Abstract
Purpose: :
To identify the stress kinases activated by retinal detachment and characterize the time course of their activation in the retina.
Methods: :
Using adult Brown-Norway rats, retina-RPE separation was produced via subretinal injection of 1% hyaluronic acid. Retinas were harvested after detachment at the following time points: 2hr, 4hr, 8hr, 24hr and 48hr. Attached retinas served as controls. Following protein extraction from harvested retinal lysates, protein separation via SDS gel electrophoresis and immunoblotting were used to determine the levels of phosphorylated p44/42, JNK and p38 activation. Immunoprecipitation and Western blotting were used to assess phospho-cJUN levels to monitor JNK activity.
Results: :
Increased levels of activated stress kinases were seen following experimental retinal detachment at various time points. Activation of p44/42 (ERK) kinase was observed to increase gradually at earlier time points (2h, 4h, 8h), followed by a return to baseline levels after 24 hours. Activation of JNK as measured by phospho-cJUN also paralleled that of p44/42, with early activation (2h, 4h, 8h). Phosphorylation of p38 occurred 24 hours after retinal detachment and persisted until 48 hours.
Conclusions: :
Experimental retinal detachment induces activation of several members of the MAP kinase family via increased levels of phosphorylation. The timing of this activation varied from one stress kinase to another, suggesting both an early and a late stress response in the setting of retinal detachment. Future studies will evaluate the effects of targeted inhibition of these kinases on photoreceptor apoptosis following retina-RPE separation.
Keywords: retinal detachment • stress response • signal transduction