| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
It has been postulated that, in the TSH beta promoter, a DMA sequence immediately down stream to the transcription start site may have critical role to mediate the negative regulation driven by thyroid hormone (T3) and its receptor (TR) (Chin, W. W. et al.(1993) Recent. Prog.Horm. Res. 48 : 393-414). We designated this region as Negative Regulatory Element (NRE) and reported that histone deacetylase (HDAC) 2 may be recruited by TR in a T3 dependent manner (Sasaki S, et al. (1999) EMBO J. 18(19):5389-5398). The inspection of NRE sequence predicted the possibility that high mobility group (HMG) proteins may bind NRE and modulate the function of T3 bound TR Using gel shift assay, we confirmed that HMG protein really bind to NRE in T alpha T1 cell which has been established recently as thyrotroph cell line. In addition, we identified a HMG protein, Sox11, using RT-PCR with degenerated primers. The existence of Sox11 was confirmed by the gel sift assay with specific antibody. Furthermore, we established an experimental system in which we can detect the negative regulation of TSH beta gene in monkey kidney cell line, CV 1. The establishment of this experimental system enabled us to analyze the precise mechanisms of the negative regulation of TSH beta gene much easier than before. Using this system, we found that the overexpression of Sox11 eliminated the negative regulation of TSH beta gene by T3 and TR. Surprisingly, however, this system revealed that the negative regulation was maintained even after the destruction of NRE. Further studies suggested the possibility that the transcription factors, Pit1 and GATA2, may not only be critical to activate TSH beta promoter but also the main target of negative regulation by liganded TR.
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