title: Par-1 promotes a hepatic mode of apical protein trafficking in MDCK cells.
abstract: Simple (i.e., nonstratified) epithelial cells use two different routes to target their newly synthesized luminal plasma membrane proteins to the cell surface: a direct route from the Golgi complex, as in the kidney-derived MDCK cell line, or an indirect route that involves a intermediate stop at the ab-luminal (basolateral) membrane, as in hepatocytes. The mechanisms or proteins responsible for these different protein targeting strategies are not known. Here, we show that increased expression of EMK1, a mammalian ortholog of Caenorhabditis elegans Par-1, in MDCK cells promotes a switch from a direct to a transcytotic mode of apical protein delivery and other trafficking changes typical of hepatocytes. These results, together with our recent demonstration that PAR-1 promotes morphological features of hepatocytes in MDCK cells, indicate that Par-1 modulates the developmental decision to build a columnar versus a hepatic epithelial cell. To our knowledge, Par-1 is the first gene assigned to this task in epithelial morphogenesis.
authors.affiliation: Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: David
authors.initials: D
authors.lastname: Cohen
authors.forename: Enrique
authors.initials: E
authors.lastname: Rodriguez-Boulan
authors.forename: Anne
authors.initials: A
authors.lastname: Müsch
mesh_terms: D000818:Animals; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D016764:Cell Polarity; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology; D006056:Golgi Apparatus / Q000378:metabolism; D007668:Kidney; D008099:Liver / Q000166:cytology*; D009024:Morphogenesis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D029742:Caenorhabditis elegans Proteins; C489440:EMK1 protein, Canis familiaris; C409406:PAR-1 protein, C elegans; D017346:Protein Serine-Threonine Kinases