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Inhibition of glucocorticoid-induced alteration of vimentin by a glucocorticoid receptor antagonist RU486 in the organ-cultured rat lens.

Xie GL, Yan H, Lu ZF - Mol. Vis. (2011)

Bottom Line: The lenses of the untreated group and the RU486+Dex group remained transparent throughout the incubation.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China.

ABSTRACT

Purpose: 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.

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Related in: MedlinePlus

Morphological changes of the cultured rat lens. A: Control group; B: Dex group; C: RU486+Dex group. TEM, original magnification 120,000×). In the dexamethasone (Dex) group (B), the orderly arrangement of cell-junctions was disrupted compared with of the control group (A). In the group treated with both RU486 and Dex (RU486+Dex; C), no disruption was observed, which suggested that the morphological changes induced by Dex were blocked by RU486.
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f2: Morphological changes of the cultured rat lens. A: Control group; B: Dex group; C: RU486+Dex group. TEM, original magnification 120,000×). In the dexamethasone (Dex) group (B), the orderly arrangement of cell-junctions was disrupted compared with of the control group (A). In the group treated with both RU486 and Dex (RU486+Dex; C), no disruption was observed, which suggested that the morphological changes induced by Dex were blocked by RU486.

Mentions: Transmission electron microscopy (TEM) showed an orderly arrangement and normal appearance of the cell junctions in the control group (Figure 2A) and the RU486+Dex group (Figure 2C). However, in the Dex group, the cell junction was disrupted and the lenses consisted of abnormal cells that exhibited vacuoles and expanded extracellular lacunae (Figure 2B).


Inhibition of glucocorticoid-induced alteration of vimentin by a glucocorticoid receptor antagonist RU486 in the organ-cultured rat lens.

Xie GL, Yan H, Lu ZF - Mol. Vis. (2011)

Morphological changes of the cultured rat lens. A: Control group; B: Dex group; C: RU486+Dex group. TEM, original magnification 120,000×). In the dexamethasone (Dex) group (B), the orderly arrangement of cell-junctions was disrupted compared with of the control group (A). In the group treated with both RU486 and Dex (RU486+Dex; C), no disruption was observed, which suggested that the morphological changes induced by Dex were blocked by RU486.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3021571&req=5

f2: Morphological changes of the cultured rat lens. A: Control group; B: Dex group; C: RU486+Dex group. TEM, original magnification 120,000×). In the dexamethasone (Dex) group (B), the orderly arrangement of cell-junctions was disrupted compared with of the control group (A). In the group treated with both RU486 and Dex (RU486+Dex; C), no disruption was observed, which suggested that the morphological changes induced by Dex were blocked by RU486.
Mentions: Transmission electron microscopy (TEM) showed an orderly arrangement and normal appearance of the cell junctions in the control group (Figure 2A) and the RU486+Dex group (Figure 2C). However, in the Dex group, the cell junction was disrupted and the lenses consisted of abnormal cells that exhibited vacuoles and expanded extracellular lacunae (Figure 2B).

Bottom Line: The lenses of the untreated group and the RU486+Dex group remained transparent throughout the incubation.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China.

ABSTRACT

Purpose: 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.

Show MeSH
Related in: MedlinePlus