References of "Motte, Patrick"
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See detailPromoter analysis of the three HMA4 copies in the zinc hyperaccumulator Arabidopsis halleri
Nouet, Cécile ULg; Cebula, Justyna; Motte, Patrick ULg et al

Poster (2011, August)

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See detailExpression of the metal homeostasis gene FRD3 in two Arabidopsis species
Charlier, Jean-Benoît ULg; Polese, Catherine ULg; Krämer, Ute et al

Poster (2011, August)

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See detailRSZ22, a dynamic nucleocytoplasmic shuttling SR splicing factor
Tillemans, Vinciane ULg; Rausin, Glwadys; Stankovic, Nancy ULg et al

Poster (2011, March)

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See detailChloroplastic and mitochondrial metal homeostasis.
Nouet, Cécile ULg; Motte, Patrick ULg; Hanikenne, Marc ULg

in Trends in Plant Science (2011), 16(7), 395-404

Transition metal deficiency has a strong impact on the growth and survival of an organism. Indeed, transition metals, such as iron, copper, manganese and zinc, constitute essential cofactors for many key ... [more ▼]

Transition metal deficiency has a strong impact on the growth and survival of an organism. Indeed, transition metals, such as iron, copper, manganese and zinc, constitute essential cofactors for many key cellular functions. Both photosynthesis and respiration rely on metal cofactor-mediated electron transport chains. Chloroplasts and mitochondria are, therefore, organelles with high metal ion demand and represent essential components of the metal homeostasis network in photosynthetic cells. In this review, we describe the metal requirements of chloroplasts and mitochondria, the acclimation of their functions to metal deficiency and recent advances in our understanding of their contributions to cellular metal homeostasis, the control of the cellular redox status and the synthesis of metal cofactors. [less ▲]

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See detailDynamic Nucleocytoplasmic Shuttling of an Arabidopsis SR Splicing Factor: Role of the RNA-Binding Domains
Rausin, Glwadys ULg; Tillemans, Vinciane ULg; Stankovic, Nancy ULg et al

in Plant Physiology (2010), 153

Serine/arginine-rich (SR) proteins are essential nuclear-localized splicing factors. We have investigated the dynamic subcellular distribution of the Arabidopsis (Arabidopsis thaliana) RSZp22 protein, a ... [more ▼]

Serine/arginine-rich (SR) proteins are essential nuclear-localized splicing factors. We have investigated the dynamic subcellular distribution of the Arabidopsis (Arabidopsis thaliana) RSZp22 protein, a homolog of the human 9G8 SR factor. Little is known about the determinants underlying the control of plant SR protein dynamics, and so far most studies relied on ectopic transient overexpression. Here, we provide a detailed analysis of the RSZp22 expression profile and describe its nucleocytoplasmic shuttling properties in specific cell types. Comparison of transient ectopic- and stable tissue-specific expression highlights the advantages of both approaches for nuclear protein dynamic studies. By site-directed mutagenesis of RSZp22 RNA-binding sequences, we show that functional RNA recognition motif RNP1 and zinc-knuckle are dispensable for the exclusive protein nuclear localization and speckle-like distribution. Fluorescence resonance energy transfer imaging also revealed that these motifs are implicated in RSZp22 molecular interactions. Furthermore, the RNA-binding motif mutants are defective for their export through the CRM1/XPO1/Exportin-1 receptor pathway but retain nucleocytoplasmic mobility. Moreover, our data suggest that CRM1 is a putative export receptor for mRNPs in plants. [less ▲]

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See detailNkx6.1 and nkx6.2 regulate alpha- and beta-cell formation in zebrafish by acting on pancreatic endocrine progenitor cells.
Binot, Anne-Catherine; Manfroid, Isabelle ULg; Flasse, Lydie ULg et al

in Developmental Biology (2010), 340(2), 397-407

In mice, the Nkx6 genes are crucial to alpha- and beta-cell differentiation, but the molecular mechanisms by which they regulate pancreatic subtype specification remain elusive. Here it is shown that in ... [more ▼]

