Microbial regulation of hexokinase 2 links mitochondrial metabolism and cell death in colitis

ABSTRACT Mycobacterium tuberculosis induces metabolic reprogramming in macrophages like the Warburg effect. This enhances antimicrobial performance at the expense of increased inflammation, which may promote a pathogen-permissive host environment. Since the NAD+-dependent protein deacetylase Sirtuin 3 (SIRT3) is an important regulator of mitochondrial metabolism and cellular redox homeostasis, we hypothesized that SIRT3 modulation mediates M. tuberculosis-induced metabolic reprogramming. Infection of immortalized and primary murine macrophages resulted in reduced levels of SIRT3 mRNA and protein and perturbation of SIRT3-regulated enzymes in the tricarboxylic acid cycle, electron transport chain, and glycolytic pathway. These changes were associated with increased reactive oxygen species and reduced antioxidant scavenging, thereby triggering mitochondrial stress and macrophage cell death. Relevance to tuberculosis disease in vivo was indicated by greater bacterial burden and immune pathology in M. tuberculosis-infected Sirt3−/− mice. CD11b+ lung leukocytes isolated from infected Sirt3−/− mice showed decreased levels of enzymes involved in central mitochondrial metabolic pathways, along with increased reactive oxygen species. Bacterial burden was also greater in lungs of LysMcreSirt3L2/L2 mice, demonstrating the importance of macrophage-specific SIRT3 after infection. These results support the model of SIRT3 as a major upstream regulatory factor, leading to metabolic reprogramming in macrophages by M. tuberculosis. IMPORTANCE Tuberculosis, the disease caused by the bacterium M. tuberculosis, remains one of the top 10 causes of death worldwide. Macrophages, the first cells to encounter M. tuberculosis and critical for defense against infection, are hijacked by M. tuberculosis as a protected growth niche. M. tuberculosis-infected macrophages undergo metabolic reprogramming where key mitochondrial pathways are modulated, but the mechanisms driving this metabolic shift is unknown. Our study demonstrates that M. tuberculosis downregulates Sirtuin 3 (SIRT3), an important regulator of mitochondrial metabolism, leading to SIRT3-dependent transcriptional downregulation of mitochondrial metabolic proteins, which is followed by oxidative stress and macrophage necrosis. This study identifies SIRT3 modulation as a key event in M. tuberculosis-induced metabolic reprograming in macrophages that defend against tuberculosis.

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The Balance of Glucose Metabolism and Cell Death: Uncovering Protective and Lethal Effects of Hexokinase-2

Bioenergetics Open access ◽

10.4172/2167-7662.1000e105 ◽

2012 ◽

Vol 01 (02) ◽

Author(s):

Kyle S. McCommis ◽

Christopher P. Baines

Keyword(s):

Cell Death ◽

Glucose Metabolism ◽

Lethal Effects ◽

Hexokinase 2

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PO-032 Displacement of hexokinase 2 from mitochondria induces mitochondrial Ca2 +overload and caspase-independent cell death in cancer cells

10.1136/esmoopen-2018-eacr25.567 ◽

2018 ◽

Author(s):

F Ciscato ◽

R Filadi ◽

I Masgras ◽

M Pizzi ◽

O Marin ◽

...

Keyword(s):

Cell Death ◽

Cancer Cells ◽

Hexokinase 2

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Inhibition of mitochondrial metabolism by methyl-2-cyano-3,12-dioxooleana-1,9-diene-28-oate induces apoptotic or autophagic cell death in chronic myeloid leukemia cells

Molecular Cancer Therapeutics ◽

10.1158/1535-7163.mct-07-0553 ◽

2008 ◽

Vol 7 (5) ◽

pp. 1130-1139 ◽

Cited By ~ 34

Author(s):

Ismael Samudio ◽

Svitlana Kurinna ◽

Peter Ruvolo ◽

Borys Korchin ◽

Hagop Kantarjian ◽

...

