Inhibition of glucocorticoid-induced alteration of vimentin by a glucocorticoid receptor antagonist RU486 in the organ-cultured rat lens.
OBJECTIVE
Long-term application of glucocorticoids as a treatment for conditions such as allergy, autoimmune diseases, and transplantation presents a high risk of development of steroid-induced cataract. The presence of a functional glucocorticoid receptor (GR) in human and rat lens epithelial cells suggests a direct and specific targeting of these lens cells by glucocorticoids. One important cytoskeletal protein in lens epithelial cells is vimentin, which plays an important role in maintaining the normal lens morphology and function. Previous studies have shown that vimentin is involved in signal transduction, changes in cell structure and differentiation, and apoptosis. Based on a model of steroid-induced cataract from our previous study, the present study focuses on whether changes in vimentin can be induced in vitro through specific GR activation in glucocorticoid-induced cataracts of the rat lens.


METHODS
Clear rat lenses, cultured in vitro, were treated with or without dexamethasone (Dex) or RU486 (a glucocorticoid receptor antagonist). Lenses were cultured for 7 days at 37 °C under 5% CO₂, and were observed daily with an inverted microscope. Changes in morphology were followed by Hematoxylin-eosin (HE) staining, transmission electron microscopy, and immunohistochemistry. The expression of vimentin mRNA and protein was examined by reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis, respectively, in the capsule-epithelium and fiber tissue of the lenses.


RESULTS
Opacity was obviously present at day 7 in the Dex group. The lenses of the untreated group and the RU486+Dex group remained transparent throughout the incubation. Electron microscopy showed an orderly arrangement of fiber cells and normal cell junctions in the control group and the RU486+Dex group. However, in the Dex group, fiber cells were disarranged and the cell-cell junctions exhibited lacunae. The expression of vimentin protein in the lens capsule-epithelium and fiber tissue decreased in the Dex-treated group, but normal expression of vimentin mRNA was maintained.


