TGF-β1 mediates 70-kDa heat shock protein induction due to ultraviolet irradiation in human skin fibroblasts

Ultraviolet B (UVB) alters the expression of heat shock protein 70 (HSP70) in cultured fibroblast cells derived from human skin. However, the nature of the signal transduction pathway remains to be determined. Transforming growth factor-beta (TGF-beta) has a large variety of biological functions, including cell growth control, modulation of inflammation and immunoregulation. In this study, we examined whether TGF-beta is associated with the process of HSP70 expression induced by UVB irradiation. The constitutive expression of TGF-beta 1 mRNA and HSP70 expression in human skin fibroblast cells were detected using reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The results indicate that: (1) UVB irradiation stimulates HSP70 expression in a dose- and time-dependent manner, (2) constitutive expression of TGF-beta 1 mRNA is detected after UVB irradiation, the level of which peaks at 4 h after 10 mJ cm(-2) of UVB irradiation, (3) HSP70 expression is induced by TGF-beta 1 without UVB irradiation, and (4) HSP70 expression induction with UVB irradiation is inhibited by preincubation of the cells with the anti-TGF-beta type II receptor antibody. Our results suggest that HSP70 expression induced by UVB involves the autocrine signalling of TGF-beta production.