The Drosophila gypsy insulator supports transvection in the presence of the vestigial enhancer

PLoS One. 2013 Nov 13;8(11):e81331. doi: 10.1371/journal.pone.0081331. eCollection 2013.

Abstract

Though operationally defined as cis-regulatory elements, enhancers can also communicate with promoters on a separate homolog in trans, a mechanism that has been suggested to account for the ability of certain alleles of the same gene to complement one another in a process otherwise known as transvection. This homolog-pairing dependent process is facilitated in Drosophila by chromatin-associated pairing proteins, many of which remain unknown and their mechanism of action uncharacterized. Here we have tested the role of the gypsy chromatin insulator in facilitating pairing and communication between enhancers and promoters in trans using a transgenic eGFP reporter system engineered to allow for targeted deletions in the vestigial Boundary Enhancer (vgBE) and the hsp70 minimal promoter, along with one or two flanking gypsy elements. We found a modest 2.5-3x increase in eGFP reporter levels from homozygotes carrying an intact copy of the reporter on each homolog compared to unpaired hemizygotes, although this behavior was independent of gypsy. However, detectable levels of GFP protein along the DV wing boundary in trans-heterozygotes lacking a single enhancer and promoter was only observed in the presence of two flanking gypsy elements. Our results demonstrate that gypsy can stimulate enhancer-promoter communication in trans throughout the genome in a context-dependent manner, likely through modulation of local chromatin dynamics once pairing has been established by other elements and highlights chromatin structure as the master regulator of this phenomenon.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Chromatin / genetics*
  • Chromatin / metabolism
  • Drosophila / genetics*
  • Drosophila / metabolism
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Enhancer Elements, Genetic*
  • Gene Expression
  • Gene Expression Regulation
  • Gene Order
  • Genes, Reporter
  • Insulator Elements*
  • Male
  • Mutation
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Promoter Regions, Genetic

Substances

  • Chromatin
  • Drosophila Proteins
  • Nuclear Proteins
  • vg protein, Drosophila