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Updated: Mar 30, 2026
Automated Detection and Analysis of Exocytosis
Published on: September 11, 2021
Cargo-selective apical exocytosis in epithelial cells is conducted by Myo5B, Slp4a, Vamp7, and Syntaxin 3
Georg F Vogel1, Katharina M C Klee2, Andreas R Janecke3
1Division of Cell Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria Division of Histology and Embryology, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Abstract:
Mutations in the motor protein Myosin Vb (Myo5B) or the soluble NSF attachment protein receptor Syntaxin 3 (Stx3) disturb epithelial polarity and cause microvillus inclusion disease (MVID), a lethal hereditary enteropathy affecting neonates. To understand the molecular mechanism of Myo5B and Stx3 interplay, we used genome editing to introduce a defined Myo5B patient mutation in a human epithelial cell line. Our results demonstrate a selective role of Myo5B and Stx3 for apical cargo exocytosis in polarized epithelial cells. Apical exocytosis of NHE3, CFTR (cystic fibrosis transmembrane conductance regulator), and GLUT5 required an interaction cascade of Rab11, Myo5B, Slp4a, Munc18-2, and Vamp7 with Stx3, which cooperate in the final steps of this selective apical traffic pathway. The brush border enzymes DPPIV and sucrase-isomaltase still correctly localize at the apical plasma membrane independent of this pathway. Hence, our work demonstrates how Myo5B, Stx3, Slp4a, Vamp7, Munc18-2, and Rab8/11 cooperate during selective apical cargo trafficking and exocytosis in epithelial cells and thereby provides further insight into MVID pathophysiology.
Insights
Mutations in Myosin Vb (Myo5B) and Syntaxin 3 (Stx3) disrupt epithelial cell polarity. This study reveals their crucial role in selective apical exocytosis, essential for intestinal function and MVID pathogenesis.
Area of Science:
- Cell Biology
- Molecular Biology
- Gastroenterology
Background:
- Mutations in Myosin Vb (Myo5B) and Syntaxin 3 (Stx3) lead to microvillus inclusion disease (MVID), a severe neonatal enteropathy.
- Epithelial polarity is critical for intestinal function, and its disruption causes significant disease.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying the interplay between Myo5B and Stx3 in epithelial cells.
- To understand the selective apical exocytosis pathway involving these proteins.
Main Methods:
- Utilized genome editing to introduce a Myo5B patient mutation into a human epithelial cell line.
- Investigated the role of Myo5B and Stx3 in the trafficking and exocytosis of specific apical cargo proteins.
Main Results:
- Demonstrated a selective role for Myo5B and Stx3 in the apical exocytosis of proteins like NHE3, CFTR, and GLUT5.
- Identified an interaction cascade involving Rab11, Myo5B, Slp4a, Munc18-2, and Vamp7 with Stx3 in apical cargo trafficking.
- Showed that brush border enzymes (DPPIV, sucrase-isomaltase) localize apically independently of this specific pathway.
Conclusions:
- Myo5B, Stx3, and associated proteins (Rab11, Slp4a, Munc18-2, Vamp7) cooperate in a selective apical cargo trafficking and exocytosis pathway.
- Provides critical insights into the pathophysiology of microvillus inclusion disease (MVID).
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