Biogenesis of epithelial cell plasma membranes

Area of Science:

• Cell biology
• Virology
• Membrane trafficking

Background:

• Polarized epithelial cells, like MDCK cells, model how newly synthesized glycoproteins reach specific plasma membrane domains.
• Enveloped viruses exhibit asymmetric assembly, budding from apical (influenza, SV5) or basolateral (VSV) surfaces.

Purpose of the Study:

• To investigate the intracellular routes and sorting mechanisms of viral glycoproteins in polarized epithelial cells.
• To understand how glycoproteins are directed to specific viral budding sites.

Main Methods:

• Utilized Madin-Darby Canine Kidney (MDCK) cell monolayers for experiments.
• Employed double infection with influenza and vesicular stomatitis virus (VSV).
• Applied immunoelectron microscopy to visualize glycoprotein localization and viral assembly.

Main Results:

• Influenza and VSV glycoproteins share the same Golgi apparatus, indicating sorting occurs within or after this organelle.
• Influenza HA glycoprotein accumulates apically, while VSV G protein is found on both apical and basolateral membranes.
• VSV virion assembly is restricted to basolateral domains despite G protein presence on apical surfaces.

Conclusions:

• Glycoprotein localization alone does not solely determine viral budding sites.
• Additional cellular or viral factors likely mediate the selection of specific budding domains.
• Apical G protein may require transfer to the basolateral domain for competent VSV assembly.