Na+/H+ Exchanger Regulatory Factor 1 Research Articles

Immunohistochemical analyses of neural stem cell lineage markers in normal feline brains and glial tumors.

Neural stem cell (NSC) lineage cells have not been fully identified in feline brains, and the NSC-like nature of feline glial tumors has not been determined. In this study, 6 normal cat brains (3 newborn and 3 older cats) and 13 feline glial tumors were analyzed using immunohistochemical NSC lineage markers. The feline glial tumors were subjected to immunohistochemical scoring followed by hierarchical cluster analysis. In newborn brains, glial acidic fibrillary protein (GFAP)/nestin/sex-determining region Y-box transcription factor 2 (SOX2)-immunopositive NSCs, SOX2-immunopositive intermediate progenitor cells, oligodendrocyte transcription factor 2 (OLIG2)/platelet-derived growth factor receptor-α (PDGFR-α)-immunopositive oligodendrocyte precursor cells (OPCs), OLIG2/GFAP-immunopositive immature astrocytes, and neuronal nuclear (NeuN)/β-3 tubulin-immunopositive mature neuronal cells were observed. The apical membrane of NSCs was also immunopositive for Na+/H+ exchanger regulatory factor 1 (NHERF1). In mature brains, the NSC lineage cells were similar to those of the newborn brains. A total of 13 glial tumors consisted of 2 oligodendrogliomas, 4 astrocytomas, 3 subependymomas, and 4 ependymomas. Astrocytomas, subependymomas, and ependymomas were immunopositive for GFAP, nestin, and SOX2. Subependymomas and ependymomas showed dot-like or apical membrane immunolabeling for NHERF1, respectively. Astrocytomas were immunopositive for OLIG2. Oligodendrogliomas and subependymomas were immunopositive for OLIG2 and PDGFR-α. Feline glial tumors also showed variable immunolabeling for β-3 tubulin, NeuN, and synaptophysin. Based on these results, feline astrocytomas, subependymomas, and ependymomas appear to have an NSC-like immunophenotype. In addition, astrocytomas, subependymomas, and ependymomas have the characteristics of glial, oligodendrocyte precursor, and ependymal cells, respectively. Feline oligodendrogliomas likely have an OPC-like immunophenotype. In addition, feline glial tumors may have multipotential stemness for differentiation into neuronal cells. These preliminary results should be validated by gene expression analyses in future studies with larger case numbers.

Alteration of Na/H exchange regulatory factor-1 protein levels in anogenital lesions positive for mucosal high-risk human papillomavirus type 16

Mucosal high-risk (HR) human papillomaviruses (HPV) are associated with anogenital carcinogenesis. The products of two early genes, E6 and E7, act as major viral oncoproteins. Functional studies in experimental models showed that HPV16 E6 induces degradation of the PDZ protein, the Na+/H+ exchanger regulatory factor-1 (NHERF-1). Here, we determined NHERF-1 protein levels by immunohistochemistry (IHC) in (i) benign anogenital warts (n = 8) (ii) premalignant lesions (L-SIL and H-SIL) (n = 43) and (iii) invasive cervical squamous cell carcinomas (SCC) (n = 17). A decrease of NHERF-1 protein level was not observed in genital warts in comparison to healthy epithelium. Conversely, a clearly decrease in NHERF-1 protein levels was observed in HPV16-positive pre-malignant and malignant lesions, while the phenomenon was much attenuated in lesions induced by other HR HPV types. In conclusion, these findings show that mucosal HPV types differently impact on NHERF-1 protein level in benign and malignant anogenital lesions.

The Biological Relevance of NHERF1 Protein in Gynecological Tumors.

Gynecological cancer management remains challenging and a better understanding of molecular mechanisms that lead to carcinogenesis and development of these diseases is needed to improve the therapeutic approaches. The Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein that contains modular protein-interaction domains able to interact with molecules with an impact on carcinogenesis and cancer progression. During recent years, its involvement in gynecological cancers has been explored, suggesting that NHERF1 could be a potential biomarker for the development of new targeted therapies suitable to the management of these tumors. This comprehensive review provides an update on the recent study on NHERF1 activity and its pathological role in cervical and ovarian cancer, as well as on its probable involvement in the therapeutic landscape of these cancer types.

