B6.129S4-Itk^tm1Litt/PlsJ

Stock number: 024845
Research areas: Cell Biology Research, Immunology, Inflammation and Autoimmunity Research

Description

Itk^-/- mice may be useful for studying the role of ITK in the proliferation and activation of lymphocytes.

Detailed description

Itk^-/- mice have a STOP codon inserted into exon 2, and a neo cassette replaces exon 4 and part of exon 3, of the IL2 inducible T cell kinase (Itk) gene, abolishing gene expression. Itk is a member of Tec family of tyrosine kinases. Itk, a nonreceptor tyrosine kinase, is expressed in naive and activated T cells and is involved in T cell receptor (TCR) signaling where it phosphorylates Phospholipase-C gamma. Mutations affecting Itk impair TCR-induced Ca2+ mobilization and ERK activation. Itk is also involved in TCR-driven actin cytoskeleton reorganization and integrin adhesion regulation. Itk-deficient mice exhibit a decrease in peripheral T cells numbers, decreased T cell proliferation, and abnormal T cell phenotypes. Specifically, they show a 30-50% decrease in CD4 numbers and increased expression of activation/memory markers, particularly in CD8 cells, where almost all cells are CD8⁺CD44^loCD122^lo T cells and CD8⁺ T cells. They also exhibit defects in thymic development of CD8⁺CD44^hiCD122^hi. They also exhibit defects in thymic positive and negative selection and have abnormal ratios of splenic and thymic T and B cells. Itk-deficient mice show specific defects in responses to Th2-inducing immune challenges in vivo and show altered cytokine production in vivo and in vitro. Mice homozygous for this allele are viable and fertile.

Development

A targeting vector was designed to insert a STOP codon in exon 2 and to replace exon 4 and part of exon 3 of the IL2 inducible T cell kinase (Itk) gene with a neomycin resistance (neo) cassette. The construct was electroporated into 129S4/SvJae-derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric males were bred to C57BL/6J females. These mice were backcrossed for 10 generations to C57BL/6J background. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Itk^tm1Litt
Name: targeted mutation 1, Dan R Littman
MGI accession ID: MGI:2178820
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Itk
Marker name: IL2 inducible T cell kinase
Chromosome: 11
Strain of origin: 129S4/SvJae
Molecular note: Exon 4 and part of exon 3 of this gene was replaced with a PGK(G)neopA cassette via homologous recombination. A stop codon was engineered at position 78 to further ensure a null allele. PCR and Southern blot analysis confirmed the presence of the targeted mutation, and Western blot analysis determined no Itk protein was present in thymocytes of homozygous mutant animals.