cAMP/phorbol ester response element is involved in transcriptional regulation of the human replacement histone gene H3.3B.

The human histone H3.3B gene belongs to the group of replacement histone genes, which are up-regulated during differentiation of cells. Here we provide evidence that a cAMP response element/PMA response element (CRE/TRE) located in the proximal promoter contributes to the expression of the H3.3B gene. (1) Band shift and supershift analysis demonstrated the binding of AP-1 and transcription factors of the CRE-binding protein/activating-transcription-factor family to the H3.3B CRE/TRE. (2) Treatment of HeLa cells with PMA led to a 4-fold increase in H3. 3B mRNA levels within 2 h, whereas transcription of the cell cycle-dependent H3 histone genes remained constant. In contrast with PMA, cAMP did not affect H3.3B transcription. (3) PMA treatment of cells transiently transfected with H3.3B promoter constructs linked to a luciferase gene caused a 4-5-fold increase in reporter gene activity, whereas mutation of the CRE/TRE element abolished the PMA response. These results demonstrate that activation of the protein kinase C pathway by PMA results in an early up-regulation of H3.3B gene expression via the CRE/TRE element. Furthermore treatment with PMA apparently leads to differential induction of H3 histone subtype genes and this in turn can result in a remodelling of chromatin structure of cells before or during differentiation processes.