Role of TATA-element in transcription from glucocorticoid receptor-responsive model promoters

Transcription activation properties of the rat glucocorticoid receptor (GR) on minimal, TATA-box containing or depleted promoters have been tested. We show that a cluster of Glucocorticoid Responsive Elements (GRE), upon activation by the GR, is sufficient to mediate abundant RNA-polymerase II transcription. We find that in absence of a bona fide TATA-element transcription initiates at a distance of 45-55bp from the activated GRE cluster with a marked preference for sequences homologous to the initiator element (Inr). Analyzing defined, bi-directional transcription units we demonstrate that the apparent reduction of specific transcription in strong, TATA-depleted promoters, is mainly due to loss of short-range promoter polarization. The implications for long-range promoter/enhancer communication mechanisms are also discussed.