The epigenetic regulation of gene expression is critical for ensuring the proper deployment and stability of defined genome transcription programs at specific developmental stages. The cellular memory of stable gene e...The epigenetic regulation of gene expression is critical for ensuring the proper deployment and stability of defined genome transcription programs at specific developmental stages. The cellular memory of stable gene expression states during animal and plant development is mediated by the opposing activities of Polycomb group （PcG） factors and trithorax group （trxG） factors. Yet, despite their importance, only a few trxG factors have been characterized in plants and their rotes in regulating plant development are poorly defined. In this work, we report that the closely related Arabidopsis trxG genes ULTRAPETALA1 （ULT1） and ULT2 have overlapping functions in regulating shoot and floral stem cell accumula- tion, with ULT1 playing a major role but ULT2 also making a minor contribution. The two genes also have a novel, redun- dant activity in establishing the apical-basal polarity axis of the gynoecium, indicating that they function in differentiating tissues. Like ULT1 proteins, ULT2 proteins have a dual nuclear and cytoplasmic localization, and the two proteins physically associate in planta. Finally, we demonstrate that ULT1 and ULT2 have very similar overexpression phenotypes and regulate a common set of key development target genes, including floral MADS-box genes and class I KNOX genes. Our results reveal that chromatin remodeling mediated by the ULT1 and ULT2 proteins is necessary to control the development of mer- istems and reproductive organs. They also suggest that, like their animal counterparts, plant trxG proteins may function in multi-protein complexes to up-regulate the expression of key stage- and tissue-specific developmental regulatory genes.展开更多
基金This work is supported by the Portuguese Foundation for Science and Technology （SFRH/BD/22517/2005 - Ph.D fellow- ship to H.R.R） and the National Science Foundation （IOS- 1052050 to J.C.F.）.We thank Patricia Zambryski, Jennifer Nemhauser, Chris Day, David Ehrhardt, and Robert Blanvillain for providing materi- als, Ludmila Tyler for assistance developing the ult2 alleles, Minna Mahonen, and Paul Hussey and Lilyana Chandra for technical assistance. No conflict of interest declared.
文摘The epigenetic regulation of gene expression is critical for ensuring the proper deployment and stability of defined genome transcription programs at specific developmental stages. The cellular memory of stable gene expression states during animal and plant development is mediated by the opposing activities of Polycomb group （PcG） factors and trithorax group （trxG） factors. Yet, despite their importance, only a few trxG factors have been characterized in plants and their rotes in regulating plant development are poorly defined. In this work, we report that the closely related Arabidopsis trxG genes ULTRAPETALA1 （ULT1） and ULT2 have overlapping functions in regulating shoot and floral stem cell accumula- tion, with ULT1 playing a major role but ULT2 also making a minor contribution. The two genes also have a novel, redun- dant activity in establishing the apical-basal polarity axis of the gynoecium, indicating that they function in differentiating tissues. Like ULT1 proteins, ULT2 proteins have a dual nuclear and cytoplasmic localization, and the two proteins physically associate in planta. Finally, we demonstrate that ULT1 and ULT2 have very similar overexpression phenotypes and regulate a common set of key development target genes, including floral MADS-box genes and class I KNOX genes. Our results reveal that chromatin remodeling mediated by the ULT1 and ULT2 proteins is necessary to control the development of mer- istems and reproductive organs. They also suggest that, like their animal counterparts, plant trxG proteins may function in multi-protein complexes to up-regulate the expression of key stage- and tissue-specific developmental regulatory genes.
