title: N-myc downstream-regulated gene 4, up-regulated by tumor necrosis factor-α and nuclear factor kappa B, aggravates cardiac ischemia/reperfusion injury by inhibiting reperfusion injury salvage kinase pathway.
abstract: N-myc downstream-regulated gene 4 (NDRG4) is expressed weakly in heart and has been reported to modulate cardiac development and QT interval duration, but the role of NDRG4 in myocardial ischemia/reperfusion (I/R) injury remains unknown. In the present study, we analyzed the expression as well as potential function of cardiac NDRG4 and investigated how NDRG4 expression is regulated by inflammation. We found that NDRG4 was weakly expressed in cardiomyocytes and that its expression increased significantly both in I/R injured heart and in hypoxia-reoxygenation (H/R) injured neonatal rat ventricular myocytes (NRVMs). The increased NDRG4 expression aggravated myocardial I/R injury by inhibiting the activation of the reperfusion injury salvage kinase (RISK) pathway. Forced over-expression of NDRG4 inhibited RISK activation and exacerbated injury not only in I/R injured heart, but also in H/R treated NRVMs, whereas short hairpin RNA (shRNA)-mediated knock-down of NDRG4 enhanced RISK activation and attenuated injury. Upon injury, myocardial NDRG4 expression was induced by tumor necrosis factor-α (TNF-α) through nuclear factor kappa B (NF-κB), and we found that pre-treatment with inhibitors of either TNF-α or NF-κB blocked NDRG4 expression as well as I/R injury in vivo and H/R injury in vitro. Our study indicates that up-regulation of NDRG4 aggravates myocardial I/R injury by inhibiting activation of the RISK pathway, thereby identifying NDRG4 as a potential therapeutic target in I/R injury.
authors.affiliation: Department of Physiology, Fourth Military Medical University, Xi'an, 710032, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Department of International Medical, China-Japan Frindship Hospital, Beijing, 100029, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Tang
authors.affiliation: Institute of Orthopaedics, Xi'jing Hospital, Fourth Military Medical University, Xi'an, 710032, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Department of Histology and Embryology, Fourth Military Medical University, Xi'an, 710032, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Histology and Embryology, Fourth Military Medical University, Xi'an, 710032, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Histology and Embryology, Fourth Military Medical University, Xi'an, 710032, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Interventional Radiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China.
authors.forename: Wei-dong
authors.initials: WD
authors.lastname: Gong
authors.affiliation: Department of Interventional Radiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China. tdjrfsk@fmmu.edu.cn.
authors.forename: Zhi-qun
authors.initials: ZQ
authors.lastname: Wu
authors.affiliation: Department of Histology and Embryology, Fourth Military Medical University, Xi'an, 710032, China. zcc198822@126.com.
authors.forename: Chu-chao
authors.initials: CC
authors.lastname: Zhu
authors.affiliation: Department of Histology and Embryology, Fourth Military Medical University, Xi'an, 710032, China. zhangyq@fmmu.edu.cn.
authors.forename: Yuan-qiang
authors.initials: YQ
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D008297:Male; D008810:Mice, Inbred C57BL; D009124:Muscle Proteins / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D009124:Muscle Proteins; D016328:NF-kappa B; C527709:Ndrg4 protein, mouse; C486613:Ndrg4 protein, rat; D009419:Nerve Tissue Proteins; D014409:Tumor Necrosis Factor-alpha
keywords: Ischemia/reperfusion (I/R); N-myc downstream-regulated gene 4 (NDRG4); Nuclear factor kappa B (NF-κB); Reperfusion injury salvage kinase (RISK); Tumor necrosis factor-α (TNF-α)