Transcription factor cycling on the insulin promoter

Using MIN6 β-cells and chromatin immunoprecipitation (ChIP) assays, the chronological sequence of binding of MafA, E47/β2 and PDX-1 to the insulin promoter in living β-cells were investigated. All four factors were shown to bind to the mouse insulin 2 promoter in a cyclical manner with a periodicity of approximately 10–15 min. The cyclical binding of MafA, E47 and β2 was largely unaffected by the glucose or insulin concentration in the media. However, the binding and cycling of PDX-1 was markedly abolished in low glucose (1 mM), and this was reversed in the presence of low concentrations of insulin.