Inhibition of 6-hydroxydopamine-induced endoplasmic reticulum stress by l-carnosine in SH-SY5Y cells.
Conditions that cause endoplasmic reticulum malfunction (ER stress) play a key role in the development of various human diseases including neurodegenerative diseases. Carnosine is an endogenous peptide, present in excitable tissues such as brain and skeletal muscle. Although there are reports suggesting that carnosine has a biological role independent of its antioxidant activity, there have been no reports of the effects of carnosine on the ER stress response. We investigated the effects of carnosine on 6-hydroxydopamine (6-OHDA)-induced cell death and ER stress in SH-SY5Y cells. After assessing control cell viability in serum-free conditions for 24h (100% viability), we found that 50 microM 6-OHDA reduced cell viability to 76.4% of control values, whereas addition of 10mM carnosine significantly reduced cell death to 96.1% viability in a dose-dependent manner. Consistent with its cytoprotective action, carnosine markedly inhibited subsequent ER stress responses, including phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha) and c-jun, expression of glucose regulatory protein 78 and C/EBP homologous protein, and mRNA splicing of X-box protein 1. The measurement of reactive oxygen species (ROS) generation by 6-OHDA showed that addition of 10mM carnosine slightly but obviously inhibits the 6-OHDA-induced ROS production. In conclusion, our results show that carnosine almost completely inhibits 6-OHDA-induced ER stress responses and cytotoxicity, and that slight antioxidant activity of carnosine against 6-OHDA is observed. Further in vivo studies are needed to investigate clinical uses for carnosine.
Oh
Yun-Mi
YM
Department of Pharmacology and Medicinal Toxicological Research Center, Inha Research Institute for Medical Sciences, Republic of Korea.
Jang
Eun-Hee
EH
Ko
Jeong-Hyeon
JH
Kang
Ju-Hee
JH
Park
Chang-Shin
CS
Han
Seung Baik
SB
Kim
Jun Sig
JS
Kim
Kyung Hwan
KH
Pie
Jae-Eun
JE
Shin
Dong Wun
DW
D002336:Carnosine / Q000008:administration & dosage*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000502:physiology; D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D018696:Neuroprotective Agents / Q000008:administration & dosage*; D009498:Neurotoxins / Q000633:toxicity*; D016627:Oxidopamine / Q000633:toxicity*; D010766:Phosphorylation / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012326:RNA Splicing / Q000187:drug effects / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
D000091342:Endoplasmic Reticulum Chaperone BiP; D015852:Eukaryotic Initiation Factor-2; D006360:Heat-Shock Proteins; D018696:Neuroprotective Agents; D009498:Neurotoxins; D016755:Proto-Oncogene Proteins c-jun; D017382:Reactive Oxygen Species; D002336:Carnosine; D016627:Oxidopamine