Tyk2 knock-out mice

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Table of contents

ACKNOWLEDGMENTS
LIST OF ABREVIATIONS
LIST OF FIGURES
RÉSUMÉ
INTRODUCTION
1. CYTOKINE SIGNALING
1.1. !-helical cytokines and their receptors
1.1.1. Erythropoietin and interferon !: two representative !-helical cytokines
1.1.2. Class I and class II receptors
1.2. The Jak/STAT signaling pathway
1.2.1. The Jak tyrosine kinase family
1.2.2. The STAT transcription factors
1.3. Signal termination/downmodulation
1.3.1. The SOCS family of cytokine-signaling repressors, the PIAS family of STAT inhibitors and Jak-STAT phosphatases
1.3.2. Cytokine response modulation through availability of signaling components
2. TYK2 IN CYTOKINE SIGNALING
2.1. Type I IFNs
2.1.1. The type I IFN receptor
2.1.2. Jak and STAT activation by type I IFN
2.1.3. Tyk2 as a chaperone
2.1.4. Type I IFN and SLE
2.2. Cytokines utilizing the common IL-10R2: IL-10, IL-22, IL-26 and IFN »
2.3. Cytokines utilizing IL-12R#1: IL-12 and IL-23
2.4. Physiopathological consequences of Tyk2 deficiency
2.4.1. Tyk2 knock-out mice
2.4.2. Human Tyk2 deficiency
3. STRUCTURE/FUNCTION ORGANIZATION OF THE JAK KINASES
3.1. The N-terminal region: FERM and SH2-like domains
3.1.1. A new Tyk2 interacting protein: Jakmip1
3.2. The kinase-like domain as a sensor of ligand binding
3.2.1. Jak2V617F in Polycythemia vera
3.3. The tyrosine kinase domain
OBJECTIVES
The role of Pot1 in IFN! signaling
The Tyk2V678F mutant in a homo- vs heterodimeric receptor context
The effect of the P1104A on Tyk2 activity
MATERIALS AND METHODS
Cell lines
siRNA and plasmids
SDS-PAGE and Western blot
Tyk2 immunoprecipitation and in vitro kinase assay
Luciferase reporter assay
PCR
FACS
Immunofluorescence studies
RESULTS
POT1: A NEW TYK2 INTERACTING PROTEIN
Previous data
Database analyses of Pot1 mRNA transcripts
Mapping of Pot1 transcripts
Subcellular localisation of the murine Pot1
Functional studies of Pot1
Identification of Pot1 interactors by yeast two-hybrid screen
GIT1
The role of GIT1 in IFN! signaling.
TYK2 MUTATIONS
V678F, an activating mutation of Tyk2
Tyk2V678F basal phosphorylation in vivo and in vitro
The V678F mutant leads to basal STAT3 phosphorylation but normal IFN! induced signaling
Analysis of the Tyk2V678F mutant placed in a homodimeric receptor complex
Equivalent basal STAT3 phosphorylation level in 11,1 and EpoR/R1 clones
Analysis of the Tyk2P1104A mutant
Impaired in vivo auto/transphosphorylation of Tyk2 P1104A
Tyk2 P1104A rescues IFN! signaling
Tyk2P1104A cannot auto/transphosphorylate itself in vitro
DISCUSSION
Pot1
Pot1/Tyk2 interaction
Pot1 isoforms and localization
Pot1 is not implicated in the IFN!-induced transcriptional response in 293T cells
Pot1 interacting proteins
Tyk2V678F
The regulatory role of the KL domain
Tyk2 loss-of-function mutations
Tyk2V678F: a gain-of-function phenotype
Tyk2V678F has no effect on IFN!-induced signaling, but leads to basal STAT3 phosphorylation
Preferential Tyk2-STAT3 interaction
The prerequisite of a homodimeric receptor for Jak2V617F-mediated transformation
Tyk2V678F placed in a homodimeric receptor context confers ligand hypersensitivity
The effect of Tyk2V678F on STAT3 basal phosphorylation is not linear
A general model of IFN-induced STAT activation
Jak2V617F- and Tyk2V678F-mediated STAT5 activation
Physiological consequences of constitutively active Tyk2
Tyk2P1104A
PERSPECTIVES
Pot1
Tyk2V678F
Tyk2P1104A
REFERENCES