Control of AKR fibroblast phenotype by fibronectin: regulation of cell-surface fibronectin binding receptor by fibronectin

J Cell Physiol. 1994 Dec;161(3):470-82. doi: 10.1002/jcp.1041610310.

Abstract

Results of previous studies show that the expression of fibronectin and its cell-surface fibronectin binding receptor is coregulated in 3-methylchloranthrene transformation of normal AKR-2B cells to form AKR-MCA cells and in N,N,-dimethylformamide (DMF) induction of differentiation of transformed AKR-MCA cells (1990, J. Cell. Physiol., 143:445). In this study, we tested the coregulation hypothesis by transfection experiments using an antisense fibronectin expression vector. We determined the effect of antisense fibronectin RNA expression on untransformed AKR-2B cells, and on the responses of transformed AKR-MCA cells to DMF treatment. Expression of antisense fibronectin RNA in AKR-2B cells down-modulated fibronectin production, reduced adhesion to extracellular fibronectin, and altered cellular morphology. Saturation binding and Scatchard analyses using radiolabelled fibronectin revealed a concurrent down-modulation of cell-surface fibronectin binding sites, but the binding affinity of the receptor for the ligand was not affected. Immunoblotting and immunostaining revealed down-modulation of the expression of alpha 5 beta 1 integrins. Expression of antisense fibronectin RNA in AKR-MCA cells down-modulated the ability of DMF to restore normal fibronectin production, cell-surface fibronectin binding receptor, adhesion to extracellular fibronectin, and cellular morphology. These studies show that both fibronectin and its cell-surface fibronectin binding receptor were tightly regulated during transformation and induction of differentiation in these cells, that the ligand and its cell-surface fibronectin binding receptor worked together to bring about phenotypic changes, and that fibronectin production regulated the expression of its cell-surface fibronectin binding receptor.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Adhesion
  • Cell Division
  • Cell Size
  • Down-Regulation
  • Fibroblasts / cytology*
  • Fibronectins / physiology*
  • Gene Expression
  • Mice
  • Mice, Inbred AKR
  • RNA, Antisense
  • RNA, Messenger / genetics
  • Receptors, Fibronectin / metabolism*

Substances

  • Fibronectins
  • RNA, Antisense
  • RNA, Messenger
  • Receptors, Fibronectin