Affordable Access

Publisher Website

The Deletion of Transforming Growth Factor-β-Induced Myofibroblasts Depends on Growth Conditions and Actin Organization

Authors
Journal
American Journal Of Pathology
0002-9440
Publisher
Elsevier
Publication Date
Volume
155
Issue
6
Identifiers
DOI: 10.1016/s0002-9440(10)65527-7
Keywords
  • Tgf-β Induction Of Microfibroblasts
Disciplines
  • Biology

Abstract

Myofibroblasts are important but transient mediators of normal wound contraction and are characterized phenotypically by their high levels of α-smooth-muscle actin (SMA). During wound maturation, these cells disappear. We have examined the mechanisms that lead to myofibroblast deletion in a fibroblast culture model. Transforming growth factor-β (TGF-β) was used to increase SMA content in gingival fibroblasts (three- to sixfold). After replating TGF-β-induced cells at low density with serum, there was a fivefold decrease in SMA protein content, SMA protein synthesis, and SMA mRNA as cells proliferated. These reductions were due to reduced SMA mRNA stability. For TGF-β-induced cells plated at high density without serum (ie, quiescent conditions), protein content was reduced by only 20% over 12 days. TGF-β protected SMA-positive cells against apoptosis in serum-free cultures. Those cells that were protected against apoptosis exhibited well-developed stress fibers enriched in SMA. We conclude that, in quiescent myofibroblasts, SMA protein turnover is slow, and cells are long-lived. In proliferative conditions SMA protein and mRNA turn over quickly, and the myofibroblast phenotype dissipates. The reduced apoptosis of myofibroblasts in quiescent conditions is due in part to the organization of SMA into stress fibers.

There are no comments yet on this publication. Be the first to share your thoughts.