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Abstract #18538 Published in IGR 3-3
Expression of small heat shock proteins and intermediate filaments in the human optic nerve head astrocytes exposed to elevated hydrostatic pressure in vitro
Salvador-Silva M; Ricard CS; Agapova OA; Yang P; Hernandez MRJournal of Neuroscience Research 2001; 66: 59-73
The small heat shock proteins (sHSP), αB-crystallin and Hsp27 are chaperone molecules that maintain the integrity of intermediate filament (IF) network and prevent unfolding of cellular proteins induced by stress. In the optic nerve head (ONH) of eyes with glaucoma, reactive astrocytes expressed Hsp27, perhaps in response to stress related to elevated intraocular pressure. In this study, the authors determined the effect of elevated hydrostatic pressure (HP) in the synthesis, distribution and co-localization of αB-crystallin and Hsp27 with IF in cultured ONH astrocytes. Astrocyte monolayers were pressurized to 60 mmHg (92% air 8% CO2) and incubated at 37°C for six, 24, or 48 hours. Controls were exposed to ambient pressure. Cells were analyzed by immunocytochemistry, Western blot and immunoprecipitation using antibodies to Hsp27, αB-crystallin, vimentin or GFAP. Control astrocytes seemed flat, polygonal with short processes. αB-crystallin appeared granular in the perinuclear area and filamentous in the cell periphery. Fine granular Hsp27 was distributed throughout the cytoplasm. GFAP and vimentin co-localized with Hsp27 in the cytoplasm. Astrocytes exposed to HP were star-shaped with long processes. Hsp27 was condensed in large granules around the nucleus. GFAP and vimentin co-localized with Hsp27 and αB-crystallin in the perinuclear area. Western blot and metabolic labelling detected increased synthesis of Hsp27, GFAP and vimentin, but no change in αB-crystallin. These results indicated that GFAP and vimentin associate with Hsp27 and αB-crystallin in ONH astrocytes. HP affected the integrity of the cytoskeleton consistent with morphological changes. Small HSP may reinforce and maintain IF integrity in response to HP.
Dr M.R. Hernandez, Department of Ophthalmology, Washington University School of Medicine, Campus Box 8096, 660 S Euclid Avenue, St Louis, MO 63110, USA. hernandezr@vision.wustl.edu
Classification:
1.2 Population genetics (Part of: 1 General aspects)