Abstract
Epithelial to mesenchymal transition (EMT) not only occurs during embryonic development and in response to injury, but is an important element in cancer progression. EMT and its reverse process, mesenchymal to epithelial transition (MET) is controlled by a network of transcriptional regulators and can be influenced by posttranscriptional and posttranslational modifications. EMT/MET involves many effectors that can activate and repress these transitions, often yielding a spectrum of cell phenotypes. Recent studies have shown that the miR-200 family and the transcriptional suppressor ZEB1 are important contributors to EMT. Our previous data showed that forced expression of SPRR2a was a powerful inducer of EMT and supports the findings by others that SPRR gene members are highly upregulated during epithelial remodeling in a variety of organs. Here, using SPRR2a cells, we characterize the role of acetyltransferases on the microRNA-200c/141 promoter and their effect on the epithelial/mesenchymal status of the cells. We show that the deacetylase inhibitor TSA as well as P300 and PCAF can cause a shift towards epithelial characteristics in HUCCT-1-SPRR2a cells. We demonstrate that both P300 and PCAF act as cofactors for ZEB1, forming a P300/PCAF/ZEB1 complex on the miR200c/141 promoter. This binding results in lysine acetylation of ZEB1 and a release of ZEB1 suppression on miR-200c/141 transcription. Furthermore, disruption of P300 and PCAF interactions dramatically down regulates miR-200c/141 promoter activity, indicating a PCAF/P300 cooperative function in regulating the transcriptional suppressor/activator role of ZEB1. These data demonstrate a novel mechanism of miRNA regulation in mediating cell phenotype.
Highlights
The KAT3 histone acetyltransferases cAMP response element-binding protein (CREB) binding protein (CBP) and P300 have at least 400 interacting protein partners, thereby acting as hubs in gene regulatory networks [1]
Several studies suggest that disruption of P300/CREB binding protein (CBP) occurs in many human diseases including cancer [4], inflammatory lung diseases [5], and viral infections [6]
We show that the acetyltransferases P300 and PCAF activate miR200c/141 transcription by interacting at its promoter region via the cysteine-histidine rich (CH3) domain of P300
Summary
The KAT3 histone acetyltransferases CREB binding protein (CBP) and P300 have at least 400 interacting protein partners, thereby acting as hubs in gene regulatory networks [1]. SPRR2a cells show some increase in miR200c/141 expression after AZA treatment as well, indicating that this gene is regulated in part by DNA methylation [20]. SPRR2a induced EMT in HuCCT-1 cells correlates with changes in E-cadherin, ZEB1, vimentin, and S100A4 expression, while other EMT-associated genes such as TWIST or SNAIL remain unchanged (gene array and real time PCR; data not shown).
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