Functional role and regulation of permeability-glycoprotein (P-gp) in the fetal membrane during drug transportation.

Na+ /H+ exchange regulatory factor-1 (NHERF-1) is a class I PDZ (PSD95/Discs-large/ZO-1) binding protein involved in cell-surface expression and stabilization of transporter proteins, including permeability-glycoprotein (P-gp) in various cell types. P-gp, expressed in placental trophoblasts, is an efflux transporter protein that influences the pharmacokinetics of various drugs used during pregnancy. Previously we have reported that NHERF-1 regulates fetal membrane inflammation. However, the role of NHERF-1 in regulating P-gp in the fetal membrane during drug transportation remains unclear. This study determined the interplay between NHERF-1 and P-gp in human fetal membrane cells. Fetal membranes from normal, term cesareans were screened for P-gp by immunohistochemistry (IHC). Chorionic trophoblast (CTC), with the highest expression of P-gp among fetal membrane cells, was further used to test interactive properties between NHERF-1 and P-gp. BeWo (placental trophoblast cell line) cells were used as a control. Immunoprecipitation (IP) of CTC lysates using the P-gp antibody followed by western blot determined co-precipitation of NHERF-1. Silencing NHERF-1 using small interfering RNA further tested the relevance of NHERF-1 in P-gp expression and function in CTC and BeWo cells. NHERF-1 regulation of P-gp's efflux function (drug resistance) was further tested using the ENZOTM efflux dye kit. Immunohistochemistry localized, and western blot confirmed P-gp in human fetal membranes, primarily in the CTC with limited expression in the amnion epithelial layer. P-gp expression in the membranes was similar to that seen in the placenta. IP data showed P-gp co-precipitating with NHERF1. Silencing of NHERF-1 resulted in significant drug resistance suggesting P-gp function mediated through NHERF1 in CTCs. Proinflammatory mediator NHERF-1 regulates P-gp and control drug transportation across the fetal membranes. Our data suggest a novel functional role for fetal membranes during pregnancy. Besides the placenta, fetal membranes may also regulate efflux of materials at the feto-maternal interface and control drug transport during pregnancy.

Scaffold Protein Na+/H+ Exchanger Regulatory Factor 1 (NHERF1) Protect Tenofovir-Induced Nephrotoxicity by Regulating Na+/Pi Cotransporter (Npt) and Intracellular Phosphorus Balance

Scaffold Protein Na+/H+ Exchanger Regulatory Factor 1 (NHERF1) Protect Tenofovir-Induced Nephrotoxicity by Regulating Na+/Pi Cotransporter (Npt) and Intracellular Phosphorus Balance

Na/H Exchange Regulatory Factor 1 Deficient Mice Show Evidence of Oxidative Stress and Altered Cisplatin Pharmacokinetics.

(1) Background: One third of patients who receive cisplatin develop an acute kidney injury. We previously demonstrated the Na/H Exchange Regulatory Factor 1 (NHERF1) loss resulted in increased kidney enzyme activity of the pentose phosphate pathway and was associated with more severe cisplatin nephrotoxicity. We hypothesized that changes in proximal tubule biochemical pathways associated with NHERF1 loss alters renal metabolism of cisplatin or response to cisplatin, resulting in exacerbated nephrotoxicity. (2) Methods: 2–4 month-old male wild-type and NHERF1 knock out littermate mice were treated with either vehicle or cisplatin (20 mg/kg dose IP), with samples taken at either 4, 24, or 72 h. Kidney injury was determined by urinary neutrophil gelatinase-associated lipocalin and histology. Glutathione metabolites were measured by HPLC and genes involved in glutathione synthesis were measured by qPCR. Kidney handling of cisplatin was assessed by a kidney cortex measurement of γ-glutamyl transferase activity, Western blot for γ-glutamyl transferase and cysteine S-conjugate beta lyase, and ICP-MS for platinum content. (3) Results: At 24 h knock out kidneys show evidence of greater tubular injury after cisplatin and exhibit a decreased reduced/oxidized glutathione ratio under baseline conditions in comparison to wild-type. KO kidneys fail to show an increase in γ-glutamyl transferase activity and experience a more rapid decline in tissue platinum when compared to wild-type. (4) Conclusions: Knock out kidneys show evidence of greater oxidative stress than wild-type accompanied by a greater degree of early injury in response to cisplatin. NHERF1 loss has no effect on the initial accumulation of cisplatin in the kidney cortex but is associated with an altered redox status which may alter the activity of enzymes involved in cisplatin metabolism.

