Gene structure and properties of TIGR, an olfactomedin-related glycoprotein cloned from glucocorticoid-induced trabecular meshwork cells.
Expression of the trabecular meshwork inducible glucocorticoid response (TIGR) gene progressively increases from barely detectable levels to greater than 2% of total cellular mRNA over 10 days exposure of trabecular meshwork (TM) cells to dexamethasone. Cycloheximide blocked most of the TIGR mRNA induction, suggesting a requirement for ongoing protein synthesis. The genomic structure of TIGR (approximately 20 kilobases) consists of 3 exons, and a 5-kilobase promoter region that contains 13 predicted hormone response elements, including several glucocorticoid regulatory elements, and other potentially important regulatory motifs. TIGR cDNA encodes an olfactomedin-related glycoprotein of 504 amino acids with motifs for N- and O-linked glycosylation, glycosaminoglycan initiation, hyaluronic acid binding, and leucine zippers. Recombinant TIGR (rTIGR) showed oligomerization and specific binding to TM cells. Anti-rTIGR antibody detected multiple translational/post-translational forms of TIGR produced by the cells (including secreted 66 kDa/55 kDa glycoproteins/proteins in the media and 55 kDa cellular proteins), whereas Northern blot showed a single mRNA species. The findings suggest potential mechanisms by which TIGR could obstruct the aqueous humor fluid flow and participate in the pathogenesis of glaucoma.
Nguyen
T D
TD
Cellular Pharmacology Laboratories, Department of Ophthalmology, School of Medicine, University of California, San Francisco, California 94143-0730, USA. thai@cgl.ucsf.edu
Chen
P
P
Huang
W D
WD
Chen
H
H
Johnson
D
D
Polansky
J R
JR
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D003907:Dexamethasone / Q000494:pharmacology; D019281:Dimerization; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005136:Eye Proteins / Q000235:genetics*; D005901:Glaucoma / Q000209:etiology; D005938:Glucocorticoids / Q000494:pharmacology; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D011499:Protein Processing, Post-Translational; D017386:Sequence Homology, Amino Acid; D014129:Trabecular Meshwork / Q000187:drug effects / Q000502:physiology*; D000099179:Myocilin
D003598:Cytoskeletal Proteins; D003907:Dexamethasone; D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; D005938:Glucocorticoids; D006023:Glycoproteins; D000099179:Myocilin; C081451:olfactomedin