title: Role of SH2-containing tyrosine phosphatase Shp2 in mouse corneal epithelial stratification.
abstract: OBJECTIVE
  Shp2 protein tyrosine phosphatase mediates a wide variety of receptor tyrosine kinases (RTK) cell signaling. Herein, we investigate the role of Shp2 in corneal morphogenesis and homeostasis.
  
  
  METHODS
  Shp2 was conditionally knocked out (Shp2(cko)) in Krt14-rtTA;tet-O-Cre;Shp2(f/f) triple transgenic mice administrated with doxycycline (Dox) from postnatal day 1 (P1) to P10, P15, and P25, respectively. In addition, corneal epithelial debridement was performed in adult (P42) mice treated with or without Dox for 8 days (from P42-P50). Mouse eyes were then subjected to histology and immunohistochemistry.
  
  
  RESULTS
  Shp2(cko) revealed impaired stratification of conjunctival and corneal epithelia during morphogenesis. Likewise, Shp2(cko) failed to restore epithelial stratification after a corneal epithelial wound in adult Shp2(cko). At the cellular level, the ratio of proliferating cell nuclear antigen (PCNA-positive)/total basal cells remained unchanged, but cells in G2/M (survivin-positive) phase was significantly increased in Shp2(cko) as compared with those in the control littermate. Interestingly, deltaN-p63 (ΔNp63) expression and the asymmetric division of the basal cells were coincidentally dampened in Shp2(cko). Transmission electron microscopic study showed that desmosome and hemidesmosome densities were reduced in the corneal epithelium of Shp2(cko). Immunohistochemistry also demonstrated that expression of E-cadherin/β-catenin junction and laminin-β1 was extensively downregulated in Shp2(cko). On the other hand, corneal epithelium lacking Shp2 remained positive for K14, Pax-6, and keratin 12 (K12), suggesting that Shp2 was dispensable for the corneal epithelial-type differentiation.
  
  
  CONCLUSIONS
  These data argued that Shp2 deficiency predominantly impacted p63-dependent cell division and cell adhesive ability, which resulted in the impairment of stratification during corneal epithelial development and wound healing.
authors.affiliation: Edith J. Crawley Vision Research Center/Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, Ohio.
authors.forename: Gracia Y
authors.initials: GY
authors.lastname: Ng
authors.forename: Lung-Kun
authors.initials: LK
authors.lastname: Yeh
authors.forename: Yujin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hongshan
authors.initials: H
authors.lastname: Liu
authors.forename: Gen-Sheng
authors.initials: GS
authors.lastname: Feng
authors.forename: Winston W Y
authors.initials: WW
authors.lastname: Kao
authors.forename: Chia-Yang
authors.initials: CY
authors.lastname: Liu
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D002452:Cell Count; D002454:Cell Differentiation; D003315:Cornea / Q000378:metabolism / Q000648:ultrastructure; D065306:Corneal Injuries; D004195:Disease Models, Animal; D019573:Epithelium, Corneal / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D009024:Morphogenesis; D015398:Signal Transduction; D018909:src Homology Domains
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C492010:SH2B1 protein, rat
keywords: Shp2; corneal epithelium; knockout animals; p63; stratification