ACE2 interaction with cytoplasmic PDZ protein enhances SARS-CoV-2 invasion

SummarySARS-CoV-2 is responsible for the global COVID-19 pandemic. Angiotensin converting enzyme 2 (ACE2) is the membrane-delimited receptor for SARS-CoV-2. Lung, intestine, and kidney, major sites of viral infection, express ACE2 that harbors an intracellular, carboxy-terminal PDZ-recognition motif. These organs prominently express the PDZ protein Na+/H+ exchanger regulatory factor-1 (NHERF1). Here, we report NHERF1 tethers ACE2 and augments SARS-CoV-2 cell entry. ACE2 directly binds both NHERF1 PDZ domains. Disruption of either NHERF1 PDZ core-binding motif or the ACE2 PDZ recognition sequence eliminates interaction. Proximity ligation assays establish that ACE2 and NHERF1 interact at constitutive expression levels in human lung and intestine cells. Ablating ACE2 interaction with NHERF1 accelerated SARS-CoV-2 cell entry. Conversely, elimination of the ACE2 C-terminal PDZ-binding motif decreased ACE2 membrane residence and reduced pseudotyped virus entry. We conclude that the PDZ interaction of ACE2 with NHERF1 facilitates SARS-CoV-2 internalization. β-Arrestin is likely indispensable, as with G protein-coupled receptors.

MO340THE EFFECT OF NA+/PI COTRANSPORTER IN TENOFOVIR INDUCED NEPHROTOXITY BY REGULATING INTRACELLULAR PHOSPHORUS BALANCE AND MITOCHONDRIAL FUNCTION

Abstract Background and Aims Tenofovir disoproxil fumarate (TDF), a reverse transcriptase inhibitor used to treat virus infections, could cause proximal tubular (PT) dysfunctions and eGFR decline with mitochondria damages. PDZ domain containing 1 (PDZK1), PDZK1-interacting protein 1 (PDZK1IP1), and Na+/H+ exchanger regulatory factor 1 (NHERF1) are scaffold proteins or membrane-associated proteins that influence the localization and function of membrane proteins. We tried to investigate the changes of both proximal tubular transporters and membrane-associated proteins in TDF induced nephrotoxic model. Method C57/BL6 mice (n = 8) were gavaged daily with 10mg/kg/d, 50mg/kg/d of TDF for 8 weeks. The human renal tubular epithelial cells (HK-2) were grown and received 24 to 72 h exposure to 0–128 µM TDF or vehicle. Results Chronic TDF administration to mice and HK-2 cells resulted in PT damages including swollen and exfoliated tubular epithelial cells, brush border cilia lodging and dissolving, and serum creatinine elevation (P<0.05, mean 10.23±2.683 vs. 27.18±18.41) compared to the control group. The Na+/Pi cotransporter (Npt) and sodium-glucose cotransporter type 2 (SGLT-2) were decreased in the kidneys of TDF treated mice and HK-2 cells. The intracellular phosphorus concentrations decreased with the increase of TDF concentration and the extension of TDF treatment time, which were in line with down-regulated Npt expressions. Mitochondrial morphological changes were seen in TDF treated mice and HK-2 cells by electron microscope, including unclear boundaries, damaged membrane structures, disappeared mitochondrial cristae, and fragmented mitochondria or abnormal giant mitochondria in PT cells. The expression of cytochrome b was reduced by 52.0% (P<0.0001), indicating the damages of mitochondrial respiratory chain. ATP levels which reflected mitochondrial functions were also decreased after TDF treatment in HK-2 cells with a time- and dose-dependent relationship. Conclusion TDF may down-regulate Npt expression, leading to decreased intracellular phosphorus concentrations, mitochondrial dysfunctions, and finally kidney injury.

