title: Olfactomedin 2: expression in the eye and interaction with other olfactomedin domain-containing proteins.
abstract: OBJECTIVE
  Olfactomedin 2 (OLFM2) belongs to the family of olfactomedin domain-containing proteins. Genetic data suggest its association with glaucoma in Japanese patients. However, its functions are still elusive. In this study, the properties of mammalian OLFM2 were investigated.
  
  
  METHODS
  Expression of the rat and mouse Olfm2 gene was studied by using real-time PCR and in situ hybridization. Substitutions were introduced into OLFM2 by mutagenesis in vitro. Intracellular localization of OLFM2 was studied by confocal microscopy after transient transfection in HEK293 cells. Interaction of OLFM2 with olfactomedin 1 (Olfm1), olfactomedin 3 (Olfm3), myocilin, and gliomedin was studied by using co-immunoprecipitation.
  
  
  RESULTS
  Two major human OLFM2 mRNAs encode secreted proteins with a length of 454 and 478 amino acids. OLFM2 is more closely related to OLFM1 and -3 than to any other family members. Olfm2 showed the most dynamic expression pattern compared with Olfm1 and -3 during mouse eye development and was expressed preferentially in the developing retinal ganglion cell layer. Among three OLFM2 substitutions tested (T86M, R144Q, and L420S), only L420S completely blocked secretion of the protein. OLFM2 interacted with Olfm1 and -3, but not with myocilin and gliomedin. Co-transfection of the L420S mutant with wild-type Olfm1 and -3 significantly inhibited secretion of Olfm1 and -3.
  
  
  CONCLUSIONS
  Highly conserved OLFM2 protein may play an important role in the course of retinal and eye development. Severe mutations in one of the closely related olfactomedin domain-containing proteins (Olfm1-3) may block the secretion and probably the activity of all three family members, leading to more pronounced diseases of the retina than the knockout of individual genes.
authors.affiliation: Section of Molecular Mechanisms of Glaucoma, Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Afia
authors.initials: A
authors.lastname: Sultana
authors.forename: Naoki
authors.initials: N
authors.lastname: Nakaya
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Senatorov
authors.forename: Stanislav I
authors.initials: SI
authors.lastname: Tomarev
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005123:Eye / Q000196:embryology* / Q000254:growth & development; D005136:Eye Proteins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D057809:HEK293 Cells / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics*; D025941:Protein Interaction Mapping; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D000099179:Myocilin
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; D006023:Glycoproteins; D012333:RNA, Messenger; D000099179:Myocilin; C520020:gliomedin protein, mouse; C504359:gliomedin, rat; C081451:olfactomedin