Salt-inducible kinase represses cAMP-dependent protein kinase-mediated activation of human cholesterol side chain cleavage cytochrome P450 promoter through the CREB basic leucine zipper domain.
Salt-inducible kinase (SIK), one of the serine/threonine protein kinases, was transiently expressed in Y1 cells during the early phase of the ACTH/cAMP-dependent protein kinase (PKA)-mediated signal transduction. The overexpression of SIK(N), the SIK's N-terminal kinase domain, repressed the expression of the side chain cleavage cytochrome P450 (CYP11A) gene. To elucidate the mechanism of the repression by SIK, several CYP11A promoter constructs were tested for the promoter activities in the presence of PKA and/or SIK(N). A cAMP-response element (CRE)-like sequence present in the promoter was shown to be responsible not only for the PKA-mediated promoter activation but also for the SIK(N)-mediated repression. When the Gal4 DNA binding domain-linked full-length CRE-binding protein (CREB) construct was cotransfected with Gal4 reporter gene, SIK(N) repressed the PKA-induced reporter gene expression. However, SIK(N) could not repress the PKA-induced reporter activity conferred by Gal4 DNA binding domain-linked basic leucine zipper (bZIP)-less CREB or bZIP-disrupted CREB. On the other hand, SIK(N) could repress the kinase-inducible domain-disrupted CREB-dependent reporter gene expression in the presence of PKA. The in vitro kinase reaction studies showed that SIK(N) could not phosphorylate CREB, and PKA failed to phosphorylate SIK(N). Taken together, these results suggest that SIK(N), cooperating with PKA, may act on the CREB's bZIP domain and repress the CREB-mediated transcriptional activation of the CYP11A gene.
Doi
Junko
J
Department of Molecular Physiological Chemistry, Osaka University Medical School H-1, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
Takemori
Hiroshi
H
Lin
Xing-zi
XZ
Horike
Nanao
N
Katoh
Yoshiko
Y
Okamoto
Mitsuhiro
M
D001483:Base Sequence; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics* / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D017931:DNA Primers; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D002786:Cholesterol Side-Chain Cleavage Enzyme; D017346:Protein Serine-Threonine Kinases; C120299:Sik1 protein, rat; D017868:Cyclic AMP-Dependent Protein Kinases