Adaptive responses induced by 24S-hydroxycholesterol through liver X receptor pathway reduce 7-ketocholesterol-caused neuronal cell death

Akishi Okabe, Yasuomi Urano, Sayoko Itoh, Naoto Suda, Rina Kotani, Yuki Nishimura, Yoshiro Saito, Noriko Noguchi

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

Lipid peroxidation products have been known to induce cellular adaptive responses and enhance tolerance against subsequent oxidative stress through up-regulation of antioxidant compounds and enzymes. 24S-hydroxycholesterol (24SOHC) which is endogenously produced oxysterol in the brain plays an important role in maintaining brain cholesterol homeostasis. In this study, we evaluated adaptive responses induced by brain-specific oxysterol 24SOHC in human neuroblastoma SH-SY5Y cells. Cells treated with 24SOHC at sub-lethal concentrations showed significant reduction in cell death induced by subsequent treatment with 7-ketocholesterol (7KC) in both undifferentiated and retinoic acid-differentiated SH-SY5Y cells. These adaptive responses were also induced by other oxysterols such as 25-hydroxycholesterol and 27-hydroxycholesterol which are known to be ligands of liver X receptor (LXR). Co-treatment of 24SOHC with 9- cis retinoic acid, a retinoid X receptor ligand, enhanced the adaptive responses. Knockdown of LXRβ by siRNA diminished the adaptive responses induced by 24SOHC almost completely. The treatment with 24SOHC induced the expression of LXR target genes, such as ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1). The 24SOHC-induced adaptive responses were significantly attenuated by siRNA for ABCG1 but not by siRNA for ABCA1. Taken together, these results strongly suggest that 24SOHC at sub-lethal concentrations induces adaptive responses via transcriptional activation of LXR signaling pathway, thereby protecting neuronal cells from subsequent 7KC-induced cytotoxicity.

Original languageEnglish
Pages (from-to)28-35
Number of pages8
JournalRedox Biology
Volume2
Issue number1
DOIs
Publication statusPublished - 2014
Externally publishedYes

Keywords

  • 24S-hydroxycholesterol
  • 7-ketocholesterol
  • ATP-binding cassette transporter G1
  • Adaptive responses
  • Cell death
  • Liver X receptor

ASJC Scopus subject areas

  • Organic Chemistry
  • Clinical Biochemistry

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