Abstract
Purpose: :
Diabetic Retinopathy is characterized by accelerated apoptosis of retinal microvascular cells. Caspase-14 is a unique member of the caspase family because it’s mainly activated and expressed in the epidermis and is absent from most adult tissues. The role of caspase-14 in ocular tissue remains relatively unexplored. We previously showed that caspase-14 is expressed in retinal cells involved in maintaining vascular homeostasis. Our results indicated a marked increase in the level of caspase-14 in diabetic mouse and human subjects as compared to the control (ARVO, 2011, E-Abstract 3564). Thus, the goal of the current study was to determine the impact of caspase-14 expression on retinal microvascular cells.
Methods: :
Retinal pericytes (PC) and endothelial cells (EC) isolated from C57BL/6J immorto-mice were subjected to normal glucose (5.5 mM), high glucose (40.5mM) or osmotic control (5.5 mM D-glucose and 35 mM L-glucose). This was followed by the assessment of caspase-14 protein and mRNA levels by Western blotting and qRT-PCR, respectively. Retinal PC and EC were also infected with adenoviruses expressing human caspase-14 or GFP. The number of apoptotic cells was then determined using TUNEL assay and the levels of cleaved PARP-1 and caspase-3 were determined by Western blotting and FACS analysis, respectively.
Results: :
High glucose increased expression of caspase-14 in PC and EC. There was significant increase in the number of apoptotic cells in EC expressing caspase-14. This was associated with a significant increase in the levels of cleaved PARP-1 and caspase-3. However, the level of caspase-3 did not change in PC expressing caspase-14 (P<0.05).
Conclusions: :
Our findings suggest that caspase-14 may play a role in the pathogenesis of DR, perhaps through enhancing apoptosis of retinal EC.
Keywords: apoptosis/cell death • diabetic retinopathy