title: The mitochondrial uncoupler DNP triggers brain cell mTOR signaling network reprogramming and CREB pathway up-regulation.
abstract: Mitochondrial metabolism is highly responsive to nutrient availability and ongoing activity in neuronal circuits. The molecular mechanisms by which brain cells respond to an increase in cellular energy expenditure are largely unknown. Mild mitochondrial uncoupling enhances cellular energy expenditure in mitochondria and can be induced with 2,4-dinitrophenol (DNP), a proton ionophore previously used for weight loss. We found that DNP treatment reduces mitochondrial membrane potential, increases intracellular Ca(2+) levels and reduces oxidative stress in cerebral cortical neurons. Gene expression profiling of the cerebral cortex of DNP-treated mice revealed reprogramming of signaling cascades that included suppression of the mammalian target of rapamycin (mTOR) and insulin--PI3K - MAPK pathways, and up-regulation of tuberous sclerosis complex 2, a negative regulator of mTOR. Genes encoding proteins involved in autophagy processes were up-regulated in response to DNP. CREB (cAMP-response element-binding protein) signaling, Arc and brain-derived neurotrophic factor, which play important roles in synaptic plasticity and adaptive cellular stress responses, were up-regulated in response to DNP, and DNP-treated mice exhibited improved performance in a test of learning and memory. Immunoblot analysis verified that key DNP-induced changes in gene expression resulted in corresponding changes at the protein level. Our findings suggest that mild mitochondrial uncoupling triggers an integrated signaling response in brain cells characterized by reprogramming of mTOR and insulin signaling, and up-regulation of pathways involved in adaptive stress responses, molecular waste disposal, and synaptic plasticity. Physiological bioenergetic challenges such as exercise and fasting can enhance neuroplasticity and protect neurons against injury and neurodegeneration. Here, we show that the mitochondrial uncoupling agent 2,4-dinitrophenol (DNP) elicits adaptive signaling responses in the cerebral cortex involving activation of Ca(2+) -CREB and autophagy pathways, and inhibition of mTOR and insulin signaling pathways. The molecular reprogramming induced by DNP, which is similar to that of exercise and fasting, is associated with improved learning and memory, suggesting potential therapeutic applications for DNP.
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
authors.affiliation: Gene Expression and Genomics Unit, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Gharavi
authors.affiliation: Department of Pharmacy, College of Pharmacy, Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Busan, Korea.
authors.forename: Hee Ra
authors.initials: HR
authors.lastname: Park
authors.affiliation: Department of Pharmacy, College of Pharmacy, Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Busan, Korea.
authors.forename: Jaewon
authors.initials: J
authors.lastname: Lee
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Sana
authors.initials: S
authors.lastname: Siddiqui
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Telljohann
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Nassar
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Roy G
authors.initials: RG
authors.lastname: Cutler
authors.affiliation: Gene Expression and Genomics Unit, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Becker
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland, USA.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Mattson
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D058570:TOR Serine-Threonine Kinases / Q000096:biosynthesis*; D014475:Uncoupling Agents / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D014475:Uncoupling Agents; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D019297:2,4-Dinitrophenol
keywords: 2,4-dinitrophenol; BDNF; CREB; autophagy; insulin signaling; mTOR