RESUMO
Zymogenic cells (ZCs), acid-producing parietal cells (PCs), and mucus-secreting pit cells are the principal epithelial lineages in the stomachs of adult mice and humans. Each lineage is derived from the multipotent gastric stem cell and undergoes perpetual renewal within discrete mucosal invaginations (gastric units). In this report, we analyze the molecular features of ZCs and their contributions to gastric epithelial homeostasis. GeneChip analysis yielded a dataset of 57 mRNAs encoding known proteins and 14 ESTs enriched in adult mouse ZCs. This dataset, obtained from comparisons of cellular populations purified by counterflow elutriation and lectin panning, was validated by real-time quantitative reverse transcription-PCR studies of the in vivo expression of selected genes using cells harvested from different regions of gastric units by laser capture microdissection. ZC-enriched mRNAs include regulators of angiogenesis (e.g. platelet-derived growth factors A and B). Because PCs are enriched in transcripts encoding other angiogenic factors (e.g. Vegfb), the contributions of these two lineages to vascular development was examined by performing quantitative three-dimensional imaging of the capillary networks that surround gastric units in two types of mice. In normal adult gnotobiotic FVB/N animals, network density is on average 2-fold higher in ZC- and PC-containing units located in the proximal (corpus) region of the stomach compared with units positioned in the distal (antral) region that lack these lineages (p < 0.01). Gnotobiotic transgenic mice with an engineered ablation of all ZCs and PCs have a 2-fold reduction in capillary network density in their corpus region gastric units compared with the corpus units of normal littermates (p < 0.01). These results support an emerging theme that angiogenesis in the adult mouse gut is modulated by cross-talk between its epithelial lineages and the underlying mesenchyme.
