Importin 13 serves as a potential marker for corneal epithelial progenitor cells.
Importin13 (IPO13), the newest member of importin-beta family discovered recently, is a unique nucleus-cytoplasm bidirectional transport receptor protein. In this study, IPO13 expression in human corneal tissue, limbal epithelial primary explant and clonal culture was evaluated by immunostaining and reverse-transcription polymerase chain reasgon. IPO13 function was evaluated in the corneal epithelial culture treated with IPO13 inhibitor, or fetal bovine serum (FBS)-containing Dulbecco's modified Eagle's medium (DMEM) medium by colony-forming efficiency, clone growth capacity, MTT, immunostaining, and Western blotting assay. IPO13 protein was expressed mainly in nuclei of limbal epithelial basal cells, but not in the other cell layers of limbus and full thickness of corneal epithelia. IPO13 was expressed in the majority of epithelial cells in early-stage clones and in the margin of late-stage clones. IPO13 was positively expressed in mouse TKE2 progenitor cells cultured in keratinocyte serum-free defined medium, while it became negative in FBS-containing DMEM, which promoted TKE2 cell differentiation. In the presence of IPO13 inhibitor, IPO13 expression and the proliferative capacity decreased in human limbal epithelial clones and mouse TKE2 cells, which were accompanied with the cell differentiation. In conclusion, our findings demonstrate for the first time that IPO13 is uniquely expressed by human limbal basal epithelial cells, and plays an important role in maintaining the phenotype, high proliferative potential, and less differentiation of corneal epithelial progenitor cells, suggesting that IPO13 could serve as a novel potential marker for corneal epithelial progenitor cells.
Wang
Hua
H
Eye Institute and Affiliated Xiamen Eye Center, Xiamen University, Xiamen, Fujian, China.
Tao
Tao
T
Tang
Jing
J
Mao
Yi-Hui
YH
Li
Wei
W
Peng
Juan
J
Tan
Gang
G
Zhou
Yue-Ping
YP
Zhong
Jing-Xiang
JX
Tseng
Scheffer C G
SC
Kawakita
Tetsuya
T
Zhao
Yong-Xiang
YX
Liu
Zu-Guo
ZG
D000293:Adolescent; D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism*; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008875:Middle Aged; D041681:NIH 3T3 Cells; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D055815:Young Adult
D015415:Biomarkers; D006131:Growth Inhibitors; C527880:IPO13 protein, human; D028884:Karyopherins; D012333:RNA, Messenger