Transcription factors involved in brassinosteroid repressed gene expression and their regulation by BIN2 kinase

Abstract

Brassinosteroids (BRs) play important roles in plant growth, development and responses to environmental cues. BRs signal through plasma membrane-localized receptors to control BES1/BZR1 family transcription factors, which mediate the expression of thousands of genes. BRs activate and repress approximately equal numbers of genes. BES1/BZR1 interact with other transcription factors, histone-modifying enzymes, and transcription elongation factors to activate BR-induced genes. However, the mechanisms by which BES1/BZR1 mediate the BR-repressed gene expression are not well understood. Recent studies revealed that 2 BR-repressed transcription factors, MYBL2 and HAT1, cooperate with BES1 to downregulate BR-repressed genes expression. Moreover, BIN2 kinase, a well-established negative regulator in the BR signaling pathway, phosphorylates MYBL2 and HAT1. While BIN2 phosphorylates and destabilizes BES1/BZR1, BIN2 phosphorylated MYBL2 and HAT1 appear to be stabilized. These results not only extended our understanding of BR-repressed gene expression, but also revealed multiple inputs of BR signaling into BR transcriptional networks.

Keywords: :

• Brassinosteroids
• BES1
• HAT1
• MYBL2
• BIN2
• phosphorylation
• protein stability
• signaling
• Arabidopsis thaliana

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Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

This work was supported by United States National Science Foundation (NSF) grant (IOS-1257631) and Plant Science Institute (to YY), Doctoral Foundation of the Ministry of Education (20110181110059 and 20120181130008), and Sichuan Nature Science Foundation (2010JQ0080).