title: Characterization of LRRFIP1.
abstract: LRRFIP1 has been identified as a regulator of toll-like receptor (TLR) pathway signaling; however, little is known about its own regulation and function. This study was undertaken to characterize the biochemical properties and its regulation. Over-expression of full length LRRFIP1 led to enhanced responses to lipopolysaccharide (LPS). We examined its expression in monocytic cell lines because they express a broad range of TLRs. We found that its level of expression was not altered by LPS or phorbol myristate acetate (PMA) but that it was up-regulated by nicotine, influenza infection, and serum starvation. Phosphorylation was examined because of the bioinformatically predicted serine phosphorylation sites. Serine phosphorylation was detected and was altered by both poly I:C and nicotine. Finally, we examined the regulation of intracellular localization in response to dsRNA and found that LRRFIP1 colocalized with labeled dsRNA in monocyte lysosomal structures but not with lysosomes lacking dsRNA. These data suggest that LRRFIP1 is phosphorylated in response to immunologic stimuli and it is directed to lysosomal structures.
authors.affiliation: The Children's Hospital of Philadelphia, The University of Pennsylvania School of Medicine, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Arakawa
authors.forename: Asen
authors.initials: A
authors.lastname: Bagashev
authors.forename: Li
authors.initials: L
authors.lastname: Song
authors.forename: Kelly
authors.initials: K
authors.lastname: Maurer
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Sullivan
mesh_terms: D000818:Animals; D002460:Cell Line; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007251:Influenza, Human / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D009000:Monocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism* / Q000648:ultrastructure; D009538:Nicotine / Q000378:metabolism / Q000494:pharmacology; D010766:Phosphorylation; D011070:Poly I-C / Q000378:metabolism / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism / Q000494:pharmacology; D051193:Toll-Like Receptors / Q000276:immunology / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016207:Cytokines; C114370:LRRFIP1 protein, human; D008070:Lipopolysaccharides; D012330:RNA, Double-Stranded; D016601:RNA-Binding Proteins; D051193:Toll-Like Receptors; D009538:Nicotine; D013755:Tetradecanoylphorbol Acetate; D011070:Poly I-C