Na+/H+ exchanger regulatory factor 1 (NHERF1) enhances MRGPRX2-mediated mast cell anaphylaxis

Abstract Anaphylaxis is a severe life-threatening allergic reaction that is caused by mast cell hyperactivity. Two different mast cell receptors play critical roles in mediating anaphylaxis: 1) the IgE receptor that is stimulated by IgE-bound allergen and 2) the MRGPRX2 receptor that can bind to several cationic molecules and FDA-approved drugs resulting in mast cell activation. Activated mast cells degranulate to release proinflammatory mediators. We have recently identified that Na+/H+ exchanger regulatory factor 1 (NHERF1) regulates IgE-dependent mast cell activation in vitro and promotes passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA) in vivo. In the current study, we investigated the role of this adapter molecule in affecting IgE-independent mast cell activation via the MrgprB2 (mouse orthologue of human MRGPRX2) receptor using a novel mouse strain, Cpa3-Cre+ NHERF1fl/fl that lacks NHERF1 in mast cells. PCA and PSA to compound 48/80 (a known MrgprB2 agonist) were significantly attenuated in the Cpa3-Cre+ NHERF1fl/fl mice as compared to control Cpa3-Cre− NHERF1fl/fl mice. In agreement with our in vivo data, peritoneal mast cells isolated from Cpa3-Cre+ NHERF1fl/fl mice showed a significant reduction in mast cell degranulation to the MrgprB2 ligands, compound 48/80 and substance P. Additionally, NHERF1-silenced human LAD2 mast cells showed decreased degranulation to these ligands as well. Collectively, our data suggests that NHERF1 promotes mast cell activation though the MRGPRX2/MrgprB2 receptor and determining the mechanisms through which NHERF1 modulates MRGPRX2 responses will lend insights into the development of new therapeutics for anaphylaxis and other allergic diseases.

Dysregulation of ion transport in the lung epithelium infected with SARS-CoV-2.

Dysregulation of ion transport in the lung epithelium infected with SARS-CoV-2.

NHERF1/EBP50 as a Target for Modulation of MRP Function in HepG2 Cells.

As increased expression and activities of efflux transporters (ETs) often cause drug resistance in cancers, we tried modulating ET activity in cancer cells, using scaffold proteins such as ezrin/radixin/moesin (ERM) proteins, and Na+/H+ exchanger regulatory factor-1 (NHERF1)/ERM-binding phosphoprotein of 50 kDa (EBP50). To see whether EBP50 modulated ET activities in human liver cancer HepG2 cells, we used EBP50 siRNA and a designed TAT-PDZ1 peptide. The EBP50 knockdown (EBP50KD) cells had significantly higher intracellular accumulations of Rho123 and carboxy-dichlorofluorescein (CDF), but not H33342 (i.e., the respective substrates of P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), and breast cancer resistance protein (BCRP)), compared with control HepG2, suggesting that EBP50 knockdown in HepG2 cells decreased activity of P-gp and MRP but not BCRP. Treatment with TAT-PDZ1 peptide (>1 pM) resulted in significantly higher CDF accumulation in HepG2 cells, which persisted for ≥180 min after TAT-PDZ1 peptide treatment. These results imply that EBP50 can modulate ET activities. To our knowledge, this is the first report on using a competitive peptide to modulate interactions between MRP and EBP50.

A Critical Role for Na+/H+ Exchanger Regulatory Factor 1 in Modulating FcεRI-Mediated Mast Cell Activation.

Mast cells are tissue-resident immune cells that play pivotal roles in initiating and amplifying allergic/anaphylactic reactions in humans. Their activation occurs via multiple mechanisms, which include cross-linking of the IgE-bound, high-affinity IgE receptors (FcεRI) by allergens or Ags and the binding of anaphylatoxins such as C3a to its receptor, C3aR. We have previously demonstrated that the Na+/H+ exchanger regulatory factor 1 (NHERF1) promotes C3aR functions in human mast cells. In the current study, we show that NHERF1 regulates mast cell response following FcεRI stimulation. Specifically, intracellular Ca2+ mobilization, activation of the MAPKs (ERK1/2 and P38), and production of cytokines (IL-13 and IL-6) following exposure to IgE/Ag were significantly reduced in mast cells from NHERF1+/‒ mice. In agreement with our in vitro data, mast cell-mediated passive cutaneous anaphylaxis and passive systemic anaphylaxis were reduced in NHERF1+/‒ mice and mast cell-deficient KitW-sh/W-sh mice engrafted with NHERF1+/‒ mast cells. Mechanistically, the levels of microRNAs (miRNAs) that regulate mast cell responses, miRNA 155-3p and miRNA 155-5p, were altered in mast cells from NHERF1+/‒ mice. Moreover, NHERF1 rapidly localized to the nucleus of mast cells following FcεRI stimulation. In summary, our results suggest that the NHERF1 acts as an adapter molecule and promotes IgE/Ag-induced mast cell activation. Further elucidating the mechanisms through which NHERF1 modulates mast cell responses will lend insights into the development of new therapeutic strategies to target mast cells during anaphylaxis or other allergic diseases.

