PIASx acts as an Elk-1 coactivator by facilitating derepression.
The ETS-domain transcription factor Elk-1 is a MAP kinase-inducible transcriptional activator protein. However, in the basal state, its activity is repressed by SUMO-dependent histone deacetylase (HDAC) recruitment. Relief of this repression accompanies the activation process. Here, we demonstrate that PIASx(alpha) acts to facilitate this derepression process. Members of the PIAS family of proteins can act as E3 enzymes that enhance the sumoylation status of a variety of substrates. However, PIASx-mediated coactivation of Elk-1 occurs in an E3 activity-independent manner. PIASx(alpha) binds to Elk-1 in vivo and enhances its transcriptional activity. The coactivating properties of PIASx(alpha) require Elk-1 to be modified with SUMO and the integrity of the SUMO binding motif in PIASx(alpha). PIASx(alpha) activates Elk-1 through alterations in the HAT/HDAC activities associated with Elk-1. In particular, PIASx(alpha) facilitates the loss of the repressive HDAC-2 from sumoylated Elk-1, a key event in the activation of Elk-1 in response to signalling through the ERK MAP kinase pathway. Our data therefore reveal a novel coactivator function for PIASx(alpha) through reversing SUMO-mediated repression of transcription factor activity.
Yang
Shen-Hsi
SH
Faculty of Life Sciences, University of Manchester, Manchester, UK.
Sharrocks
Andrew D
AD
D000107:Acetylation; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D050828:Protein Inhibitors of Activated STAT; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D050807:ets-Domain Protein Elk-1
D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; D009687:Nuclear Proteins; C501001:PIAS2 protein, human; D050828:Protein Inhibitors of Activated STAT; D011518:Proto-Oncogene Proteins; D025842:SUMO-1 Protein; D015534:Trans-Activators; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D006655:Histone Deacetylases