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SUMMARY:AP2-type transcription factors regulate stem cell fate in the moss
  Physcomitrella patens - Dr Tsuyoshi Aoyama
DTSTART:20131101T130000Z
DTEND:20131101T132500Z
UID:TALK48381@talks.cam.ac.uk
CONTACT:Dr Yoan Coudert
DESCRIPTION:Stem cells are characterized by their ability to self-renew an
 d give rise to differentiated cells. Several types of stem cells to produc
 e different types of differentiated cells are formed during development. T
 heir appropriate regulation is necessary for development of multicellular 
 organisms.\n\nThe moss Physcomitrella patens is a good model organism to r
 esearch how different types of stem cell identity are determined. In P. pa
 tens\, two different types of stem cells\, gametophore apical stem cells a
 nd protonema apical stem cells\, are derived from side branch initial cell
 s. This stem cell formation process is controlled by two phytohormones\, a
 uxin and cytokinin. However\, molecular mechanisms for such a stem cell fo
 rmation has been largely unknown.\n\nHere we show that four AP2-type trans
 cription factors are indispensable for the formation of gametophore apical
  stem cells from side branch initial cells. We named the four P. patens ge
 nes APB1\, APB2\, APB3\, and APB4. Quadruple disruption of all APB genes d
 isrupted gametophore apical stem cell formation\, even in the presence of 
 cytokinin\, which induces gametophore apical stem cell in the wild type. T
 ime-lapse observation showed that side branch initial cells do not acquire
  gametophore apical stem cell identity and directly differentiate into pro
 tonema apical stem cells based on their morphology. Signals of APB-YFP fus
 ion proteins were continuously detected during gametophore apical stem cel
 l formation\, whereas the signals disappeared during protonema apical stem
  cell formation. We conclude that the APB genes function as a molecular sw
 itch to regulate the identity of stem cells in P. patens. In order to reve
 al how APB genes determine the gametophore stem cell identity\, the transc
 riptome analysis was performed. Overexpression of APB4 gene induced differ
 ent types of gene sets depending on the presence of cytokinin. These data 
 suggest that the possibility that APB genes interact with cytokinin signal
 ing and control specific type of gene sets necessary for gametophore stem 
 cell formation. 
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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