Differential regulation of respiratory chain subunits by a CREB-dependent signal transduction pathway. Role of cyclic AMP in cytochrome c and COXIV gene expression.
In vertebrate organisms, the molecular mechanisms by which extracellular signals regulate mitochondrial function and biogenesis are largely unknown. We have previously identified multiple cis-acting elements in both cytochrome c and cytochrome oxidase subunit IV (COXIV) genes that are likely targets for the regulated expression of respiratory chain components. We now demonstrate that cytochrome c but not COXIV mRNA is induced by cAMP through a mechanism involving transcriptional activation. Maximal induction occurs within 3 h and does not require de novo protein synthesis. The differential response of these genes is mediated by two distinct cAMP response elements (CREs) in the cytochrome c promoter region. Both elements function independently to drive cAMP-dependent expression from a heterologous promoter and within the proper cytochrome c promoter context. In addition, the binding properties of both elements to nuclear factors were characterized by competition DNase I footprinting, methylation interference footprinting, site-directed mutagenesis, and UV-induced DNA-protein cross-linking. The results are all consistent with the specific recognition of both CREs by CRE binding protein (CREB). A highly purified preparation of recombinant CREB formed a specific complex with each of the cytochrome c CREs identical to that formed with a crude nuclear fraction. In addition, the trans-activation of cytochrome c gene expression by recombinant CREB and protein kinase A in transfected cells was completely dependent on functional CREs within the promoter. These results establish that respiratory chain gene expression can be regulated directly by cAMP through a CREB-dependent signal transduction pathway.
Gopalakrishnan
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L
Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
Scarpulla
R C
RC
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D003574:Cytochrome c Group / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D004790:Enzyme Induction; D015870:Gene Expression; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D015533:Transcriptional Activation
D017362:Cyclic AMP Response Element-Binding Protein; D003574:Cytochrome c Group; D010446:Peptide Fragments; D012333:RNA, Messenger; D004247:DNA; D000242:Cyclic AMP; D003576:Electron Transport Complex IV