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

Singh B, Bogatcheva G, Starchenko A, Sinnaeve J, Lapierre LA, Williams JA, Goldenring JR, Coffey RJ
J Cell Sci. 2015 128 (18): 3444-55

PMID: 26272915 · PMCID: PMC4582402 · DOI:10.1242/jcs.170852

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.

© 2015. Published by The Company of Biologists Ltd.

MeSH Terms (12)

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

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