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FAPP2 is involved in the transport of apical cargo in polarized MDCK cells

Otilia V Vieira1, Paul Verkade, Aki Manninen

  • 1Max Planck Institute for Molecular Cell Biology and Genetics, 01307, Dresden, Germany.

The Journal of Cell Biology
|August 17, 2005
PubMed

Insights

Phosphatidylinositol-4-phosphate (PI(4)P) is crucial for Golgi transport. FAPP2 specifically mediates apical cargo transport from the Golgi to the plasma membrane in MDCK cells, while not affecting basolateral pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Phosphatidylinositol-4-phosphate (PI(4)P) is a key phosphoinositide in the Golgi complex.
  • PI(4)P plays a significant role in cargo transport from the trans-Golgi network (TGN) to the plasma membrane (PM).
  • Polarized Madin-Darby canine kidney (MDCK) cells are a model system for studying apical and basolateral transport pathways.

Purpose of the Study:

  • To investigate the specific role of PI(4)P and its associated proteins in apical and basolateral cargo transport in MDCK cells.
  • To determine whether FAPP1 or FAPP2 are involved in PI(4)P-mediated transport pathways.

Main Methods:

  • Overexpression of a PI(4)P-specific pleckstrin homology (PH) domain-containing fluorescent protein to assess PI(4)P function.
  • Adenovirus-mediated RNA interference (RNAi) to deplete FAPP1 and FAPP2.
  • Analysis of apical and basolateral cargo transport from the Golgi to the PM.

Main Results:

  • Overexpression of the PI(4)P-binding PH domain inhibited both apical and basolateral transport.
  • RNAi-mediated depletion of FAPP2 specifically decreased the transport of apical cargo from the Golgi.
  • Depletion of FAPP1 did not affect cargo transport.
  • FAPP2 was not implicated in the transport of basolateral cargo.

Conclusions:

  • FAPP2 plays a specific and essential role in the apical transport pathway in polarized MDCK cells.
  • PI(4)P is critical for both apical and basolateral transport, but FAPP2's function is restricted to the apical pathway.

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