Non-classical export of epimorphin and its adhesion to αv-integrin in regulation of epithelial morphogenesis

Y Hirai, CM Nelson, K Yamazaki… - Journal of cell …, 2007 - journals.biologists.com
Y Hirai, CM Nelson, K Yamazaki, K Takebe, J Przybylo, B Madden, DC Radisky
Journal of cell science, 2007journals.biologists.com
Epimorphin (also known as syntaxin 2) acts as an epithelial morphogen when secreted by
stromal cells of the mammary gland, lung, liver, colon, pancreas and other tissues, but the
same molecule functions within the cell to mediate membrane fusion. How this molecule,
which lacks a signal sequence and contains a transmembrane domain at the C-terminus,
translocates across the plasma membrane and is secreted to become a morphogen, and
how it initiates morphogenic events is not clear. Here, we show that epimorphin is secreted …
Epimorphin (also known as syntaxin 2) acts as an epithelial morphogen when secreted by stromal cells of the mammary gland, lung, liver, colon, pancreas and other tissues, but the same molecule functions within the cell to mediate membrane fusion. How this molecule, which lacks a signal sequence and contains a transmembrane domain at the C-terminus, translocates across the plasma membrane and is secreted to become a morphogen, and how it initiates morphogenic events is not clear. Here, we show that epimorphin is secreted through a non-classical mechanism, similar to that previously described for secretion of the leaderless protein FGF1, and we identify the key molecular elements responsible for translocation and secretion from the cell. We also show that secreted epimorphin binds to αv-integrin-containing receptors on target epithelial cells, leading to activation of specific downstream signaling pathways and induction of epithelial morphogenesis. These findings provide key insight into how epimorphin functions as an epithelial morphogen.
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