| Research Abstract |
1. Mechanism of Gastric Epithelial Differentiation : In the avsence of mesenchymes, fetal rat gastric epithelial cells differentiated into surface mucous cells which express cathepsin E in primary culture, but when cocultured with mesenchymes, many (20-80%, depending on culture condition) pepsinogen-expressing cells appeared in the epithelial cells in culture. Parietal cells, however, never differentiated even when the cells were cultured under the kidney capsule of syngeneic hosts. Thus, we conclude that (1) surface mucous cells antonomously dfferentiate in the absence of any inducing factors, (2) mesenchymes are necessary for the differentiation of mucous neck and chief cells, and (3) other inducing factors (such as nervous stimuli) would be needed for the differentiation of parietal cells.
2. The role of Hepatocyte Growth Factor (HGF) in the Glandular Stomach : We have previously reported that HGF region-specifically stimulates gastro-intestinal epithelial growth in primary culture, and suffested that HGF mediates epithelial-mesenchymal interaction in the glandular stomach. Here we examined the expression of HGF and its receptor in the developing glandular stomach. Quantitative RT-PCR showed that expression of both HGF and its receptor was highest at 17-18 days of gestation when the epithelia are converted form stratified to simple glandular ones, indicating that HGF control the epithelial morphogenesis.
3. Activation of HGF by HGF activator (HGFA) : It is recently reported that HGF is secreted from mesenchyme as inactive pro-form, and activated by the action of HGFA.Examination of HGFA expression in developing gastro-intestinal tract revealed that HGFA is expressed only in epithelia but not in mesenchymes, and that HGFA is expressed highly in the colon, moderately in the small intestine and glandular stomach, little in forestomach.
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