Multisite NHERF1 phosphorylation controls GRK6A regulation of hormone-sensitive phosphate transport

The type II sodium-dependent phosphate cotransporter (NPT2A) mediates renal phosphate uptake. The NPT2A is regulated by parathyroid hormone (PTH) and fibroblast growth factor 23, which requires Na+/H+ exchange regulatory factor-1 (NHERF1), a multidomain PDZ-containing phosphoprotein. Phosphocycling controls the association between NHERF1 and the NPT2A. Here, we characterize the critical involvement of G protein–coupled receptor kinase 6A (GRK6A) in mediating PTH-sensitive phosphate transport by targeted phosphorylation coupled with NHERF1 conformational rearrangement, which in turn allows phosphorylation at a secondary site. GRK6A, through its carboxy-terminal PDZ recognition motif, binds NHERF1 PDZ1 with greater affinity than PDZ2. However, the association between NHERF1 PDZ2 and GRK6A is necessary for PTH action. Ser162, a PKCα phosphorylation site in PDZ2, regulates the binding affinity between PDZ2 and GRK6A. Substitution of Ser162 with alanine (S162A) blocks the PTH action but does not disrupt the interaction between NHERF1 and the NPT2A. Replacement of Ser162 with aspartic acid (S162D) abrogates the interaction between NHERF1 and the NPT2A and concurrently PTH action. We used amber codon suppression to generate a phosphorylated Ser162(pSer162)-PDZ2 variant. KD values determined by fluorescence anisotropy indicate that incorporation of pSer162 increased the binding affinity to the carboxy terminus of GRK6A 2-fold compared with WT PDZ2. Molecular dynamics simulations predict formation of an electrostatic network between pSer162 and Asp183 of PDZ2 and Arg at position −1 of the GRK6A PDZ-binding motif. Our results suggest that PDZ2 plays a regulatory role in PTH-sensitive NPT2A-mediated phosphate transport and phosphorylation of Ser162 in PDZ2 modulates the interaction with GRK6A.

Sodium Hydrogen Exchanger Regulatory Factor-1 (NHERF1) Regulates Fetal Membrane Inflammation.

The fetal inflammatory response, a key contributor of infection-associated preterm birth (PTB), is mediated by nuclear factor kappa B (NF-kB) activation. Na+/H+ exchanger regulatory factor-1 (NHERF1) is an adapter protein that can regulate intracellular signal transduction and thus influence NF-kB activation. Accordingly, NHERF1 has been reported to enhance proinflammatory cytokine release and amplify inflammation in a NF-kB-dependent fashion in different cell types. The objective of this study was to examine the role of NHERF1 in regulating fetal membrane inflammation during PTB. We evaluated the levels of NHERF1 in human fetal membranes from term labor (TL), term not in labor (TNIL), and PTB and in a CD1 mouse model of PTB induced by lipopolysaccharide (LPS). Additionally, primary cultures of fetal membrane cells were treated with LPS, and NHERF1 expression and cytokine production were evaluated. Gene silencing methods using small interfering RNA targeting NHERF1 were used to determine the functional relevance of NHERF1 in primary cultures. NHERF1 expression was significantly (p < 0.001) higher in TL and PTB membranes compared to TNIL membranes, and this coincided with enhanced (p < 0.01) interleukin (IL)-6 and IL-8 expression levels. LPS-treated animals delivering PTB had increased levels of NHERF1, IL-6, and IL-8 compared to phosphate-buffered saline (PBS; control) animals. Silencing of NHERF1 expression resulted in a significant reduction in NF-kB activation and IL-6 and IL-8 production as well as increased IL-10 production. In conclusion, downregulation of NHERF1 increased anti-inflammatory IL-10, and reducing NHERF1 expression could be a potential therapeutic strategy to reduce the risk of infection/inflammation associated with PTB.

