The non-canonical NOTCH1 ligand Delta-like 1 homolog (DLK1) self interacts in mammals

Int J Biol Macromol. 2017 Apr;97:460-467. doi: 10.1016/j.ijbiomac.2017.01.067. Epub 2017 Jan 15.

Abstract

Delta-like 1 homolog (DLK1) is an imprinted gene, which is widely expressed during mammalian development and plays a pivotal role in differentiation of various tissue types. Most recently, we have shown that DLK1 interacts with NOTCH1, yet several Notch independent mechanisms have previously been suggested as well, but only poorly confirmed in a mammalian context. In the present study, we employed the mammalian two-hybrid (MTH) system, a genetic in vivo protein-protein interaction system, to show robust DLK1-DLK1, DLK1-FnI (Fibronectin) and DLK1-CFR (cysteine-rich FGF receptor) interactions, whereas the proposed DLK1-IGFBP1 interaction was not supported by MTH. Very little has previously been described on the DLK1 self-interaction. Herein, we showed by immunoprecipitation as well as Sulfo-SBED label transfer that the DLK1-DLK1 interaction likely is part of Dlk1's function in preadipocytes. Furthermore our data suggest that DLK1 interacts with itself through EGF domain 4 and 5, which is distinct from the recently described NOTCH1-DLK1 interaction, which occurs between EGF domain 5 and 6. This opens up the possibility that Notch independent mechanisms like the DLK1-DLK1 interaction may modulate the non-canonical NOTCH1-DLK1 interaction further complexing this system.

Keywords: Delta-like 1 homolog (Dlk1); EGF-repeats; Ligand; Receptor; Self-interacting protein.

MeSH terms

  • Animals
  • Calcium-Binding Proteins
  • Fibronectins / metabolism
  • HEK293 Cells
  • Humans
  • Intercellular Signaling Peptides and Proteins / chemistry
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Ligands
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Mice
  • NIH 3T3 Cells
  • Protein Aggregates*
  • Protein Binding
  • Protein Domains
  • Receptor, Notch1 / metabolism*
  • Receptors, Fibroblast Growth Factor / metabolism
  • Signal Transduction

Substances

  • Calcium-Binding Proteins
  • DLK1 protein, human
  • Dlk1 protein, mouse
  • Fibronectins
  • Intercellular Signaling Peptides and Proteins
  • Ligands
  • Membrane Proteins
  • Protein Aggregates
  • Receptor, Notch1
  • Receptors, Fibroblast Growth Factor