Mechanism for Nucleocytoplasmic Shuttling of Histone Deacetylase 7

Hung-Ying Kao,André Verdel,Chih-Cheng Tsai,Cynthia Simon,Henry Juguilon,Saadi Khochbin

doi:10.1074/jbc.m107631200

Hung-Ying Kao, André Verdel + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m107631200

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Abstract

Here we show that HDAC7, a member of the class II histone deacetylases, specifically targets several members of myocyte enhancer factors, MEF2A, -2C, and -2D, and inhibits their transcriptional activity. Furthermore, we demonstrate that DNA-bound MEF2C is capable of recruiting HDAC7, demonstrating that the HDAC7-dependent repression of transcription is not due to the inhibition of the MEF2 DNA binding activity. The data also suggest that the promoter bound MEF2 is potentially capable of remodeling adjacent nucleosomes via the recruitment of HDAC7. We have also observed a nucleocytoplasmic shuttling of HDAC7 and dissected the mechanism involved. In NIH3T3 cells, HDAC7 was primarily localized in the cytoplasm, essentially due to an active CRM1-dependent export of the protein from the nucleus. Interestingly, in HeLa cells, HDAC7 was predominantly nuclear. In these cells we could restore the cytoplasmic localization of HDAC7 by expressing CaMK I. This CaMK I-induced nuclear export of HDAC7 was abolished when three critical serines, Ser-178, Ser-344, and Ser-479, of HDAC7 were mutated. We show that these serines are involved in the direct interaction of HDAC7 with 14-3-3. Mutations of these serine residues weakened the association with 14-3-3 and dramatically enhanced the repression activity of HDAC7 in NIH3T3 cells, but not in HeLa cells. Data presented in this work clearly show that the signal dependent subcellular localization of HDAC7 is essential in controlling its activities. The data also show that the cellular concentration of factors such as 14-3-3, CaMK I, and other yet unknown molecules may determine the subcellular localization of an individual HDAC member in a cell type and HDAC-specific manner.

Highlights

We show that HDAC7, a member of the class II histone deacetylases, targets several members of myocyte enhancer factors, MEF2A, -2C, and -2D, and inhibits their transcriptional activity
We show that the nucleocytoplasmic shuttling of HDAC7 is intimately linked to the control of its activity and our data indicate that the presence and the abundance of molecules such as 14-3-3 and CaMK I can account for the different subcellular localization of HDAC7 in various cell lines
Yellow fluorescence protein (YFP)tagged HDAC7 and MEF2A were co-transfected into HeLa cells

Summary

Regulation of gene expression in eukaryotic cells is achieved

Through the recruitment of promoter-specific transcription factors and the basal transcription apparatus associated with the reorganization of chromatin on the promoter. It has been recently suggested that promoter-specific transcription factors recruit either coactivators or co-repressors to achieve their positive or negative regulation. Four MEF2 proteins (MEF2A-D) have been identified and they bind to their cognate DNA sequence as homodimers or heterodimers Both positive and negative regulators have been shown to influence the transcriptional activity of MEF2 [30]. Class II histone deacetylases, HDAC4 and HDAC5, repress MEF2 activity through direct physical interaction [18, 33,34,35,36]. A number of other transcription factors including MyoD have been shown to play a role in regulating MEF2 activity through direct association [37,38,39,40,41]. We show that the nucleocytoplasmic shuttling of HDAC7 is intimately linked to the control of its activity and our data indicate that the presence and the abundance of molecules such as 14-3-3 and CaMK I can account for the different subcellular localization of HDAC7 in various cell lines

EXPERIMENTAL PROCEDURES

RESULTS

Nucleocytoplasmic Shuttling of Class II HDACs

DISCUSSION

Saadi Khochbin