Mechanistic Insight for Enhanced Cisplatin (CIS) Nephrotoxicity in Na-H Exchanger Regulatory Factor 1 (NHERF1) Deficiency

Mechanistic Insight for Enhanced Cisplatin (CIS) Nephrotoxicity in Na-H Exchanger Regulatory Factor 1 (NHERF1) Deficiency

NHERF1 Loss Upregulates Enzymes of the Pentose Phosphate Pathway in Kidney Cortex.

(1) Background: We previously showed Na/H exchange regulatory factor 1 (NHERF1) loss resulted in increased susceptibility to cisplatin nephrotoxicity. NHERF1-deficient cultured proximal tubule cells and proximal tubules from NHERF1 knockout (KO) mice exhibit altered mitochondrial protein expression and poor survival. We hypothesized that NHERF1 loss results in changes in metabolic pathways and/or mitochondrial dysfunction, leading to increased sensitivity to cisplatin nephrotoxicity. (2) Methods: Two to 4-month-old male wildtype (WT) and KO mice were treated with vehicle or cisplatin (20 mg/kg dose IP). After 72 h, kidney cortex homogenates were utilized for metabolic enzyme activities. Non-treated kidneys were used to isolate mitochondria for mitochondrial respiration via the Seahorse XF24 analyzer. Non-treated kidneys were also used for LC-MS analysis to evaluate kidney ATP abundance, and electron microscopy (EM) was utilized to evaluate mitochondrial morphology and number. (3) Results: KO mouse kidneys exhibit significant increases in malic enzyme and glucose-6 phosphate dehydrogenase activity under baseline conditions but in no other gluconeogenic or glycolytic enzymes. NHERF1 loss does not decrease kidney ATP content. Mitochondrial morphology, number, and area appeared normal. Isolated mitochondria function was similar between WT and KO. Conclusions: KO kidneys experience a shift in metabolism to the pentose phosphate pathway, which may sensitize them to the oxidative stress imposed by cisplatin.

Altered absorptive function in the gall bladder during cholesterol gallstone formation is associated with abnormal NHE3 complex formation.

Dysfunction of the Na+/H+ exchanger 3 (NHE3) contributes to the formation of cholesterol gallstones. We aimed to investigate whether NHE3 dysfunction is associated with abnormalities in NHE3 complex formation. We fed C57BL/6 mice with control or lithogenic diet and study the expression of NHE3, ezrin, and Na+/H+ exchanger regulatory factor 1 (NHERF1) in the gallbladder (GB) using RT-PCR and western blot. Immunofluorescence and immunoprecipitation were performed to investigate the interactions of NHE3 with ezrin or NHERF1. To explore the initiating factor that leads to NHE3 dysfunction, we stimulated cholangiocarcinoma cells with taurochenodeoxycholate (TCDC) and/or forskolin. The effects of TCDC on the expression of NHE3 regulatory proteins, as well as their bindings to NHE3, were detected by western blot and immunoprecipitation. Enzyme-linked immunosorbent assay was used to study the regulation of cAMP production by TCDC. The expression of NHERF1 and ezrin phosphorylation level were increased in the gallbladder epithelial cells (GBECs) of C57BL/6 mice with cholesterol gallstones. Immunofluorescence studies demonstrated that the subcellular localization of ezrin and NHERF1 were similar to that of NHE3 in GBECs. Immunoprecipitation revealed that ezrin formed macrocomplex with NHE3, which were enhanced after gallstone formation. TCDC increased forskolin-induced cAMP accumulation, and NHERF1 and PKCα expression in cholangiocarcinoma cells. Under the synergistic effect of forskolin, TCDC stimulated ezrin phosphorylation, with enhanced interaction between ezrin and NHE3. The formation of cholesterol gallstones is associated with abnormal formation of NHE3 complexes. Decreased biliary TCDC may be an initiating factor that leads to abnormal GB absorption.

