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Analyzing the Function of Small GTPases by Microinjection of Plasmids into Polarized Epithelial Cells
Published on: May 31, 2011
Secretory cargo composition affects polarized secretion in MDCK epithelial cells.
Brigitte H Fasciotto1, Ulrike Kühn, David V Cohn
1University of Louisville School of Dentistry, Louisville, KY 40292, USA.
Molecular and Cellular Biochemistry
|December 1, 2007
Summary
Chromogranin A acts as a "sorting escort" to direct parathyroid hormone to the apical surface of epithelial cells. This finding offers a novel strategy for targeted protein secretion in gene therapy applications.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Polarized epithelial cells exhibit distinct apical and basolateral secretion pathways.
- Predicting the secretion route of foreign proteins in epithelial cells is challenging.
- Targeted protein secretion is crucial for gene therapy applications in secretory epithelia.
Purpose of the Study:
- To investigate the secretion pathway of parathyroid hormone (PTH), furin, and chromogranin A in polarized epithelial cells (MDCK cells).
- To determine if chromogranin A can influence the polarized secretion of PTH.
- To explore the potential of using secretory proteins as "sorting escorts" for targeted protein delivery.
Main Methods:
- Expression of PTH, furin, and chromogranin A in MDCK cells.
- Analysis of protein secretion at apical and basolateral surfaces.
- Investigating the role of chromogranin A in PTH sorting.
- Assessing the cholesterol dependence of chromogranin A apical secretion.
Main Results:
- Chromogranin A and secreted furin were primarily secreted apically.
- Parathyroid hormone was predominantly secreted basolaterally (60%).
- Co-expression with chromogranin A shifted PTH secretion to 65% apical.
- Apical secretion of chromogranin A was cholesterol-dependent but did not involve its N-terminal domain.
Conclusions:
- Chromogranin A can function as a "sorting escort" to direct parathyroid hormone to the apical secretion pathway.
- Secreted proteins can be engineered as "sorting escorts" to control the apical secretion of other proteins.
- This mechanism provides a novel approach for targeted protein expression in epithelial cells for therapeutic purposes.
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