title: Physiological expression of lens α-, β-, and γ-crystallins in murine and human corneas.
abstract: OBJECTIVE
  How corneal transparency is formed/maintained remains largely unclear. A group of enzymes which are referred to as enzymatic crystallins were proposed to contribute to corneal transparency in various animals. This study investigated whether the three classical lens crystallins, namely α-, β-, and γ-crystallins, exist in mouse and human corneas.
  
  
  METHODS
  Mice, human tissues, and cultured corneal cells were studied. The expression of lens crystallins in corneas or in cultured corneal cells were detected at the mRNA level by quantitative reverse transcription-PCR (QRT-PCR) and at the protein level by immunohistochemistry or western blotting. To check the effect of exogenous factor on expression of lens crystallins, cultured corneal cells were challenged with lipopolysaccharide or hydrogen peroxide and the expression of lens crystallins was monitored.
  
  
  RESULTS
  QRT-PCR revealed that the relative expression level of lens crystallins in C57BL/6 corneas were higher than in Balb/c corneas. Immunohistochemistry study showed that expression of αA-crystallin started from the embryonic stage, lasted untill old age, and was largely restricted to the epithelium or endothelium of the corneas. β- and γ-crystallins also were found in murine corneal epithelium. Upon treatment with lipopolysaccharide or hydrogen peroxide of cultured corneal epithelial cells, lens crystallins expression was significantly increased as detected by QRT-PCR or western blot assay. Further, both fetal corneal epithelial cultures and limbal stem cell cultures from adult human tissues were positive for lens crystallin immunofluorescence or immunohistochemistry staining.
  
  
  CONCLUSIONS
  Lens crystallins are expressed in mammalian corneas and cultured corneal cells. The expression levels depended on the animal strains or cell status. The physiologic and pathological significance of lens crystallins in corneas deserves more investigation.
authors.affiliation: Shandong Provincial Key Lab of Ophthalmology, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao, China.
authors.forename: Shengwei
authors.initials: S
authors.lastname: Ren
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.forename: Changkai
authors.initials: C
authors.lastname: Jia
authors.forename: Xia
authors.initials: X
authors.lastname: Qi
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003459:Crystallins / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007908:Lens, Crystalline / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL
chemical_list: D003459:Crystallins; D008070:Lipopolysaccharides; D006861:Hydrogen Peroxide