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Recettore per l’IFNα

Università degli Studi di TorinoScuola Universitaria per le Biotecnologie

Corso di Laurea Specialistica in Biotecnologie Molecolari

Riccardo Pizzo

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Complesso ifnar1-ifnar2

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Organizzazione dei geni

Locus del recettore delle citochine di classe II nell’uomo,nel topo, nel pollo

Hardy MP. et al., “Multiple regions within the promoter of murine Ifnar-2 gene confer basal and inducible expression”, Biochem.J. 365:355,2002

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Organizzazione del gene IFNAR1

Diop G. et al., “Exhaustive genotyping of the interferon alpha receptor 1 (IFNAR1) gene and association of an IFNAR1 protein variant with AIDS progression or susceptibility to HIV-1 infection in a French AIDS cohort”, Biomed Pharmacother. 60:569,2006

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Organizzazione del gene IFNAR2

Varianti di splicing

huIFNAR-2a = forma solubilehuIFNAR-2b = forma tronca

huIFNAR-2c = forma completa = 515 aminoacidiHardy MP. et al., “Multiple regions within the promoter of murine Ifnar-2 gene confer basal and inducible expression”, Biochem.J. 365:355,2002

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Formazione del complesso IFNAR1-IFNAR2-IFNα

IFNAR2 EC

Chill J.H.. et al., “The human type I interferon receptor: NMR structure reveals the molecular basis of ligand binding”, Structure 11:791,2003

Istidine nel sito di legame

Meccanismo di dissociazione del complesso ternario

Domini SD perpendicolari

Strisce idrofobiche e idrofiliche parallele

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IFNAR1

SD1

SD2

SD3

SD4

IFNAR1 IFNAR2

IFNα

SD4 corretta orientazione dei domini SD1-2-3 Alta efficienza di

reclutamento di IFNAR1 nel complesso ternario

SD1-2-3 legame a bassa affinità con IFNα

IFNAR1 aumenta di 20 volte l’affinità di legame di IFNAR2

Cajean-Feroldi C. et al., “Identification of residues of the IFNAR1 chain of type I human interferon receptor critical for ligand binding and biological activity”, Biochemistry 43:12498,2004

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Lamken P. et al., “Functional cartography of the ectodomain of type I interferon receptor subunit ifnar1”, J.Mol.Biol. 350:476 ,2005

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Trasduzione del segnale

Blocco della proliferazione+apoptosi

Takaoka A. et Yanai H., “Interferon signaling network in innate defence”, Cell Microbiol . 8:907 ,2006

Jak/Stat

Takaoka A. et Taniguchi T., “New aspects of IFNα-β signalling in immunity, oncogenesis and bone metabolism”, Cancer sci. 94:405 ,2003

ERK2/p38

Stat5-CrkL

PKCδ

PI3K

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PI3K sopravvivenzaapoptosi VS

Pokrovskaja K. et al., “Alternative signaling pathways regulating type I interferon-induced apoptosis”, J Interferon Cytokine Res. . 25:799 ,2005

Caraglia M. et al., “Alpha-interferon and its effests on signal trasduction pathways”, J Cell Physiol . 202:323 ,2005

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1)Trasduzione del segnale mediato dal dominio citoplasmatico ICD di IFNAR2

IFNAR2

1°clivaggioformazione del membrane stub =58kD

2°clivaggio formazione dell’ICD =34kD

Proteolisi attivata da IFNα+ PMA+ TNFα+ p38MAPK+ PKCδ+ EGF

Preseniline coinvolte nel clivaggio di IFNAR2

INFNAR2 ICD localizza nel nucleo

Inibizione della trascrizione mediato da HDAC per costrutti contenenti promotore TK

Attivazione della trascrizione mediato da Stat2 per costrutti contenenti promotore α-globina+VHL

Saleh A.ZM. et al., “Regulated proteolysis of the IFNaR2 subunit of the interferon-alpha receptor”, Oncogene. 23:7076,2004

El Fiky A. et al., “Intracellular domain of the IFNaR2 interferon receptor subunit mediates transcription via Stat2”, J Cell Physiol . 204:567 ,2005

Modulazione del segnale

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Ifnar1 proteina2)Modulazione del segnale mediato da IFNAR2 solubile

IFNAR2a vs IFNAR2c

Western blots di siero,liquido peritoneale,urina di topo adulto

Quantificazione dell’espressione dell’mRNA di IFNAR2 in tessuti di topo adulto

Inibizione dell’attività indotta dall’INFα dell’ 2’5’ OASLuc L ad opera di IFNAR-2a

Inibizione dell’effetto antiproliferativo dell’IFNα su timociti primari ad opera di IFNAR-2a ricombinante

IFNAR-2a inibisce l’attività dell’IFNα Hardy MP. et al., “The soluble murine type I interferon receptor Ifnar-2 is present in serum, is independently regulated,and has both agonistic and antagonist properties”, Blood 97:473,2001

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Complementazione dell’attività antiproliferativa indotta dall’INFα in timociti IFNAR-2 -/- ad opera di IFNAR-2a

IFNAR-2a può formare un complesso con IFNAR1 capace di mediare una parziale risposta antiproliferativa

Il segnale indotto da IFNα può essere trasdotto in assenza del dominio intracellulare di IFNAR-2c

