- Identification of TPA - Response Element (TRE) in the Rat Thyrotropin - Releasing Hormone (TRH) Gene.
-
Woon Won Jung, Young Kil Choi, In Myung Yang, Kwang Sik Seo, Jeong Taek Woo, Sung Woon Kim, Jin Woo Kim, Young Seol Kim, Young Kil Choi, Seung Joon Park
-
J Korean Endocr Soc. 1994;10(3):200-213. Published online November 6, 2019
-
-
-
 Abstract
 PDF
- There are two potential imperfect copies of the TRE consensus sequence between -47 and -113bp position on 5' upstream of the rat TRH gene. The upstream element(5'-TGcCgTCA-3') is located between -101 bp and -94 bp, and the downstream element(5'-TGAcCTCA-3') is positioned between -59bp and -52bp relative to the stranscription start site. The downstream variant differs from the consensus sequence of TRE(AP-1)(5'-TGACTCA-3'), by addition of one nucleotide. As there is no direct evidence that TPA stimulates the transcription of rat TRH gene, and there is no study to define TRE of the rat TRH gene, we performed Northern blot assay, transient gene expression study and gel shift assay to identify TRE. TRH mRNA expression of CA77 cells was increased about 2-2.5 fold 30 min after TPA stimulation. When PC12 cells were stimulated by TPA after transfection of the plasmids containing serially deleted 5'upstream of the rat TRH gene ligated to luciferase gene, the transcription of luciferase gene was increased more than 3.2 fold with the plasmid pTRH(-600/84)Luc and pTRH(-113/84)Luc. However, the transcriptional activation was remarkably decreased less than 1.6 fold with pTRH(-77/84)Luc, pTRH(-47/84)Luc, and pTRH(6/84)Luc. The plasmid containing the sequence of -108/-79 did not show any significant activation in both of basal and TPA-stimulated transcription, whereas the plasmid containing the sequence of -70/-41 showed a slight but significant transcriptional activation by TPA. The plasmid containing the sequence of -114/-47 showed remarkable increase in basal transcription and TPA induced transcription of luciferase gene. Gel shift assay revealed that the oligonucleotides spanning -108/-79 and -70/-41 bound to c-Jun, whereas the oligonucleotides spanning -40/1, 1/30, 31/60, 61/84 did not bind. The oligonucleotide of -70/-41 bound to c-Jun with higher affinity compared to that of -108/-79. The one base pair mutant of -70/-41(deletion of C from the middle of TGACCTCA) bound to c-Jun with higher affinity, whereas the one base pair replaced mutant(C to G) bound with lower affinity compared to the wild type oligonucleotide. These results suggest that the rat TRH gene expression is stimulated by TPA to a smaller degree compared to that of other genes, and the two elements act cooperatively as TRE. The downstream TRE variant is mainly responsible for TPA response and c-Jun binding, and the upstream variant play a permissive role for transcriptional activation. The addition of one nucleotide C in the downstream element may be responsible for the relatively lower response of the rat TRH gene to TPA.
- Characterization of Cyclic AMP Response Element (CRE) in the Promoter of the Rat Thyrotropin Releasing Hormone (TRH) Gene.
-
Woon Won Jung, In Myung Yang, Kwang Sik Seo, Seok Won Jung
-
J Korean Endocr Soc. 1994;9(3):190-199. Published online November 6, 2019
-
-
-
Abstract
PDF
- We investigated whether the two variant elements of CRE(TGcCGTCA[5'CRE], TGACcTCA[3'CRE]) in the 5'flanking region of the rat TRH gene, which are different from the CRE consensus sequence(5'-TGACGTCA-3') by one base pair, are responsive to cAMP, and whether the one base pair difference is responsible for the degree of cAMP responsiveness of the gene. When CA 77 cells were stimulated with forskolin and isobutylmethylxanthine for 4 hours, the level of TRH mRNA was increased by only two fold. The transient gene expression study using serial 5'deletion of the TRH gene in PC12 cells showed that the region between-113 and-77, which includes 5'CRE, was crucial for the cAMP resonsiveness. When the plasmid, which contains the 30 bp oligonucleotide including either 5'CRE or 3'CRE ligated to the enhancerless RSV promoter, was transfected into PC12 cells, it did not significantly affect not only the basal transcription but cAMP responsiveness. The 65 bp oligonucleotide including both 5'CRE and 3'CRE, however, increased both of the basal transcription and cAMP-stimulated transcription by 2-3 fold. When the sequence of 5'CRE was converted to that of the CRE consensus by replacing one base pair, the cAMP responsiveness was increased by two fold although the basal transcription was not increased. The one base pair mutant of 3'CRE increased both of the basal and cAMP-stimulated transcription by 3-4 fold. These results suggest that there are the two variant CREs in rat TRH gene, which are relatively weak CRE compared to the CREs of other neuropeptide genes and cooperative for the activation of both the basal and cAMP-stimulated transcription. The one base pair difference of the variant CREs from the CRE consensus sequence is responsible for the weak responsiveness to cAMP.
|
KES
