Over 100 different types of epithelial cells perform essential vectorial functions required for homeostasis and survival of the organism. A key property underlying these functions is polarity, i.e. the ability of epithelial cells to localize different transporters, channels and hormone receptors to opposite (apical and basolateral) domains of their plasma membrane (PM). The experiments proposed will utilize state of the art molecular, biochemical and microscopic techniques to elucidate fundamental mechanisms involved in epithelial polarization. The proposed experiments follow up on our group's recent finding that clathrin plays a broad role of clathrin in basolateral protein sorting and that some epithelia lack the basolateral sorting adaptor AP-1B.
Specific aim 1 will investigate in detail the roles of clathrin adaptors AP-1A and AP-1B, two major basolateral sorting adaptors, in carrier assembly by quantitative 4D 3-color live imaging analysis. We will search for trafficking machinery engaged by AP-1A and AP-1B using a proteomics approach developed by Bernard Hoflack (Dresden).
Specific aim 2 will investigate the role of clathrin adaptors AP-2, AP-3, AP-4 and GGAs in polarized trafficking, using siRNA and ad hoc trafficking assays. The experiments will focus both on MDCK cells and on kidney proximal tubule epithelium, which lacks AP-1B.
Specific aim 3 will investigate the role of Golgins and rabs in polarized trafficking, combining Golgin knock-down and inhibition of candidate rabs with trafficking assays for a panel of apical and basolateral cargos. We will test the hypothesis that TGN Golgins, elongated coil-coil molecules that bind membranes via rabs, mediate highly dynamic physical interactions between TGN and recycling endosomes that are required for efficient polarized sorting.
Specific aim 4 will characterize the specific steps regulated by rabs 6,8,10, 11,17,25 in polarized trafficking, using ad hoc assays to explore these steps. The studies proposed will contribute to a deeper understanding of epithelial trafficking mechanisms, which, in turn, is likely to help understand and develop cures for human diseases.

Public Health Relevance

Human organs contain over 100 different types of epithelial types, which perform vital functions for the organism that depend on a fundamental property, polarity. The long term objective of this proposal is to elucidate the molecular mechanisms responsible for the establishment and maintenance of epithelial cell polarity. Because loss of polarity may cause cancer and diseases of the kidney, liver and other epithelial organs, the experiments proposed are bound to generate information relevant to preventing and curing human disease.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cellular and Molecular Biology of the Kidney Study Section (CMBK)
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Ainsztein, Alexandra M
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Weill Medical College of Cornell University
Schools of Medicine
New York
United States
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Tanos, Barbara E; Yeaman, Charles; Rodriguez-Boulan, Enrique (2018) An emerging role for IQGAP1 in tight junction control. Small GTPases 9:375-383
Caceres, Paulo S; Benedicto, Ignacio; Lehmann, Guillermo L et al. (2017) Directional Fluid Transport across Organ-Blood Barriers: Physiology and Cell Biology. Cold Spring Harb Perspect Biol 9:
Benedicto, Ignacio; Lehmann, Guillermo L; Ginsberg, Michael et al. (2017) Concerted regulation of retinal pigment epithelium basement membrane and barrier function by angiocrine factors. Nat Commun 8:15374
Perez Bay, Andres E; Schreiner, Ryan; Benedicto, Ignacio et al. (2016) The fast-recycling receptor Megalin defines the apical recycling pathway of epithelial cells. Nat Commun 7:11550
Tanos, Barbara E; Perez Bay, Andres E; Salvarezza, Susana et al. (2015) IQGAP1 controls tight junction formation through differential regulation of claudin recruitment. J Cell Sci 128:853-62
Song, Minseok; Giza, Joanna; Proenca, Catia C et al. (2015) Slitrk5 Mediates BDNF-Dependent TrkB Receptor Trafficking and Signaling. Dev Cell 33:690-702
de la Fuente-Ortega, Erwin; Gravotta, Diego; Perez Bay, Andres et al. (2015) Basolateral sorting of chloride channel 2 is mediated by interactions between a dileucine motif and the clathrin adaptor AP-1. Mol Biol Cell 26:1728-42
Bay, Andres E Perez; Schreiner, Ryan; Rodriguez-Boulan, Enrique (2015) Structural and functional analysis of endosomal compartments in epithelial cells. Methods Cell Biol 130:271-88
Perez Bay, Andres E; Schreiner, Ryan; Benedicto, Ignacio et al. (2014) Galectin-4-mediated transcytosis of transferrin receptor. J Cell Sci 127:4457-69
Lehmann, Guillermo L; Benedicto, Ignacio; Philp, Nancy J et al. (2014) Plasma membrane protein polarity and trafficking in RPE cells: past, present and future. Exp Eye Res 126:5-15

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