IFNAR-2a inibitorio

IFNAR-2a stimolatorio

Hardy MP. et al., “The soluble murine type I interferon receptor Ifnar-2 is present in serum, is independently regulated,and has both agonistic and antagonist properties”, Blood 97:473,2001

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3)Modulazione del segnale mediato da cross-competizione

EpoR/IFNAR1 chimera downmodula la risposta a IFNα

IL-12Rβ1 downmodula la risposta a IFNα

EpoR/IFNAR1 chimera+ IL-12Rβ1 interferiscono con il pathway JAK-STAT

EpoR/IFNAR1 chimera+ IL-12Rβ1 riducono i livelli di IFNAR1 in membrana

Riduzione di IFNAR1 dipende da Tyk2

Dondi E. et al., “Down-modulation of type I interferon responses by receptor cross-competition for a shared Jak kinase”, J.Biol.Chem. 276:47004,2001

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Downregolazione del segnale

Fosfatasi= SHP1+SHP2+TcPTP

SOCS

PIAS

Crm1

David M., “Signal transduction by type I interferons”, BioTechniques. 33:S58,2002

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Dowregolazione di IFNAR1

IFNα induce degradazione

Degradazione nei lisosomi

Stimolazione con IFNα attiva Tyk2

Tyk2 induce la fosforilazione di Ser535 di IFNAR1

Marijanovic Z. et al., “TYK2 activity promotes ligand-induced IFNAR1 proteolysis”, Biochem.J. 397:31,2006

Ser535 di IFNAR1 è necessaria per il legame con β-Trcp

Ser535 di IFNAR1 è necessaria per l’ubiquitinazione

Kumar K.G. et al., “Phosphorylation and specific ubiquitin acceptor sites are required for ubiquitination and degradation of tha IFNAR1 subunit of type I interferon receptor”, J.Biol.Chem. 279:46614,2004

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Hardy MP. et al., “Multiple regions within the promoter of murine Ifnar-2 gene confer basal and inducible expression”, Biochem.J. 365:355,2002

Diop G. et al., “Exhaustive genotyping of the interferon alpha receptor 1 (IFNAR1) gene and association of an IFNAR1 protein variant with AIDS progression or susceptibility to HIV-1 infection in a French AIDS cohort”, Biomed Pharmacother. 60:569,2006

Chill J.H.. et al., “The human type I interferon receptor: NMR structure reveals the molecular basis of ligand binding”, Structure 11:791,2003

Cajean-Feroldi C. et al., “Identification of residues of the IFNAR1 chain of type I human interferon receptor critical for ligand binding and biological activity”, Biochemistry 43:12498,2004

Lamken P. et al., “Functional cartography of the ectodomain of type I interferon receptor subunit ifnar1”, J.Mol.Biol. 350:476 ,2005

Takaoka A. et Taniguchi T., “New aspects of IFNα-β signalling in immunity, oncogenesis and bone metabolism”, Cancer sci. 94:405 ,2003

Takaoka A. et Yanai H., “Interferon signaling network in innate defence”, Cell Microbiol . 8:907 ,2006

Pokrovskaja K. et al., “Alternative signaling pathways regulating type I interferon-induced apoptosis”, J Interferon Cytokine Res. 25:799 ,2005

Caraglia M. et al., “Alpha-interferon and its effests on signal trasduction pathways”, J Cell Physiol . 202:323 ,2005

Saleh A.ZM. et al., “Regulated proteolysis of the IFNaR2 subunit of the interferon-alpha receptor”, Oncogene. 23:7076,2004

El Fiky A. et al., “Intracellular domain of the IFNaR2 interferon receptor subunit mediates transcription via Stat2”, J Cell Physiol . 204:567 ,2005

Hardy MP. et al., “The soluble murine type I interferon receptor Ifnar-2 is present in serum, is independently regulated,and has both agonistic and antagonist properties”, Blood 97:473,2001

Bibliografia

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Kumar K.G. et al., “Phosphorylation and specific ubiquitin acceptor sites are required for ubiquitination and degradation of tha IFNAR1 subunit of type I interferon receptor”, J.Biol.Chem. 279:46614,2004

Dondi E. et al., “Down-modulation of type I interferon responses by receptor cross-competition for a shared Jak kinase”, J.Biol.Chem. 276:47004,2001

Pestka S. et al., “Interferons, interferon-like cytokines, and their receptors”, Immunol. rev. 202:8,2004

Asselin-Paturel E. et al., “Production of type I interferons:plasmocytoid dendritic cells and beyond”, J Exp Med. . 202:461,2005

Lamken P. et al., “Ligand-induced assembling of type I interferon receptor on supported lipid bilayers”, J.Mol.Biol. 341:303,2004

Cali Cutrone E. et al., “Identification of critical residues in bovine IFNAR-1 responsible for interferon binding”, J.Biol.Chem. 276:17140,2001

Bekisz J. et al., “Human interferons alpha, beta and omega”, Growth factors. 22:243,2004

Deonarain R. et al., “Interferon-α-β receptor interactions:a complex story unfolding”, Curr Pharm Des. . 8:2131,2002

David M., “Signal transduction by type I interferons”, BioTechniques. 33:S58,2002

Marijanovic Z. et al., “TYK2 activity promotes ligand-induced IFNAR1 proteolysis”, Biochem.J. 397:31,2006