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VIP17/MAL, a lipid raft-associated protein, is involved in apical transport in MDCK cells

K H Cheong1, D Zacchetti, E E Schneeberger

  • 1European Molecular Biology Laboratory, Cell Biology and Biophysics Programme, D69012 Heidelberg and Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany.

Proceedings of the National Academy of Sciences of the United States of America
|May 26, 1999
PubMed

Insights

VIP17/MAL protein influences apical protein transport in Madin-Darby canine kidney (MDCK) cells. Modulating VIP17/MAL levels affects apical cell surface delivery and organization, highlighting its role in apical transport machinery.

Area of Science:

  • Cell Biology
  • Membrane Trafficking
  • Protein Sorting

Background:

  • Apical proteins are delivered from the trans-Golgi network to the plasma membrane via sphingolipid-cholesterol rafts.
  • VIP17/MAL is a tetraspan membrane protein found in post-Golgi vesicles and on the apical cell surface of MDCK cells.

Purpose of the Study:

  • To investigate the role of VIP17/MAL in apical protein transport.
  • To determine how altering VIP17/MAL levels affects apical cell surface morphology and protein delivery.

Main Methods:

  • Overexpression of VIP17/MAL in MDCK cells.
  • Expression of antisense RNA against VIP17/MAL in MDCK cells.
  • Analysis of apical protein markers (hemagglutinin, clusterin, gp114, GPI-anchored protein) and basolateral marker (E-cadherin) distribution.

Main Results:

  • VIP17/MAL overexpression increased apical delivery and expanded apical domains.
  • Antisense RNA against VIP17/MAL led to Golgi accumulation and impaired apical transport of various apical proteins.
  • E-cadherin basolateral distribution remained unaffected by antisense RNA expression.

Conclusions:

  • VIP17/MAL is functionally involved in apical protein transport.
  • VIP17/MAL may be a key component in clustering lipid rafts with apical cargo for transport carrier formation.

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