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c‐ Jun N‐terminal kinase regulates mitochondrial bioenergetics by modulating pyruvate dehydrogenase activity in primary cortical neurons
Author(s) -
Zhou Qiongqiong,
Lam Philip Y.,
Han Derick,
Cadenas Enrique
Publication year - 2008
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04957.x
Subject(s) - pyruvate dehydrogenase complex , pyruvate dehydrogenase kinase , citric acid cycle , pyruvate dehydrogenase phosphatase , pyruvate decarboxylation , biochemistry , mitochondrion , biology , pkm2 , microbiology and biotechnology , phosphorylation , kinase , pyruvate kinase , glycolysis , metabolism , enzyme
This study examines the role of c‐ jun N‐terminal kinase (JNK) in mitochondrial signaling and bioenergetics in primary cortical neurons and isolated rat brain mitochondria. Exposure of neurons to either anisomycin (an activator of JNK/p38 mitogen‐activated protein kinases) or H 2 O 2 resulted in activation (phosphorylation) of JNK (mostly p46 JNK1 ) and its translocation to mitochondria. Experiments with mitochondria isolated from either rat brain or primary cortical neurons and incubated with proteinase K revealed that phosphorylated JNK was associated with the outer mitochondrial membrane; this association resulted in the phosphorylation of the E 1α subunit of pyruvate dehydrogenase, a key enzyme that catalyzes the oxidative decarboxylation of pyruvate and that links two major metabolic pathways: glycolysis and the tricarboxylic acid cycle. JNK‐mediated phosphorylation of pyruvate dehydrogenase was not observed in experiments carried out with mitoplasts, thus suggesting the requirement of intact, functional mitochondria for this effect. JNK‐mediated phosphorylation of pyruvate dehydrogenase was associated with a decline in its activity and, consequently, a shift to anaerobic pyruvate metabolism: the latter was confirmed by increased accumulation of lactic acid and decreased overall energy production (ATP levels). Pyruvate dehydrogenase appears to be a specific phosphorylation target for JNK, for other kinases, such as protein kinase A and protein kinase C did not elicit pyruvate dehydrogenase phosphorylation and did not decrease the activity of the complex. These results suggest that JNK mediates a signaling pathway that regulates metabolic functions in mitochondria as part of a network that coordinates cytosolic and mitochondrial processes relevant for cell function.