The PERK/Nrf2 pathway mediates endoplasmic reticulum stress-induced injury by upregulating endoplasmic reticulophagy in H9c2 cardiomyoblasts

• Published in: Life sciences (1973) 2019-11, Vol.237, p.116944-116944, Article 116944
• Main Authors: Tao, Tianqi, Wang, Jianli, Wang, Xiaoreng, Wang, You, Mao, Huimin, Liu, Xiuhua
• Format: Article
• Language: English
• Subjects: Activating Transcription Factor 4 - metabolism; Animals; Apoptosis; Beclin-1 - metabolism; Calreticulin; Cell injury; Cells, Cultured; Cellular stress response; eIF-2 Kinase - metabolism; Endoplasmic reticulophagy; Endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum - pathology; Endoplasmic Reticulum Stress; H9c2 cell; Immunofluorescence; Inhibitors; Injuries; Kinases; Microtubule-Associated Proteins - metabolism; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; NF-E2-Related Factor 2 - metabolism; Nuclear factor erythroid 2-related factor 2; Nuclear transport; Oxidative Stress; Phosphorylation; Protein kinase R; Protein kinase R-like ER kinase; Rats; Signal Transduction; Staining; Thapsigargin; Translocation; Transmission electron microscopy; Tunicamycin; Western blotting
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2019.116944

Endoplasmic reticulum stress (ERS) is an evolutionarily conserved cell stress response. Recently, it was found that ERS induces not only apoptosis but also endoplasmic reticulophagy (ER-phagy). A previous study demonstrated that inhibition of ER-phagy alleviates cell injury. The purpose of this study was to investigate the involvement of the protein kinase R-like ER kinase (PERK)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in ERS-induced ER-phagy in H9c2 cardiomyoblasts. To address this aim, cells were treated with ERS inhibitors and a Nrf2 inhibitor before establishment of thapsigargin (TG)- or tunicamycin (TM)-induced ERS models in H9c2 cardiomyoblasts. Transmission electron microscopy and immunofluorescence staining were used to detect ER-phagy. Western blotting was employed to detect the levels of calreticulin (CRT), total and phosphorylated PERK, nuclear Nrf2, activated transcription factor 4 (ATF4), light chain 3B (LC3B)-II and Beclin 1. Immunofluorescence staining was used to assess subcellular location of Nrf2. TG or TM induced H9c2 cell injury and ER-phagy and upregulated CRT expression, PERK phosphorylation, Nrf2 nuclear translocation, and expression of ATF4, Beclin 1, and LC3B-II compared with control cells. Treatment with ERS inhibitors decreased TG- or TM-induced ER-phagy, downregulated CRT expression, PERK phosphorylation, Nrf2 nuclear translocation and the expression of ATF4, Beclin 1 and LC3B-II. Moreover, a Nrf2 inhibitor downregulated the expression of ATF4, Beclin 1 and LC3B-II and alleviated TG- or TM-induced ER-phagy and H9c2 cell injury. These findings suggest that the PERK/Nrf2 pathway mediates upregulation of ER-phagy, thereby inducing cell injury in H9c2 cardiomyoblasts.