title: Caenorhabditis elegans Heterochromatin protein 1 (HPL-2) links developmental plasticity, longevity and lipid metabolism.
abstract: BACKGROUND
  Heterochromatin protein 1 (HP1) family proteins have a well-characterized role in heterochromatin packaging and gene regulation. Their function in organismal development, however, is less well understood. Here we used genome-wide expression profiling to assess novel functions of the Caenorhabditis elegans HP1 homolog HPL-2 at specific developmental stages.
  
  
  RESULTS
  We show that HPL-2 regulates the expression of germline genes, extracellular matrix components and genes involved in lipid metabolism. Comparison of our expression data with HPL-2 ChIP-on-chip profiles reveals that a significant number of genes up- and down-regulated in the absence of HPL-2 are bound by HPL-2. Germline genes are specifically up-regulated in hpl-2 mutants, consistent with the function of HPL-2 as a repressor of ectopic germ cell fate. In addition, microarray results and phenotypic analysis suggest that HPL-2 regulates the dauer developmental decision, a striking example of phenotypic plasticity in which environmental conditions determine developmental fate. HPL-2 acts in dauer at least partly through modulation of daf-2/IIS and TGF-β signaling pathways, major determinants of the dauer program. hpl-2 mutants also show increased longevity and altered lipid metabolism, hallmarks of the long-lived, stress resistant dauers.
  
  
  CONCLUSIONS
  Our results suggest that the worm HP1 homologue HPL-2 may coordinately regulate dauer diapause, longevity and lipid metabolism, three processes dependent on developmental input and environmental conditions. Our findings are of general interest as a paradigm of how chromatin factors can both stabilize development by buffering environmental variation, and guide the organism through remodeling events that require plasticity of cell fate regulation.
authors.affiliation: Laboratory of Molecular and Cellular Biology, CNRS, Université de Lyon, Ecole Normale Supérieure, Lyon Cedex 07, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Meister
authors.forename: Sonia
authors.initials: S
authors.lastname: Schott
authors.forename: Cécile
authors.initials: C
authors.lastname: Bedet
authors.forename: Yu
authors.initials: Y
authors.lastname: Xiao
authors.forename: Sabine
authors.initials: S
authors.lastname: Rohner
authors.forename: Selena
authors.initials: S
authors.lastname: Bodennec
authors.forename: Bruno
authors.initials: B
authors.lastname: Hudry
authors.forename: Laurent
authors.initials: L
authors.lastname: Molin
authors.forename: Florence
authors.initials: F
authors.lastname: Solari
authors.forename: Susan M
authors.initials: SM
authors.lastname: Gasser
authors.forename: Francesca
authors.initials: F
authors.lastname: Palladino
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D004777:Environment; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000254:growth & development / Q000378:metabolism; D057850:Hermaphroditic Organisms; D006570:Heterochromatin / Q000235:genetics; D050356:Lipid Metabolism / Q000235:genetics*; D008136:Longevity / Q000235:genetics*; D008297:Male; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D002868:Chromosomal Proteins, Non-Histone; C514742:HPL-2 protein, C elegans; D006570:Heterochromatin; D012097:Repressor Proteins; D016212:Transforming Growth Factor beta; C107483:DAF-2 protein, C elegans; D011972:Receptor, Insulin