Role of Heat Shock Protein 47 in Transdifferentiation of Human Tenon's Fibroblasts to Myofibroblasts

Background: Heat shock protein 47 (Hsp47) is a well-known molecular chaperone in collagen synthesis and maturation. The aim of this study is to investigate its putative role in the transdifferentiation of Tenon's fibroblasts to myofibroblasts. Methods: Primary cultured human Tenon's fibroblasts were exposed to transforming growth factor-beta 1 (TGF-beta 1) for up to 48 hours. The mRNA levels of Hsp47 and a smooth muscle actin (aSMA) were determined by quantitative real time RT-PCR. After delivery of small interfering RNA (siRNA) molecules targeting Hsp47 into the cells, the expression of Hsp47 and aSMA proteins was determined by western immunoblotting. Results: TGF-beta 1 increased the mRNA expressions of both Hsp47 and aSMA in human Tenon's fibroblasts, as determined by quantitative real time RT-PCR. However, it induced the protein expression of only aSMA but not Hsp47, as determined by western immunoblots. When siRNAs specific for Hsp47 were introduced into those cells, the TGF-beta 1-induced expression of aSMA was significantly attenuated on western immunoblots; after 48 hours of exposure to TGF-beta 1, the relative densities of immunobands were 11.58 for the TGF-beta 1 only group and 2.75 for the siRNA treatment group, compared with the no treatment control group (p < 0.001). Conclusions: Our data suggest that Hsp47 may be related to the TGF-beta 1-induced transdifferentiation of human Tenon's fibroblasts to myofibroblasts.