In mice, the Nkx6 genes are crucial to alpha- and beta-cell differentiation, but the molecular mechanisms by which they regulate pancreatic subtype specification remain elusive. Here it is shown that in zebrafish, nkx6.1 and nkx6.2 are co-expressed at early stages in the first pancreatic endocrine progenitors, but that their expression domains gradually segregate into different layers, nkx6.1 being expressed ventrally with respect to the forming islet while nkx6.2 is expressed mainly in beta-cells. Knockdown of nkx6.2 or nkx6.1 expression leads to nearly complete loss of alpha-cells but has no effect on beta-, delta-, or epsilon-cells. In contrast, nkx6.1/nkx6.2 double knockdown leads additionally to a drastic reduction of beta-cells. Synergy between the effects of nkx6.1 and nkx6.2 knockdown on both beta- and alpha-cell differentiation suggests that nkx6.1 and nkx6.2 have the same biological activity, the required total nkx6 threshold being higher for alpha-cell than for beta-cell differentiation. Finally, we demonstrate that the nkx6 act on the establishment of the pancreatic endocrine progenitor pool whose size is correlated with the total nkx6 expression level. On the basis of our data, we propose a model in which nkx6.1 and nkx6.2, by allowing the establishment of the endocrine progenitor pool, control alpha- and beta-cell differentiation. [less ▲]

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See detailExpression of the metal homeostasis gene FRD3 in two Arabidopsis species
Charlier, Jean-Benoit ULg; Polese, Catherine; Motte, Patrick ULg et al

Poster (2010, January 26)

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See detailKnock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green alga Chlamydomonas reinhardtii.
Remacle, Claire ULg; Coosemans, Nadine ULg; Jans, Frédéric ULg et al

in Plant Molecular Biology (2010), 74(3), 223-2363

The COX3 gene encodes a core subunit of mitochondrial cytochrome c oxidase (complex IV) whereas the COX17 gene encodes a chaperone delivering copper to the enzyme. Mutants of these two genes were isolated ... [more ▼]

The COX3 gene encodes a core subunit of mitochondrial cytochrome c oxidase (complex IV) whereas the COX17 gene encodes a chaperone delivering copper to the enzyme. Mutants of these two genes were isolated by RNA interference in the microalga Chlamydomonas. The COX3 mRNA was completely lacking in the cox3-RNAi mutant and no activity and assembly of complex IV were detected. The cox17-RNAi mutant presented a reduced level of COX17 mRNA, a reduced activity of the cytochrome c oxidase but no modification of its amount. The cox3-RNAi mutant had only 40% of the wild-type rate of dark respiration which was cyanide-insensitive. The mutant presented a 60% decrease of H(2)O(2) production in the dark compared to wild type, which probably accounts for a reduced electron leakage by respiratory complexes III and IV. In contrast, the cox17-RNAi mutant showed no modification of respiration and of H(2)O(2) production in the dark but a two to threefold increase of H(2)O(2) in the light compared to wild type and the cox3-RNAi mutant. The cox17-RNAi mutant was more sensitive to cadmium than the wild-type and cox3-RNAi strains. This suggested that besides its role in complex IV assembly, Cox17 could have additional functions in the cell such as metal detoxification or Reactive Oxygen Species protection or signaling. Concerning Cox3, its role in Chlamydomonas complex IV is similar to that of other eukaryotes although this subunit is encoded in the nuclear genome in the alga contrary to the situation found in all other organisms. [less ▲]

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See detailADAMTS-2 functions as anti-angiogenic and anti-tumoral molecule independently of its catalytic activity.
Dubail, Johanne ULg; Kesteloot, F.; Deroanne, Christophe ULg et al

in Cellular & Molecular Life Sciences (2010)

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ... [more ▼]

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ADAMTS-2 is also able to reduce proliferation of endothelial cells, and to induce their retraction and detachment from the substrate resulting in apoptosis. Dephosphorylation of Erk1/2 and MLC largely precedes the ADAMTS-2 induced morphological alterations. In 3-D culture models, ADAMTS-2 strongly reduced branching of capillary-like structures formed by endothelial cells and their long-term maintenance and inhibited vessels formation in embryoid bodies (EB). Growth and vascularization of tumors formed in nude mice by HEK 293-EBNA cells expressing ADAMTS-2 were drastically reduced. A similar anti-tumoral activity was observed when using cells expressing recombinant deleted forms of ADAMTS-2, including catalytically inactive enzyme. Nucleolin, a nuclear protein also found to be associated with the cell membrane, was identified as a potential receptor mediating the antiangiogenic properties of ADAMTS-2. [less ▲]

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See detailEvolution of metal hyperaccumulation in Arabidopsis halleri
Hanikenne, Marc ULg; Kroymann, Juergen; Talke, Ina N. et al

