Role of fibronectin deposition in branching morphogenesis of MDCK cells
Research field:Kidney physiology
Authors:Jiang ST, Tang MJ
Address of presenting
author:		Department of Physiology, NCKU Medical College, Tainan, Taiwan
E-mail:mjtang1@mail.ncku.edu.tw
Phone:886-6-2353535ext5425
Fax:886-6-2362780
Text of abstract Introduction
MDCK epithelial cells grown in collagen gel in the presence of HGF form branching tubules. To delineate whether MDCK branching tubules construct the basal lamina, we characterized the composition of the extracellular matrix deposited by MDCK cells. The tubule-lining cells produced an apparently incomplete basal lamina containing a discontinuous laminin substratum. In addition, a thick layer of fibronectin surrounded the basal cell surface of branching tubule. In an attempt to delineate the role of fibronectin deposition in branching morphogenesis, we conducted this study.

Methods
MDCK cells cultured in collagen gel were employed. We first used arginine-glycine-aspartate peptides containing disintegrin rhodostomin to disturb the interactions between fibronectin and cell surface integrins. Furthermore, we established several stable transfectants expressing fibronectin antisense RNA to examine the role of fibronectin in branching morphogenesis directly.

Results
Rhodostomin inhibited the formation of branching tubules. The transfectants expressing fibronectin antisense RNA exhibited relatively lower levels of synthesized fibronectin and markedly diminshed growth rates of branching tubules than the control clone. An inhibition of branching morphogenesis induced by the overexpression of fibronectin antisense RNA was manifested by the decrease in cell growth rates and cell migration.

Conclusions
These results indicat that the deposition of fibronectin underlying the tubule-linin epithelium serves to enhance cell proliferation and migration, and hance facilitates the branching tubulogenesis of MDCK cells.

References
Jiang, ST et al. 1999. Kidney Int 56,92-103
Lin, HH et al. 1999. Kidney Int 55, 168-179
Jiang, ST et al. 2000. Kidney Int 57, (in press)

Keywords:fibronectin, branching tubulogenesis, MDCK cell, collagen gel, migration.

Created 2000-03-04