Charles Albert Shull & Stephen Hales Prize Awardee Symposium
Chen, Xuemei , Yang, Zhiyong , Yu, Bin , Kim, YunJu .
HEN1 in microRNA biogenesis and plant development.
We have been studying mechanisms underlying cell fate specification in Arabidopsis flower development. An Arabidopsis flower has four types of floral organs sepal and petal, also known as perianth organs, and stamen and carpel, also known as reproductive organs. The identities of the four organ types are determined by the activities of the ABC classes of transcription factors. AP2, a class A gene, and AG, a class C gene, specify the perianth and reproductive organs respectively. AP2 and AG act antagonistically to restrict each others activities to their proper domains in the floral meristem. We performed a sensitized genetic screen to identify other genes that act in reproductive organ identity specification. Several HUA ENHANCER (HEN) genes were identified in the screen and subsequent work on HEN1 led us to conclude that post-transcriptional mechanisms also contribute to cell fate specification in flower development. In particular, miR172, a microRNA, represses the expression of AP2 to allow the proper patterning of reproductive organs by AG.
A second research direction of our laboratory is to study microRNA metabolism. We found that HEN1 is a general factor in microRNA biogenesis. It serves as a microRNA methyltransferase that adds a methyl group onto the 2 OH of the 3 terminal ribose. Therefore, our work on HEN1 uncovered a new step in microRNA metabolism methylation of the 3 terminal nucleotide at the 2 OH. This 2-O-methyl group protects microRNAs from a 3-to-5 exonuclease activity and from a uridylation activity that target the 3 OH.
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1 - University of California, Riverside, Department of Botany and Plant Sciences, Riverside, CA, 92521, USA
2 - University of California, Riverside, Department of Botany and Plant Sciences
Presentation Type: ASPB Major Symposium
Location: International Ballroom/Hilton
Date: Saturday, July 7th, 2007
Time: 3:00 PM