Identification of a novel positive cis-control element in the Cd4 gene
CD4 helper T cells coordinate the immune response and are highly dependent on the expression of the Cd4 gene for proper development and function. The function of a promoter, an enhancer and a silencer have been well documented and together explain how the Cd4 gene gets turned on in CD4 T cells and off in CD8 T cells. However once turned on, the amount and timing of Cd4 expression varies during T cell development and activation. This modulation of CD4 surface levels is essential for proper lineage specification and T cell function. Yet, how subtle changes of CD4 expression are regulated remains unclear. We have recently identified a novel positive cis-acting transcriptional regulatory element (NCE) in the Cd4 locus. Here we demonstrate that NCE enhances Cd4 promoter function in position and orientation independent manner using a transient transfection assay with an eGFP reporter construct in RLM11 murine thymoma cell line. This formally demonstrates that NCE functions as an enhancer.