title: Estradiol biosynthesis in canine lens epithelial cells.
abstract: OBJECTIVE
  To confirm that lens epithelial cells (LEC) synthesize 17β-estradiol, active estrogen, and to identify the pathway(s) by which normal and cataractous LEC synthesize 17β-estradiol.
  
  
  METHODS
  ELISA was used to measure estradiol in aqueous humor; immunohistochemical staining was used to localize estradiol, testosterone and sulfatase; tritiated water release assay was used to measure aromatase activity; and qRT-PCR was used to quantify expression of aromatase and sulfatase in normal and cataractous canine and human LEC.
  
  
  RESULTS
  Canine eyes with and without cataracts had no differences in aqueous humor estradiol levels; however, cataractous LEC had more intense immunoreactivity for estradiol than normal LEC. There were little to no differences in canine sulfatase protein and mRNA expression when normal and cataractous LEC were compared. qRT-PCR demonstrated that canine cataractous LEC had significantly higher expression of aromatase; this was confirmed with the tritiated water release assay. Similar to dogs, human cataracts had both sulfatase and aromatase mRNA expression.
  
  
  CONCLUSIONS
  Normal and cataractous LEC can synthesize estradiol by the sulfatase pathway; however, cataractous LEC appear to use the aromatase pathway as well. Because no differences in aqueous humor estradiol levels were detected, we suspect that estradiol synthesized by the sulfatase pathway is secreted into the aqueous humor; whereas, estradiol synthesized by the aromatase pathway is used for, as yet unknown, intracrine purposes.
authors.affiliation: Veterinary Clinical Sciences .
authors.forename: Carmen M H
authors.initials: CM
authors.lastname: Colitz
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.forename: Yasuro
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Curtis A
authors.initials: CA
authors.lastname: Barden
authors.forename: Heather L
authors.initials: HL
authors.lastname: Chandler
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002386:Cataract / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D007908:Lens, Crystalline / Q000378:metabolism* / Q000473:pathology
chemical_list: D004958:Estradiol
keywords: Aromatase; cataract; estrogen; lens epithelium; sulfatase