title: Cyclophilin A is required for CXCR4-mediated nuclear export of heterogeneous nuclear ribonucleoprotein A2, activation and nuclear translocation of ERK1/2, and chemotactic cell migration.
abstract: The chemokine receptor CXCR4-mediated signaling cascades play an important role in cell proliferation and migration, but the underlying mechanisms by which the receptor signaling is regulated remain incompletely understood. Here, we demonstrate that CXCR4 was co-immunoprecipitated with cyclophilin A (CyPA) from the lysate of HEK293 cells stably expressing CXCR4. Although both the glutathione S-transferase-CXCR4 N- and C-terminal fusion proteins were associated with the purified CyPA, truncation of the C-terminal domain of CXCR4 robustly inhibited the receptor co-immunoprecipitation with CyPA in intact cells, thereby suggesting a critical role of the receptor C terminus in this interaction. Ligand stimulation of CXCR4 induced CyPA phosphorylation and nuclear translocation, both of which were inhibited by truncation of the C-terminal domain of CXCR4. CyPA was associated with transportin 1, and knockdown of transportin 1 by RNA interference (RNAi) blocked CXCL12-induced nuclear translocation of CyPA, thereby suggesting a transportin 1-mediated nuclear import of CyPA. CyPA formed a complex with heterogeneous nuclear ribonucleoprotein (hnRNP) A2, which underwent nuclear export in response to activation of CXCR4. Interestingly, the CXCR4-mediated nuclear export of hnRNP A2 was blocked by RNAi of CyPA. Moreover, CXCR4-evoked activation of extracellular signal-regulated kinase 1/2 (ERK1/2) was attenuated by CyPA RNAi, by overexpression of a PPIase-deficient mutant of CyPA (CyPA-R55A), and by pretreatment of the immunosuppressive drugs, cyclosporine A and sanglifehrin A. Finally, CXCL12-induced chemotaxis of HEK293 cells stably expressing CXCR4 or Jurkat T cells was inhibited by CyPA RNAi or CsA treatment.
authors.affiliation: Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Pan
authors.affiliation: Department of Veterans Affairs and Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, Tennessee 37208.
authors.forename: Cherry
authors.initials: C
authors.lastname: Luo
authors.affiliation: Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Runsheng
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Veterans Affairs and Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, Tennessee 37208.
authors.forename: Aimin
authors.initials: A
authors.lastname: Qiao
authors.affiliation: Department of Pathology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Veterans Affairs and Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, Tennessee 37208.
authors.forename: Marjelo
authors.initials: M
authors.lastname: Mines
authors.affiliation: Department of Veterans Affairs and Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, Tennessee 37208.
authors.forename: Alfred M
authors.initials: AM
authors.lastname: Nyanda
authors.affiliation: Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Jingwu
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Veterans Affairs and Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, Tennessee 37208. Electronic address: gfan@mmc.edu.
authors.forename: Guo-Huang
authors.initials: GH
authors.lastname: Fan
mesh_terms: D002460:Cell Line; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002633:Chemotaxis / Q000235:genetics / Q000502:physiology; D021984:Cyclophilin A / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011485:Protein Binding; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D028961:beta Karyopherins / Q000235:genetics / Q000378:metabolism
chemical_list: D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; D011994:Recombinant Proteins; C108121:TNPO1 protein, human; D028961:beta Karyopherins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D021984:Cyclophilin A