title: Inducible expression of cre recombinase in the retinal pigmented epithelium.
abstract: OBJECTIVE
  The retinal pigmented epithelium (RPE) expresses many genes that play important roles in the support and maintenance of photoreceptors. The present study was conducted to develop a system amenable to the dissection of the temporal function of these genes, specifically within RPE cells. Transgenic mice were generated and characterized in which the expression of Cre recombinase could be specifically induced within the RPE.
  
  
  METHODS
  Transgenic mice carrying the human vitelliform macular dystrophy-2 (VMD2) promoter (P(VMD2))-directed reverse tetracycline-dependent transactivator (rtTA) and the tetracycline-responsive element (TRE)-directed cre were generated. Inducible Cre expression was achieved by feeding doxycycline to these mice and was characterized by using a Cre-activatable lacZ reporter mouse strain (R26R).
  
  
  RESULTS
  A beta-galactosidase assay of rtTA/Cre-R26R mice demonstrated that the basal level of Cre expression without doxycycline induction was negligible. Addition of doxycycline led to induction of RPE-specific Cre expression/function at least from embryonic day 9 to postnatal day 60. The highest induction occurred at approximately postnatal day 4. As measured by ERG and histology, retinal function and morphology were normal in 10-month-old rtTA/Cre mice that were treated with doxycycline at weaning age.
  
  
  CONCLUSIONS
  Transgenic mice were generated that express Cre recombinase in the RPE in an inducible fashion. These mice will be useful for studies of the RPE-specific role of genes that are expressed in the RPE as well as other cells, particularly for avoiding embryonic lethality and dissecting the function of genes that play dual roles in development and adulthood.
authors.affiliation: Department of Medicine and Harold Hamm Oklahoma Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. yun-le@ouhsc.edu
authors.forename: Yun-Zheng
authors.initials: YZ
authors.lastname: Le
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Peng-Cheng
authors.initials: PC
authors.lastname: Rao
authors.forename: Lixing
authors.initials: L
authors.lastname: Zheng
authors.forename: Robert E
authors.initials: RE
authors.lastname: Anderson
authors.forename: Noriko
authors.initials: N
authors.lastname: Esumi
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Zack
authors.forename: Meili
authors.initials: M
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000075002:Bestrophins; D018118:Chloride Channels / Q000235:genetics; D004318:Doxycycline / Q000008:administration & dosage; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D019426:Integrases / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000201:enzymology*; D010957:Plasmids; D011401:Promoter Regions, Genetic / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: C113133:BEST1 protein, human; D000075002:Bestrophins; D018118:Chloride Channels; D005136:Eye Proteins; C045073:Cre recombinase; D019426:Integrases; D001616:beta-Galactosidase; D004318:Doxycycline