Inducible cAMP early repressor can modulate tyrosine hydroxylase gene expression after stimulation of cAMP synthesis.
Members of the CREB/CREM/ATF family of transcription factors either enhance or repress transcription after binding to the cAMP response elements (CREs) of numerous genes. The rat gene for tyrosine hydroxylase (TH) bears a canonical CRE, at base pairs -38 through -45 from the transcription initiation site, that is essential for basal and cAMP-stimulated transcription (Kim, K.-S., Lee, M. K., Carroll, J., and Joh, T. H. (1993) J. Biol. Chem. 268, 15689-15695; Lazaroff, M., Patankar, S., Yoon, S. O., and Chikaraishi, D. M. (1995) J. Biol. Chem. 270, 21579-21589). The current study identifies CRE-binding proteins induced in pharmacological paradigms characterized by TH activation. PC12- and rat adrenal gland-derived nuclear proteins retarded a TH-CRE oligonucleotide in gel mobility shift assays with virtually identical patterns. These differed substantially from patterns exhibited by extracts from locus ceruleus or from neuroblastoma (SK-N-BE()C) and locus ceruleus-derived (CATH.a) cell lines. Forskolin stimulation of PC12 cells and reserpine treatment of rats increased, in nuclear extracts derived from cells and adrenal glands, respectively, the amount of a fast moving CRE/protein complex that was supershifted by an anti-CREM antibody. Subsequent Western, Northern, and polymerase chain reaction analyses indicated that a specific member of the CREM family, the inducible cAMP early repressor (ICER), was strongly induced in both systems. Cotransfection of PC12 cells with TH2400CAT plasmid and the expression vector pCMV-ICER-Ib demonstrated that ICER efficiently represses the transcriptional activity of the TH gene promoter. In addition, PKA-stimulated transcriptional activity of the promoter was effectively suppressed by ICER. These results suggest that ICER can modulate cAMP-stimulated transcription of the TH gene and provide a model accounting for rapid reversal of increased TH transcription following elevations in cAMP.
Tinti
C
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Laboratory of Molecular Neurobiology, Cornell University Medical College at The Burke Medical Research Institute, White Plains, New York 10605, USA.
Conti
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B
Cubells
J F
JF
Kim
K S
KS
Baker
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H
Joh
T H
TH
D051696:Activating Transcription Factors; D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D001798:Blood Proteins / Q000096:biosynthesis / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D051786:Cyclic AMP Response Element Modulator; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis / Q000378:metabolism*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008125:Locus Coeruleus; D008297:Male; D009447:Neuroblastoma; D016716:PC12 Cells; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins / Q000096:biosynthesis / Q000378:metabolism; D012110:Reserpine / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014162:Transfection; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
D051696:Activating Transcription Factors; D001798:Blood Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051786:Cyclic AMP Response Element Modulator; D012110:Reserpine; D014446:Tyrosine 3-Monooxygenase; D015500:Chloramphenicol O-Acetyltransferase