Morphology and biogenesis of endosomal compartments in epithelial cells

Persistent Link:
http://hdl.handle.net/10150/279796
Title:
Morphology and biogenesis of endosomal compartments in epithelial cells
Author:
Gokay, Kerimi Erden
Issue Date:
2000
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Epithelial tissues which line the body cavities and tubules typically face two environments that are biochemically and physically different from each other. Consequently, these cells possess two structurally and functionally distinct plasma membrane domains; an apical domain facing the lumenal or the free surface and a basolateral domain facing the basement membrane and the intercellular space. Furthermore, via processes such as domain selective absorption, secretion and transcytosis, epithelial cells not only maintain these trans-epithelial differences but also actively contribute to their generation. Therefore, maintenance of high fidelity in polarized protein sorting and membrane trafficking aee of cardinal importance in all epithelia for their proper function. Although the central role membrane trafficking plays in generation and maintenance of epithelial cell polarity is clear, nature of the endosomal compartment(s) involved and the molecular determinants employed in this process remains ill-defined. In this study, using a unique apical endosomal marker, endotubin, and a model polarized epithelial cell line, Madin-Darby canine kidney (MDCK), we characterize the endotubin-positive endosomes as a subset of apical early endosomes which can be reached with an endocytic marker only when it is internalized apically. Furthermore, we show that endotubin-positive endosomes do not contain basolaterally recycling transferrin or the small GTPase Rab 11 and therefore they are distinct from the previously described apical recycling endosomes (ARE) in MDCK cells. In addition, using a panel of endotubin mutants we characterize two cytoplasmic sorting signals, a hydrophobic cluster and a casein kinase II phosphorylation site, as the molecular determinants required for polarized sorting and endosomal targeting of this molecule. Also, using a panel of domain exchange chimeras we show that endotubin cytoplasmic domain is sufficient to mediate apical sorting and early endosomal targeting of an unrelated protein in MDCK cells. Nevertheless, overexpression of these chimeras but not a mutant form defective in endosomal targeting results in missorting of the construct to the basolateral domain. These results indicate that, the endotubin-positive apical endosomes possess a saturable sorting machinery capable of recognizing the cytoplasmic sorting determinants here we characterize.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Molecular.; Biology, Cell.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Cell Biology and Anatomy
Degree Grantor:
University of Arizona
Advisor:
Wilson, Jean M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleMorphology and biogenesis of endosomal compartments in epithelial cellsen_US
dc.creatorGokay, Kerimi Erdenen_US
dc.contributor.authorGokay, Kerimi Erdenen_US
dc.date.issued2000en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEpithelial tissues which line the body cavities and tubules typically face two environments that are biochemically and physically different from each other. Consequently, these cells possess two structurally and functionally distinct plasma membrane domains; an apical domain facing the lumenal or the free surface and a basolateral domain facing the basement membrane and the intercellular space. Furthermore, via processes such as domain selective absorption, secretion and transcytosis, epithelial cells not only maintain these trans-epithelial differences but also actively contribute to their generation. Therefore, maintenance of high fidelity in polarized protein sorting and membrane trafficking aee of cardinal importance in all epithelia for their proper function. Although the central role membrane trafficking plays in generation and maintenance of epithelial cell polarity is clear, nature of the endosomal compartment(s) involved and the molecular determinants employed in this process remains ill-defined. In this study, using a unique apical endosomal marker, endotubin, and a model polarized epithelial cell line, Madin-Darby canine kidney (MDCK), we characterize the endotubin-positive endosomes as a subset of apical early endosomes which can be reached with an endocytic marker only when it is internalized apically. Furthermore, we show that endotubin-positive endosomes do not contain basolaterally recycling transferrin or the small GTPase Rab 11 and therefore they are distinct from the previously described apical recycling endosomes (ARE) in MDCK cells. In addition, using a panel of endotubin mutants we characterize two cytoplasmic sorting signals, a hydrophobic cluster and a casein kinase II phosphorylation site, as the molecular determinants required for polarized sorting and endosomal targeting of this molecule. Also, using a panel of domain exchange chimeras we show that endotubin cytoplasmic domain is sufficient to mediate apical sorting and early endosomal targeting of an unrelated protein in MDCK cells. Nevertheless, overexpression of these chimeras but not a mutant form defective in endosomal targeting results in missorting of the construct to the basolateral domain. These results indicate that, the endotubin-positive apical endosomes possess a saturable sorting machinery capable of recognizing the cytoplasmic sorting determinants here we characterize.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Molecular.en_US
dc.subjectBiology, Cell.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineCell Biology and Anatomyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWilson, Jean M.en_US
dc.identifier.proquest3002523en_US
dc.identifier.bibrecord.b41426770en_US
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