Cholesterol induces pancreatic β cell apoptosis through oxidative stress pathway

Abstract

Type 2 diabetes is often associated with high blood cholesterol. Here, we investigated the effect of cholesterol loading on MIN6 cells derived from pancreatic β cells. Exposure of MIN6 cells to cholesterol-induced apoptosis in time-and dose-dependent manner. Treatment with methyl-β-cyclodextrin that removes cholesterol from plasma membrane prevented the cells from cholesterolinduced apoptosis. Western blot analysis revealed that the levels of phosphorylated-p38 mitogen-activated protein kinase (P-p38 MAPK) and c-Jun N-terminal kinases (P-JNK) were significantly increased after the cholesterol loading, suggesting that the stress-activated protein kinase signaling was stimulated. A specific p38 inhibitor rescued MIN6 cells from cholesterol-induced apoptosis, while JNK inhibitor failed, suggesting the importance of activation of p38 MAPK signaling in response to cholesterol. The expression of Bip and CHOP, the endoplasmic reticulum (ER) stress markers, remained unaffected, indicating that the ER stress may not be involved in the cytotoxicity of cholesterol on the MΙΝ6 cells. The intracellular concentration of reactive oxygen species measured by use of 2′,7′-dichlorofluorescin diacetate was significantly increased after cholesterol loading, demonstrating the induced apoptosis was mediated through oxidative stress. Addition of reduced form of glutathione in the medium rescued MIN6 cells from apoptosis induced by cholesterol loading. Taken together, these results demonstrate that the free cholesterol loading can induce apoptosis of MIN6 cells mediated by oxidative stress and the activation of p38 MAPK signaling.

3,4-dihydroxyphenylacetic acid, a microbiota-derived metabolite of quercetin, protects against pancreatic β-cells dysfunction induced by high cholesterol

“…In addition, this effect on cell viability was corroborated by the fact that cholesterol also induced a 35% increase in LDH leakage and trypan blue (data not shown). In line with the current study, Lu et al reported that cholesterol decreased Min6 cell attachments to the flask bottom by 30% after 24 h of incubation [8].…”

“…Interestingly, the loss of ABCG1 expression in β-cells impaired insulin secretion, where ABCG1 acts primarily to regulate the subcellular cholesterol distribution in β-cells; thus a critical role for pancreatic β cell-specific cholesterol homeostasis seems to be involved in insulin secretion as well as in β cell dysfunction in diabetes [6]. Few in vitro studies have been carried out to elucidate the underlying mechanism of cholesterol-induced insulin secretion impairment; their results suggest that cholesterol may induce β-cell dysfunction by promoting apoptosis through oxidative stress pathways [7,8], mitochondrial damage [9] and alteration in membrane fluidity [10]. This is particularly interesting since pancreatic β-cells are considered to be particularly susceptible to oxidative stress due to their relatively low antioxidant enzyme content [11].…”

Supercritical carbon dioxide hops extracts with antimicrobial properties

“…This was confirmed for brassicasterol (ergo-5,22-dien-3β-ol). Of note, it has been reported that intracellular cholesterol accumulation induces apoptosis of pancreatic cells [27].…”

The membrane topological analysis of 3β-hydroxysteroid-Δ24 reductase (DHCR24) on endoplasmic reticulum

“…Intracellular ROS levels were measured using a fluorescent dye technique (Lu et al 2011). N2A cells were cultured on glass coverslips and were treated for 30 min with 20 mM 2 0 ,7 0 -dichlorofluorescin diacetate (H 2 DCFDA; Molecular Probes, Eugene, OR, USA) in PBS.…”