Abstract
Purpose:
To identify genes that might play a role both trabecular meshwork (TM) in both primary open-angle glaucoma (POAG) and a model of steroid glaucoma.
Methods:
Gene expression profiling was analyzed by Affymetrix GeneChips from three cultured TM cell lines in response to long-term dexamethasone (DEX) treatment. Probes that showed >1.5 fold change were evaluated for differential expression of similar direction and magnitude in microarrays using native TM tissue in eyes from six POAG donors and six normal donors matched for sex, age, and approximate age. Similar normalization and filtering cutoffs were performed on each data set. Microarray findings were confirmed by quantitative PCR (qPCR) using Taqman primers. DNA sequencing and microarray hybridizations were performed at the University of Michigan DNA Sequencing and Microarray Core Facility.
Results:
Microarray analysis of gene expression in cultured TM cells treated with or without DEX yielded 409 differentially expressed probes. Only one gene was differentially expressed in both the DEX and POAG data sets, ACTG2 (Actin, gamma2, smooth muscle, Enteric). ACTG2 expression had an average increase of 6.8-fold in response to DEX-treatment in three TM cell lines and 2.96-fold increase in glaucomatous globes. These expression changes were confirmed by qPCR. The presence or absence of a HindIII RFLP in ACTG2 did not segregate with disease status.
Conclusions:
Cross-linked actin networks (CLANs ) have been shown to increase in POAG TM tissue and in a model used for the study of steroid glaucoma: DEX-treated cultured TM cells; it is interesting to note that ACTG2, which produces gamma actin, increases expression in both of these circumstances. Determining the genes involved in the formation of CLANs, distinctive actin structures, provides important tools for the study of trabecular meshwork function and the role of CLANs in steroid glaucoma and POAG. Our findings suggest a need to further explore the role of gamma actin in CLAN formation.
Keywords: 533 gene/expression •
735 trabecular meshwork •
487 corticosteroids