title: Protein localization in the human eye and genetic screen of opticin.
abstract: The opticin (OPTC) gene encodes a protein that is a member of the small leucine-rich repeat protein (SLRP) family. OPTC is located on chromosome 1q31-q32 within an age-related macular degeneration (AMD) susceptibility locus. We have developed an affinity-purified N-terminal anti-opticin antibody and used it to examine opticin expression in human eye tissues. The antibody was also used for opticin protein localization in human eye sections. Immunoblots of human eye tissues detected a predominant band of approximately 62 kDa in size in iris, trabecular meshwork/ciliary body, retina, vitreous, and optic nerve. Immunohistochemical experiments revealed that opticin is specifically localized in human cornea, iris, ciliary body, vitreous, choroid and retina. Due to opticin's protein profile in the eye, we have also screened OPTC for mutations in individuals with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) or AMD. We identified four sequence variations, all of which were observed in normal controls except for the Arg229Cys change. Three amino acid substitutions (Ile182Thr, Arg229Cys and Arg325Trp) were in residues conserved in dog, mouse, pig and human. The Arg229Cys alteration was present in a homozygous state in one individual with neovascular AMD. Examination of the other AMD afflicted family members showed that the OPTC Arg229Cys variant did not segregate with the disorder within the family. The protein localization pattern of opticin and our preliminary screen of AMD patients suggest that a larger AMD patient screen may be warranted.
authors.affiliation: Department of Ophthalmology, University of Alberta, Edmonton, AB, Canada T6G-2H7.
authors.forename: James S
authors.initials: JS
authors.lastname: Friedman
authors.forename: Mathieu
authors.initials: M
authors.lastname: Faucher
authors.forename: Paul
authors.initials: P
authors.lastname: Hiscott
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Biron
authors.forename: Mario
authors.initials: M
authors.lastname: Malenfant
authors.forename: Pierre
authors.initials: P
authors.lastname: Turcotte
authors.forename: Vincent
authors.initials: V
authors.lastname: Raymond
authors.forename: Michael A
authors.initials: MA
authors.lastname: Walter
mesh_terms: D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018076:DNA, Complementary; D004285:Dogs; D016326:Extracellular Matrix Proteins / Q000032:analysis* / Q000235:genetics; D005123:Eye / Q000378:metabolism*; D005260:Female; D005820:Genetic Testing; D014644:Genetic Variation; D005901:Glaucoma / Q000235:genetics / Q000378:metabolism; D005902:Glaucoma, Open-Angle / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008268:Macular Degeneration / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010375:Pedigree; D011509:Proteoglycans / Q000032:analysis* / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013552:Swine
chemical_list: D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; C404108:OPTC protein, human; C498607:Optc protein, mouse; D011509:Proteoglycans