CONCLUSIONS
These results suggest that the GR-mediated reduction in vimentin may be involved in the formation of steroid-induced cataract.
Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China.
Guo-Li
GL
Xie
Hong
H
Yan
Zi-Fan
ZF
Lu
D000818:Animals; D003599:Cytoskeleton / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism*; D006727:Hormone Antagonists / Q000494:pharmacology; D007908:Lens, Crystalline / Q000187:drug effects*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D015735:Mifepristone / Q000494:pharmacology*; D009924:Organ Culture Techniques / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors*; D015398:Signal Transduction; D013256:Steroids / Q000378:metabolism; D013997:Time Factors; D014746:Vimentin / Q000096:biosynthesis*
D005938:Glucocorticoids; D006727:Hormone Antagonists; D011965:Receptors, Glucocorticoid; D013256:Steroids; D014746:Vimentin; D015735:Mifepristone; D003907:Dexamethasone
Proc Natl Acad Sci U S A. 1982 May;79(10):3320-4
6808508
Ophthalmic Res. 2001 Mar-Apr;33(2):68-74
11244350
J Clin Invest. 1984 Nov;74(5):1803-10
6501572
J Neurosurg. 2005 Apr;102(4):715-20
15871515
Arch Ophthalmol. 1965 Jun;73:818-21
14302515
Invest Ophthalmol Vis Sci. 2000 Jun;41(7):1846-52
10845608
Cell Mol Life Sci. 1997 Jan;53(1):1-12
9117989
Hum Mol Genet. 2009 Mar 15;18(6):1052-7
19126778
Invest Ophthalmol Vis Sci. 2000 Jun;41(7):1629-38
10845579
Surgery. 1975 Jul;78(1):27-33
1138397
Nature. 1978 Mar 9;272(5649):175-7
564467
Eur J Pharmacol. 1993 Oct 15;247(2):145-54
8282004
Curr Eye Res. 2000 Dec;21(6):926-33
11262616
Exp Eye Res. 2001 Jun;72(6):687-94
11384157
Curr Opin Rheumatol. 1991 Jun;3(3):373-9
1883691
Exp Cell Res. 1981 Jan;131(1):41-6
7192560
Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1971;183(3):203-9
5316303
Invest Ophthalmol Vis Sci. 2003 May;44(5):2034-40
12714641
N Engl J Med. 2004 Nov 11;351(20):2087-100
15537907
Biochem J. 1993 Jun 1;292 ( Pt 2):577-83
8389140
Science. 1987 Jul 17;237(4812):268-75
3037703
Exp Eye Res. 1985 Mar;40(3):385-92
4065233
Exp Eye Res. 1997 Oct;65(4):507-16
9464184
Invest Ophthalmol Vis Sci. 2001 Mar;42(3):735-42
11222535
Invest Ophthalmol Vis Sci. 2003 May;44(5):2041-6
12714642
Mol Vis. 2005 Nov 23;11:1018-40
16319822
J Pediatr Ophthalmol Strabismus. 1993 May-Jun;30(3):142-4
8350220
Exp Eye Res. 2001 Aug;73(2):213-9
11446771
Steroids. 1991 Feb;56(2):52-8
2020978
Mol Cell Endocrinol. 2001 Feb 28;173(1-2):121-5
11223183
Curr Opin Pharmacol. 2003 Aug;3(4):404-11
12901950
J Cell Biol. 1980 Jun;85(3):881-9
7190151
Cell Death Differ. 2002 May;9(5):486-92
11973607
Invest Ophthalmol Vis Sci. 2007 Apr;48(4):1724-34
17389505
J Cell Biol. 1989 Oct;109(4 Pt 1):1653-64
2793935
Br J Ophthalmol. 1969 Jun;53(6):361-72
5794952
Ann Ophthalmol. 1981 Jan;13(1):29-32
7018341
Clin Exp Ophthalmol. 2006 Nov;34(8):794-6
17073904
Invest Ophthalmol Vis Sci. 1996 Jul;37(8):1502-8
8675392
Exp Cell Res. 1997 Sep 15;235(2):421-30
9299167
Adv Exp Med Biol. 1986;196:67-80
3012984
Ophthalmic Res. 2006;38(5):303-8
16974132
Surv Ophthalmol. 1986 Sep-Oct;31(2):102-10
3541262
Mol Cell Endocrinol. 1995 Jan;107(1):41-54
7796934
Exp Cell Res. 1980 Jun;127(2):309-27
7189714
Exp Eye Res. 2009 Feb;88(2):248-56
18541233
Invest Ophthalmol Vis Sci. 1995 Jul;36(8):1709-13
7601651
J Ocul Pharmacol Ther. 2007 Oct;23(5):403-20
17900234
Nippon Ganka Gakkai Zasshi. 1984 Mar;88(3):550-8
6464874
Exp Eye Res. 2002 Jun;74(6):703-17
12126944
Exp Eye Res. 1984 Feb;38(2):195-202
6370709
Metabolism. 1974 Feb;23(2):159-202
4359315
Hepatology. 2008 Sep;48(3):909-19
18712785
J Cell Biol. 1997 Sep 22;138(6):1379-94
9298992
J Cell Biol. 1985 Jun;100(6):1962-7
3158665
JAMA. 1960 Sep 10;174:166-71
13801171
J Cell Biol. 1985 Jun;100(6):1955-61
3158664
Invest Ophthalmol Vis Sci. 1994 Sep;35(10):3711-23
8088958
J Ocul Pharmacol Ther. 2005 Feb;21(1):11-27
15718824
PLoS One. 2009 Jun 29;4(6):e6084
19562035
Curr Eye Res. 1986 Jan;5(1):37-40
3956234
Acta Ophthalmol (Copenh). 1979 Jun;57(3):461-9
474090
Life Sci. 2004 Nov 5;75(25):3027-33
15474554
Exp Eye Res. 1996 Dec;63(6):673-81
9068374
J Cell Sci. 1995 Apr;108 ( Pt 4):1397-406
7615661
Exp Eye Res. 2010 Oct;91(4):544-9
20637751