title: Quantitative FLIM-FRET Microscopy to Monitor Nanoscale Chromatin Compaction In Vivo Reveals Structural Roles of Condensin Complexes.
abstract: How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer)-based fluorescence lifetime imaging microscopy (FLIM) approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells. Using RNAi and repetitive extrachromosomal array approaches, we defined the heterochromatin state and showed that its architecture presents a nanoscale-compacted organization controlled by Heterochromatin Protein-1 (HP1) and SETDB1 H3-lysine-9 methyltransferase homologs in vivo. Next, we functionally explored condensin complexes. We found that condensin I and condensin II are essential for heterochromatin compaction and that condensin I additionally controls lowly compacted regions. Our data show that, in living animals, nanoscale chromatin compaction is controlled not only by histone modifiers and readers but also by condensin complexes.
authors.affiliation: Institute of Molecular Genetics (IGMM), CNRS, UMR-5535, 34293 Montpellier, France; University of Montpellier, 34090 Montpellier, France. Electronic address: david.lleres@igmm.cnrs.fr.
authors.forename: David
authors.initials: D
authors.lastname: Llères
authors.affiliation: University of Montpellier, 34090 Montpellier, France; Cell Biology Research Center of Montpellier, CNRS, UMR-5237, 34293 Montpellier, France. Electronic address: aymeric.bailly@crbm.cnrs.fr.
authors.forename: Aymeric P
authors.initials: AP
authors.lastname: Bailly
authors.affiliation: University of Montpellier, 34090 Montpellier, France; Cell Biology Research Center of Montpellier, CNRS, UMR-5237, 34293 Montpellier, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Perrin
authors.affiliation: Nucleic Acids Structure Research Group, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: David G
authors.initials: DG
authors.lastname: Norman
authors.affiliation: University of Montpellier, 34090 Montpellier, France; Cell Biology Research Center of Montpellier, CNRS, UMR-5237, 34293 Montpellier, France.
authors.forename: Dimitris P
authors.initials: DP
authors.lastname: Xirodimas
authors.affiliation: Institute of Molecular Genetics (IGMM), CNRS, UMR-5535, 34293 Montpellier, France; University of Montpellier, 34090 Montpellier, France. Electronic address: robert.feil@igmm.cnrs.fr.
authors.forename: Robert
authors.initials: R
authors.lastname: Feil
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics*; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D002875:Chromosomes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000235:genetics; D008856:Microscopy, Fluorescence / Q000379:methods; D046912:Multiprotein Complexes / Q000235:genetics*
chemical_list: D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006570:Heterochromatin; D006657:Histones; D046912:Multiprotein Complexes; C108312:condensin complexes; D000090266:Chromobox Protein Homolog 5; D000251:Adenosine Triphosphatases
keywords: C. elegans; FLIM-FRET imaging; HP1; chromatin compaction; chromosome structure; condensin; heterochromatin; meiosis