| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2003: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
It is believed that growth hormone(GH) and prolactin(PRL) are derived from a common ancestral gene, whereas each hormone is secreted from distinct cell type in the anterior pituitary gland in mammals. It is also widely accepted that GH and PRL cells are differentiate from the common precursor cells since these cell types commonly express pituitary specific transcription factor, pit-1. The mechanisms responsible for the differentiation of these two cell types are, however, still obscure. In this study, I tried to examine whether these two cell types differentiate from precursors independently or one of them differentiate first and become the mother cells of another cell type.
The 5'-upstream region of GH, PRL, and pit-1 that required for the cell type specific expression of the reporter gene were PCR amplified and the reporter plasmids were constructed that express the fluolescent protein, CFP, under the direction of these promoters. These plasmids successfully labeled GH or PRL cells with CFP when introduced into isolated pituitary cells from adult male rat. However, the expression of CFP was extremely low when introduced into fetal pituitary gland, probably due to the weak promoter activity in the fetal pituitary cells. These results indicate that further enhancement of the sensitivity of the detection system is required for the application of this method to the study of cell type determination that occurs in the fetal pituitary gland.
I also established the PCR-technology for the detection of the hormone mRNA expression in the single pituitary cells. As a consequence, it is revealed that nearly 50% of GH cells also express PRL mRNA, suggesting that there are an unexpectedly large number of cells that express multiple mRNAs. It is considered to be of importance to establish the regulatory mechanisms for the expression of GH and PRL gene in the single cells.
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