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 cytop...

The interaction between late endocytic structures and microtubules in polarized cells was studied using a procedure previously shown to cause microtubule-dependent redistribution of lysosomes in fibroblasts and macrophages (Heuser, J. 1989. J. Cell Biol. 108:855-864). In cultured rat hippocampal neurons, low cytoplasmic pH caused cation-independent mannose-6-phosphate receptor-enriched structur...

The small GTPase Rho is believed to regulate the actin cytoskeleton and cell adhesion through its specific targets. We previously identified the Rho targets: protein kinase N, Rho-associated kinase (Rho-kinase), and the myosin-binding subunit (MBS) of myosin phosphatase. We found that in MDCK epithelial cells, MBS accumulated at the tetradecanoylphorbol-13-acetate (TPA)-induced membrane rufflin...

Microtubule-disrupting drugs (nocodazole, colchicine) and cytochalasin D, which inhibits the polymerization of the actin microfilaments, were used to study the role of the cytoskeleton in protein secretion in the polarized Madin-Darby canine kidney (MDCK) epithelial cells. Two proteins were analyzed. The gp 80 glycoprotein complex, which in untreated cells is sorted into the apical pathway and ...

The action of a number of toxins used in the formation of immunotoxins was studied in polarized cells. Diphtheria toxin inhibited protein synthesis most efficiently when added to the basolateral side of the kidney cells, MDCK-I, MDBK and Pt K2, and the colon carcinoma cell Caco-2. Similar findings were made with Pseudomonas aeruginosa exotoxin A in MDCK-I, Pt K2, and Caco-2 cells, and with mode...

We have characterized the polarity of the transferrin receptor in the epithelial Madin-Darby canine kidney (MDCK) cell line. The receptor is present in approximately 165,000 copies per cell, migrates as a diffuse band upon SDS gel electrophoresis with Mr 90,000, displays a dissociation constant for diferritransferrin at neutral pH of approximately 2 nM, and is active in essentially all of the c...

The interaction of Pseudomonas aeruginosa type IV pili and the glycosphingolipid asialo-GM1 (aGM1) can mediate bacterial adherence to epithelial cells, but the steps subsequent to this adherence have not been elucidated. To investigate the result of the interaction of pili and aGM1, we used polarized epithelial monolayers of Madin-Darby canine kidney (MDCK) cells in culture, which contained lit...

The metastatic cascade describes the escape of primary tumour cells to distant secondary sites. Cells at the leading tumour edge are thought to undergo epithelial-mesenchymal transition (EMT), to enhance their motility and invasion for spreading. Whether EMT cells directly promote tumour angiogenesis, and the role of exosomes (30-150 nm extracellular vesicles) remains largely unknown. We examin...

BACKGROUND/AIMS Defective tissue repair underlies renal tissue degeneration during chronic kidney disease (CKD) progression. Unbalanced presence of TGF-β opposes effective cell proliferation and differentiation processes, necessary to replace damaged epithelia. TGF-β also retains arrested cells in a fibrotic phenotype responsible for irreversible scarring. In order to identify prospective molec...

Epithelial-mesenchymal transition (EMT) describes a morphogenetic program which confers mesenchymal cell properties, such as reduced cell-cell contact and increased cell migration and invasion, to epithelial cells. Here we investigate the role of the pleiotropic transcription/splicing factor and RNA-binding protein nuclease-sensitive element-binding protein 1 (YBX1/YB-1) in increasing the oncog...