Proteomic analysis of the trabecular meshwork of rats in a steroid-induced ocular hypertension model: downregulation of type I collagen C-propeptides.
OBJECTIVE
To investigate global protein expression profiles in the trabecular meshwork (TM) of normal and glucocorticoid-induced ocular hypertensive rat eyes by proteomic analysis, which has not yet been conducted to date.


METHODS
A rat ocular hypertension model was produced by topical application of dexamethasone (DEX) for 4 weeks. Age-matched untreated rats served as controls. Intraocular pressure (IOP) was monitored by an electronic tonometer. TM protein expression profiling and protein identification was carried out by a two-dimensional fluorescence differential gel electrophoresis (2-D DIGE) system and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, respectively.


RESULTS
In DEX-treated rats, average IOP was elevated significantly, as compared with controls. By the DEX treatment, 14 TM protein spots were up- or downregulated consistently in 2-D DIGE analyses. Proteins exhibiting more than 2-fold statistically significant change were identified by MALDI-TOF mass spectrometry. alpha A-Crystallin and beta A(3)-crystallin were upregulated, while the C-propeptides of type I collagen were downregulated.


CONCLUSIONS
Relatively short-term glucocorticoid application induced alteration in the expression of a number of proteins, including downregulation of type I collagen C-propeptides. This could reflect impaired collagen turnover in the TM of glucocorticoid-treated eyes.
Department of Ophthalmology and Visual Sciences, School of Medicine, University of the Ryukyus, Okinawa, Japan.
Manabu
M
Shinzato
Yoshito
Y
Yamashiro
Nariko
N
Miyara
Akihiro
A
Iwamatsu
Kouji
K
Takeuchi
Masato
M
Umikawa
Maitsetseg
M
Bayarjargal
Ken-ichi
K
Kariya
Shoichi
S
Sawaguchi
D000818:Animals; D024042:Collagen Type I / Q000378:metabolism*; D003459:Crystallins / Q000378:metabolism; D003907:Dexamethasone; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D005938:Glucocorticoids; D007429:Intraocular Pressure; D008297:Male; D013058:Mass Spectrometry; D009798:Ocular Hypertension / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D011498:Protein Precursors / Q000378:metabolism*; D040901:Proteomics; D051381:Rats; D017208:Rats, Wistar; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014129:Trabecular Meshwork / Q000378:metabolism*; D015854:Up-Regulation; D038202:alpha-Crystallin A Chain
D024042:Collagen Type I; D003459:Crystallins; D005938:Glucocorticoids; D011498:Protein Precursors; D038202:alpha-Crystallin A Chain; C526189:betaA3-crystallin, rat; D003907:Dexamethasone