AQP2-Induced Acceleration of Renal Cell Proliferation Involves the Activation of a Regulatory Volume Increase Mechanism Dependent on NHE2

J Cell Biochem. 2017 May;118(5):967-978. doi: 10.1002/jcb.25602. Epub 2017 Jan 5.

Abstract

We have previously shown in renal cells that expression of the water channel Aquaporin 2 (AQP2) increases the rate of cell proliferation by shortening the transit time through the S and G2 /M phases of the cell cycle. This acceleration is due, at least in part, to a down-regulation of regulatory volume decrease (RVD) mechanisms when volume needs to be increased in order to proceed into the S phase. We hypothesize that in order to increase cell volume, RVD mechanisms may be overtaken by regulatory volume increase mechanisms (RVI). In this study, we investigated if the isoform 2 of the Na+ /H+ exchanger (NHE2), the main ion transporter involved in RVI responses, contributed to the AQP2-increased renal cell proliferation. Three cortical collecting duct cell lines were used: WT-RCCD1 (not expressing AQPs), AQP2-RCCD1 (transfected with AQP2), and mpkCCDc14 (with inducible AQP2 expression). We here demonstrate, for the first time, that both NHE2 protein activity and expression were increased in AQP2-expressing cells. NHE2 inhibition decreased cell proliferation and delayed cell cycle progression by slowing S and G2 /M phases only if AQP2 was expressed. Finally, we observed that only in AQP2-expressing cells a NHE2-dependent RVI response was activated in the S phase. These observations suggest that the AQP2-increased proliferation involves the activation of a regulatory volume increase mechanism dependent on NHE2. Therefore, we propose that the accelerated proliferation of AQP2-expressing cells requires a coordinated modulation of the RVD/RVI activity that contributes to cell volume changes during cell cycle progression. J. Cell. Biochem. 118: 967-978, 2017. © 2016 Wiley Periodicals, Inc.

Keywords: AQUAPORIN 2; CELL PROLIFERATION; Na+/H+ EXCHANGER; REGULATORY VOLUME INCREASE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aquaporin 2 / genetics
  • Aquaporin 2 / metabolism*
  • Cell Cycle
  • Cell Line
  • Cell Proliferation
  • Cell Size
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism
  • Kidney Cortex / cytology*
  • Kidney Cortex / metabolism
  • Rats
  • Sodium-Hydrogen Exchangers / genetics*
  • Sodium-Hydrogen Exchangers / metabolism*

Substances

  • Aqp2 protein, rat
  • Aquaporin 2
  • Slc9a2 protein, rat
  • Sodium-Hydrogen Exchangers