Cells
PubMed: 35603967
DOI: 10.1002/advs.202105126 -
Nature Cell Biology Jun 2022Mitochondrial metabolites regulate leukaemic and normal stem cells by affecting epigenetic marks. How mitochondrial enzymes localize to the nucleus to control stem cell...
Mitochondrial metabolites regulate leukaemic and normal stem cells by affecting epigenetic marks. How mitochondrial enzymes localize to the nucleus to control stem cell function is less understood. We discovered that the mitochondrial metabolic enzyme hexokinase 2 (HK2) localizes to the nucleus in leukaemic and normal haematopoietic stem cells. Overexpression of nuclear HK2 increases leukaemic stem cell properties and decreases differentiation, whereas selective nuclear HK2 knockdown promotes differentiation and decreases stem cell function. Nuclear HK2 localization is phosphorylation-dependent, requires active import and export, and regulates differentiation independently of its enzymatic activity. HK2 interacts with nuclear proteins regulating chromatin openness, increasing chromatin accessibilities at leukaemic stem cell-positive signature and DNA-repair sites. Nuclear HK2 overexpression decreases double-strand breaks and confers chemoresistance, which may contribute to the mechanism by which leukaemic stem cells resist DNA-damaging agents. Thus, we describe a non-canonical mechanism by which mitochondrial enzymes influence stem cell function independently of their metabolic function.
Topics: Chromatin; DNA; Hematopoietic Stem Cells; Hexokinase; Humans; Leukemia, Myeloid, Acute
PubMed: 35668135
DOI: 10.1038/s41556-022-00925-9 -
Molecular Cell Mar 2023Hexokinase 2 (HK2) plays a multifaceted role in the regulation of cellular activities. A new study by Hu et al. delineated a critical role of HK2 in governing...
Hexokinase 2 (HK2) plays a multifaceted role in the regulation of cellular activities. A new study by Hu et al. delineated a critical role of HK2 in governing glycolytic flux and mitochondrial activity, thereby modulating microglial functions in maladaptive inflammation in brain diseases.
Topics: Hexokinase; Microglia; Gatekeeping; Mitochondria; Glycolysis; Glucose
PubMed: 36931254
DOI: 10.1016/j.molcel.2023.02.022 -
Journal of Molecular and Cellular... Jan 2015As mediators of the first enzymatic step in glucose metabolism, hexokinases (HKs) orchestrate a variety of catabolic and anabolic uses of glucose, regulate antioxidant... (Review)
Review
As mediators of the first enzymatic step in glucose metabolism, hexokinases (HKs) orchestrate a variety of catabolic and anabolic uses of glucose, regulate antioxidant power by generating NADPH for glutathione reduction, and modulate cell death processes by directly interacting with the voltage-dependent anion channel (VDAC), a regulatory component of the mitochondrial permeability transition pore (mPTP). Here we summarize the current state-of-knowledge about HKs and their role in protecting the heart from ischemia/reperfusion (I/R) injury, reviewing: 1) the properties of different HK isoforms and how their function is regulated by their subcellular localization; 2) how HKs modulate glucose metabolism and energy production during I/R; 3) the molecular mechanisms by which HKs influence mPTP opening and cellular injury during I/R; and 4) how different metabolic and HK profiles correlate with susceptibility to I/R injury and cardioprotective efficacy in cancer cells, neonatal hearts, and normal, hypertrophied and failing adult hearts, and how these difference may guide novel therapeutic strategies to limit I/R injury in the heart. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease".
Topics: Animals; Glucose; Heart Diseases; Hexokinase; Humans; Isoenzymes; Metabolome; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Reperfusion Injury; Myocardium; Neoplasms
PubMed: 25264175
DOI: 10.1016/j.yjmcc.2014.09.020 -
Journal of Gastroenterology Sep 2023Therapies for cholangiocarcinoma are largely limited and ineffective. Herein, we examined the role of the FGF and VEGF pathways in regulating lymphangiogenesis and PD-L1...
BACKGROUND
Therapies for cholangiocarcinoma are largely limited and ineffective. Herein, we examined the role of the FGF and VEGF pathways in regulating lymphangiogenesis and PD-L1 expression in intrahepatic cholangiocarcinoma (iCCA).
METHODS
The lymphangiogenic functions of FGF and VEGF were evaluated in lymphatic endothelial cells (LECs) and iCCA xenograft mouse models. The relationship between VEGF and hexokinase 2 (HK2) was validated in LECs by western blot, immunofluorescence, ChIP and luciferase reporter assays. The efficacy of the combination therapy was assessed in LECs and xenograft models. Microarray analysis was used to evaluate the pathological relationships of FGFR1 and VEGFR3 with HK2 in human lymphatic vessels.
RESULTS
FGF promoted lymphangiogenesis through c-MYC-dependent modulation of HK2 expression. VEGFC also upregulated HK2 expression. Mechanistically, VEGFC phosphorylated components of the PI3K/Akt/mTOR axis to upregulate HIF-1α expression at the translational level, and HIF-1α then bound to the HK2 promoter region to activate its transcription. More importantly, dual FGFR and VEGFR inhibition with infigratinib and SAR131675 almost completely inhibited lymphangiogenesis, and significantly suppressed iCCA tumor growth and progression by reducing PD-L1 expression in LECs.
CONCLUSIONS
Dual FGFR and VEGFR inhibition inhibits lymphangiogenesis through suppression of c-MYC-dependent and HIF-1α-mediated HK2 expression, respectively. HK2 downregulation decreased glycolytic activity and further attenuated PD-L1 expression. Our findings suggest that dual FGFR and VEGFR blockade is an effective novel combination strategy to inhibit lymphangiogenesis and improve immunocompetence in iCCA.
Topics: Humans; Mice; Animals; Lymphangiogenesis; B7-H1 Antigen; Hexokinase; Vascular Endothelial Growth Factor A; Endothelial Cells; Phosphatidylinositol 3-Kinases; Cholangiocarcinoma
PubMed: 37433897
DOI: 10.1007/s00535-023-02012-8