8(S)-hydroxyeicosatetraenoic acid is the lipoxygenase metabolite of arachidonic acid that regulates epithelial cell migration in the rat cornea.
BACKGROUND
We previously found that the inhibition of lipoxygenases resulted in delayed epithelial wound closure in organ-cultured rat corneas. The present study was undertaken to determine the lipoxygenase enzyme and metabolite(s) responsible for regulating reepithelialization and their mechanism of action.


METHODS
The effects of esculetin--an established lipoxygenase inhibitor--on endogenous hydroxyeicosatetraenoic acids (HETEs) production, epithelial wound closure, filamentous-actin (F-actin) cytoskeleton, and mitotic rate were investigated using a cell-culture assay and an organ-culture assay of rat corneal epithelium.


RESULTS
Lipoxygenase inhibition by esculetin, which resulted in the disruption of F-actin organization and a decrease in the mitotic rate, delayed wound closure in both cell- and organ-culture assays. Normal corneoscleral rims metabolized [3H]arachidonic acid to 12-HETE (major metabolite), 8-HETE, and 9-HETE. HETE synthesis was inhibited by esculetin in a dose-dependent fashion. Chiral-phase analysis revealed that they contained only (S)-enantiomers, which indicated that they were lipoxygenase metabolites. The inhibitory effects of esculetin on F-actin organization and epithelial wound closure in an organ-culture assay were totally reversed by exogenously added 8(S)-HETE, whereas 12- and 9-HETE had no effect. However, none of the HETEs reversed the decreased mitotic rate or achieved complete wound closure in the cell-culture assay.


CONCLUSIONS
These results suggest that 8(S)-HETE is the key metabolite of arachidonic acid that regulates corneal epithelial cell migration during wound healing. The metabolite responsible for cell proliferation remains to be determined.
Yamada
M
M
Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. yamadam@mc.med.keio.ac.jp
Proia
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AD
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism* / Q000494:pharmacology; D008084:Lipoxygenase / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008940:Mitotic Index; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014468:Umbelliferones / Q000494:pharmacology; D014945:Wound Healing / Q000502:physiology
D000199:Actins; D006893:Hydroxyeicosatetraenoic Acids; D016859:Lipoxygenase Inhibitors; D014468:Umbelliferones; D016718:Arachidonic Acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C047628:8-hydroxyeicosatetraenoic acid; D008084:Lipoxygenase; C007628:esculetin