| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Enteropeptidase (Enterokinase EC 3, 4, 21,9) is considered to be a key enzyme in the intestinal protein digestion. Because of its medical and physiological importance, we have cloned rat enteropeptidase cDNA and analyzed the expression of the enzyme both in the protein and gene level during the development of the intestine. In addition we also analyzed the effect of hydrocortisone on enteropeptidase expression.
Analysis of the RNAs by RT-PCR revealed that the mRNA expression is observed mainly in the duodenum and also a low level of the mRNA expression in the other parts of the small intestine, i.e. jejunum and ileum. Immunohistochemical analysis confirmed the above-mentioned results. In the duodenal epithelia, a gradient in the enzyme expression from the villous tip to the crypt is observed immunohistochemically ; the expression was higher in the former (i.e. microvilli) than the latter (i.e. crypt). Analysis of the RNA from the separated intestinal crypt and villous portions also revealed essentially the same result in the gene level. In addition, the gene expression was observed in 19-day fetal rat duodenum, and it increased with the procession of morphological maturation of the duodenal mucosa. And the protien expressiotx was also observed shortly after the gene expression. Since its mRNA and the enzyme activity revealed the same distribution, rat enteropeptidase expression was considered to be regulated mainly at the level of gene transcription. And the hydrocortisone regulated its expression directly, probably through the steroid receptors. These results clearly indicate that the biosynthesis of rat enteropeptidase is strictly regulated spatio-temporally and also under the influence of hormonal factors including hydrocortisone.
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