title: Unique expression pattern and functional role of periostin in human limbal stem cells.
abstract: Periostin is a non-structural matricellular protein. Little is known about periostin in human limbal stem cells (LSCs). This study was to explore the unique expression pattern and functional role of periostin in maintaining the properties of human LSCs. Fresh donor corneal tissues were used to make cryosections for evaluation of periostin expression on ex vivo tissues. Primary human limbal epithelial cells (HLECs) were generated from limbal explant culture. In vitro culture models for proliferation and epithelial regeneration were performed to explore functional role of periostin in LSCs. The mRNA expression was determined by reverse transcription and quantitative real-time PCR (RT-qPCR), and the protein production and localization were detected by immunofluorescent staining and Western blot analysis. Periostin protein was found to be exclusively immunolocalized in the basal layer of human limbal epithelium. Periostin localization was well matched with nuclear factor p63, but not with corneal epithelial differentiation marker Keratin 3. Periostin transcripts was also highly expressed in limbal than corneal epithelium. In primary HLECs, periostin expression at mRNA and protein levels was significantly higher in 50% and 70% confluent cultures at exponential growth stage than in 100% confluent cultures at slow growth or quiescent condition. This expression pattern was similar to other stem/progenitor cell markers (p63, integrin β1 and TCF4). Periostin expression at transcripts, protein and immunoreactivity levels increased significantly during epithelial regeneration in wound healing process, especially in 16-24 hours at wound edge, which was accompanied by similar upregulation and activation of p63, integrin β1 and TCF4. Our findings demonstrated that periostin is exclusively produced by limbal basal epithelium and co-localized with p63, where limbal stem cells reside. Periostin promotes HLEC proliferation and regeneration with accompanied activation of stem/progenitor cell markers p63, integrin β1 and TCF4, suggesting its novel role in maintaining the phenotype and functional properties of LSC.
authors: The Eye Institute, Xiamen University, Xiamen, China; Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America.
authors: Yangluowa
authors: Y
authors: Qu
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America; Zhongshan Ophthalmic Center, State Key laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China.
authors: Wei
authors: W
authors: Chi
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America; Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.
authors: Xia
authors: X
authors: Hua
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America.
authors: Ruzhi
authors: R
authors: Deng
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America.
authors: Jin
authors: J
authors: Li
authors: The Eye Institute, Xiamen University, Xiamen, China.
authors: Zuguo
authors: Z
authors: Liu
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America.
authors: Stephen C
authors: SC
authors: Pflugfelder
authors: Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America.
authors: De-Quan
authors: DQ
authors: Li
mesh_terms: D000328:Adult; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000235:genetics; D049109:Cell Proliferation; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000166:cytology* / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D016850:Limbus Corneae / Q000166:cytology* / Q000502:physiology; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors / Q000032:analysis; D025521:Tumor Suppressor Proteins / Q000032:analysis; D014945:Wound Healing; D055815:Young Adult
chemical_list: D015815:Cell Adhesion Molecules; C512835:POSTN protein, human; D012333:RNA, Messenger; C115051:TP63 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins