Laminin-Cell Membrane Binding Proteins in Small Intestinal Epithelial Cells

Abstract

The regulation of cell proliferation, migration and differentiation under physiological conditions and in adaptional patterns is still not well understood. The interaction of intestinal epithelial cells with the basement membrane may influence cell adhesion and migration. One potential mechanism involves cell surface binding proteins, which induce the biological response when occupied by the basement membrane component. Immunoblotting experiments on isolated epithelial cell membranes from the normal duodenum of adult rats using specific antibodies revealed major laminin-binding cell membrane components with an M_r of 66–69 kD, similar to the putative laminin receptor described for other tissues. The specific interaction between these cell membrane binding proteins and the proteolytic fragment laminin P1 originating from the central core of the laminin molecule could be further demonstrated by slot blot assays. Immunohistological examinations of normal small intestinal mucosa revealed that the 67-kD laminin-binding proteins were present on the basolateral cell surfaces of epithelial cells lining the base of the crypt of Lieberkühn, but were absent from cells lining the mouth of the crypts or the villi.