Oxidative stress-induced apoptotic insults to rat osteoblasts are attenuated by nitric oxide pretreatment via GATA-5-involved regulation of Bcl-X L gene expression and protein translocation.
Nitric oxide (NO) has biphasic effects on regulating osteoblast survival and death. This study was aimed to evaluate the effects of NO pretreatment on hydrogen peroxide (HP)-induced insults of rat osteoblasts and the possible mechanisms. Exposure of osteoblasts prepared from rat calvarias to HP significantly increased intracellular reactive oxygen species levels, decreased alkaline phosphatase activity and cell survival, and ultimately induced cell apoptosis. However, NO pretreatment lowered HP-induced oxidative stress and apoptotic insults. In parallel, HP increased Bax levels and its translocation from the cytoplasm to mitochondria. NO pretreatment caused significant attenuations in HP-induced modulations in Bax synthesis and translocation. In contrast, pretreatment with NO enhanced levels and translocation of antiapoptotic Bcl-XL protein in rat osteoblasts. RNA analyses further revealed that HP inhibited Bcl-XL mRNA expression without affecting Bax mRNA levels. In comparison, NO induced Bcl-XL mRNA production and alleviated HP-caused inhibition of this mRNA expression. As to the mechanism, HP suppressed RNA and protein levels of transcription factor GATA-5 in rat osteoblasts. Pretreatment with NO induced GATA-5 mRNA and protein expressions and simultaneously attenuated HP-induced inhibition of this gene's expression. Consequently, GATA-5 knockdown using RNA interference inhibited Bcl-XL mRNA expression and concurrently lowered NO's protection against HP-induced apoptotic insults. Therefore, this study showed that NO can protect rat osteoblasts from HP-induced apoptotic insults. The protective mechanisms are mediated by GATA-5-mediated transcriptional induction of Bcl-X L gene, and translocational modulation of Bcl-XL and Bax proteins.
Department of Anesthesiology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.|Anesthetics and Toxicology Research Center, Taipei Medical University Hospital, Taipei, Taiwan.
Gong-Jhe
GJ
Wu
Division of General Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei, Taiwan.
Weu
W
Wang
Cell Physiology and Molecular Image Research Center, Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan.
Yi-Ling
YL
Lin
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Shing Hwa
SH
Liu
Anesthetics and Toxicology Research Center, Taipei Medical University Hospital, Taipei, Taiwan. rmchen@tmu.edu.tw.|Cell Physiology and Molecular Image Research Center, Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan. rmchen@tmu.edu.tw.|Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, 250 Wu-Hsing St., Taipei, 110, Taiwan. rmchen@tmu.edu.tw.
Ruei-Ming
RM
Chen
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D050992:GATA5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000633:toxicity; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D021381:Protein Transport / Q000187:drug effects; D017208:Rats, Wistar; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism; D051020:bcl-X Protein / Q000235:genetics* / Q000378:metabolism
C494828:Bax protein, rat; C494813:Bcl2l1 protein, rat; D050992:GATA5 Transcription Factor; C494757:Gata5 protein, rat; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D009569:Nitric Oxide; D006861:Hydrogen Peroxide
Apoptosis; Bcl-XL; GATA-5; Nitric oxide; Osteoblasts; Oxidative stress