Mitochondrial reactive oxygen species (ROS) inhibition ameliorates palmitate-induced INS-1 beta cell death

Abstract

The purpose of this study is to explore the possible link between oxidative stress and endoplasmic reticulum (ER) stress in palmitate (PA) induced apoptosis of INS-1 cells, and to figure out the main source of reactive oxygen species (ROS) and the effect of ROS inhibition on the level of ER stress. In this study, INS-1 cells were exposed to PA and oleate for the indicated times. Cell viability and apoptosis were measured by MTT and ELISA; ROS was detected by the probe DCFH-DA and MitoSOX Red using flow cytometer; and the ER stress-related chaperones were measured by western blotting and real time PCR. The level of JNK phosphorylation was also measured by western blotting. The results showed that, in PA-treated cells, apoptosis increased in a dose-dependent way. ROS generation was mainly increased through mitochondrion, and ROS inhibition reduced the expression of some ER chaperones and transcription factors levels. Also, inhibition of JNK phosphorylation ameliorated PA-induced apoptosis. It is concluded that, ROS inhibition, especially inhibiting the ROS from mitochondria, may reduce the expression of some ER stress-related effectors and show a protective role in PA-induced pancreatic beta-cell apoptosis.

Asbestos-Induced Alveolar Epithelial Cell Apoptosis. The Role of Endoplasmic Reticulum Stress Response

“…Our data with asbestosexposed AECs implicating mitochondrial ROS in triggering ER stress also concur with studies showing that antioxidants, including those targeted to the mitochondria, attenuate oxidative stress-induced ER stress and apoptosis in other cell types (30)(31)(32)(33). Mitochondria-targeted antioxidants protect against oxidantinduced ER stress and intrinsic apoptosis of pancreatic beta cells (31,33). Mitochondrial ROS activate the UPR in cancer cells, 21 release by a Fura-2 assay (representative data depicted from two separate experiments).…”

“…These findings implicating mitochondrial ROS production as the principal source of asbestos-induced free radicals in our model are in accord with our prior studies that include the following: (1) p0-A549 cells lacking mitochondrial DNA and incapable of mitochondrial ROS production, are protected against asbestosinduced DNA damage, p53 activation, and apoptosis (7,8,22); (2) using highly sensitive reduction-oxidation-sensitive green fluorescent proteins targeted to the mitochondria or cytoplasm to detect ROS production, we have previously reported that the mitochondria are the primary source of ROS generation (42); (3) the mitochondria-regulated (intrinsic) death pathway is the primary pathway mediating AEC apoptosis in vitro (7); and (4) a mitochondria-targeted DNA repair protein (8-oxoguanine DNA glycosylase) or mitochondrial aconitase 2 overexpression each prevent oxidant-induced AEC apoptosis, despite high levels of mitochondrial ROS production (42). Our data with asbestosexposed AECs implicating mitochondrial ROS in triggering ER stress also concur with studies showing that antioxidants, including those targeted to the mitochondria, attenuate oxidative stress-induced ER stress and apoptosis in other cell types (30)(31)(32)(33). Mitochondria-targeted antioxidants protect against oxidantinduced ER stress and intrinsic apoptosis of pancreatic beta cells (31,33).…”

Inhibition of SH2-domain-containing inositol 5-phosphatase (SHIP2) ameliorates palmitate induced-apoptosis through regulating Akt/FOXO1 pathway and ROS production in HepG2 cells

“…A growing body of evidence suggests that the oxidative stress due to excessive production of ROS is the main contributor to the pathophysiology of diabetic complications [21,30]. Increasing ROS production has been demonstrated to account for apoptosis in response to palmitate in numerous cell lines [31,32]. However, the role of ROS in stimulating lipoapoptosis appears to be cell-type dependent as palmitate-treated neonatal cardiomyocytes undergo apoptosis independently of the oxidative stress [33].…”

Prolonged insulin treatment sensitizes apoptosis pathways in pancreatic β cells

“…Excess accumulation of ROS in pancreatic β cells induces both oxidative and endoplasmic reticulum (ER) stress, which triggers the unfolded protein response (UPR) (Vanderford 2010) which may lead, if sustained, to β-cell dysfunction and apoptosis (Kitiphongspattana et al 2007, Lin et al 2012. To examine whether insulin might alter expression of UPR-associated genes, we determined the mRNA levels of Bip, Xbp1, Atf4 and Chop (Walter & Ron 2011) in MIN6 cells treated with insulin for 24-48 h. As shown in Fig.…”