An alternatively spliced CXCL16 isoform expressed by dendritic cells is a secreted chemoattractant for CXCR6+ cells.
DC are professional APCs that initiate and regulate adaptive immune responses by interacting with naïve and memory T cells. Chemokines released by DC play an essential role in T cell recruitment and in the maintenance of antigen-specific T cell-DC conjugates. Here, we characterized the expression of the T cell-attracting chemokine CXCL16 by murine DC. We demonstrate that through alternative RNA splicing, DC not only express the previously characterized transmembrane CXCL16 isoform, which can be cleaved from the cell surface, but also a novel isoform lacking the transmembrane and cytoplasmic domains. Transfection of HEK293 cells shows that this novel isoform, termed CXCL16v, is not expressed on the cell membrane but is secreted as a protein of approximately 10 kDa. Quantitative PCR demonstrates that CXCL16v is broadly expressed in lymphoid and nonlymphoid tissues resembling the tissue distribution of DC. Indeed, CXCL16v mRNA is expressed significantly by spleen DC and BM-DC. Moreover, we show that mature DC have increased CXCL16v mRNA levels and express transmembrane and soluble CXCL16 proteins. Finally, we show that CXCL16v specifically attracts cells expressing the chemokine receptor CXCR6. Our data demonstrate that mature DC express secreted, transmembrane, and cleaved CXCL16 isoforms to recruit and communicate efficiently with CXCR6(+) lymphoid cells.
van der Voort
Robbert
R
Laboratory Medicine, Laboratory of Hematology and Tumor Immunology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Verweij
Viviènne
V
de Witte
Theo M
TM
Lasonder
Edwin
E
Adema
Gosse J
GJ
Dolstra
Harry
H
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D000075743:Chemokine CXCL16; D054427:Chemokine CXCL6 / Q000235:genetics*; D002630:Chemotactic Factors / Q000378:metabolism*; D002853:Chromatography, Liquid; D003713:Dendritic Cells / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D054387:Receptors, CXCR / Q000235:genetics*; D000075744:Receptors, CXCR6; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D053719:Tandem Mass Spectrometry
D000075743:Chemokine CXCL16; D054427:Chemokine CXCL6; D002630:Chemotactic Factors; C498926:Cxcl16 protein, mouse; C482906:Cxcr6 protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D054387:Receptors, CXCR; D000075744:Receptors, CXCR6