title: The ocular surface phenotype of Muc5ac and Muc5b null mice.
abstract: OBJECTIVE
  Recent development of mice null for either Muc5ac or Muc5b mucin allows study of their specific roles at the mouse ocular surface. A recent report indicated that Muc5ac null mice show an ocular surface phenotype similar to that seen in dry eye syndrome. The purpose of our study was to determine the effect of lack of Muc5ac or Muc5b on the ocular surface, and to determine if environmental desiccating stress exacerbated a phenotype.
  
  
  METHODS
  Muc5ac null and Muc5b null mice, and their wild-type controls were examined for ocular surface defects by fluorescein staining. The number of goblet cells per area of conjunctival epithelium was counted, and levels of mucin gene expression and genes associated with epithelial stress, keratinization, and differentiation, known to be altered in dry eye syndrome, were assayed. To determine if the null mice would respond more to desiccating stress than their wild-type controls, they were challenged in a controlled environment chamber (CEC) and assessed for changes in fluorescein staining, tear volume, and inflammatory cells within the conjunctival and corneal epithelia.
  
  
  RESULTS
  Unlike the previous study, we found no ocular surface phenotype in the Muc5ac null mice, even after exposure to desiccating environmental stress. Similarly, no ocular surface phenotype was present in the Muc5b null mice, either before or after exposure to a dry environment in the CEC.
  
  
  CONCLUSIONS
  Our results indicate that deleting either the Muc5ac or Muc5b gene is insufficient to create an observable dry eye phenotype on the ocular surface of these mice.
authors: Schepens Eye Research Institute/Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts.
authors: Christina Kaiser
authors: CK
authors: Marko
authors: Ann S
authors: AS
authors: Tisdale
authors: Sandra
authors: S
authors: Spurr-Michaud
authors: Christopher
authors: C
authors: Evans
authors: Ilene K
authors: IK
authors: Gipson
mesh_terms: D000818:Animals; D003228:Conjunctiva / Q000378:metabolism* / Q000473:pathology; D003315:Cornea / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D015352:Dry Eye Syndromes / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D055271:Mucin 5AC / Q000096:biosynthesis / Q000235:genetics*; D055257:Mucin-5B / Q000096:biosynthesis / Q000235:genetics*; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C524679:Muc5ac protein, mouse; C524579:Muc5b protein, mouse; D055271:Mucin 5AC; D055257:Mucin-5B; D012333:RNA, Messenger
keywords: animal models; dry eye; mucins