Involvement of p27(KIP1) degradation by Skp2 in the regulation of proliferation in response to wounding of corneal epithelium.
OBJECTIVE
To examine the expression of the p27(KIP1)in the normal and epithelial-scraped cornea and whether degradation of p27(KIP1)by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium.


METHODS
C57Bl6, p27(KIP1-/-), Skp2(-/-), and Skp2(-/-)/p27(KIP1-/-) double-knockout mice were examined. Normal and epithelial-scraped corneas were analyzed by immunocytochemistry using anti-p27(KIP1) antibody. Cells in the S phase of DNA synthesis were analyzed by immunocytochemistry using anti-bromodeoxyuridine (BrdU) antibody.


RESULTS
The p27(KIP1) was expressed in basal cells of the central and peripheral region of the cornea and limbus. This expression was not detected 24 hours after the epithelial scraping, when there were many cells in the S phase of DNA synthesis in the corneal epithelium. There were no obvious differences in the thickness and anti-BrdU staining in the corneal epithelium of p27(KIP1-/-) mice from that of control animals. Twenty-four hours after epithelial scraping in the Skp2(-/-) mice, the corneal epithelium was thinner than in wild-type mice and had many p27(KIP1)-positive cells and few BrdU-positive cells. In contrast, 24 hours after epithelial scraping in the Skp2(-/-)/p27(KIP1)(-/-) double-knockout mice, the corneal epithelium was as thick as in wild-type mice and had many BrdU-positive cells.


CONCLUSIONS
These results suggest that degradation of p27(KIP1) by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium.
Yoshida
Kazuhiko
K
Department of Ophthalmology, Hokkaido University School of Medicine, Sapporo, Japan. kyoshida@med.hokudai.ac.jp
Nakayama
Keiko
K
Nagahama
Hiroyasu
H
Harada
Takayuki
T
Harada
Chikako
C
Imaki
Junko
J
Matsuda
Akira
A
Yamamoto
Kazuyuki
K
Ito
Miyuki
M
Ohno
Shigeaki
S
Nakayama
Kei-Ichi
K
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000502:physiology*; D002455:Cell Division; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication; D004791:Enzyme Inhibitors / Q000378:metabolism*; D019573:Epithelium, Corneal / Q000293:injuries* / Q000378:metabolism / Q000473:pathology; D005131:Eye Injuries / Q000378:metabolism* / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D044786:S-Phase Kinase-Associated Proteins; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D014945:Wound Healing
C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D044786:S-Phase Kinase-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004247:DNA; D018844:Cyclin-Dependent Kinases