EXPRESSION OF OCI-5 GLYPICAN-3 DURING INTESTINAL MORPHOGENESIS - REGULATION BY CELL-SHAPE IN INTESTINAL EPITHELIAL-CELLS

OCI-5, the rat homologue of human glypican 3 (GPC3), is believed to be involved in morphogenesis and growth control during development. The finding that GPC3 is mutated in patients with the Simpson-Golabi-Behme l overgrowth syndrome is consistent with this idea. In this report, us ing RNA in situ hybridization, expression of OCI-5 in the developing i ntestine is detected in both endoderm-and mesenchyme-derived cells in a phased manner related to age and proximal/distal position. To invest igate the mechanism of its regulation during intestinal development, O CI-5 expression was studied in the primitive rat intestinal epithelial cell line IEC-18. The expression of the OCI-5 transcript is increased in IEC-18 cells at confluence, in low calcium media, and during spher oid culture, all conditions which result in the cells acquiring a more rounded cell shape. In contrast, cytoskeletal disruption with colchic ine causes cells to flatten and spread and abolishes both the confluen ce-and the low calcium-dependent induction of OCI-5. Treatment with va nadate, a phosphatase inhibitor, causes cells to acquire a spindle-sha ped morphology and prevents OCI-5 induction in all situations. Nuclear run-on analysis demonstrates that the rate of OCI-5 transcription is increased at confluence, in low calcium media, and during spheroid cul ture of IEC-18, and decreased by treatment of cells with colchicine. T ogether, these data suggest that OCI-5 expression is regulated in IEC- 18 by cell shape. The pattern of expression of OCI-5 in the developing intestine is consistent with it playing a role in epithelial-mesenchy mal interactions during intestinal morphogenesis, when cell shape chan ges are likely to occur. (C) 1997 Academic Press.