| In the present study, we found that endoplasmic reticulum (ER) resident stress chaperones, such as calreticulin, glucose regulated protein 78, glucose regulated protein 94, ER protein 57, and protein disulfide isomerase were more abundant in embryonic brain, heart and eye than in adult tissues. Both eukaryotic translation initiation factor 2alpha (eIF-2alpha) and phospho-eIF-2alpha, which inhibits general protein synthesis, were more abundant in embryonic brain and eye compared to adult. Spliced X-box binding protein-1 mRNA, which is an indicator of the unfolded protein response, was detected in embryonic brain and eye tissues. A partially glycosylated form of activating transcription factor 6alpha, an indicator of ER stress, was also detected in embryonic brain. Active forms of caspase-7 and caspase-12 were found to be more abundant in embryonic tissues than in adult. Thus, our data suggest that ER stress may exist and induce apoptosis via the activation of caspases during embryonic development. |
