Gene expression profile of human trabecular meshwork cells in response to long-term dexamethasone exposure.
OBJECTIVE
Topical use of dexamethasone has long been associated with steroid induced-glaucoma, although the mechanism is unknown. We applied a strict filtering of comparative microarray data to more than 18,000 genes to evaluate global gene expression of cultured human trabecular meshwork cells in response to treatment with dexamethasone.


METHODS
Three human trabecular meshwork cell primary cultures from nonglaucomatous donors were incubated with and without dexamethasone for 21 days. Relative gene expression was evaluated by analysis of U133A GeneChip and the results validated using quantitative polymerase chain reaction (PCR).


RESULTS
Application of strict filtering to include only genes with statistically significant differences in gene expression across all three trabecular meshwork cell cultures produced a list of 1,260 genes. Significant changes in signal level were observed, including 23 upregulated and 18 downregulated genes that changed greater than three fold in each of three cell cultures. Using quantitative PCR we found changes greater than a thousand fold for two genes (SLP1 and SAA2) and changes greater than a hundred fold for another five genes (ANGPTL7, MYOC, SAA1, SERPINA3, and ZBTB16).


CONCLUSIONS
Expression changes in trabecular meshwork cells in response to dexamethasone treatment indicate that a group of actins and actin-associated proteins are involved in the development of cross-linked actin networks that form in response to dexamethasone. A trend was identified toward decreased expression of protease genes accompanied by an increased expression of protease inhibitors. Such a trend in nonproteasomal proteolysis conceivably affects gene product levels above the level of transcription. Only two genes, MYOC and IGFBP2, showed significantly elevated expression after dexamethasone treatment in our study and the other three previously published reports of primary culture trabecular meshwork cell gene expression.
Department of Ophthalmology and Visual Sciences, The University of Michigan, Ann Arbor, MI, USA. rozsa@umich.edu
Frank W
FW
Rozsa
David M
DM
Reed
Kathleen M
KM
Scott
Hemant
H
Pawar
Sayoko E
SE
Moroi
Theresa Guckian
TG
Kijek
Charles M
CM
Krafchak
Mohammad I
MI
Othman
Douglas
D
Vollrath
Victor M
VM
Elner
Julia E
JE
Richards
D000293:Adolescent; D002478:Cells, Cultured; D002648:Child; D003598:Cytoskeletal Proteins / Q000235:genetics; D003907:Dexamethasone / Q000008:administration & dosage* / Q000494:pharmacology; D015536:Down-Regulation; D004334:Drug Administration Schedule; D005136:Eye Proteins / Q000235:genetics; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D014129:Trabecular Meshwork / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation; D000099179:Myocilin
D003598:Cytoskeletal Proteins; D003907:Dexamethasone; D005136:Eye Proteins; D006023:Glycoproteins; D000099179:Myocilin