SEA0400, a specific inhibitor of the Na+-Ca2+ exchanger, attenuates sodium nitroprusside-induced apoptosis in cultured rat microglia.
1. Using SEA0400, a potent and selective inhibitor of the Na+-Ca2+ exchanger (NCX), we examined whether NCX is involved in nitric oxide (NO)-induced disturbance of endoplasmic reticulum (ER) Ca2+ homeostasis followed by apoptosis in cultured rat microglia. 2. Sodium nitroprusside (SNP), an NO donor, decreased cell viability in a dose- and time-dependent manner with apoptotic cell death in cultured microglia. 3. Treatment with SNP decreased the ER Ca2+ levels as evaluated by measuring the increase in cytosolic Ca2+ level induced by exposing cells to thapsigargin, an irreversible inhibitor of ER Ca2+-ATPase. 4. The treatment with SNP also increased mRNA expression of CHOP and GPR78, makers of ER stress. 5. SEA0400 at 0.3-1.0 microM protected microglia against SNP-induced apoptosis. 6. SEA0400 blocked not only the SNP-induced decrease in ER Ca2+ levels but also SNP-induced increase in CHOP and GRP78 mRNAs. 7. SEA0400 did not affect capacitative Ca2+ entry in the presence and absence of SNP. 8. SNP increased Na+-dependent 45Ca2+ uptake and this increase was blocked by SEA0400. 9. These results suggest that SNP induces apoptosis via the ER stress pathway and SEA0400 attenuates SNP-induced apoptosis via suppression of the ER stress in cultured microglia. Our findings imply that NCX plays a role in ER Ca2+ depletion under pathological conditions.
Nagano
Takayuki
T
Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan.
Osakada
Masakazu
M
Ago
Yukio
Y
Koyama
Yutaka
Y
Baba
Akemichi
A
Maeda
Sadaaki
S
Takemura
Motohiko
M
Matsuda
Toshio
T
D000814:Aniline Compounds / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D017628:Microglia / Q000187:drug effects*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D010647:Phenyl Ethers / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors*; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
D000814:Aniline Compounds; D022762:CCAAT-Enhancer-Binding Proteins; D002118:Calcium; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D010647:Phenyl Ethers; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D051742:Transcription Factor CHOP; D014157:Transcription Factors; C497251:Ddit3 protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C430918:SEA 0400