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J Physiol
2015 Feb 01;5933:541-58. doi: 10.1113/jphysiol.2014.284307.
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Phosphatidylinositol 4,5-bisphosphate degradation inhibits the Na+/bicarbonate cotransporter NBCe1-B and -C variants expressed in Xenopus oocytes.
Thornell IM
,
Bevensee MO
.
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KEY POINTS: We previously reported that the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2 ) directly stimulates heterologously expressed electrogenic Na(+)/bicarbonate cotransporter NBCe1-A in an excised macropatch from the Xenopus oocyte, and indirectly stimulates NBCe1-B and -C in the intact oocyte primarily through inositol 1,4,5-trisphosphate/Ca(2+). In the current study, we expand on a previous observation that PIP2 may also directly stimulate NBCe1 in the intact oocyte. In this study on oocytes, we co-expressed either NBCe1-B or -C and a voltage-sensitive phosphatase (VSP), which depletes PIP2 without changing inositol 1,4,5-trisphosphate, and monitored NBCe1-mediated currents with the two-electrode voltage-clamp technique or pHi changes using Vm/pH-sensitive microelectrodes. Activating VSP inhibited NBCe1-B and -C outward currents and NBCe1-mediated pHi increases, and changes in NBCe1 activity paralleled changes in surface PIP2. This study is a quantitative assessment of PIP2 itself as a regulator of NBCe1-B and -C in the intact cell, and represents the first use of VSP to characterize the PIP2 sensitivity of a transporter. These data combined with our previous work demonstrate that NBCe1-B and -C are regulated by two PIP2-mediated signalling pathways. Specifically, a decrease in PIP2 per se can inhibit NBCe1, whereas hydrolysis of PIP2 to inositol 1,4,5-trisphosphate/Ca(2+) can stimulate the transporter.
ABSTRACT: The electrogenic Na(+)/bicarbonate cotransporter (NBCe1) of the Slc4 gene family is a powerful regulator of intracellular pH (pHi) and extracellular pH (pHo), and contributes to solute reabsorption and secretion in many epithelia. Using Xenopus laevis oocytes expressing NBCe1 variants, we have previously reported that the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) directly stimulates NBCe1-A in an excised macropatch, and indirectly stimulates NBCe1-B and -C in the intact oocyte primarily through inositol 1,4,5-trisphosphate (InsP3)/Ca(2+). In the current study, we used the two-electrode voltage-clamp technique alone or in combination with pH/voltage-sensitive microelectrodes or confocal fluorescence imaging of plasma membrane PIP2 to characterize the PIP2 sensitivity of NBCe1-B and -C in whole oocytes by co-expressing a voltage-sensitive phosphatase (VSP) that decreases PIP2 and bypasses the InsP3/Ca(2+) pathway. An oocyte depolarization that activated VSP only transiently stimulated the NBCe1-B/C current, consistent with an initial rapid depolarization-induced NBCe1 activation, and then a subsequent slower VSP-mediated NBCe1 inhibition. Upon repolarization, the NBCe1 current decreased, and then slowly recovered with an exponential time course that paralleled PIP2 resynthesis as measured with a PIP2-sensitive fluorophore and confocal imaging. A subthreshold depolarization that minimally activated VSP caused a more sustained increase in NBCe1 current, and did not lead to an exponential current recovery following repolarization. Similar results were obtained with oocytes expressing a catalytically dead VSP mutant at all depolarized potentials. Depleting endoplasmic reticulum Ca(2+) did not inhibit the NBCe1 current recovery following repolarization from VSP activation, demonstrating that changes in InsP3/Ca(2+) were not responsible. This study demonstrates for the first time that depleting PIP2 per se inhibits NBCe1 activity. The data in conjunction with previous findings implicate a dual PIP2 regulatory pathway for NBCe1 involving both PIP2 itself and generated InsP3/Ca(2+).
Abuladze,
Molecular cloning, chromosomal localization, tissue distribution, and functional expression of the human pancreatic sodium bicarbonate cotransporter.
1998, Pubmed,
Xenbase
Abuladze,
Molecular cloning, chromosomal localization, tissue distribution, and functional expression of the human pancreatic sodium bicarbonate cotransporter.