Keyword(s):

Cell Death ◽

Chronic Myeloid Leukemia ◽

Myeloid Leukemia ◽

Mitochondrial Metabolism ◽

Autophagic Cell Death ◽

Leukemia Cells

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The role and mechanisms of hexokinase-2-mediated protection against cardiac cell death and disease

10.32469/10355/40110 ◽

2013 ◽

Author(s):

Kyle Stephan McCommis

Keyword(s):

Cell Death ◽

Cardiac Cell ◽

Hexokinase 2

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Targeting Glycolysis and Compensatory Mitochondrial Metabolism in Multiple Myeloma with FDA Approved Ritonavir and Metformin Via Synthetic Lethality

Blood ◽

10.1182/blood.v120.21.4016.4016 ◽

2012 ◽

Vol 120 (21) ◽

pp. 4016-4016 ◽

Cited By ~ 1

Author(s):

Kehinde U. A. Adekola ◽

Maylyn Martinez ◽

Steven T. Rosen ◽

Mala Shanmugam

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Synthetic Lethality ◽

Glucose Consumption ◽

Inhibitory Effect ◽

Mitochondrial Metabolism ◽

Hiv Protease ◽

Metformin Treatment ◽

Cells Cultured ◽

Resistant Cells

Abstract Abstract 4016 Multiple Myeloma (MM) is an incurable plasma cell malignancy accounting for 11,000 deaths annually in the US and 20% of deaths from all hematological malignancies. MM is one of myriad malignancies exhibiting enhanced glucose consumption associated with an aerobic glycolytic phenotype (i.e. the Warburg effect). We have recently published a study defining key glucose transporters responsible for facilitating glucose entry in myeloma and observed that MM cells exhibit reliance on constitutively cell surface-localized GLUT4 for basal glucose consumption. MM cells cultured in the absence of glucose or upon GLUT4 suppression exhibit either overt apoptosis (sensitive phenotype) or growth arrest (resistant phenotype). To further demonstrate the clinical utility of targeting GLUT4 for MM therapy we tested a HIV protease inhibitor ritonavir that has an off-target inhibitory effect on GLUT4. Treatment of MM cells with physiologically achievable concentrations of ritonavir blocks glucose entry resulting in MM cell death or growth suppression. The objective of this study was to define those metabolic pathways in resistant MM cell lines which compensate for the decrease in cellular glucose and protect the cells from toxicity caused by glucose-deprivation or GLUT4 suppression. We hypothesized that resistant cells (i.e. JJN3) cultured in the absence of glucose revert to mitochondrial metabolism or autophagy to prevent cell death. The autophagy inhibitor chloroquine did not sensitize resistant cells cultured in the absence of glucose, ruling out autophagy as a source of compensatory metabolites. We next established that the mitochondrial substrates 2-methyl pyruvate or galactose rescue sensitive cells from toxicity caused by culture in the lack of glucose (Fig. 1A). These results suggest the potential for mitochondrial metabolism to rescue cell death ensuing upon inhibition of glycolysis. We therefore treated the resistant JJN3 cells with mitochondrial inhibitors metformin or rotenone to determine if we could elicit toxicity upon glucose-withdrawal. Indeed, resistant cells were sensitized to glucose-withdrawal upon treatment with complex 1 inhibitors metformin (Figure 1B) or rotenone. Metformin treatment alone had a minimal impact on the viability of resistant cells cultured in the presence of glucose (Fig. 1B). To simulate glucose-withdrawal we tested the ability of ritonavir (HIV protease inhibitor that has an off target inhibitory effect on GLUT4) to elicit toxicity in combination with metformin in the resistant cells. Our studies revealed that addition of ritonavir with metformin synergizes to elicit toxicity in resistant cells (Fig. 1C). This synergy was also observed in additional MM cell lines (KMS11 and U266). The biguanide metformin is the most commonly prescribed anti-hyperglycemic drug for the treatment of Type II diabetes. Epidemiologic studies have correlated metformin with a reduced risk of cancer in diabetics earning the drug recognition as a possible anti-neoplastic agent for various types of malignancies. This combinatorial regimen of ritonavir and metformin was not toxic in normal PBMC. The selective tumor specific synthetic lethality induced in ritonavir treated resistant cells upon metformin treatment is detected at doses that are clinically achievable with both compounds. We have initiated studies to evaluate this combination in mouse models of myeloma and patient samples. HIV patients chronically treated with ritonavir who exhibit diabetic symptoms have been treated with metformin indicating this combination treatment is well tolerated in humans. Our studies reveal a potent combinatorial regimen involving repurposed, FDA approved, ritonavir and metformin for the treatment of MM and potentially other glucose-driven malignancies. Disclosures: No relevant conflicts of interest to declare.

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