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Abstract #9117 Published in IGR 5-2
Low dose latrunculin-A inhibits dexamethasone-induced changes in the actin cytoskeleton and alters extracellular matrix protein expression in cultured human trabecular meshwork cells
Liu X; Wu Z; Sheibani N; Brandt CR; Polansky JR; Kaufman PLExperimental Eye Research 2003; 77: 181-188
The authors determined the effects of a low dose of the actin-disrupting agent latrunculin (LAT)-A on dexamethasone (DEX)-induced changes in actin organization, focal adhesions, and the production of extracellular matrix proteins in cultured human trabecular meshwork (HTM) cells. HTM cells were cultured to a highly confluent stage with stable endothelium-like morphology, and were incubated with 0.1 or 0.2 DEX and/or 0.1 LAT-A. Changes in the actin cytoskeleton and vinculin-containing focal contacts were evaluated by immunofluorescence microscopy. Expression of thrombospondin-1 (TSP1) and fibronectin (FN) in HTM cells was evaluated by Western blot analysis. The results showed that DEX induced morphological changes and actin reorganization in HTM cells. The cells partly recovered after DEX withdrawal, but the addition of low dose LAT-A hastened the recovery. In addition, DEX failed to induce changes when co-incubated with LAT-A for at least four weeks, and for at least two weeks when cells were pre-treated with LAT-A for two weeks. HTM cells treated with 0.1 LAT-A for only five days showed mild disorganization of the actin cytoskeleton and focal adhesions, which persisted during the four weeks of treatment. DEX stimulated production of FN in HTM cells independent of LAT-A treatment. LAT-A and, to a lesser extent, DEX inhibited production of TSP1 by HTM cells. Although LAT-A is not a DEX receptor antagonist, it is able to prevent the effects of DEX on the actin cytoskeleton in cultured HTM cells at a dose subthreshold for increasing outflow facility in monkeys. This suggests that LAT-A at low doses may be useful in treating steroid and other glaucomas. TSP1 may be an important target for LAT-A in HTM cells and modulation of TSP may influence the actin cytoskeleton of the trabecular meshwork (TM), and consequently, intraocular pressure.
Classification:
2.5.1 Trabecular meshwork (Part of: 2 Anatomical structures in glaucoma > 2.5 Meshwork)
3.3 Immunohistochemistry (Part of: 3 Laboratory methods)
3.5 Molecular biology incl. SiRNA (Part of: 3 Laboratory methods)
3.6 Cellular biology (Part of: 3 Laboratory methods)
