O-fucosylation of DLL3 is required for its function during somitogenesis

PLoS One. 2015 Apr 9;10(4):e0123776. doi: 10.1371/journal.pone.0123776. eCollection 2015.

Abstract

Delta-like 3 (DLL3) is a member of the DSL family of Notch ligands in amniotes. In contrast to DLL1 and DLL4, the other Delta-like proteins in the mouse, DLL3 does not bind in trans to Notch and does not activate the receptor, but shows cis-interaction and cis-inhibitory properties on Notch signaling in vitro. Loss of the DSL protein DLL3 in the mouse results in severe somite patterning defects, which are virtually indistinguishable from the defects in mice that lack lunatic fringe (LFNG), a glycosyltransferase involved in modifying Notch signaling. Like LFNG, DLL3 is located within the trans-Golgi, however, its biochemical function is still unclear. Here, we show that i) both proteins interact, ii) epidermal growth factor like repeats 2 and 5 of DLL3 are O-fucosylated at consensus sites for POFUT1, and iii) further modified by FNG proteins in vitro. Embryos double homozygous for null mutations in Dll3 and Lfng are phenotypically indistinguishable from the single mutants supporting a potential common function. Mutation of the O-fucosylation sites in DLL3 does not disrupt the interaction of DLL3 with LFNG or full length Notch1or DLL1, and O-fucosylation-deficient DLL3 can still inhibit Notch in cis in vitro. However, in contrast to wild type DLL3, O-fucosylation-deficient DLL3 cannot compensate for the loss of endogenous DLL3 during somitogenesis in the embryo. Together our results suggest that the cis-inhibitory activity of DLL3 observed in cultured cells might not fully reflect its assumed essential physiological property, suggest that DLL3 and LFNG act together, and strongly supports that modification of DLL3 by O-linked fucose is essential for its function during somitogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Calcium-Binding Proteins
  • Cricetinae
  • Cricetulus
  • Fucose / metabolism*
  • Glycosyltransferases / metabolism
  • Immunohistochemistry
  • Immunoprecipitation
  • In Situ Hybridization
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Membrane Proteins / metabolism*
  • Mice
  • Morphogenesis / physiology*
  • Receptors, Notch / metabolism
  • Somites / embryology*
  • trans-Golgi Network / metabolism

Substances

  • Calcium-Binding Proteins
  • Dlk1 protein, mouse
  • Dll3 protein, mouse
  • Intercellular Signaling Peptides and Proteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Receptors, Notch
  • Fucose
  • Glycosyltransferases
  • Lfng protein, mouse

Grant support

This work was supported by a grant of the German Research Council (DFG; http://www.dfg.de) to AG (GO 449/9-3), and by funding of the Cluster of Excellence “From Regenerative Biology to Reconstructive Therapy” (http://www.mh-hannover.de/rebirth.html). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.