Induction of lateral lumens through disruption of a monoleucine-based basolateral-sorting motif in betacellulin

J Cell Sci. 2015 Sep 15;128(18):3444-55. doi: 10.1242/jcs.170852. Epub 2015 Aug 13.


Directed delivery of EGF receptor (EGFR) ligands to the apical or basolateral surface is a crucial regulatory step in the initiation of EGFR signaling in polarized epithelial cells. Herein, we show that the EGFR ligand betacellulin (BTC) is preferentially sorted to the basolateral surface of polarized MDCK cells. By using sequential truncations and site-directed mutagenesis within the BTC cytoplasmic domain, combined with selective cell-surface biotinylation and immunofluorescence, we have uncovered a monoleucine-based basolateral-sorting motif (EExxxL, specifically (156)EEMETL(161)). Disruption of this sorting motif led to equivalent apical and basolateral localization of BTC. Unlike other EGFR ligands, BTC mistrafficking induced formation of lateral lumens in polarized MDCK cells, and this process was significantly attenuated by inhibition of EGFR. Additionally, expression of a cancer-associated somatic BTC mutation (E156K) led to BTC mistrafficking and induced lateral lumens in MDCK cells. Overexpression of BTC, especially mistrafficking forms, increased the growth of MDCK cells. These results uncover a unique role for BTC mistrafficking in promoting epithelial reorganization.

Keywords: Betacellulin; EGFR signaling; Epithelial polarity; Lateral lumens; MDCK cells; Polarized trafficking.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Betacellulin* / genetics
  • Betacellulin* / metabolism
  • Cell Polarity*
  • Dogs
  • EGF Family of Proteins
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism
  • Fluorescent Antibody Technique
  • Madin Darby Canine Kidney Cells
  • Mutation
  • Protein Sorting Signals / genetics
  • Protein Structure, Tertiary


  • Betacellulin
  • EGF Family of Proteins
  • Protein Sorting Signals
  • ErbB Receptors