Endoplasmic reticulum stress signaling involvement in manganese-induced nerve cell damage in organotypic brain slice cultures.
Overexposure to manganese (Mn) has been known to induce neuronal damage. However, the mechanisms underlying the neurotoxicity of Mn are still incompletely understood but seem to involve endoplasmic reticulum (ER) stress. The current study investigated whether ER stress signaling was involved in Mn-induced neurotoxicity in organotypic brain slices. After the brain slices were respectively exposed to 400μM Mn for 0, 6, 12, 18, 24h, there was a time-dependent increase in apoptotic cell death in slices and levels of lactate dehydrogenase (LDH) in the culture medium. Moreover, Mn was found to upregulate GRP78/94, CHOP and caspase-12 expression. Furthermore, PERK phosphorylation, PERK-mediated phosphorylation of eIF2a and ATF4 mRNA expression increased. IRE1 activation and Xbp1 mRNA splicing also increased. However, ATF6 p90 levels did not change. The findings clearly demonstrated that Mn induced the ER stress via activation of PERK and IRE1 signaling pathway, which contributed to the occurrence of apoptosis in cultured slices.
Department of Environmental Health, School of Public Health, China Medical University, People's Republic of China. Electronic address: xubin@mail.cmu.edu.cn.
Bin
B
Xu
Ming
M
Shan
Fei
F
Wang
Yu
Y
Deng
Wei
W
Liu
Shu
S
Feng
Tian-Yao
TY
Yang
Zhao-Fa
ZF
Xu
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001921:Brain / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects*; D006360:Heat-Shock Proteins / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008345:Manganese / Q000633:toxicity*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D046509:Tissue Culture Techniques; D019892:eIF-2 Kinase / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
D006360:Heat-Shock Proteins; D007770:L-Lactate Dehydrogenase; D008345:Manganese; D008562:Membrane Glycoproteins; D019892:eIF-2 Kinase; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C053387:endoplasmin
78-kDa glucose-regulated protein; 94-kDa glucose-regulated protein; ANOVA; ATF6; Apoptosis; C/EBP homologous protein; CHOP; ER; Endoplasmic reticulum stress; GRP78; GRP94; HBSS; Hank's balanced salt solution; IRE1; LDH; MMT; Manganese; Mn; Neurotoxicity; PERK; PI; UPR; activating transcription factor 6; eIF2α; endoplasmic reticulum; inositol-requiring enzyme 1; lactate dehydrogenase; manganese; methylcyclopentadienyl Mn tricarbonyl; one-way analysis of variance; pancreatic ER kinase RNA (PKR) like ER kinase; propidiumiodide; unfolded protein response; α subunit of eukaryotic translation initiation factor 2