Sonic hedgehog-c-Jun N-terminal kinase-zinc finger protein Gli1 signaling protects against high glucose concentration-induced reactive oxygen species generation in human fibroblasts

Diabetes mellitus (DM) complications affect patients and cause varying damage. Skin ulcers exhibit difficulties in wound healing, and the regulatory basis for this remains unclear. High glucose concentration (HG) was utilized to mimic DM in cultured cells. Reverse transcription-quantitative polymerase chain reaction, western blotting and fluorescence dye analyses were performed to analyze the effects of hedgehog signaling in regulation of HG or diabetes in fibroblasts. HG-stress suppressed hedgehog-signaling gene expression, whereas the apoptosis and inflammatory response markers, Caspase-3 and plasminogen activator inhibitor-1 (PAI1), respectively, were induced. In addition, HG-stress inhibited the fibroblast proliferation rate. In parallel, treatment with Sonic hedgehog (Shh), an activator of hedgehog signaling, together with HG eliminated effects of HG on expression of hedgehog-signaling genes, Caspase-3 and PAI1, and rescued the cell proliferation rate in fibroblasts. In addition, Shh application activated c-Jun N-terminal kinase (JNK), which was inhibited by HG stress. sp600125, a JNK specific inhibitor, treatment inhibited the effect of Shh on fibroblast proliferation and hedgehog-signaling marker gene expression. Furthermore, zinc finger protein Gli1 (Gli1) overexpression partially eliminated the effect of HG and sp600125 on fibroblast proliferation, and reduced HG-induced ROS generation in fibroblasts. Together, these results indicate that HG stress inhibits hedgehog signaling, and Shh-JNK-Gli1 pathway positively regulates HG-induced damage on fibroblasts.