DDIT3/CHOP promotes LPS/ATP-induced pyroptosis in osteoblasts via mitophagy inhibition

• Published in: Biochimica et biophysica acta. Molecular cell research Vol. 1871; no. 4; p. 119712
• Main Authors: Dong, Zhipeng, Yang, Beining, Jia, Meie, Yang, Chang, Wang, Shuo, Mu, Hailin, Wang, Jiawei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2024
• Subjects: DDIT3/CHOP; Mitophagy; Osteoblast; Pyroptosis; DDIT3/CHOP; Osteoblast; Pyroptosis; Mitophagy
• ISSN: 0167-4889; 1879-2596
• DOI: 10.1016/j.bbamcr.2024.119712

Inflammatory environments can trigger endoplasmic reticulum (ER) stress and lead to pyroptosis in various tissues and cells, including liver, brain, and immune cells. As a key factor of ER stress, DNA damage-inducible transcript 3 (DDIT3)/CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) is upregulated in osteoblasts during inflammatory stimulation. DDIT3/CHOP may therefore regulate osteoblast pyroptosis in inflammatory conditions. During this investigation, we found that lipopolysaccharides (LPS)/adenosine 5′-triphosphate (ATP) stimulation in vitro induced osteoblasts to undergo pyroptosis, and the expression of DDIT3/CHOP was increased during this process. The overexpression of DDIT3/CHOP further promoted osteoblast pyroptosis as evidenced by the increased expression of the inflammasome NLR family pyrin domain containing 3 (NLRP3) and ratios of caspase-1 p20/caspase-1 and cleaved gasdermin D (GSDMD)/GSDMD. To explore the specific mechanism of this effect, we found through fluorescence imaging and Western blot analysis that LPS/ATP stimulation promoted PTEN-induced kinase 1 (PINK1)/E3 ubiquitin-protein ligase parkin (Parkin)-mediated mitophagy in osteoblasts, and this alteration was suppressed by the DDIT3/CHOP overexpression, resulting in increased ratio of pyroptosis compared with the control groups. The impact of DDIT3/CHOP on pyroptosis in osteoblasts was reversed by the application of carbonyl cyanide 3-chlorophenylhydrazone (CCCP), a specific mitophagy agonist. Therefore, our data demonstrated that DDIT3/CHOP promotes osteoblast pyroptosis by inhibiting PINK1/Parkin-mediated mitophagy in an inflammatory environment. •DDIT3/CHOP was upregulated in primary osteoblasts after LPS/ATP stimulation.•Altering DDIT3/CHOP expression affected osteoblast cell viability and pyroptosis after LPS/ATP stimulation.•DDIT3/CHOP inhibited PINK1/Parkin-mediated mitophagy, thereby promoting LPS/ATP-related pyroptotic activation in osteoblasts.