Conference (2009, March 04)

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See detailOrigin and evolution of SR proteins in Eukaryotes
Califice, Sophie ULg; Baurain, Denis ULg; Hanikenne, Marc ULg et al

Poster (2009, February 05)

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See detailZebrafish Sox7 and Sox18 function together to control arterial-venous identity
Pendeville-Samain, Hélène ULg; Winandy, Marie ULg; Manfroid, Isabelle ULg et al

in Developmental Biology (2008), 317(2), 405-16

Sox7 and Sox18 are members of the F-subgroup of Sox transcription factors family and are mostly expressed in endothelial compartments. In humans, dominant mutations in Sox18 are the underlying cause of ... [more ▼]

Sox7 and Sox18 are members of the F-subgroup of Sox transcription factors family and are mostly expressed in endothelial compartments. In humans, dominant mutations in Sox18 are the underlying cause of the severe hypotrichosis-lymphedema-telangiectasia disorder characterized by vascular defects. However little is known about which vasculogenic processes Sox7 and Sox18 regulate in vivo. We cloned the orthologs of Sox7 and Sox18 in zebrafish, analysed their expression pattern and performed functional analyses. Both genes are expressed in the lateral plate mesoderm during somitogenesis. At later stages, Sox18 is expressed in all axial vessels whereas Sox7 expression is mainly restricted to the dorsal aorta. Knockdown of Sox7 or Sox18 alone failed to reveal any phenotype. In contrast, blocking the two genes simultaneously led to embryos displaying dysmorphogenesis of the proximal aorta and arteriovenous shunts, all of which can account for the lack of circulation observed in the trunk and tail. Gene expression analyses performed with general endothelial markers on double morphants revealed that Sox7 and Sox18 are dispensable for the initial specification and positioning of the major trunk vessels. However, morphants display ectopic expression of the venous Flt4 marker in the dorsal aorta and a concomitant reduction of the artery-specific markers EphrinB2a and Gridlock. The striking similarities between the phenotype of Sox7/Sox18 morphants and Gridlock mutants strongly suggest that Sox7 and Sox18 control arterial-venous identity by regulating Gridlock expression. [less ▲]

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See detailEvolution of metal hyperaccumulation required cis-regulatory changes and triplication of HMA4
Hanikenne, Marc ULg; Talke, Ina N.; Haydon, Michael J. et al

in Nature (2008), 453

Little is known about the types of mutations underlying the evolution of species-specific traits. The metal hyperaccumulator Arabidopsis halleri has the rare ability to colonize heavy-metal-polluted soils ... [more ▼]

Little is known about the types of mutations underlying the evolution of species-specific traits. The metal hyperaccumulator Arabidopsis halleri has the rare ability to colonize heavy-metal-polluted soils, and, as an extremophile sister species of Arabidopsis thaliana, it is a powerful model for research on adaptation. A. halleri naturally accumulates and tolerates leaf concentrations as high as 2.2% zinc and 0.28% cadmium in dry biomass. On the basis of transcriptomics studies, metal hyperaccumulation in A. halleri has been associated with more than 30 candidate genes that are expressed at higher levels in A. halleri than in A. thaliana. Some of these genes have been genetically mapped to broad chromosomal segments of between 4 and 24 cM co-segregating with Zn and Cd hypertolerance. However, the in planta loss-of-function approaches required to demonstrate the contribution of a given candidate gene to metal hyperaccumulation or hypertolerance have not been pursued to date. Using RNA interference to downregulate HMA4 (HEAVY METAL ATPASE 4) expression, we show here that Zn hyperaccumulation and full hypertolerance to Cd and Zn in A. halleri depend on the metal pump HMA4. Contrary to a postulated global trans regulatory factor governing high expression of numerous metal hyperaccumulation genes, we demonstrate that enhanced expression of HMA4 in A. halleri is attributable to a combination of modified cis-regulatory sequences and copy number expansion, in comparison to A. thaliana. Transfer of an A. halleri HMA4 gene to A. thaliana recapitulates Zn partitioning into xylem vessels and the constitutive transcriptional upregulation of Zn deficiency response genes characteristic of Zn hyperaccumulators. Our results demonstrate the importance of cis-regulatory mutations and gene copy number expansion in the evolution of a complex naturally selected extreme trait. The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils and for bio-fortification. [less ▲]

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