TNF stimulates nuclear export and secretion of IL-15 by acting on CRM1 and ARF6.
Interleukin (IL)-15 is a ubiquitously expressed cytokine that in the basal state is mainly localized intracellularly, including the nucleus. Unexpectedly, tumor necrosis factor-α (TNF) time-dependently induced nuclear export of IL-15Rα and IL15. This process was inhibited by leptomycine B (LMB), a specific inhibitor of nuclear export receptor chromosomal region maintenance 1 (CRM1). In the presence of TNF, LMB co-treatment led to accumulation of both IL-15Rα and IL-15 in the nucleus of HeLa cells, suggesting that CRM1 facilitates nuclear export and that TNF enhances CRM1 activity. Once in the cytoplasm, IL-15 showed partial co-localization with late endosomes but very little with other organelles tested 4 h after TNF treatment. IL-15Rα showed co-localization with both early and late endosomes, and to a lesser extent with endoplasmic reticulum and Golgi. This indicates different kinetics and possibly different trafficking routes of IL-15 from its specific receptor. The TNF-induced secretion of IL-15 was attenuated by pretreatment of cells by brefeldin A that inhibits ER-to-Golgi transport, or by use of domain negative ADP-ribosylation factor 6 (ARF6) that interferes with exocytotic sorting. We conclude that TNF abolishes nuclear localization of IL-15 and IL-15Rα by acting on CRM1, and it facilitates exocytosis of IL-15 with the involvement of ARF6.
Pennington Biomedical Research Center, Baton Rouge, Louisana, United States of America.
Suidong
S
Ouyang
Hung
H
Hsuchou
Abba J
AJ
Kastin
Weihong
W
Pan
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D015153:Blotting, Western; D020126:Brefeldin A / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D019409:Interleukin-15 / Q000378:metabolism*; D053720:Interleukin-15 Receptor alpha Subunit / Q000235:genetics / Q000378:metabolism; D028884:Karyopherins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D011485:Protein Binding; D021381:Protein Transport / Q000187:drug effects; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000097606:Exportin 1 Protein
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors; D020126:Brefeldin A; D005231:Fatty Acids, Unsaturated; D049452:Green Fluorescent Proteins; D019409:Interleukin-15; D053720:Interleukin-15 Receptor alpha Subunit; D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D014409:Tumor Necrosis Factor-alpha; D000097606:Exportin 1 Protein; C000715348:ARF6 protein, human; C038753:leptomycin B