Insulin, not leptin, promotes in vitro cell migration to heal monolayer wounds in human corneal epithelium.
OBJECTIVE
To investigate the effects of insulin and leptin on in vitro wound healing of transformed human corneal epithelial cell monolayers and to identify cellular (migration versus proliferation) and intracellular signaling mechanisms.


METHODS
Scratch wounds were created in monolayers of an immortalized human corneal epithelial cell (HCEC) line. The wounded monolayers were exposed to insulin and leptin. Wound areas were measured every hour after wounding for up to 8 hours. Phosphoinositide 3-kinase (PI3-kinase) and mitogen-activated protein (MAP)-kinase signaling was analyzed with Western blot. The actions of insulin were also examined after incubation with inhibitors to extracellular signal regulated kinase (ERK 1/2) and PI3-kinase.


RESULTS
The presence of insulin, but not leptin facilitated closure of wounds created in corneal epithelial cell monolayers. Phosphorylation of ERK 1/2 and Akt was stimulated after exposure of the monolayers to insulin. Inhibitors of PI3-kinase and ERK 1/2 prevented or reduced insulin-induced corneal wound healing, respectively.


CONCLUSIONS
Exposure of corneal epithelium to insulin facilitated closure of in vitro small wounds through enhanced cell migration instead of proliferation, which depended on ERK 1/2 and PI3-kinase signaling. These data suggest a mechanism by which insulin may influence corneal wound healing in vitro. In vivo, disruptions to the insulin signaling pathway observed in diseases such as diabetes might account for the delayed wound healing and corneal defects.
Shanley
Lynne J
LJ
Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom.
McCaig
Colin D
CD
Forrester
John V
JV
Zhao
Min
M
D015153:Blotting, Western; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000187:drug effects*; D004261:DNA Replication; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019573:Epithelium, Corneal / Q000166:cytology* / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology*; D020738:Leptin / Q000494:pharmacology*; D018613:Microscopy, Confocal; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin / Q000378:metabolism; D054411:Receptors, Leptin; D014945:Wound Healing / Q000187:drug effects*
D004791:Enzyme Inhibitors; D007328:Insulin; D020738:Leptin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin; D054411:Receptors, Leptin; C515448:LEPR protein, human; C494918:AKT1 protein, human