Aquaporin‐2 and Na⁺/H⁺ exchanger isoform 1 modulate the efficiency of renal cell migration

Abstract

Aquaporin-2 (AQP2) promotes renal cell migration by the modulation of integrin β1 trafficking and the turnover of focal adhesions. The aim of this study was to investigate whether AQP2 also works in cooperation with Na + /H + exchanger isoform 1 (NHE1), another well-known protein involved in the regulation of cell migration.Our results showed that the lamellipodia of AQP2-expressing cells exhibit significantly smaller volumes and areas of focal adhesions and more alkaline intracellular pH due to increased NHE1 activity than AQP2-null cells. The blockage of AQP2, or its physically-associated calcium channel TRPV4, significantly reduced lamellipodia NHE1 activity. NHE1 blockage significantly reduced the rate of cell migration, the number of lamellipodia, and the assembly of F-actin only in AQP2expressing cells. Our data suggest that AQP2 modulates the activity of NHE1 through its calcium channel partner TRPV4, thereby determining pH-dependent actin polymerization, providing mechanical stability to delineate lamellipodia structure and defining the efficiency of cell migration.

Release of ATP by TRPV4 activation is dependent upon the expression of AQP2 in renal cells

“…The authors propose that the interaction between AQP2 and integrin β1 modulates integrin trafficking and turnover at focal adhesion sites, thereby contributing to cell migration. We recently confirmed that the presence of AQP2 on the plasma membrane promotes cell migration in association with TRPV4 (Di Giusto et al, 2019).…”

“…We then look for potential implications of ATPe modulation of P2 receptors in AQP2‐expressing cells. Having in mind that we recently published that AQP2 together with TRPV4 accelerates cell migration (Di Giusto et al, 2019), as well as compelling evidence, demonstrating that calcium and ATP act as a coordinating second messenger in this process (Jiang, Mousawi, Yang, & Roger, 2017), we investigated the modulation of purinergic signaling in cell migration of WT‐RCCD 1 and AQP2‐RCCD 1 cells by using the wound healing assay (Figure S6). Figure 7 shows, as we previously informed, that cells‐expressing AQP2 migrate faster than WT‐RCCD 1.…”

“…TRPV4 modulate the activity of NHE1, thereby determining pHdependent actin polymerization, providing mechanical stability to delineate lamellipodia structure and defining the efficiency of cell migration (Di Giusto et al, 2019). Furthermore, ATP release was previously reported to stimulate P2Y receptors and concomitantly trigger Ca 2+ influx through Ca 2+ -permeable channels, which then initiate cell migration (Takada, Furuya, & Sokabe, 2014).…”

Acidic preconditioning induced intracellular acid adaptation to protect renal injury via dynamic phosphorylation of focal adhesion kinase dependent activation of sodium hydrogen exchanger 1

“…In migrating cells, NHE1 localizes at the leading edge of lamellipodia and coordinates with various ion channels to in uence cell polarity and directional migration by promoting sodium in ux and regulating cytoskeletal dynamics. Previous research has found that AQP2-mediated Ca 2+ -dependent NHE1 activation is associated with migration in rat renal cortical collecting duct epithelial cells [30]. Furthermore, NHE1 located at the rear of lamellipodia accelerates the movement of these cells, providing collective driving forces for MDCK cell migration [26,31].…”

Hydrogen, Bicarbonate, and Their Associated Exchangers in Cell Volume Regulation

“…In addition to channels that directly transport Ca 2+ , Ca 2+ is a second messenger that often regulates the activity of various ion channels and transporters (Mahnensmith and Aronson, 1985 ; Garty and Palmer, 1997 ; Ruiz et al, 1999 ; Shieh et al, 2000 ). For example, the activity of NHE1 can be modulated by Ca 2+ through TRPV4, determining pH-dependent actin polymerization, providing mechanical stability to delineate lamellipodia structure, and defining the efficiency of cell migration (Di Giusto et al, 2020 ). Ca 2+ also affects the structure and dynamics of the cytoskeleton (Oertner and Matus, 2005 ; Hepler, 2016 ; Zhao et al, 2019 ; Maity et al, 2020 ), which further impacts the distribution and function of ion channel (Levina et al, 1994 ; Steele and Fedida, 2014 ; Vallés et al, 2015 ).…”