TSA protects H9c2 cells against thapsigargin-induced apoptosis related to endoplasmic reticulum stress-mediated mitochondrial injury

Endoplasmic reticulum stress (ERS) activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. Recently, TSA has shown protective effects on ERS and its mechanisms related to ER pathway has been previously characterized. However, whether TSA exerts its protective role via metabolic events remain largely undefined. Objectives: To explore the possible involvement of the metabolic changes during ERS and to better understand how TSA influence mitochondrial function to facilitate cellular adaptation. Results: TSA is an inhibitor of histone deacetylase which could significantly inhibit H9c2 cell apoptosis induced by Thapsigargin (TG). It also intervene the decrease of mitochondrial membrane potential. By immunofluorescence staining, we have shown that GRP78 was concentrated in the perinuclear region and co-localized with ER. However, treatments with TG and TSA could let it overlap with the mitochondrial marker MitoTracker. Cellular fractionation also confirmed the location of GRP78 in mitochondrion. Conclusions: TSA decreases ERS-induced cell apoptosis and mitochondrial injury may related to enhance the location of GRP78 in mitochondrion.