CHARACTERIZATION OF MONOCLONAL-ANTIBODIES AGAINST TENASCIN-C - NO APPARENT EFFECT ON KIDNEY DEVELOPMENT IN-VITRO

Tenascin-C is an extracellular matrix glycoprotein found in embryonic mesenchyme. The precise biological function of tenascin-C is unknown, but different parts of the molecule have effects on cell adhesion and other cellular activities. We studied the expression and role of tenas cin-C in the embryonic mouse kidney. By Northern blots, no tenascin-C was detectable in uninduced mesenchyme from day 11 embryonic kidneys, but after 24 hours of in vitro culture both major splice variants of t enascin-C were detected. The larger variant was the predominant form. By in situ hybridization tenascin-C mRNA in 13-day old embryonic kidne ys was detected in the mesenchyme surrounding newly formed epithelial structures. In 17-day old embryonic kidneys, tenascin-C mRNA was detec ted in mesenchyme around the forming epithelial structures in the cort ex, and expression was also seen in mesenchyme surrounding the capsula r epithelium of glomeruli. In newborn kidneys, expression had shifted to the medulla but was still confined to mesenchymal areas. We have ch aracterized 6 new monoclonal antibodies against mouse tenascin-C, whic h all stain embryonic kidneys from different stages in a pattern consi stent with earlier reports and with the mRNA data. The binding sites o f the monoclonal antibodies on the tenascin-C molecule were mapped to discrete regions of tenascin-C. These six and five previously describe d antibodies against tenascin-C were tested in antibody perturbation e xperiments. Three of these have been shown by in vitro assays to pertu rb function of other cell types. Despite this, none of them inhibited development of mouse kidneys in organ culture, although they were test ed at 1 mg/ml. It raises the possibility that tenascin-C is not crucia l for kidney development. Alternatively, tenascin-C has more subtle fu nctions which could not be identified with the assays used here.