15th International Conference on Arabidopsis Research - TAIR

T09-023
Role of E2F transcription factor in the control of
Arabidopsis cell growth and differentiation
Elena Ramírez-Parra(1), Angeles López-Matas(1), Corinne Fründt(1), Crisanto
Gutiérrez(1)
1-Centro de Biología Molecular "Severo Ochoa" CSIC-UAM
2-Centro de Biología Molecular "Severo Ochoa" CSIC-UAM
3-Centro de Biología Molecular "Severo Ochoa" CSIC-UAM
4-Centro de Biología Molecular "Severo Ochoa" CSIC-UAM
The balance between cell proliferation and differentiation is crucial in
multicellular organisms, where it is regulated by complex gene expression
networks. This is particularly relevant in plants since organogenesis is a continuous
post-embryonic process. Transcription factors E2F/DP are a complex
multigenic family, crucial for controlling expression of genes involved in cell
cycle transitions, both in animals and plants.
In Arabidopsis, an in silico search of genes potentially regulated by E2F,
revealed that this transcription factor may be implicated not only in direct
control of cell cycle-related gene expression, but also in the regulation of
other functional process, e.g. transcription, stress and defence or signalling.
The analysis of Arabidopsis transgenic plants expressing a DP gene containing
a truncated DNA binding domain, which likely has a dominant-negative
effect on AtE2Fa, b and c, three typical E2F members which require DP for
efficient DNA binding, show alteration in the expression levels of some of the
identified targets.
In addition, a novel subfamily of E2F transcription factors has been identified,
showing an atypical functional domain distribution. We have investigated the
function of Arabidopsis E2Ff, an atypical member of the E2F family, which
acts independently of a dimerization partner (DP). The study of its promoter
activity indicates an interesting tissue-specific expression pattern. Transgenic
plants with altered E2Ff expression levels show morphologic alterations
in hypocotyl and root development with a deficient cellular expansion and
tissue-specific deregulation of genes involved in several processes. Altogether,
our results strongly support that the E2F pathway plays a crucial role in
regulating both cell cycle-dependent and independent pathways.
T09 Genetic Mechanisms (Transcriptional and Chromatin Regulation)
T09-024
Sub-nuclear localization of chromatin remodeling
factor DDM1
Katarzyna Olczak(1), John Gittins(1), Andrzej Jerzmanowski(1, 2), Jan Brzeski(1)
1-Institute of Biochemistry and Biophysics PAS, Pawinskiego 5A, 02-106 Warsaw, POLAND
2-Warsaw University, Pawinskiego 5A, 02-106 Warsaw, POLAND
Decrease in DNA methylation 1 (DDM1) protein plays a crucial role in the
maintenance of DNA methylation status in Arabidopsis thaliana. Depletion of
DDM1 function also results in the aberrant pattern of histone H3 methylation
at the Lysine 9. DDM1 is a member of the broad SWI2/SNF2 protein family.
We have recently demonstrated that recombinant DDM1 is an ATP-dependent
chromatin remodeling enzyme. Here we present results of the study on
sub-nuclear localization of DDM1. This study demonstrates DDM1 enrichment
in pericentromeric heterochromatin. We also show the analysis of the
effect of various mutations on DDM1 localization.
15 th <strong>International</strong> <strong>Conference</strong> on Arabidopsis Research 2004 · Berlin