cAMP-dependent phosphorylation of the nuclear encoded 18-kDa (IP) subunit of respiratory complex I and activation of the complex in serum-starved mouse fibroblast cultures.
A study is presented on the in vivo effect of elevated cAMP levels induced by cholera toxin on the phosphorylation of subunits of the mitochondrial respiratory complexes and their activities in Balb/c 3T3 mouse fibroblast cultures. Treatment of serum-starved fibroblasts with cholera toxin promoted serine phosphorylation in the 18-kDa subunit of complex I. Phosphorylation of the 18-kDa subunit, in response to cholera toxin treatment of fibroblasts, was accompanied by a 2-3-fold enhancement of the rotenone-sensitive endogenous respiration of fibroblasts, of the rotenone-sensitive NADH oxidase, and of the NADH:ubiquinone oxidoreductase activity of complex I. Direct exposure of fibroblasts to dibutyryl cAMP resulted in an equally potent stimulation of the NADH:ubiquinone oxidoreductase activity. Stimulation of complex I activity and respiration with NAD-linked substrates were also observed upon short incubation of isolated fibroblast mitoplasts with dibutyryl cAMP and ATP, which also promoted phosphorylation of the 18-kDa subunit. These observations document an extension of cAMP-mediated intracellular signal transduction to the regulation of cellular respiration.
Scacco
S
S
Department of Cell and Molecular Biology, Northwestern Medical School, Chicago, Illinois 60611, USA.
Vergari
R
R
Scarpulla
R C
RC
Technikova-Dobrova
Z
Z
Sardanelli
A
A
Lambo
R
R
Lorusso
V
V
Papa
S
S
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism*; D016895:Culture Media, Serum-Free; D000242:Cyclic AMP / Q000502:physiology*; D042967:Electron Transport Complex I; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D016895:Culture Media, Serum-Free; D046911:Macromolecular Substances; D003994:Bucladesine; D000242:Cyclic AMP; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I