Nucleic Acids Research Advance Access originally published online on August 30, 2008
Nucleic Acids Research 2008 36(17):5571-5580; doi:10.1093/nar/gkn538
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Nucleic Acids Research, 2008, Vol. 36, No. 17 5571-5580
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Gene regulation, Chromatin and Epigenetics |
Activated transcription via mammalian amino acid response elements does not require enhanced recruitment of the Mediator complex
Department of Biochemistry and Molecular Biology, Genetics Institute, Shands Cancer Center and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610, USA
* To whom correspondence should be addressed. Tel: +1 352 392 2711; Fax: +1 352 392 6511; Email: mkilberg{at}ufl.edu
Received June 30, 2008. Revised July 19, 2008. Accepted August 6, 2008.
It is unclear whether Mediator complex in yeast is necessary for all RNA polymerase II (Pol II) transcription or if it is limited to genes activated by environmental stress. In mammals, amino acid limitation induces SNAT2 transcription through ATF4 binding at an amino acid response element. ATF4 is the functional counterpart to the yeast amino acid-dependent regulator GCN4 and GCN4 recruits Mediator during transcriptional activation. Consistent with enhanced SNAT2 transcription activity, the present data demonstrate that amino acid limitation increased SNAT2 promoter association of the general transcription factors that make up the preinitiation complex, including Pol II, but there was no increase in Mediator recruitment. Furthermore, siRNA knockdown of eight Mediator subunits caused no significant decrease in SNAT2 transcription. The estrogen-dependent pS2 gene was used as a positive control for both the ChIP and the siRNA approaches and the data demonstrated the requirement for Mediator recruitment. These results document that activation of the SNAT2 gene by the mammalian amino acid response pathway occurs independently of enhanced Mediator recruitment.