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Polarization-dependent selective transport to the apical membrane by KIF5B in MDCK cells

Fanny Jaulin1, Xiaoxiao Xue, Enrique Rodriguez-Boulan

  • 1Department of Cell and Developmental Biology, Weill-Cornell Medical College, 1300 York Avenue, New York, NY 10021, USA.

Developmental Cell
|October 11, 2007
PubMed

Insights

Epithelial cells use specific kinesin-5B (KIF5B) motors for transporting apical proteins after establishing cell polarity. This motor switching is crucial for directed protein movement during epithelial cell polarization.

Area of Science:

  • Cell Biology
  • Molecular Motors
  • Epithelial Cell Biology

Background:

  • Microtubule-based transport is vital in epithelial cells, yet the specific motors and their regulation during cell polarization remain unclear.
  • Understanding motor involvement is key to deciphering how epithelial cells establish and maintain their distinct apical and basolateral domains.

Purpose of the Study:

  • To identify the specific microtubule motors responsible for post-Golgi transport of apical proteins in polarized epithelial cells.
  • To investigate the regulation of these motors during the acquisition of epithelial cell polarity.

Main Methods:

  • Utilized time-lapse imaging of EB1-GFP in Madin-Darby canine kidney (MDCK) cells to observe microtubule dynamics.
  • Employed dominant-negative KIF5B expression and function-blocking KIF5 antibodies to assess motor function.
  • Conducted immunoprecipitation assays to confirm protein interactions in polarized and non-polarized cells.

Main Results:

  • KIF5B was identified as the motor mediating post-Golgi transport of the apical marker p75-GFP specifically in polarized MDCK cells.
  • Inhibition of KIF5B function selectively disrupted apical protein transport after cell polarization.
  • KIF5B was found to interact with p75-GFP only in polarized epithelial cells, indicating a polarity-dependent interaction.

Conclusions:

  • Epithelial cells selectively utilize specific microtubule motors, such as KIF5B, for apical protein transport.
  • Epithelial cells switch their kinesin motors for post-Golgi transport as they acquire polarity.
  • This motor switching mechanism is essential for the directed trafficking of apical proteins during epithelial polarization.

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