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Involvement of NHERF1 in apical membrane localization of MRP4 in polarized kidney cells

Md Tozammel Hoque1, Gwenaëlle Conseil, Susan P C Cole

  • 1Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, Kingston, ON, Canada.

Biochemical and Biophysical Research Communications
|December 17, 2008
PubMed

Insights

The adaptor protein NHERF1 controls the location of multidrug resistance protein 4 (MRP4) in kidney cells. NHERF1 directs MRP4 to apical membranes, impacting drug resistance and cellular transport.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Pharmacology

Background:

  • Multidrug resistance protein 4 (MRP4/ABCC4) is an ATP-binding cassette transporter involved in efflux of various substrates, including drugs and endogenous compounds.
  • MRP4 localization in polarized cells can be either apical or basolateral, influencing its function.
  • The adaptor protein NHERF1 has been linked to MRP4 internalization in non-polarized cells.

Purpose of the Study:

  • To investigate the role of NHERF1 in determining the apical or basolateral localization of MRP4 in polarized mammalian kidney cells.
  • To elucidate the mechanism by which NHERF1 influences MRP4 trafficking.

Main Methods:

  • Comparative analysis of NHERF1 and MRP4 expression and localization in polarized MDCKI and LLC-PK1 cells.
  • Ectopic expression of FLAG-tagged NHERF1 in MDCKI cells.
  • Stable expression of eGFP-tagged MRP4 in MDCKI cells.
  • Assessment of MRP4 trafficking upon NHERF1 overexpression.

Main Results:

  • Polarized MDCKI cells, with basolateral MRP4, exhibited significantly lower NHERF1 levels compared to LLC-PK1 cells with apical MRP4.
  • Ectopic expression of NHERF1 in MDCKI cells induced the apical trafficking of endogenous MRP4.
  • Overexpression of NHERF1 in MDCKI cells stably expressing eGFP-MRP4 promoted the apical localization of eGFP-MRP4.

Conclusions:

  • NHERF1 is a critical determinant of MRP4 apical membrane trafficking in mammalian kidney cells.
  • NHERF1's presence or absence influences the polarized localization of MRP4, thereby affecting its transport functions.
  • These findings provide insights into the regulation of transporter localization and its implications for cellular physiology and drug resistance.

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