Adenovirus-mediated transfer of a truncated transforming growth factor- β (TGF-β) type II receptor completely and specifically abolishes diverse signaling by TGF-β in vascular wall cells in primary culture

Abstract

We constructed an adenoviral vector expressing a mutated human type II transforming growth factor-β (TGF-β) receptor that was truncated of its kinase domain (AdexCATβTR) and examined whether this truncated receptor could abolish signaling by TGF-β using arterial endothelial cells and smooth muscle cells, as well as a lung epithelial cell line (Mv1Lu). Infection of cells with AdexCATβTR induced expression of the truncated receptor, the amount of which would be excessive compared with those of both full-length type I and type II receptors, as assessed by levels of their mRNAs. The antiproliferative effect of TGF-β was completely eliminated in both endothelial cells and Mv1Lu that were infected with AdexCATβTR. The transcriptional activation by TGF-β of plasminogen activator inhibitor-1 and fibronectin was entirely suppressed. Abrogation of the TGF-β-enhanced production of type I collagen in infected smooth muscle cells was confirmed by immunocytostaining and by [14C]proline incorporation in a quantitative manner. Mitogenic response to other growth factors remained unaffected in infected cells. Our data demonstrated that the adenovirus-mediated transfer of a truncated type II TGF-β receptor completely and specifically abolishes the diverse effects of TGF-β as a dominant-negative mutation, supporting the hypothesis that both the type I and type II receptors are required for all signaling by TGF-β. This method may facilitate the clarification of the role of TGF-β both in vitro and in vivo.