dlk acts as a negative regulator of Notch1 activation through interactions with specific EGF-like repeats

Exp Cell Res. 2005 Feb 15;303(2):343-59. doi: 10.1016/j.yexcr.2004.10.001. Epub 2004 Nov 2.


The protein dlk, encoded by the Dlk1 gene, belongs to the Notch epidermal growth factor (EGF)-like family of receptors and ligands, which participate in cell fate decisions during development. The molecular mechanisms by which dlk regulates cell differentiation remain unknown. By using the yeast two-hybrid system, we found that dlk interacts with Notch1 in a specific manner. Moreover, by using luciferase as a reporter gene under the control of a CSL/RBP-Jk/CBF-1-dependent promoter in the dlk-negative, Notch1-positive Balb/c 14 cell line, we found that addition of synthetic dlk EGF-like peptides to the culture medium or forced expression of dlk decreases endogenous Notch activity. Furthermore, the expression of the gene Hes-1, a target for Notch1 activation, diminishes in confluent Balb/c14 cells transfected with an expression construct encoding for the extracellular EGF-like region of dlk. The expression of Dlk1 and Notch1 increases in 3T3-L1 cells maintained in a confluent state for several days, which is associated with a concomitant decrease in Hes-1 expression. On the other hand, the decrease of Dlk1 expression in 3T3-L1 cells by antisense cDNA transfection is associated with an increase in Hes-1 expression. These results suggest that dlk functionally interacts in vivo with Notch1, which may lead to the regulation of differentiation processes modulated by Notch1 activation and signaling, including adipogenesis.

MeSH terms

  • 3T3-L1 Cells
  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Line
  • DNA, Antisense / genetics
  • Epidermal Growth Factor / chemistry
  • Epidermal Growth Factor / genetics
  • Epidermal Growth Factor / metabolism
  • Gene Expression Regulation
  • Genes, Reporter
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • In Vitro Techniques
  • Intracellular Signaling Peptides and Proteins
  • Luciferases / genetics
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Receptor, Notch1
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Repetitive Sequences, Amino Acid
  • Transcription Factor HES-1
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transfection
  • Two-Hybrid System Techniques


  • Basic Helix-Loop-Helix Transcription Factors
  • DNA, Antisense
  • Hes1 protein, mouse
  • Homeodomain Proteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • NOTCH1 protein, human
  • Notch1 protein, mouse
  • Receptor, Notch1
  • Receptors, Cell Surface
  • Recombinant Proteins
  • Transcription Factor HES-1
  • Transcription Factors
  • delta protein
  • Epidermal Growth Factor
  • Luciferases