TRANSIENT EXPRESSION OF DP140, A PRODUCT OF THE DUCHENNE MUSCULAR-DYSTROPHY LOCUS, DURING KIDNEY TUBULOGENESIS

Dystroglycan is a cell surface complex which in muscle links the extra cellular matrix protein laminin-2 to the membrane associated cytoskele tal protein dystrophin. Recently it was found that dystroglycan is als o expressed in developing epithelial cells. Moreover, antibodies again st dystroglycan can perturb epithelial cell development in kidney orga n culture. Dystroglycan could provide a link between the basement memb rane and the intracellular space also in epithelial cells. However, th ere is no dystrophin in epithelial cells. By in situ hybridization her e we show prominent expression of a shorter isoform of dystrophin, Dp1 40, in embryonic kidney tubules. In addition, another isoform, Dp71, i s expressed by all studied embryonic epithelial cells. Both isoforms s hare the dystroglycan-binding region of dystrophin but lack the region known to bind to actin. Here we also characterized monoclonal antibod ies against different domains of dystrophin and used these to study th e distribution of Dp140 protein. In embryonic kidney tubules the dystr ophin antibody V1A4(2)A3 stained an intracellular antigen close to the basal cells. In contrast, no staining was observed in adult kidney. W e suggest that Dp140 is a structural component during kidney tubulogen esis but it may also be involved in signal transduction. (C) 1997 Acad emic Press.