title: Bidirectional, optical sign-dependent regulation of BMP2 gene expression in chick retinal pigment epithelium.
abstract: OBJECTIVE
  We explored the role of bone morphogenic protein 2 (BMP2) in defocus-induced ocular growth using gene expression changes in RPE as a surrogate.
  
  
  METHODS
  Young White-Leghorn chickens were used in this study. Normal gene expression of BMP2 and its receptors was examined in retina, RPE, and choroid, and BMP2 protein expression assessed in the same tissues using Western blots and immunohistochemistry. Quantitative PCR (qPCR) was used to assess the effects of short-term exposure (2 or 48 hours) to monocular +10 and -10 diopter (D) lenses, on RPE gene expression of BMP2 and its receptors. Ocular growth was assessed using A-scan ultrasonography.
  
  
  RESULTS
  In the eyes of untreated chickens, BMP2 mRNA was expressed more highly in RPE compared to retina and choroid and all three tissues expressed BMP2 protein. The gene expression for all three receptors also was detected in these tissues, with BMPR2 showing highest and BMPR1B lowest expression. BMP2 was up-regulated in the RPE from eyes wearing +10 D lenses, which exhibited shorter than normal vitreous chambers (VCDs) and thickened choroids, while BMP2 was down-regulated in the RPE from eyes wearing -10 D lenses, which developed enlarged VCDs. These treatments did not induce differential expression of BMP receptors in RPE.
  
  
  CONCLUSIONS
  That mRNA expression of BMP2 in chick RPE shows bidirectional, defocus sign-dependent changes is suggestive of a role for BMP2 in eye growth regulation, although the diffuse ocular expression of BMP2 and its receptors suggests complex growth-modulatory signal pathways.
authors.affiliation: Center for Eye Disease & Development, Vision Science Program & School of Optometry, University of California, Berkeley, Berkeley, California 94720, USA. yanzhang@berkeley.edu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yue
authors.initials: Y
authors.lastname: Liu
authors.forename: Christine F
authors.initials: CF
authors.lastname: Wildsoet
mesh_terms: D000818:Animals; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics* / Q000378:metabolism; D002645:Chickens; D002829:Choroid / Q000378:metabolism; D005139:Eyeglasses; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D012030:Refractive Errors / Q000378:metabolism*; D015203:Reproducibility of Results; D012160:Retina / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D012333:RNA, Messenger