Glaucoma is a heterogeneous eye disease that is the second leading cause of bilateral blindness worldwide. The prevalence of open angle glaucoma (OAG), the most common form of the disease, is increasing in the United States because of an aging population. Myocilin is the first gene to be conclusively associated with inherited OAG, but the mechanism(s) by which heterozygous myocilin mutations cause a dominant glaucoma phenotype is not known. In work accomplished during the last funding period, we found that mutant myocilin proteins are misfolded and accumulate as aggregates within the endoplasmic reticulum (ER) of cells. Prolonged expression of mutant myocilin resulted in death of cultured human trabecular meshwork (HTM) cells. Culturing cells at a lower temperature, a condition known to promote protein folding, increased secretion of the mutant protein and ameliorated its deleterious effects on HTM cells. Testing of a variety of mutant myocilins showed that temperature sensitive secretion is a general property and that there is a correlation between the biochemical properties of particular mutant myocilins and the severity of their associated glaucoma phenotypes. Our findings indicate that myocilin-associated glaucoma is a protein conformational disease, and suggest a progression of events in which chronic expression of misfolded, non- secreted myocilin leads to prolonged ER-stress, HTM cell dysfunction and death, and, ultimately, a dominant glaucoma phenotype. We now seek to identify the factors that influence HTM cell susceptibility to mutant myocilin expression. We will exploit differences among myocilin mutants, HTM cell lines, and culture temperature conditions to identify critical stress-induced consequences of mutant myocilin expression in cells. Knowledge of these pathways will be used to test defined hypotheses regarding manipulations that may protect HTM cells from the deleterious effects of mutant myocilin. Success of this project will indicate points for therapeutic intervention for myocilin-associated glaucoma, and may uncover aspects of HTM cell physiology that are relevant to a wider spectrum of this blinding, neurodegenerative disease. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY011405-10
Application #
7387358
Study Section
Anterior Eye Disease Study Section (AED)
Program Officer
Agarwal, Neeraj
Project Start
1996-05-01
Project End
2012-03-31
Budget Start
2008-04-01
Budget End
2009-03-31
Support Year
10
Fiscal Year
2008
Total Cost
$348,390
Indirect Cost
Name
Stanford University
Department
Genetics
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Springelkamp, Henriët; Mishra, Aniket; Hysi, Pirro G et al. (2015) Meta-analysis of Genome-Wide Association Studies Identifies Novel Loci Associated With Optic Disc Morphology. Genet Epidemiol 39:207-16
Kang, J H; Loomis, S J; Yaspan, B L et al. (2014) Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma. Eye (Lond) 28:662-71
Springelkamp, Henriët; Höhn, René; Mishra, Aniket et al. (2014) Meta-analysis of genome-wide association studies identifies novel loci that influence cupping and the glaucomatous process. Nat Commun 5:4883
Loomis, Stephanie J; Kang, Jae H; Weinreb, Robert N et al. (2014) Association of CAV1/CAV2 genomic variants with primary open-angle glaucoma overall and by gender and pattern of visual field loss. Ophthalmology 121:508-16
Liu, Yutao; Garrett, Melanie E; Yaspan, Brian L et al. (2014) DNA copy number variants of known glaucoma genes in relation to primary open-angle glaucoma. Invest Ophthalmol Vis Sci 55:8251-8
Bailey, Jessica N Cooke; Yaspan, Brian L; Pasquale, Louis R et al. (2014) Hypothesis-independent pathway analysis implicates GABA and acetyl-CoA metabolism in primary open-angle glaucoma and normal-pressure glaucoma. Hum Genet 133:1319-30
Pasquale, Louis R; Loomis, Stephanie J; Kang, Jae H et al. (2013) CDKN2B-AS1 genotype-glaucoma feature correlations in primary open-angle glaucoma patients from the United States. Am J Ophthalmol 155:342-353.e5
Ulmer, Megan; Li, Jun; Yaspan, Brian L et al. (2012) Genome-wide analysis of central corneal thickness in primary open-angle glaucoma cases in the NEIGHBOR and GLAUGEN consortia. Invest Ophthalmol Vis Sci 53:4468-74
Orwig, Susan D; Perry, Christopher W; Kim, Laura Y et al. (2012) Amyloid fibril formation by the glaucoma-associated olfactomedin domain of myocilin. J Mol Biol 421:242-55
Wiggs, Janey L; Yaspan, Brian L; Hauser, Michael A et al. (2012) Common variants at 9p21 and 8q22 are associated with increased susceptibility to optic nerve degeneration in glaucoma. PLoS Genet 8:e1002654

Showing the most recent 10 out of 23 publications