Regulation of pituitary adenylate cyclase-activating polypeptide gene transcription by TTF-1, a homeodomain-containing transcription factor.
Pituitary adenylate cyclase-activating polypeptide (PACAP) is an important hypophysiotrophic factor as well as a regulator for immune, reproductive, and neural tissues. We recently found that TTF-1, a homeodomain-containing transcription factor essential for the development of the fetal diencephalon, is postnatally expressed in the hypothalamic area and plays a transcription regulatory role for certain neurohormones. Based on the similarity of synthesis sites between PACAP and TTF-1 and, moreover, on the presence of conserved core TTF-1 binding motifs in the 5'-flanking region of the PACAP gene, we sought to uncover a regulatory role of TTF-1 in PACAP gene transcription. The TTF-1 homeodomain binds to six of the seven putative binding domains observed in the 5'-flanking region of the PACAP gene. In the C6 glioma cell-line, TTF-1 activates the PACAP promoter in a dose-dependent manner. This transactivation of PACAP by TTF-1 was totally removed when the core TTF-1 binding motif at -369 was deleted. RNase protection assays showed that TTF-1 and PACAP mRNAs have daily fluctuations in the rat hypothalamus. They both were at low levels during the day and high levels during the night. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased the PACAP mRNA level as well as TTF-1 protein content in the rat hypothalamus, suggesting that TTF-1 also regulates PACAP transcription in vivo. Moreover, the TTF-1 promoter was inhibited by molecular oscillators of CLOCK and BMAL-1. Taken together, these data suggest that TTF-1 plays an important regulatory role in the gene transcription for PACAP, which may be important for the generation of a daily rhythm of hypothalamic PACAP gene expression.
Kim
Min Sung
MS
Department of Biological Sciences, College of Natural Sciences, University of Ulsan, Ulsan 680-749, South Korea.
Hur
Min Kyu
MK
Son
Young June
YJ
Park
Jae-Il
JI
Chun
Sang Young
SY
D'Elia
Angela Valentina
AV
Damante
Giuseppe
G
Cho
Sehyung
S
Kim
Kyungjin
K
Lee
Byung Ju
BJ
D056930:ARNTL Transcription Factors; D020816:Amino Acid Motifs; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D015153:Blotting, Western; D056926:CLOCK Proteins; D004305:Dose-Response Relationship, Drug; D017353:Gene Deletion; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009479:Neuropeptides / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012260:Ribonucleases / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism; D000074482:Thyroid Nuclear Factor 1; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D008156:Luciferases; D009479:Neuropeptides; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012313:RNA; D012333:RNA, Messenger; D012260:Ribonucleases; D000074482:Thyroid Nuclear Factor 1; D015534:Trans-Activators; D014157:Transcription Factors; C495403:Adcyap1 protein, rat; C000614416:Nkx2-1 protein, rat; C538945:Clock protein, rat