Sonic hedgehog expression and role in healing corneal epithelium.
OBJECTIVE
To examine the expression pattern and roles of Sonic hedgehog (Shh) in healing corneal epithelium.


METHODS
Immunofluorescent staining and Western blot analysis were used to detect Shh, patched 1 (Ptc 1) receptors, and Gli transcription factors in corneal epithelium of Wistar rats (n = 44) at various intervals after an epithelial defect. Effects of exogenous Shh on cell proliferation and cyclin D1 expression were determined in healing corneal epithelium of organ-cultured mouse eyes.


RESULTS
Uninjured rat corneal epithelium was not labeled by anti-Shh antibody, but weakly positive for Ptc 1. Basal cells of limbal and conjunctival epithelia were labeled by antibodies against Shh and Ptc 1. Shh protein was transiently upregulated in limbal epithelium in 2 hours and was also transiently expressed in the migrating corneal epithelium with its peak at 12 hours postdebridement. Such upregulation of Shh expression was associated with a transient nuclear translocation of Gli-3 without lifting the suppression of cell proliferation in migrating epithelium postdebridement in vivo. However, an addition of Shh protein to culture medium resulted in nuclear accumulation of cyclin D1 and marked acceleration of epithelial cell proliferation in migrating corneal epithelium of an organ-cultured mouse eye.


CONCLUSIONS
Corneal epithelial debridement causes a transient upregulation of Shh expression and activation of Shh/Gli-3 signaling cascade in healing corneal and limbal epithelia. Although exogenous Shh promotes epithelial cell proliferation in corneal organ culture, its expression in migrating epithelium in vivo does not counteract the suppression of cell proliferation at the early healing phase of epithelium debridement.
Department of Ophthalmology, Wakayama Medical University, Kimiidera, Japan. shiyuza@wakayama-med.ac.jp
Shizuya
S
Saika
Yasuteru
Y
Muragaki
Yuka
Y
Okada
Takeshi
T
Miyamoto
Yoshitaka
Y
Ohnishi
Akira
A
Ooshima
Winston W-Y
WW
Kao
D000818:Animals; D015153:Blotting, Western; D002455:Cell Division; D019938:Cyclin D1 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003646:Debridement; D019573:Epithelium, Corneal / Q000378:metabolism* / Q000601:surgery; D019084:Fluorescent Antibody Technique, Indirect; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins; D009924:Organ Culture Techniques; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation; D014945:Wound Healing; D000071676:Zinc Finger Protein GLI1; D000074290:Zinc Finger Protein Gli3
D004268:DNA-Binding Proteins; C065683:GLI3 protein, human; C498521:Gli1 protein, rat; C465571:Gli3 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; C000606240:Ptch1 protein, mouse; C000606239:Ptch1 protein, rat; D011956:Receptors, Cell Surface; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D000074290:Zinc Finger Protein Gli3; D019938:Cyclin D1