Differential thyroid hormone-regulated XXXX thyrotropin beta gene expression detected by blot hybridization.

@entity35 @entity1375 @entity17001 @entity2036
In the @entity35 , there is a single @entity17001 -subunit gene represented by three exons interrupted by two introns. This gene contains two promoters which determines the synthesis of two mRNAs with 5'-untranslated regions that differ by 43 base pairs. This study evaluates the steady state levels of these @entity17001 mRNAs in various thyroidal states. Blot hybridization analyses of pituitary mRNA with synthetic probes designed to detect either one or both @entity17001 mRNAs were performed. One probe corresponds to 24 bases in the 5'-untranslated region of mRNA1 and a second corresponds to 25 @entity2036 in the coding region and detects both mRNA1 and mRNA2. These studies indicate the presence of @entity17001 mRNA species of indistinguishable size consistent with the presence of two @entity17001 mRNAs that contain slightly different 5'-untranslated regions. Comparison of pituitary RNA obtained from normal and @entity1375 @entity35 reveals that the shorter mRNA (mRNA2) is increased approximately 6- to 8-fold with @entity1375 while the abundance of the longer mRNA (mRNA1) is relatively unchanged. Treatment of either normal or @entity1375 animals with T3 decreases the abundance of mRNA2 while again mRNA1 is relatively unaffected. Thus, although both mRNAs are detected, only one mRNA is dramatically altered by thyroidal status. Therefore, the single @entity35 @entity17001 gene is transcribed into two mRNAs via the use of alternative promoters of which only one is markedly regulated by thyroid hormones.
