Expression and polarized targeting of a rab3 isoform in epithelial cells
| Autor: | Dale R. Abrahamson, M. W. Green, Gabor Berta, A Tousson, E Weber, U Gopalokrishnan, Eric J. Sorscher, P. L. St John, Tamas Jilling, T S Elton |
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| Rok vydání: | 1994 |
| Předmět: |
rab3 GTP-Binding Proteins
Molecular Sequence Data Cell Gene Expression In Vitro Techniques Biology Epithelium Exocytosis Cell Line Mice GTP-Binding Proteins Cell polarity Cell Adhesion medicine Animals Humans RNA Messenger DNA Primers Epithelial polarity Base Sequence Cell Polarity Biological Transport Epithelial Cells Articles Cell Biology Molecular biology Recombinant Proteins Cell biology medicine.anatomical_structure Cell culture Rab Intracellular |
| Zdroj: | The Journal of Cell Biology |
| ISSN: | 1540-8140 0021-9525 |
| Popis: | Pathways of polarized membrane traffic in epithelial tissues serve a variety of functions, including the generation of epithelial polarity and the regulation of vectorial transport. We have identified a candidate regulator of polarized membrane traffic in epithelial cells (i.e., rab3B), which is a member of the rab family of membrane traffic regulators. Rab3B is highly homologous to a brain-specific rab3 isoform (rab3A) that targets in a polarized fashion to the presynaptic nerve terminal, where it probably regulates exocytosis. The coding region for human rab3B was cloned from epithelial mRNA using a reverse-transcription polymerase chain reaction strategy. This cDNA clone hybridized to a single mRNA species in Northern blots of poly(A)+ RNA isolated from epithelial cell lines. A rab3B-specific antibody that was raised against recombinant fusion protein recognized a 25-kD band in immunoblots of cell lysates prepared from cultured epithelial cells (e.g., T84 and HT29-CL19A), but not from a variety of nonepithelial cells (e.g., PC12 neuroendocrine cells). Immunofluorescence analysis confirmed that rab3B protein is preferentially expressed in cultured epithelial cells as well as in a number of native epithelial tissues, including liver, small intestine, colon, and distal nephron. Rab3B localized to the apical pole very near the tight junctions between adjacent epithelial cells within all of these cell lines and native epithelial tissues, as determined by immunofluorescence and immunoelectron microscopic analysis. Moreover, this pattern of intracellular targeting was regulated by cell contact; namely, rab3B was reversibly retrieved from the cell periphery as epithelial cell contact was inhibited by reducing the extracellular Ca2+ concentration. Our results indicate that neurons and epithelial cells express homologous rab3 isoforms that target in a polarized fashion within their respective tissues. The pattern and regulation of rab3B targeting in epithelial cells implicates this monomeric GTPase as a candidate regulator of apical and/or junctional protein traffic in epithelial tissues. |
| Databáze: | OpenAIRE |
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