Analysis of nucleocytoplasmic trafficking of the HuR ligand APRIL and its influence on CD83 expression.
Dendritic cells (DC) are the most potent antigen-presenting cells of the immune system and are able to sensitize even naïve T cells. Mature DC are characterized by expression of CD83, a surface molecule that is proposed to be involved in efficient T cell activation. It has been recently shown that CD83 mRNA is transported from the nucleus to the cytoplasm in a HuR- and CRM1-dependent manner. Therefore we here investigated the impact of two known protein ligands of HuR, pp32 and APRIL, on CD83 expression. Both pp32 (ANP32A) and APRIL (ANP32B) are shuttle proteins, and it has been reported earlier that these HuR ligands can act as adaptors that link HuR and the CRM1-specific nuclear export pathway. By employing RNA interference (RNAi) technology we demonstrate that pp32 is dispensable for CD83 expression, whereas APRIL contributes to the nuclear export and subsequent translation of CD83 mRNA. Furthermore, we have determined the nuclear import signal (NLS) as well as the nuclear export signal (NES) of human APRIL. Moreover, we analyzed the status of phosphorylation of endogenous APRIL and identified threonine 244 to be an as yet unrecognized phosphate acceptor. Finally, we were able to show that phosphorylation of this specific amino acid residue regulates the nuclear export of APRIL. In sum, we report here the signal sequences in APRIL that mediate its intracellular trafficking and provide evidence that this protein ligand of HuR is an important player in the post-transcriptional regulation of CD83 expression by affecting the nucleocytoplasmic translocation of CD83 mRNA.
Fries
Barbara
B
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Heukeshoven
Jochen
J
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Hauber
Ilona
I
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Grüttner
Cordula
C
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Stocking
Carol
C
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Kehlenbach
Ralph H
RH
Zentrum für Biochemie und Molekulare Zellbiologie, Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
Hauber
Joachim
J
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the.
Chemnitz
Jan
J
Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistrasse 52, 20251 Hamburg, Germany and the. Electronic address: jan.chemnitz@hpi.uni-hamburg.de.
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D019556:COS Cells; D002467:Cell Nucleus / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D005786:Gene Expression Regulation / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019169:Jurkat Cells; D008024:Ligands; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D051379:Mice; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000502:physiology; D021382:Protein Sorting Signals / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D016601:RNA-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000097802:CD83 Antigen
D015703:Antigens, CD; D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D007136:Immunoglobulins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D009687:Nuclear Proteins; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D000097802:CD83 Antigen; C087425:ANP32A protein, human; C490341:ANP32B protein, human; C098770:ELAVL1 protein, human