title: Fas-associated factor (Faf1) is a novel CD40 interactor that regulates CD40-induced NF-κB activation via a negative feedback loop.
abstract: CD40-induced signalling through ligation with its natural ligand (CD40L/CD154) is dependent on recruitment of TRAF molecules to the cytoplasmic domain of the receptor. Here, we applied the yeast two-hybrid system to examine whether other proteins can interact with CD40. Fas-Associated Factor 1(FAF1) was isolated from a HeLa cDNA library using the CD40 cytoplasmic tail (216-278 aa) as a bait construct. FAF1 was able to interact with CD40 both in vitro and in vivo. The FAF1 N-terminal domain was sufficient to bind CD40 and required the TRAF6-binding domain within the cytoplasmic tail of CD40 for binding. CD40 ligation induced FAF1 expression in an NFκB-dependent manner. Knockdown of FAF1 prolonged CD40-induced NFκB, whereas overexpression of FAF1 suppressed CD40-induced NFκB activity and this required interaction of FAF1 with the CD40 receptor via its FID domain. Thus, we report a novel role for FAF1in regulating CD40-induced NFκB activation via a negative feedback loop. Loss of FAF1 function in certain human malignancies may contribute to oncogenesis through unchecked NFκB activation, and further understanding of this process may provide a biomarker of NFκB-targeted therapies for such malignancies.
authors.affiliation: Cancer Research UK Centre, University of Liverpool, Daulby Street, Liverpool, UK.
authors.forename: T
authors.initials: T
authors.lastname: Elmetwali
authors.affiliation: Warwick Medical School, University of Warwick, Coventry, UK.
authors.forename: L S
authors.initials: LS
authors.lastname: Young
authors.affiliation: Cancer Research UK Centre, University of Liverpool, Daulby Street, Liverpool, UK.
authors.forename: D H
authors.initials: DH
authors.lastname: Palmer
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism*; D025461:Feedback, Physiological; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D034622:RNA Interference; D015398:Signal Transduction; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D019013:CD40 Antigens; C490780:FAF1 protein, human; D016328:NF-kappa B; D048029:TNF Receptor-Associated Factor 6