Figure 4.

mutTGFβ3-activated intracellular Smad2/3 signaling is increased in the presence of integrin. (a) Murine dermal fibroblast (MDF) cells stably expressing a single copy of the Smad2/3 responsive element CAGA₍₁₂₎ and minimal promoter driving luciferase were transduced with Lnt-mutTGFβ3 or Lnt-GFP (multiplicity of infection = 10). These cells were cocultured with 293T cells overexpressing β3 integrin 293Tβ3 or 293T parental cells were. Overexpression of integrin could increase activation of mutTGFβ3 in an RGD-specific manner. The green jagged cells represent the reporter MDF/CAGA₍₁₂₎-Luc cells, the circular cells represent integrin overexpressing (top panel) or their parental line (bottom panel). The blue squares represent activated TGFβ3, the open squares represent inactive latency-associated peptide (LAP)-associated TGFβ3. LAP association with integrin activates a tethered form of TGFβ3. (b) Cocultures were grown for 48 hours then lysed and luciferase activity quantified. There was a significant increase in luciferase activity in the presence β3 integrin (n = 4 ± SEM). mutTGFβ3, mutant transforming growth factor β3.