Suchergebnisse

Assessing cell proliferation dynamics is crucial to understand the spatiotemporal control of organogenesis. Here we have generated a versatile fluorescent sensor, PlaCCI (plant cell cycle indicator) on the basis of the expression of CDT1a-CFP, H3.1-mCherry and CYCB1;1-YFP, that identifies cell cycle phases in Arabidopsis thaliana. This tool works in a variety of organs, and all markers and the antibiotic resistance are expressed from a single cassette, facilitating the selection in mutant backgrounds. We also show the robustness of PlaCCI line in live-imaging experiments to follow and quantify cell cycle phase progression ; European Union, and by institutional grants from Banco de Santander and Fundación Ramon Areces to the Centro de Biología Molecular Severo Ochoa. ; Peer reviewed

Establishing the embryonic body plan of multicellular organisms relies on precisely orchestrated cell divisions coupled with pattern formation, which, in animals, are regulated by Polycomb group (PcG) proteins. The conserved Polycomb Repressive Complex 2 (PRC2) mediates H3K27 trimethylation and comes in different flavors in Arabidopsis. The PRC2 catalytic subunit MEDEA is required for seed development; however, a role for PRC2 in embryonic patterning has been dismissed. Here, we demonstrate that embryos derived from medea eggs abort because MEDEA is required for patterning and cell lineage determination in the early embryo. Similar to PcG proteins in mammals, MEDEA regulates embryonic patterning and growth by controlling cell-cycle progression through repression of CYCD1;1, which encodes a core cell-cycle component. Thus, Arabidopsis embryogenesis is epigenetically regulated by PcG proteins, revealing that the PRC2-dependent modulation of cell-cycle progression was independently recruited to control embryonic cell proliferation and patterning in animals and plants. ; University of Z€urich, postdoctoral fellowships from European Molecular Biology Organization (ALTF69-2010) and the European Union's Marie Sk1odowska-Curie Action (Grant No. 798953) to M.B. and S.B., respectively, grants from the Ministerio de Ciencia e Innovacio´ n (RTI2018-094793-BI00) and the European Research Council (AdG 833617)

Establishing the embryonic body plan of multicellular organisms relies on precisely orchestrated cell divisions coupled with pattern formation, which, in animals, are regulated by Polycomb group (PcG) proteins. The conserved Polycomb Repressive Complex 2 (PRC2) mediates H3K27 trimethylation and comes in different flavors in Arabidopsis. The PRC2 catalytic subunit MEDEA is required for seed development; however, a role for PRC2 in embryonic patterning has been dismissed. Here, we demonstrate that embryos derived from medea eggs abort because MEDEA is required for patterning and cell lineage determination in the early embryo. Similar to PcG proteins in mammals, MEDEA regulates embryonic patterning and growth by controlling cell-cycle progression through repression of CYCD1;1, which encodes a core cell-cycle component. Thus, Arabidopsis embryogenesis is epigenetically regulated by PcG proteins, revealing that the PRC2-dependent modulation of cell-cycle progression was independently recruited to control embryonic cell proliferation and patterning in animals and plants. ; University of Z€urich, postdoctoral fellowships from European Molecular Biology Organization (ALTF69-2010) and the European Union's Marie Sk1odowska-Curie Action (Grant No. 798953) to M.B. and S.B., respectively, grants from the Ministerio de Ciencia e Innovacio´ n (RTI2018-094793-BI00) and the European Research Council (AdG 833617)

Programmed cell death (PCD) is crucial for development and homeostasis of all multicellular organisms. In human cells, the double role of extra-mitochondrial cytochrome c in triggering apoptosis and inhibiting survival pathways is well reported. In plants, however, the specific role of cytochrome c upon release from the mitochondria remains in part veiled yet death stimuli do trigger cytochrome c translocation as well. Here, we identify an Arabidopsis thaliana 14-3-3ι isoform as a cytosolic cytochrome c target and inhibitor of caspase-like activity. This finding establishes the 14-3-3ι protein as a relevant factor at the onset of plant HO-induced PCD. The in vivo and in vitro studies herein reported reveal that the interaction between cytochrome c and 14-3-3ι exhibits noticeable similarities with the complex formed by their human orthologues. Further analysis of the heterologous complexes between human and plant cytochrome c with plant 14-3-3ι and human 14-3-3ε isoforms corroborated common features. These results suggest that cytochrome c blocks p14-3-3ι so as to inhibit caspase-like proteases, which in turn promote cell death upon HO treatment. Besides establishing common biochemical features between human and plant PCD, this work sheds light onto the signaling networks of plant cell death. ; Spanish Ministry of Economy and Competitiveness (BFU2015-71017/BMC MINECO/FEDER, PGC2018-096049-B-I00 BIO/BMC MICINN/FEDER, and RTI2018-094793-B-I00 MICIU), the Andalusian Government (BIO198, US-1254317, US-1257019, P18-FR-3487 and P18-HO-4091), and the Ramón Areces Foundation. CAER was recipient of a PhD fellowship from the Fundación Cámara – University of Seville