Sonic hedgehog: its expression in a healing cornea and its role in neovascularization

[摘要] Purpose: To examine if sonic hedgehog(Shh) is involved in tissue neovascularization by using cell cultureand an animal cornea. Methods: The effects of exogenous Shh(5.0 nM), vascular endothelial growth factor (VEGF), and/or a Shhsignal inhibitor (2.5 or 10.0 μM cyclopamine) on vessel-like tubeformation of vascular endothelial cells were examined in vitro. Theeffects of Shh on the expression of angiogenic cytokines in culturedcell types were examined in cultured cells. The expression of Shh andits receptor, Patched 1 (Ptc), was examined in a vascularized mousecornea during post-alkali burn healing. The effect of exogenous Shh oncorneal neovascularization in vivo was assayed using a rat corneasystem. The effect of a topical injection of cyclopamine oncauterization-induced corneal neovascularization was then studied. Results: Adding Shh promoted vessel-liketube formation of vascular endothelial cells. This effect wascounteracted by addition of cyclopamine. Cyclopamine did not affectVEGF-enhanced tube formation. Shh did not affect the expression levelsof angiogenic cytokines in cultured cell types. mRNA and proteinexpression levels of Shh and Ptc were under the detection limit in anuninjured cornea, but Shh but not Ptc was upregulated in a healing,alkali-burned, vascularized cornea. Exogenous Shh promotedneovascularization (NV) formation in vivo in a rat cornea. Topicalcyclopmine blocked Gli signaling (blocked translocation of Gli3) andthe length of neovascularization in the peripheral corneapost-cauterization as compared with the control vehicle-treated cornea.Conclusions: Shh enhances endothelialtube formation independently through VEGF signaling in vitro. Shhsignaling is involved in the development of unfavorable cornealneovascularization in animal corneas.

[学科分类] 生物化学/生物物理