Nuclear Cell Biology - CNRS URA2582  


  HEADDr. DAVID-WATINE Brigitte / bdwati@pasteur.fr
  MEMBERSDr. BACHELLIER-BASSI Sophie / BERGER Axel/ COROT-MOREL Eve / DONNADIEU Françoise / DOUALOT Harry/ DULIEU Isabelle/ Dr. FEUERBACH Frank / Dr. GALY Vincent / Dr MHLANGA Musa, Dr NEHRBASS Ulf (nehrbass@ip-korea.org)


  Annual Report

We are studying nuclear structure / function relationships and are mainly focusing on characterizing the regulatory function and molecular determinants of gene positioning within the nuclear space. We are developing biological and informatic tools allowing the accurate measurement of single and multiple gene loci positions in living yeast cells under inactive and active conditions. We also started to study nuclear architecture-linked gene regulation during differentiation and developmental processes in nematodes.

1. Role of transcription and export machineries in spatial positioning of transcribed genes

In S. cerevisiae, domains close to the nuclear periphery are implicated in transcriptional silencing. We have also reported NPC-proximal transcriptional activation with the concomitent recruitment of induced genes from the nuclear interior to the periphery. Genetic and physical links exist between the SAGA transcription initiation complex and the mRNA export machinery at the nuclear pore complex (NPC). To analyze spatial positioning of the GAL genes in the “activated” state, we developed in collaboration with the Quantitative Image Analyses laboratory (LAIQ) an application for automatic detection and localization of single fluorescently tagged loci in 3D+time and observed that, upon induction, the GAL locus is confined close to the NE. By simultaneous detection of GAL transcripts we showed that transcription occurs preferentially while genes motility is being confined close to the NE. Finally we demonstrated that peripheral positioning is affected in SAGA, export machinery and NPC mutants.

2. Role of the nucleolus on nuclear organization

In order to analyse how genes that need to be co-regulated for ribosome biogenesis are positioned within the nuclear volume, we - in collaboration with LAIQ - extended the gene localization method by introducing a second nuclear landmark different from the NE: the nucleolus. This implementation allowed the gene position information of aligned nuclei to be merged thus giving access for the first time to statistical robust high precision localization probability maps.

3. Structural and functional nuclear organization in metazoan

In parallel of our analysis in yeast, we analyzed the structure/function relationships in metazoans using human cells in culture as well as C. elegans and D. melanogaster embryos. We started the analysis of several NE components, including the orthologs of the Mlp proteins in these organisms and are currently analyzing their function at the cell as well as at the organism level.

Keywords: functional organization, nuclear envelope, nuclear pore, genetic/epigenetic regulation, gene loci dynamics, genome stability

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  Publications

Berger AB, Cabal GG, Fabre E, Duong T, Buc H, Nehrbass U, Olivo-Marin JC, Gadal O, Zimmer C. 2008. High-resolution statistical mapping reveals gene territories in live yeast. Nat. Methods. 5:1031-7.

Bachellier-Bassi S, Gadal O, Bourout G, Nehrbass U. 2008. Cell cycle-dependent kinetochore localization of condensin complex in Saccharomyces cerevisiae. J. Struct. Biol. 162:248-59.

Berger AB, Decourty L, Badis G, Nehrbass U, Jacquier A, Gadal O. 2007. Hmo1 is required for TOR-dependent regulation of ribosomal protein gene transcription. Mol Cell Biol. 27:8015.

Zuccolo M, Alves A, Galy V, Bolhy S, Formstecher E, Racine V, Sibarita JB, Fukagawa T, Shiekhattar R, Yen T, Doye V. 2007. The human Nup107-160 nuclear pore subcomplex contributes to proper kinetochore functions. EMBO J. 26:1853.

Cabal G, Enninga J. and Mhlanga M.M. 2007. Single molecule tracking of mRNA and proteins. in 'Imaging Cellular and Molecular Biological Function' pp 235-261. S. Shorte & F. Frischknecht Eds., Springer.





Activity Reports 2009 - Institut Pasteur
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