title: Involvement of TR3/Nur77 translocation to the endoplasmic reticulum in ER stress-induced apoptosis.
abstract: Nuclear orphan receptor TR3/Nur77/NGFI-B is a novel apoptotic effector protein that initiates apoptosis largely by translocating from the nucleus to the mitochondria, causing the release of cytochrome c. However, it is possible that TR3 translocates to other organelles. The present study was designed to determine the intracellular localization of TR3 following CD437-induced nucleocytoplasmic translocation and the mechanisms involved in TR3-induced apoptosis. In human neuroblastoma SK-N-SH cells and human esophageal squamous carcinoma EC109 and EC9706 cells, 5 microM CD437 induced translocation of TR3 to the endoplasmic reticulum (ER). This distribution was confirmed by immunofluorescence analysis, subcellular fractionation analysis and coimmunoprecipitation analysis. The translocated TR3 interacted with ER-targeting Bcl-2; initiated an early release of Ca(2+) from ER; resulted in ER stress and induced apoptosis through ER-specific caspase-4 activation, together with induction of mitochondrial stress and subsequent activation of caspase-9. Our results identified a novel distribution of TR3 in the ER and defined two parallel mitochondrial- and ER-based pathways that ultimately result in apoptotic cell death.
authors.affiliation: Center for Molecular Biology, Shantou University Medical College, Shantou, Guangdong, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.forename: Xuhong
authors.initials: X
authors.lastname: Song
authors.forename: Gefei
authors.initials: G
authors.lastname: Liu
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.forename: Jianping
authors.initials: J
authors.lastname: Xie
authors.forename: Lifeng
authors.initials: L
authors.lastname: Xiao
authors.forename: Mudan
authors.initials: M
authors.lastname: Du
authors.forename: Qiaoxia
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Xu
authors.forename: Xueqiong
authors.initials: X
authors.lastname: Gan
authors.forename: Dongyang
authors.initials: D
authors.lastname: Huang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D053471:Caspases, Initiator / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000378:metabolism*; D011987:Receptors, Steroid / Q000032:analysis / Q000378:metabolism*; D012176:Retinoids / Q000494:pharmacology; D014157:Transcription Factors / Q000032:analysis / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C099555:CD 437; D004268:DNA-Binding Proteins; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D019253:Proto-Oncogene Proteins c-bcl-2; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012176:Retinoids; D014157:Transcription Factors; C093516:CASP4 protein, human; D053453:Caspase 9; D053471:Caspases, Initiator; D002118:Calcium