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The Arabidopsis CUL4-DDB1 complex interacts with MSI1 and is required to maintain MEDEA parental imprinting.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Dumbliauskas Eva, Lechner Esther, Jaciubek Miłosława, Berr Alexandre, Pazhouhandeh Maghsoud, Alioua Malek, Cognat Valerie, Brukhin Vladimir, Koncz Csaba, Grossniklaus Ueli, Molinier Jean, Genschik Pascal,
Project The genetic and molecular basis of gametogenesis and maternal effects in arabidopsis
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Original article (peer-reviewed)

Journal The EMBO journal
Volume (Issue) 30(4)
Page(s) 731 - 43
Title of proceedings The EMBO journal
DOI 10.1038/emboj.2010.359


Protein ubiquitylation regulates a broad variety of biological processes in all eukaryotes. Recent work identified a novel class of cullin-containing ubiquitin ligases (E3s) composed of CUL4, DDB1, and one WD40 protein, believed to act as a substrate receptor. Strikingly, CUL4-based E3 ligases (CRL4s) have important functions at the chromatin level, including responses to DNA damage in metazoans and plants and, in fission yeast, in heterochromatin silencing. Among putative CRL4 receptors we identified MULTICOPY SUPPRESSOR OF IRA1 (MSI1), which belongs to an evolutionary conserved protein family. MSI1-like proteins contribute to different protein complexes, including the epigenetic regulatory Polycomb repressive complex 2 (PRC2). Here, we provide evidence that Arabidopsis MSI1 physically interacts with DDB1A and is part of a multimeric protein complex including CUL4. CUL4 and DDB1 loss-of-function lead to embryo lethality. Interestingly, as in fis class mutants, cul4 mutants exhibit autonomous endosperm initiation and loss of parental imprinting of MEDEA, a target gene of the Arabidopsis PRC2 complex. In addition, after pollination both MEDEA transcript and protein accumulate in a cul4 mutant background. Overall, our work provides the first evidence of a physical and functional link between a CRL4 E3 ligase and a PRC2 complex, thus indicating a novel role of ubiquitylation in the repression of gene expression.