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Phosphorylation of Rab11-FIP2 regulates polarity in MDCK cells

Lynne A Lapierre1, Kenya M Avant, Cathy M Caldwell

  • 1Section of Surgical Sciences and Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA.

Molecular Biology of the Cell
|May 4, 2012
PubMed

Insights

Phosphorylation of Rab11-family interacting protein 2 (Rab11-FIP2) at Ser-227 is crucial for epithelial cell polarity. This modification regulates adherens and tight junction composition, impacting lumen formation in Madin-Darby canine kidney cells.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Epithelial Biology

Background:

  • Rab11-family interacting protein 2 (Rab11-FIP2) is a Rab11 effector involved in transcytosis.
  • Previous research linked Rab11-FIP2 to Madin-Darby canine kidney (MDCK) cell polarity via MARK2-mediated phosphorylation at Ser-227.

Purpose of the Study:

  • To investigate the dynamic role of Rab11-FIP2 phosphorylation at Ser-227 in regulating MDCK cell polarity.
  • To determine the impact of Rab11-FIP2 phosphorylation on junctional complex composition and lumen formation.

Main Methods:

  • Studied endogenous Rab11-FIP2 phosphorylation dynamics in MDCK cells after monolayer wounding or calcium switch.
  • Utilized non-phosphorylatable (S227A) and pseudophosphorylated (S227E) Rab11-FIP2 mutants in MDCK cells.
  • Analyzed lumen formation in MDCK cell cysts grown in Matrigel.
  • Examined adherens and tight junction composition in cells expressing Rab11-FIP2 mutants on permeable filters.

Main Results:

  • Endogenous phosphorylated Rab11-FIP2 (Ser-227) localized to vesicular plaques during polarity reestablishment.
  • Rab11-FIP2(S227A) expression resulted in loss of lumen formation in MDCK cysts.
  • Rab11-FIP2(S227E) expression led to multi-lumen cyst formation and altered adherens and tight junction composition.
  • Specific changes included altered E-cadherin, K-cadherin, p120 catenin, occludin, and claudin levels at junctions.
  • These effects on polarity were independent of myosin Vb and Rab11a.

Conclusions:

  • Ser-227 phosphorylation of Rab11-FIP2 is a key regulator of epithelial cell polarity.
  • Phosphorylation dynamically controls the composition of adherens and tight junctions.
  • Rab11-FIP2 phosphorylation influences lumenogenesis in epithelial cell cysts.

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