Mitochondrial glutaminase enhances extracellular glutamate production in HIV-1-infected macrophages: linkage to HIV-1 associated dementia.
Dysfunction in mononuclear phagocyte (MP, macrophages and microglia) immunity is thought to play a significant role in the pathogenesis of HIV-1 associated dementia (HAD). In particular, elevated extracellular concentrations of the excitatory neurotransmitter glutamate, produced by MP as a consequence of viral infection and immune activation, can induce neuronal injury. To determine the mechanism by which MP-mediated neuronal injury occurs, the concentration and rates of production of extracellular glutamate were measured in human monocyte-derived macrophage (MDM) supernatants by reverse phase high-performance liquid chromatography (RP-HPLC). Measurements were taken of supernatants from MDM infected with multiple HIV-1 strains including ADA and DJV (macrophage tropic, M-tropic), and 89.6 (dual tropic). High levels of glutamate were produced by MDM infected with M-tropic viruses. AZT, an inhibitor of HIV-1 replication, inhibited glutamate generation, demonstrating a linkage between HIV-1 infection and enhanced glutamate production. In our culture system, glutamate production was dependent upon the presence of glutamine and was inhibited by 6-diazo-5-oxo-L-norleucine, a glutaminase inhibitor. Supernatants collected from HIV-1-infected MP generated more glutamate following glutamine addition than supernatants isolated from uninfected MP. These findings implicate the involvement of a glutamate-generating enzyme, such as phosphate-activated mitochondrial glutaminase (PMG) in MP-mediated glutamate production.
Zhao
Jianxing
J
Laboratory of Neurotoxicology at the Center for Neurovirology and Neurodegenerative Disorders Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5215, USA.
Lopez
Alicia L
AL
Erichsen
David
D
Herek
Shelley
S
Cotter
Robin L
RL
Curthoys
Norman P
NP
Zheng
Jialin
J
D015526:AIDS Dementia Complex / Q000378:metabolism* / Q000821:virology; D019380:Anti-HIV Agents / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000737:chemistry / Q000378:metabolism; D018698:Glutamic Acid / Q000032:analysis / Q000096:biosynthesis*; D005972:Glutaminase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism / Q000494:pharmacology; D015658:HIV Infections / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism* / Q000821:virology; D008928:Mitochondria / Q000201:enzymology*; D009000:Monocytes / Q000166:cytology; D012333:RNA, Messenger / Q000378:metabolism; D015215:Zidovudine / Q000494:pharmacology
D019380:Anti-HIV Agents; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D005973:Glutamine; D018698:Glutamic Acid; D015215:Zidovudine; D005972:Glutaminase