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

We constructed an adenoviral vector expressing a mutated human type II transforming growth factor-beta (TGF-beta) receptor that was truncated of its kinase domain (AdexCAT beta TR) and examined whether this truncated receptor could abolish signaling by TGF-beta using arterial endothelial cells and smooth muscle cells, as well as a lung epithelial cell line (Mv1Lu). Infection of cells with AdexCAT beta TR 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-beta was completely eliminated in both endothelial cells and Mv1Lu that were infected with AdexCAT beta TR, The transcriptional activation by TGF-beta of plasminogen activator inhibitor-1 and fibronectin was entirely suppressed. Abrogation of the TGF-beta-enhanced production of type I collagen in infected smooth muscle cells was confirmed by immunocytostaining and by [C-14]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-beta receptor completely and specifically abolishes the diverse effects of TGF-beta as a dominant-negative mutation, supporting the hypothesis that both the type I and type II receptors are required for all signaling by TGF-beta. This method may facilitate the clarification of the role of TGF-beta both in vitro and in vivo.