Global Analysis of Intercellular Homeodomain Protein Transfer

Cell Rep. 2019 Jul 16;28(3):712-722.e3. doi: 10.1016/j.celrep.2019.06.056.


The homeodomain is found in hundreds of transcription factors that play roles in fate determination via cell-autonomous regulation of gene expression. However, some homeodomain-containing proteins (HPs) are thought to be secreted and penetrate neighboring cells to affect the recipient cell fate. To determine whether this is a general characteristic of HPs, we carried out a large-scale validation for intercellular transfer of HPs. Our screening reveals that intercellular transfer is a general feature of HPs, but it occurs in a cell-context-sensitive manner. We also found the secretion is not solely a function of the homeodomain, but it is supported by external motifs containing hydrophobic residues. Thus, mutations of hydrophobic residues of HPs abrogate secretion and consequently interfere with HP function in recipient cells. Collectively, our study proposes that HP transfer is an intercellular communication method that couples the functions of interacting cells.

Keywords: cell-penetrating protein; homeodomain; intercellular protein transfer; protein secretion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs / genetics
  • Animals
  • Brain / embryology
  • Brain / metabolism
  • Cell Communication / genetics*
  • Cell Line
  • Female
  • High-Throughput Screening Assays
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation
  • Pregnancy
  • Protein Transport / genetics*
  • Retina / metabolism


  • Homeodomain Proteins