1998,
Pubmed
,
Xenbase
Bae,
Chaperone stress 70 protein (STCH) binds and regulates two acid/base transporters NBCe1-B and NHE1.
2013,
Pubmed
,
Xenbase
Balla,
Phosphoinositides: tiny lipids with giant impact on cell regulation.
2013,
Pubmed
Barret,
Mutagenesis of the phosphatidylinositol 4,5-bisphosphate (PIP(2)) binding site in the NH(2)-terminal domain of ezrin correlates with its altered cellular distribution.
2000,
Pubmed
Bevensee,
An electrogenic Na(+)-HCO(-)(3) cotransporter (NBC) with a novel COOH-terminus, cloned from rat brain.
2000,
Pubmed
,
Xenbase
Boron,
Modular structure of sodium-coupled bicarbonate transporters.
2009,
Pubmed
Boron,
Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO3- transport.
1983,
Pubmed
Chesler,
Regulation and modulation of pH in the brain.
2003,
Pubmed
Chesler,
The regulation and modulation of pH in the nervous system.
1990,
Pubmed
Di Paolo,
Phosphoinositides in cell regulation and membrane dynamics.
2006,
Pubmed
Dickson,
Quantitative properties and receptor reserve of the IP(3) and calcium branch of G(q)-coupled receptor signaling.
2013,
Pubmed
Falkenburger,
Kinetics of PIP2 metabolism and KCNQ2/3 channel regulation studied with a voltage-sensitive phosphatase in living cells.
2010,
Pubmed
Falkenburger,
Quantitative properties and receptor reserve of the DAG and PKC branch of G(q)-coupled receptor signaling.
2013,
Pubmed
Gamper,
Phosphatidylinositol [correction] 4,5-bisphosphate signals underlie receptor-specific Gq/11-mediated modulation of N-type Ca2+ channels.
2004,
Pubmed
,
Xenbase
Halaszovich,
Ci-VSP is a depolarization-activated phosphatidylinositol-4,5-bisphosphate and phosphatidylinositol-3,4,5-trisphosphate 5'-phosphatase.
2009,
Pubmed
Hansen,
Structural basis of PIP2 activation of the classical inward rectifier K+ channel Kir2.2.
2011,
Pubmed
Hilgemann,
The complex and intriguing lives of PIP2 with ion channels and transporters.
2001,
Pubmed
Hong,
Convergence of IRBIT, phosphatidylinositol (4,5) bisphosphate, and WNK/SPAK kinases in regulation of the Na+-HCO3- cotransporters family.
2013,
Pubmed
Iwasaki,
A voltage-sensing phosphatase, Ci-VSP, which shares sequence identity with PTEN, dephosphorylates phosphatidylinositol 4,5-bisphosphate.
2008,
Pubmed
,
Xenbase
Kao,
Oligomeric structure and minimal functional unit of the electrogenic sodium bicarbonate cotransporter NBCe1-A.
2008,
Pubmed
Lee,
Relief of autoinhibition of the electrogenic Na-HCO(3) [corrected] cotransporter NBCe1-B: role of IRBIT vs.amino-terminal truncation.
2012,
Pubmed
,
Xenbase
Liu,
Inhibition of the Na/bicarbonate cotransporter NBCe1-A by diBAC oxonol dyes relative to niflumic acid and a stilbene.
2007,
Pubmed
,
Xenbase
Lu,
Reversible and irreversible interactions of DIDS with the human electrogenic Na/HCO3 cotransporter NBCe1-A: role of lysines in the KKMIK motif of TM5.
2007,
Pubmed
,
Xenbase
Ma,
Regulation of the epithelial sodium channel by phosphatidylinositides: experiments, implications, and speculations.
2007,
Pubmed
Majumdar,
Na-coupled bicarbonate transporters of the solute carrier 4 family in the nervous system: function, localization, and relevance to neurologic function.
2010,
Pubmed
McAlear,
A cysteine-scanning mutagenesis study of transmembrane domain 8 of the electrogenic sodium/bicarbonate cotransporter NBCe1.
2006,
Pubmed
,
Xenbase
McAlear,
Electrogenic Na/HCO3 cotransporter (NBCe1) variants expressed in Xenopus oocytes: functional comparison and roles of the amino and carboxy termini.
2006,
Pubmed
,
Xenbase
McLaughlin,
PIP(2) and proteins: interactions, organization, and information flow.
