Novel mutant mouse line emphasizes the importance of protein kinase C theta for CD4

backgroundThe protein kinase C theta (PKCθ) has an important and non-redundant function downstream of the antigen receptor and co-receptor complex in T lymphocytes. PKCθ is not only essential for activation of NF-κB, AP-1 and NFAT and subsequent interleukin-2 expression, but also critical for positive selection and development of regulatory T lymphocytes in the thymus. Several domains regulate its activity, such as a pseudosubstrate sequence mediating an auto-inhibitory intramolecular interaction, the tandem C1 domains binding diacylglycerol, and phosphorylation at conserved tyrosine, threonine as well as serine residues throughout the whole length of the protein. To address the importance of the variable domain V1 at the very N-terminus, which is encoded by exon 2, a mutated version of PKCθ was analyzed for its ability to stimulate T lymphocyte activation.

methodsT cell responses were analyzed with promoter luciferase reporter assays in Jurkat T cells transfected with PKCθ expression constructs. A mouse line expressing mutated instead of wild type PKCθ was analyzed in comparison to PKCθ-deficient and wild type mice for thymic development and T cell subsets by flow cytometry and T cell activation by quantitative RT-PCR, luminex analysis and flow cytometry.

resultsIn cell lines, the exon 2-replacing mutation impaired the transactivation of interleukin-2 expression by constitutively active mutant form of PKCθ. Moreover, analysis of a newly generated exon 2-mutant mouse line (PKCθ-E2

conclusionTaken together, PKCθ-E2