The influence of genetic variation on inducible gene expression

Abstract

Activation of the immune response is dependent on extensive changes in gene expression and it is likely that a major component of inter-individual variation in the immune response is mediated at the level of gene regulation. In this thesis the influence of genetic variation on inducible gene expression is examined in the murine immune response. Primary CD4+ splenocytes were extracted from the inbred mouse strains A/J, C57BL/6J, BALB/c, DBA/2J, and 129x1/SvJ (> 3 animals/strain) and mRNA transcript levels were measured using microarrays in both basal state and four hours after stimulation with Phorbol-12-myristate-13- acetate/Ionomycin, to mimic T cell activation. An expression change occurring during activation was defined as the difference in measured expression intensity between stimulated and basal conditions. Genetically influenced genes were identified using an ANOVA model. This identified 2607, 1145 and 506 transcripts whose expression levels are under potential genetic influence in the basal state, stimu- lated state and during activation, respectively. Using previously published data in cycloheximide treated EL4 cells (mouse cell line) to inhibit de novo protein syn- thesis, comparison to mouse cell line data implied that both primary response (e.g. Fos, Tnfaip3) and secondary response (e.g. Irf4) genes are subject to genetic influence across activation. These differentially activated genes are ideal candidates for further study into the influence of genetic variation on the mechanisms of gene induction, and provide mechanistic insight into inter-individual variation in the host response to infection. This approach was applied to investigate the impact of genetic variation of inducible gene expression in a murine diabetes model: primary CD4+ splenocytes were extracted from Insulin dependent diabetes mellitus (IDDM) pron (NOD) and resistant (B10) mice. Genetically influenced genes were identified in the basal state, stimulated state and during activation. The genetically variant inducible genes identified in this analysis represent new candidates for the investigation of IDDM aetiology, with many of them not previously associated with known IDDM risk loci. Show more