New roles of the Na+/H+ exchange regulatory factor 1 scaffolding protein: a review.

Na+/H+ exchange regulatory factor 1 (NHERF1), a member of a PDZ scaffolding protein family, was first identified as an organizer of membrane-bound protein complexes composed of hormone receptors, signal transduction pathways, and electrolyte and mineral transporters and channels. NHERF1 is involved in the regulation of Na+/H+ exchanger 3, Na+-dependent phosphate transporter 2a, and Na+-K+-ATPase through its ability to scaffold these transporters to the plasma membrane, allowing regulation of these protein complexes with their associated hormone receptors. Recently, NHERF1 has received increased interest in its involvement in a variety of functions, including cell structure and trafficking, tumorigenesis and tumor behavior, inflammatory responses, and tissue injury. In this review, we highlight the evidence for the expansive role of NHERF1 in cell biology and speculate on the implications for renal physiology and pathophysiology.

Prognostic and therapeutic implications of NHERF1 expression and regulation in colorectal cancer.

Na+ /H+ exchanger regulatory factor 1 (NHERF1) has been implicated in the tumorigenesis of several cancer types and is a potential therapeutic target. The current study evaluated the relationship between NHERF1 expression and clinical outcome in colorectal cancer (CRC). NHERF1 expression was evaluated by immunohistochemistry in 167 patients with CRCprimary tumors, 37 patients with no disease, and 27 patients with metastatic CRC (mCRC); and in the orthotopically implanted tumors in mice. NHERF1 expression was manipulated in CRC cells using inducible short hairpin RNAs to determine its biological functions. High expression of NHERF1 correlated with CRC progression and metastasis, as well as significantly worse overall survival, recurrence-free survival, and disease-specific survival. Orthotopic implantation studies demonstrated increased NHERF1 expression in liver metastases. Treatment of CRC xenografts with insulin-like growth factor 1 receptor (IGF1R) inhibitors downregulated NHERF1 expression, indicating NHERF1 is downstream of IGF1R signaling. Knockdown of NHERF1 increased apoptosis and reduced X-linked inhibitor of apoptosis protein (XIAP) and survivin expression, indicating NHERF1 is critical for CRC cell survival. NHERF1 expression levels correlated with worse prognosis in patients with CRC and plays a critical role in CRC cell survival. Together, our findings establish NHERF1 as a novel potential marker for increased risk of CRC-specific mortality and identify NHERF1 as an attractive therapeutic target for mCRC treatment.

Tumor Infiltrating Lymphocytes and NHERF1 Impact on Prognosis of Breast Cancer Patients

BACKGROUND: Breast cancer (BC) is a heterogeneous disease, and patients with apparently similar clinicopathological characteristics in clinical practice show different outcome. This study evaluated in primary BCs and in the subgroup of the triple-negative breast cancers (TNBCs) the level of tumor infiltrating lymphocytes (TILs), Na+/H+ exchanger regulatory factor 1 (NHERF1) expression, and their association respect to the clinical outcome of patients. MATERIAL AND METHODS: NHERF1 expression was assessed by immunohistochemistry in 338 BC samples; the analysis of TILs was examined using hematoxylin and eosin stained slides, according to International TILs Working Group 2014. RESULTS: Multivariate analysis identified TILs as an independent prognostic factor for DFS in the entire cohort and in the TNBC subgroup (HR, 0.32; 95% CI, 0.12–0.87; P = 0.026; and HR, 0.22; 95% CI, 0.06–0.80; P = 0.022, respectively). Univariate and survival analysis by Kaplan–Meier method revealed that patients with cytoplasmic (c) NHERF1-/TILs+ expression had better DFS than other patients (P = 0.049), and this result was also found in the TNBC subgroup (P = 0.031). Moreover, TNBC patients with cNHERF1−/TILs− expression had a worse DFS and OS than other patients (P = 0.057 and P = 0.002, respectively). CONCLUSIONS: In the complex scenario of BC and in the era of tumor immunogenicity and immunotherapy, we found an association of TIL levels and cNHERF1 expression that could be useful to identify BCs and particularly TNBC patients with different prognosis and clinical outcome.