title: An H4K16 histone acetyltransferase mediates decondensation of the X chromosome inC. elegansmales.
abstract: InC. elegans, in order to equalize gene expression between the sexes and balance X and autosomal expression, two steps are believed to be required. First, an unknown mechanism is hypothesized to upregulate the X chromosome in both sexes. This mechanism balances the X to autosomal expression in males, but creates X overexpression in hermaphrodites. Therefore, to restore the balance, hermaphrodites downregulate gene expression twofold on both X chromosomes. While many studies have focused on X chromosome downregulation, the mechanism of X upregulation is not known.
  
  
  
  To gain more insight into X upregulation, we studied the effects of chromatin condensation and histone acetylation on gene expression levels in maleC. elegans. We have found that the H4K16 histone acetyltransferase MYS-1/Tip60 mediates dramatic decondensation of the male X chromosome as measured by FISH. However, RNA-seq analysis revealed that MYS-1 contributes only slightly to upregulation of gene expression on the X chromosome. These results suggest that the level of chromosome decondensation does not necessarily correlate with the degree of gene expression change in vivo. Furthermore, the X chromosome is more sensitive to MYS-1-mediated decondensation than the autosomes, despite similar levels of H4K16ac on all chromosomes, as measured by ChIP-seq. H4K16ac levels weakly correlate with gene expression levels on both the X and the autosomes, but highly expressed genes on the X chromosome do not contain exceptionally high levels of H4K16ac.
  
  
  
  These results indicate that H4K16ac and chromosome decondensation influence regulation of the male X chromosome; however, they do not fully account for the high levels of gene expression observed on the X chromosomes.
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University Ave., Ann Arbor, MI 48109-1048 USA ; Genome Technologies, The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032 USA.
authors: Alyssa C
authors: AC
authors: Lau
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University Ave., Ann Arbor, MI 48109-1048 USA.
authors: Kevin P
authors: KP
authors: Zhu
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University Ave., Ann Arbor, MI 48109-1048 USA.
authors: Elizabeth A
authors: EA
authors: Brouhard
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University Ave., Ann Arbor, MI 48109-1048 USA.
authors: Michael B
authors: MB
authors: Davis
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 N. University Ave., Ann Arbor, MI 48109-1048 USA.
authors: Györgyi
authors: G
authors: Csankovszki
mesh_terms: D000107:Acetylation; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D047369:Chromatin Immunoprecipitation; D004303:Dosage Compensation, Genetic; D015870:Gene Expression; D051548:Histone Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D017422:Sequence Analysis, DNA; D014960:X Chromosome / Q000235:genetics / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D002843:Chromatin; D006657:Histones; D051548:Histone Acetyltransferases; C486133:MYS-1 protein, C elegans
keywords: Caenorhabditis elegans; Chromatin; Chromosome territories; Dosage compensation; Epigenetics; Gene expression; Histone acetylation