Abstract
Purpose: :
Endocytosis is an important cellular process involving the uptake and disposal of fragmented ECM and other cell debris, yet little is known concerning the specifics of this process in trabecular meshwork cells. Studies were conducted to determine the effects of Dynasore, a dynamin inhibitor, on the endosomal pathway in the TM and how this pathway impacts outflow facility.
Methods: :
Studies were conducted with Dynasore treated and control Human perfused anterior segments and porcine TM cell culture. Confocal microscopy was used to establish the distribution and localization patterns of endosomal vesicles and their potential components including dynamin, β-actin, MT-1-MMP, tubulin and the Rabs. Endosomal uptake was evaluated using TAT-tagged Qdots and Rhodamine-labeled fibronectin. Oregon Green- labeled-gelatin coated coverslips were used to evaluate proteolytic gelatin degradation potential. Anterior segment flow rates of treated and control eyes were analyzed.
Results: :
Dynasore causes a decrease in Qdot uptake and almost completely blocks labeled fibronectin uptake by TM cells. β-actin and dynamin cell distribution patterns are changed from a cell wide stain to a very localized punctuate configuration. With Dynasore, tubulin staining becomes more robust and the microtubulule organizing center is more pronounced. There is a decrease in proteolytic potential with Dynasore as assayed by gelatin degradation. Finally, outflow facility drops by 50% within 4 hours of treatment.
Conclusions: :
The dynamin inhibitor, Dynasore, causes a series of global changes within the TM cells culminating in a drop in outflow facility.
Keywords: trabecular meshwork • enzymes/enzyme inhibitors • outflow: trabecular meshwork