2002,
Pubmed
Miesenböck,
Visualizing secretion and synaptic transmission with pH-sensitive green fluorescent proteins.
1998,
Pubmed
Muallem,
Intracellular pH-regulatory mechanisms in pancreatic acinar cells. I. Characterization of H+ and HCO3- transporters.
1990,
Pubmed
Murata,
Depolarization activates the phosphoinositide phosphatase Ci-VSP, as detected in Xenopus oocytes coexpressing sensors of PIP2.
2007,
Pubmed
,
Xenbase
Murata,
Phosphoinositide phosphatase activity coupled to an intrinsic voltage sensor.
2005,
Pubmed
,
Xenbase
Parker,
The divergence, actions, roles, and relatives of sodium-coupled bicarbonate transporters.
2013,
Pubmed
Petersen,
The regulation of capacitative calcium entry by calcium and protein kinase C in Xenopus oocytes.
1994,
Pubmed
,
Xenbase
Ransom,
Glial modulation of neural excitability mediated by extracellular pH: a hypothesis revisited.
2000,
Pubmed
Romero,
Expression cloning and characterization of a renal electrogenic Na+/HCO3- cotransporter.
1997,
Pubmed
,
Xenbase
Romero,
Cloning and functional expression of rNBC, an electrogenic Na(+)-HCO3- cotransporter from rat kidney.
1998,
Pubmed
,
Xenbase
Sakata,
Coupling of the phosphatase activity of Ci-VSP to its voltage sensor activity over the entire range of voltage sensitivity.
2011,
Pubmed
,
Xenbase
Sergeev,
Determination of membrane protein transporter oligomerization in native tissue using spatial fluorescence intensity fluctuation analysis.
2012,
Pubmed
Shirakabe,
IRBIT, an inositol 1,4,5-trisphosphate receptor-binding protein, specifically binds to and activates pancreas-type Na+/HCO3- cotransporter 1 (pNBC1).
2006,
Pubmed
,
Xenbase
Stauffer,
Receptor-induced transient reduction in plasma membrane PtdIns(4,5)P2 concentration monitored in living cells.
1998,
Pubmed
Suh,
Recovery from muscarinic modulation of M current channels requires phosphatidylinositol 4,5-bisphosphate synthesis.
2002,
Pubmed
Suh,
Electrostatic interaction of internal Mg2+ with membrane PIP2 Seen with KCNQ K+ channels.
2007,
Pubmed
Sullivan,
Bicarbonate secretion by rabbit proximal colon.
1986,
Pubmed
Svichar,
Preemptive regulation of intracellular pH in hippocampal neurons by a dual mechanism of depolarization-induced alkalinization.
2011,
Pubmed
Thornell,
PIP2 hydrolysis stimulates the electrogenic Na+-bicarbonate cotransporter NBCe1-B and -C variants expressed in Xenopus laevis oocytes.
2012,
Pubmed
,
Xenbase
Vidyasagar,
Three distinct mechanisms of HCO3- secretion in rat distal colon.
2004,
Pubmed
Whorton,
Crystal structure of the mammalian GIRK2 K+ channel and gating regulation by G proteins, PIP2, and sodium.
2011,
Pubmed
,
Xenbase
Winks,
Relationship between membrane phosphatidylinositol-4,5-bisphosphate and receptor-mediated inhibition of native neuronal M channels.
2005,
Pubmed
Wu,
Phosphatidylinositol 4,5-bisphosphate (PIP2) stimulates the electrogenic Na/HCO3 cotransporter NBCe1-A expressed in Xenopus oocytes.
2009,
Pubmed
,
Xenbase
Yamaguchi,
IRBIT reduces the apparent affinity for intracellular Mg²⁺ in inhibition of the electrogenic Na⁺-HCO₃⁻ cotransporter NBCe1-B.
2012,
Pubmed
Yang,
IRBIT: it is everywhere.
2011,
Pubmed
Zaika,
Combined phosphoinositide and Ca2+ signals mediating receptor specificity toward neuronal Ca2+ channels.
2011,
Pubmed
Zhang,
PIP(2) activates KCNQ channels, and its hydrolysis underlies receptor-mediated inhibition of M currents.
2003,
Pubmed
,
Xenbase