Studies On Ehdoplasmic Reticulum Stress Of Human Lens Epithelial Cells Exposed To Different Concentrations Of Calcium Ions In Vitro

Objective:To investigate the endoplasmic reticulum stress (ERS) oncalcium-induced lens epithelial cells (LECs) apoptisis and its possible mechanism ofcataract.Method:1. Human LECs were cultured in DMEM medium and DMEM medium withadditional of1.0,5.0,7.5,10.0,15.0,20.0,25.0mmol/L of calcium for24hours.2. Calcium fluorescent probe Fluo-3and flow cytometry were used to detect thelevel of intracellular free calcium.3. Immunofluorescence technique and Western blot techniques were used to detectthe effect of dynamic concentration of calcium ions in vitro on the expression ofcalpain-2,GRP78and caspase-12.4. DAPI staining technique was used to detect cell apoptosis.Result:1. The flow cytometry images showed human LECs fluorescence intensity increasedin the calcium-treated group,the fluorescence intensity gradually increased with thecalcium concentration increased in the DMEM medium (P<0.01).2. The immunofluorescence and Western blot showed that the expression ofcalpain-2in the calcium-treated group increased compared to normal control groupin human LECs cultured in vitro (P<0.01).3. As the duration of calcium ions administration extended, protein expression levelsof GRP78and caspase-12were gradually increased(P<0.01).4. The human LECs apoptosis rate has no significant changes in DMEM mediumwith additional of1.0mmol/L calcium compared to normal controlgroup(P>0.05).When the DMEM medium with additional of5.0mmol/L calcium,the human LECs apoptosis rate increased, the difference was statistically significant (P<0.05).Conclusion:1. The expression of GRP78、 calpain-2and caspase-12increase with theconcentration of extracellular calcium increased in human LECs cultured in vitro.2. The human LECs apoptosis rate has no effect when concentration of extracellularcalcium increased slightly.While concentration of intracellular free calcium increasedabnormal levels,the cell apoptosis appeared.3. When concentration of extracellular calcium increase,it may induce the humanLECs endoplasmic reticulum stress and apoptosis by the signal transducing systemwhich containd calpain-2and caspase-12.This may be one of the cataractpathogenesis.