title: Ligand-stimulated downregulation of the alpha interferon receptor: role of protein kinase D2.
abstract: Alpha interferon (IFN-α) controls homeostasis of hematopoietic stem cells, regulates antiviral resistance, inhibits angiogenesis, and suppresses tumor growth. This cytokine is often used to treat cancers and chronic viral infections. The extent of cellular responses to IFN-α is limited by the IFN-induced ubiquitination and degradation of the IFN-α/β receptor chain 1 (IFNAR1) chain of the cognate receptor. IFNAR1 ubiquitination is facilitated by the βTrcp E3 ubiquitin ligase that is recruited to IFNAR1 upon its degron phosphorylation, which is induced by the ligand. Here we report identification of protein kinase D2 (PKD2) as a kinase that mediates the ligand-inducible phosphorylation of IFNAR1 degron and enables binding of βTrcp to the receptor. Treatment of cells with IFN-α induces catalytic activity of PKD2 and stimulates its interaction with IFNAR1. Expression and kinase activity of PKD2 are required for the ligand-inducible stimulation of IFNAR1 ubiquitination and endocytosis and for accelerated proteolytic turnover of IFNAR1. Furthermore, inhibition or knockdown of PKD2 robustly augments intracellular signaling induced by IFN-α and increases the efficacy of its antiviral effects. The mechanisms of the ligand-inducible elimination of IFNAR1 are discussed, along with the potential medical significance of this regulation.
authors.affiliation: Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Zheng
authors.forename: Juan
authors.initials: J
authors.lastname: Qian
authors.forename: Bentley
authors.initials: B
authors.lastname: Varghese
authors.forename: Darren P
authors.initials: DP
authors.lastname: Baker
authors.forename: Serge
authors.initials: S
authors.lastname: Fuchs
mesh_terms: D002460:Cell Line; D015536:Down-Regulation; D004705:Endocytosis; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology; D008024:Ligands; D010766:Phosphorylation; D000091283:Protein Kinase D2; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D053633:Receptor, Interferon alpha-beta / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D054875:Ubiquitination
chemical_list: C507964:IFNAR1 protein, human; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D008024:Ligands; D000091283:Protein Kinase D2; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D053633:Receptor, Interferon alpha-beta; D011494:Protein Kinases