Recently we discovered that the central metabolite α-ketoglutarate (α-KG) extends lifespan in C. elegans through inhibition of ATP synthase and TOR signaling. Unexpectedly, here we find that (R)-2-hydroxyglutarate ((R)-2HG), an oncometabolite that interferes with various α-KG mediated processes, extends worm lifespan similarly. (R)-2HG accumulates in human cancers carrying neomorphic mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes. We show that, like α-KG, both (R)-2HG and (S)-2HG bind and inhibit ATP synthase, and inhibit mTOR signaling; these effects are mirrored in IDH1 mutant cells, suggesting a growth suppressive function of (R)-2HG. Consistently, inhibition of ATP synthase by 2-HG or α-KG in glioblastoma cells is sufficient for growth arrest and tumor cell killing under conditions of glucose limitation, such as when ketone bodies (instead of glucose) are supplied for energy. These findings inform therapeutic strategies and open avenues for investigating the roles of 2-HG and metabolites in biology and disease.
gamma-Aminobutyric acid type A receptors containing the alpha1 subunit participate in the inhibition of the righting reflexes by isoflurane and enflurane. They are not, however, involved in the amnestic effect of isoflurane or immobilizing actions of inhaled agents.
Inhaled anesthetics are believed to produce anesthesia by their actions on ion channels. Because inhaled anesthetics robustly enhance GABA A receptor (GABA A -R) responses to GABA, these receptors are considered prime targets of anesthetic action. However, the importance of GABA A -Rs and individual GABA A -R subunits to specific anesthetic-induced behavioral effects in the intact animal is unknown. We hypothesized that inhaled anesthetics produce amnesia, as assessed by loss of fear conditioning, by acting on the forebrain GABA A -Rs that harbor the ␣1 subunit. To test this, we used global knockout mice that completely lack the ␣1 subunit and forebrain-specific, conditional knockout mice that lack the ␣1 subunit only in the hippocampus, cortex, and amygdala. Both knockout mice were 75 to 145% less sensitive to the amnestic effects of the inhaled anesthetic isoflurane. These results indicate that ␣1-containing GABA A -Rs in the hippocampus, amygdala, and/or cortex influence the amnestic effects of inhaled anesthetics and may be an important molecular target of the drug isoflurane.
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