The WEREWOLF MYB protein directly regulates CAPRICE transcription during cell fate specification in the Arabidopsis root epidermis.
The Arabidopsis root epidermis is composed of two types of cells, hair cells and non-hair cells, and their fate is determined in a position-dependent manner. WEREWOLF (WER), a R2R3 MYB protein, has been shown genetically to function as a master regulator to control both of the epidermal cell fates. To directly test the proposed role of WER in this system, we examined its subcellular localization and defined its transcriptional activation properties. We show that a WER-GFP fusion protein is functional and accumulates in the nucleus of the N-position cells in the Arabidopsis root epidermis, as expected for a transcriptional regulator. We also find that a modified WER protein with a strong activation domain (WER-VP16) promotes the formation of both epidermal cell types, supporting the view that WER specifies both cell fates. In addition, we used the glucocorticoid receptor (GR) inducible system to show that CPC transcription is regulated directly by WER. Using EMSA, we found two WER-binding sites (WBSs; WBSI and WBSII) in the CPC promoter. WER-WBSI binding was confirmed in vivo using the yeast one-hybrid assay. Binding between the WER protein and both WBSs (WBSI and WBSII), and the importance of the two WBSs in CPC promoter activity were confirmed in Arabidopsis. These results provide experimental support for the proposed role of WER as an activator of gene transcription during the specification of both epidermal cell fates.
Ryu
Kook Hui
KH
Department of Biology, Yonsei University, Sinchon 134, Seoul 120-749, Korea.
Kang
Yeon Hee
YH
Park
Young-hwan
YH
Hwang
Ildoo
I
Schiefelbein
John
J
Lee
Myeong Min
MM
D017360:Arabidopsis / Q000166:cytology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D001665:Binding Sites; D019070:Cell Lineage / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000166:cytology; D011401:Promoter Regions, Genetic; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics*; D014158:Transcription, Genetic
C511988:ATR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C511989:CPC protein, Arabidopsis; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D020598:Proto-Oncogene Proteins c-myb; C402111:WER protein, Arabidopsis