Open Access Research

Caenorhabditis elegans Heterochromatin protein 1 (HPL-2) links developmental plasticity, longevity and lipid metabolism

Peter Meister12, Sonia Schott3, Cécile Bedet3, Yu Xiao3, Sabine Rohner1, Selena Bodennec3, Bruno Hudry4, Laurent Molin5, Florence Solari5, Susan M Gasser1 and Francesca Palladino3*

Author Affiliations

1 Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland

2 Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland

3 Laboratory of Molecular and Cellular Biology, CNRS, Université de Lyon, Ecole Normale Supérieure, 69364 Lyon Cedex 07, France

4 Development Biology Institute of Marseille Luminy, UMR 6216, Case 907 - Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France

5 Center of Molecular and Cellular Physiology and Genetics, Université Lyon 1, CNRS UMR 5534, 69622 Villeurbanne, France

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Genome Biology 2011, 12:R123  doi:10.1186/gb-2011-12-12-r123

Published: 20 December 2011

Additional files

Additional file 1:

Differentially expressed genes for embryos and L3 stage larvae in wild type compared to hpl-2 mutant animals.

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Additional file 2:

Increased lin-13::GFP expression in the absence of HPL-2 activity. Expression of a lin-13::GFP translational fusion [108] in wild-type and hpl-2 mutant animals. In hpl-2 mutant animals GFP expression was particularly strong in nuclei in the head region (arrows).

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Additional file 3:

HPL-2 regulation of specific gene classes. (a-f) Venn diagrams showing overlap between: (a) genes up-regulated in L3 stage hpl-2 mutants and germline genes; (b) genes down-regulated in L3 stage hpl-2 mutants and genes induced in dauer exit; (c) genes down-regulated in L3 stage hpl-2 mutants and genes clustered in expression mountain 29 of the C. elegans three-dimensional topographical expression map; (d) genes regulated in L3 stage hpl-2 mutants and neuronally expressed genes; (e) genes down-regulated in L3 stage hpl-2 mutants and daf-16 target genes; (f) genes down-regulated in L3 stage hpl-2 mutants and aging regulated genes.

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Additional file 4:

Overlap between hpl-2-regulated genes and genes bound by HPL-2. Venn diagram showing overlap between genes regulated in L3 stage hpl-2 mutants and genes bound by HPL-2 [29].

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Additional file 5:

HPL-2 and H3K9me3 are enriched on repetitive transgenes. (a) Histogram representing the percentage of immunoprecipitation, calculated as the ratio between signal from the antibodies and signal from pre-immune serum, from ChIP experiments along a repetitive transgene. Synchronized populations of L3 wild-type or hpl-2 mutant worms carrying the trangene were subjected to immunoprecipitation using anti-HPL-2, anti-H3K9me3, or pre-immune serum as control. (b) Schematic representation of the transgene used in these experiments [109] showing the position of the primers used for qPCR analysis. Similar results were obtained for three to four independent experiments.

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Additional file 6:

Repressive histone mark levels on promoters and genes misregulated in hpl-2 mutant worms. For each gene or gene promoter, H3K9 mono-, di- and tri-methyl levels were calculated as the median level observed on the DNA stretch using data provided by the modENCODE Consortium [29]. The criterion for choosing control genes was similar expression levels. Data are presented as box-whisker representation where the bar indicates the median of all up- or down-regulated genes and the upper and lower edges of the box represent the 25th and 75th percentiles, respectively. Up-regulated genes show a significantly higher level of mono-, di- and tri-methylated H3K9, but no enrichment in H3K27 trimethylation, compared to expression-matched control genes. Down-regulated genes show a similar level of mono-, di- and tri-methylated H3K9 compared to expression-matched control genes.

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Additional file 7:

rab-3p::hpl-2cDNA::GFP transgene is expressed uniquely in neuronal cells. GFP fluorescence is detected in the synaptic-rich regions of the nervous system, including the nerve ring, ventral nerve cord, and dorsal nerve cord (arrowheads).

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Additional file 8:

Increased lifespan of hpl-2(RNAi) animals. Animals at the L4 stage were placed on RNAi or control bacteria at 20°C and allowed to lay eggs. When F1 progeny reached the L4 stage, they were transferred to 25°C for lifespan assays on plates containing 10 μM 5FU. Worms were then transferred to fresh RNAi plates every week. hpl-2 RNAi increased average lifespan by 18% (average lifespans: wild type fed control bacteria, 10.3 ± 0.42 (n = 60); wild type fed hpl-2 RNAi clone 1, 12.2 ± 0.32 days (n = 60; control comparison P = 10-3). Similar results were obtained in two independent tests.

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Additional file 9:

hpl-2 deletion does not affect the total number of germ cells produced. Data are displayed as the mean (± standard deviation) number of germ cells per gonad arm (n = 4). Germ cell number was obtained by counting germ cell nuclei stained with DAPI in dissected gonads of young adults.

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Additional file 10:

hpl-2 does not influence DAF-16::GFP localization. Adults carrying a daf-16::gfp transgene (zIs356) were placed on NGM plates at 37°C. After 45 minutes, worms were mounted onto a slide in M9 buffer. Nuclear translocation of DAF-16::GFP was visualized with a fluorescence microscope AxioImager Z1 (Zeiss) equipped with a CoolSnap HQ camera and driven by Metamorph software (Molecular Devices, France).

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Additional file 11:

The hpl-2(tm1489) deletion mutant does not affect resistance to oxidative stress. Adult hermaphrodites were incubated in M9 buffer with 100 mM paraquat. After incubation at 20°C for the specified duration, survival was measured. Worms were scored as dead when they did not respond to a mechanical stimulus. The experiment was performed three times. Mean fraction alive indicates the average survival among the multiple trials and the error bar represents the standard deviation. P-value was calculated using Student's t-test.

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Additional file 12:

hpl-2 does not influence levels of ceramides and neutral lipids. (a) Ceramides (elution fraction 2) isolated from wild-type and hpl-2 animals were loaded on thin layer chromatography plates and run in a chloroform:methanol (50:5) solvent system. (b) Neutral lipids (elution fraction 1 and 3) were deposited on thin layer chromatography plates and run in hexane:diisopropylether:acetic acid (80:20:1).

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