Regulation of intermediary metabolism by the PKCdelta signalosome in mitochondria.
PKCδ has emerged as a novel regulatory molecule of oxidative phosphorylation by targeting the pyruvate dehydrogenase complex (PDHC). We showed that activation of PKCδ leads to the dephosphorylation of pyruvate dehydrogenase kinase 2 (PDK2), thereby decreasing PDK2 activity and increasing PDH activity, accelerating oxygen consumption, and augmenting ATP synthesis. However, the molecular components that mediate PKCδ signaling in mitochondria have remained elusive so far. Here, we identify for the first time a functional complex, which includes cytochrome c as the upstream driver of PKCδ, and uses the adapter protein p66Shc as a platform with vitamin A (retinol) as a fourth partner. All four components are necessary for the activation of the PKCδ signal chain. Genetic ablation of any one of the three proteins, or retinol depletion, silences signaling. Furthermore, mutations that disrupt the interaction of cytochrome c with p66Shc, of p66Shc with PKCδ, or the deletion of the retinol-binding pocket on PKCδ, attenuate signaling. In cytochrome c-deficient cells, reintroduction of cytochrome c Fe(3+) protein restores PKCδ signaling. Taken together, these results indicate that oxidation of PKCδ is key to the activation of the pathway. The PKCδ/p66Shc/cytochrome c signalosome might have evolved to effect site-directed oxidation of zinc-finger structures of PKCδ, which harbor the activation centers and the vitamin A binding sites. Our findings define the molecular mechanisms underlying the signaling function of PKCδ in mitochondria.
Acin-Perez
Rebeca
R
Department of Neurology and Neurobiology, Weill-Cornell Medical School, New York, New York, USA.
Hoyos
Beatrice
B
Gong
Jianli
J
Vinogradov
Valerie
V
Fischman
Donald A
DA
Leitges
Michael
M
Borhan
Babak
B
Starkov
Anatoly
A
Manfredi
Giovanni
G
Hammerling
Ulrich
U
D000818:Animals; D002478:Cells, Cultured; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011767:Pyruvate Decarboxylase / Q000235:genetics / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D055765:Shc Signaling Adaptor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014801:Vitamin A / Q000235:genetics / Q000378:metabolism
D046912:Multiprotein Complexes; C000631435:Pdk2 protein, mouse; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014801:Vitamin A; D045304:Cytochromes c; D017346:Protein Serine-Threonine Kinases; D051745:Protein Kinase C-delta; D011767:Pyruvate Decarboxylase
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