Novel Phorbol Ester-binding Motif Mediates Hormonal Activation of Na+/H+ Exchanger

Wakabayashi, Shigeo; Nakamura, Tomoe Y.; Kobayashi, Soushi; Hisamitsu, Takashi

doi:10.1074/jbc.m110.130120

Cited by 29 publications

(20 citation statements)

References 57 publications

(64 reference statements)

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“…Disruption of the interaction between the LID and the membrane strongly attenuated NHE1 activity. These data are compatible with a model in which interaction of the LID with the acidic inner plasma membrane leaflet plays a crucial role in NHE1 activity, and that tighter association of the LID with the membrane underlies NHE1 activation by diacylglycerol analogs [149]. In fact, regulation by interaction of the C-terminal tail with the inner membrane leaflet may be a conserved feature of the NHE family, since similar results were obtained in a recent study of NHE3 interactions with acidic phospholipids [150].…”

Section: Ii6 Nhe1 Interactions With Other Cellular Componentssupporting

confidence: 83%

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

Boedtkjer

Bunch²,

Pedersen

2012

CPD

126

155

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The Na⁺/H⁺-exchanger 1, NHE1 (SLC9A1) and the electroneutral Na⁺,HCO₃⁻ cotransporter NBCn1 (SLC4A7) are coexpressed in a wide range of tissues. Under normal physiological conditions these transporters play an ostensibly similar role, namely that of net acid extrusion after cellular acidification. In addition, they have been implicated in multiple other cellular processes, including regulation of transepithelial transport, cell volume, cell death/survival balance, and cell motility. In spite of their apparent functional similarity, the two transporters also serve distinctly different functions and are differentially regulated. Here, we provide an update on the basic structure, function, regulation, physiology and pharmacology of NHE1 and NBCn1, with particular focus on the factors responsible for their functional similarities and differences. Finally, we highlight recent findings implicating these transporters in cancer development, and discuss issues relating to NHE1 and NBCn1 as potential targets in cancer treatment.

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Section: Ii6 Nhe1 Interactions With Other Cellular Componentssupporting

confidence: 83%

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

Boedtkjer

Bunch²,

Pedersen

2012

CPD

126

155

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“…However, significant binding was not observed between NHE1 and PS. A recent report demonstrated that a different C-terminal NHE1 peptide lipid-interacting domain (residues 542-598) bound multiple membrane phospholipids, including PS, using a different assay (31). Our data indicate that the N-terminal charged residues, some of which were deleted from the lipid-interacting domain, may be important for discriminating NHE1-phospholipid binding.…”

Section: Discussionmentioning

confidence: 71%

Phosphoinositide Binding Differentially Regulates NHE1 Na+/H+ Exchanger-dependent Proximal Tubule Cell Survival

Jawdeh

Khan

Deschênes

et al. 2011

Journal of Biological Chemistry

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“…They found that the LID domain binds phorbol esters and used FRET reporters to show increased association of the NHE1 C terminus with the plasma membrane in cells treated with phorbol esters. However, phorbol ester and PI(4,5)P 2 binding within the LID may be distinct because alanine substitutions for Leu-573 and Ile-574 were identified as mediators of phorbol ester binding (36). Recent work from Schelling and co-workers (38) suggests that decreased NHE1 activity from disrupted PI(4,5)P 2 binding contributes to apoptosis in renal tubular atrophy.…”

Section: Ph-sensitive Phospholipid Binding Regulates Nhe1 Activitymentioning

confidence: 99%

A Histidine Cluster in the Cytoplasmic Domain of the Na-H Exchanger NHE1 Confers pH-sensitive Phospholipid Binding and Regulates Transporter Activity

Webb

White

Grillo-Hill

et al. 2016

Journal of Biological Chemistry

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Edited by Roger ColbranThe Na-H exchanger NHE1 contributes to intracellular pH (pH i ) homeostasis in normal cells and the constitutively increased pH i in cancer. NHE1 activity is allosterically regulated by intracellular protons, with greater activity at lower pH i . However, the molecular mechanism for pH-dependent NHE1 activity remains incompletely resolved. We report that an evolutionarily conserved cluster of histidine residues located in the C-terminal cytoplasmic domain between two phosphatidylinositol 4,5-bisphosphate binding sites (PI(4,5)P 2 ) of NHE1 confers pH-dependent PI(4,5)P 2 binding and regulates NHE1 activity. A GST fusion of the wild type C-terminal cytoplasmic domain of NHE1 showed increased maximum PI(4,5)P 2 binding at pH 7.0 compared with pH 7.5. However, pH-sensitive binding is abolished by substitutions of the His-rich cluster to arginine (RXXR3) or alanine (AXXA3), mimicking protonated and neutral histidine residues, respectively, and the RXXR3 mutant had significantly greater PI(4,5)P 2 binding than AXXA3. When expressed in cells, NHE1 activity and pH i were significantly increased with NHE1-RXXR3 and decreased with NHE1-AXXA3 compared with wild type NHE1. Additionally, fibroblasts expressing NHE1-RXXR3 had significantly more contractile actin filaments and focal adhesions compared with fibroblasts expressing wild type NHE1, consistent with increased pH i enabling cytoskeletal remodeling. These data identify a molecular mechanism for pH-sensitive PI(4,5)P 2 binding regulating NHE1 activity and suggest that the evolutionarily conserved cluster of four histidines in the proximal cytoplasmic domain of NHE1 may constitute a proton modifier site. Moreover, a constitutively activated NHE1-RXXR3 mutant is a new tool that will be useful for studying how increased pH i contributes to cell behaviors, most notably the biology of cancer cells.Intracellular pH (pH i ) homeostasis is generally maintained near neutral to compensate for metabolic changes and environmental stresses (1). However, dysregulated pH i is seen in a number of diseases. Most cancers have constitutively increased pH i of ϳ0.4 units, which enables proliferation and metastasis (2-4). Conversely, neurodegenerative disorders, including Parkinson's and Alzheimer's diseases, are associated with constitutively decreased pH i , which is predicted to enable tau and ␤-amyloid aggregation as well as cell death (5, 6). Finely tuned pH i homeostasis is maintained by dynamic changes in ion transporter activity that is sensitive to intracellular proton concentrations. However, the molecular mechanisms that mediate pH sensing by ion transporters remain poorly understood. The ubiquitously expressed Na-H exchanger isoform NHE1 4 contributes to maintaining pH i homeostasis by generating an electroneutral influx of extracellular Na ϩ and efflux of intracellular H ϩ at the plasma membrane. To maintain pH i homeostasis, NHE1 activity increases with acidic pH i and becomes nearly quiescent at neutral pH i . However, NHE1 activity can be increased a...

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Novel Phorbol Ester-binding Motif Mediates Hormonal Activation of Na+/H+ Exchanger

Cited by 29 publications

References 57 publications

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

Phosphoinositide Binding Differentially Regulates NHE1 Na+/H+ Exchanger-dependent Proximal Tubule Cell Survival

A Histidine Cluster in the Cytoplasmic Domain of the Na-H Exchanger NHE1 Confers pH-sensitive Phospholipid Binding and Regulates Transporter Activity

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