The role of Ternary Complex factors in T-cell Positive Selection

Removal of the transcription factor SAP1a member of the Ternary Complex Factor (TCF) group of transcription factors which in conjunction with Serum Response Factor (SRF) has been shown to have a profound effect on positive selection in the thymus. When another TCF Elk1 is knocked out in mice there is no effect on positive selection unless it is on a Sap1a KO background where the phenotype is very severe. We have stimulated isolated double positive T cells (DPs) with anti-CD3 to mimic positive selection and compared basal and stimulated transcription across the four genotypes to discover the downstream targets of Sap1a involved in positive selection. The Affymetrix mouse Chip Mouse430_2 arrays were used to define gene expression profiles in purified DPs with and with out CD3 treatment from 3 mice for each genotype (Wt,SapKO, ElkKO and SAP/Elk double KO)