Alternative titles; symbols
HGNC Approved Gene Symbol: NHERF1
Cytogenetic location: 17q25.1 Genomic coordinates (GRCh38) : 17:74,748,628-74,769,353 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 17q25.1 | Nephrolithiasis/osteoporosis, hypophosphatemic, 2 | 612287 | Autosomal dominant | 3 |
NHERF1 is a cytoplasmic adaptor protein that recruits various signaling proteins, cellular receptors, ion transporters, and other proteins to the plasma membrane of epithelia and other cell types (Wang et al., 2008).
Members of the ezrin (VIL2; 123900)-radixin (RDX; 179410)-moesin (MSN; 309845) (ERM) family of membrane-cytoskeletal linking proteins have N- and C-terminal domains that associate with the plasma membrane and the actin cytoskeleton, respectively. Using affinity chromatography with the immobilized N termini of ERM proteins to capture ERM-binding proteins in membrane, Reczek et al. (1997) isolated polypeptides from placenta that migrated at 50 kD after phosphatase treatment. By micropeptide sequence analysis of these polypeptides, followed by searching an EST database, they identified a cDNA encoding SLC9A3R1, which they called EBP50. The predicted 358-amino acid SLC9A3R1 protein shares high homology with the rabbit sodium/hydrogen exchanger regulatory factor (Nherf) and contains 2 N-terminal PDZ domains of approximately 90 amino acids. SDS-PAGE and blot overlay analyses showed that recombinant SLC9A3R1 is expressed as a 50-kD protein. Immunoblot analysis detected SLC9A3R1 expression in all tissues tested except heart and skeletal muscle, with the most abundant expression detected in tissues with polarized epithelia, including kidney, small intestine, placenta, and liver. Immunofluorescence microscopy demonstrated that SLC9A3R1 colocalizes with actin in areas with abundant microvilli in placenta and intestinal brush border; the pattern of SLC9A3R1 staining was very similar to that seen for ezrin. Immunoprecipitation analysis showed that SLC9A3R1 and ezrin associate in vivo.
Murthy et al. (1998) isolated SLC9A3R1, which they termed NHERF, by screening a fetal frontal cortex cDNA library using a yeast 2-hybrid system with merlin (NF2; 607379) as bait. Northern blot analysis revealed that SLC9A3R1 was ubiquitously expressed, with highest levels in kidney, liver, and pancreas. Immunocytochemistry demonstrated that SLC9A3R1 colocalized with moesin at the ruffling membrane, microvilli, and filopodia in HeLa cells.
By deletion and mutation analyses, Murthy et al. (1998) showed that SLC9A3R1 associated with the N terminus but not with the C terminus of merlin. SLC9A3R1 was also shown to bind to moesin and radixin at the N terminus, the region with the most homology to merlin.
Bonilha and Rodriguez-Boulan (2001) identified EBP50 and SAP97 (601014) as binding partners for ezrin, an actin-binding protein crucial for morphogenesis of apical microvilli and basolateral infoldings in retinal pigment epithelial (RPE) cells. Immunofluorescence microscopy detected a polarized distribution of EBP50 at apical microvilli and of SAP97 at the basolateral surface of RPE cells, which overlapped with ezrin.
PTEN (601728) is a dual-specificity phosphatase that is targeted to the plasma membrane and antagonizes the PI3 kinase (PI3K, see PIK3CA 171834)/AKT (AKT1; 164730) signaling cascade involved in cell survival, growth, proliferation and other processes. Takahashi et al. (2006) found that PTEN interacts with NHERF1 and NHERF2 (SLC9A3R2; 606553) adaptor proteins. A ternary complex was formed between PTEN, NHERF proteins and PDGFR (see PDGFRA, 173490), resulting in activation of the PI3K pathway upon PDGF (see PDGFA, 173430) binding. In Nherf1 -/- mouse embryonic fibroblasts, activation of the PI3K pathway by Pdgfr was prolonged in comparison with wildtype cells, consistent with defective Pten recruitment to Pdgfr in the absence of Nherf1. Depletion of Nherf2 by small interfering RNA similarly increased PI3K signaling. Loss of Nherf1 enhanced Pdgf-induced cytoskeletal rearrangements and chemotactic migration. Takahashi et al. (2006) concluded that NHERF proteins recruit PTEN to PDGFR to restrict PI3K activation.
Cardone et al. (2007) stated that NHERF1 is overexpressed in several tumors compared with normal tissues. Using Western blot and immunohistochemical analyses, they found that NHERF1 was overexpressed in 100% of human tumor breast samples analyzed. In normal breast epithelia, NHERF1 expression was limited to apical membranes, but in tumor lobular tissue, NHERF1 was also expressed intracellularly. NHERF1 expression increased with tumor dedifferentiation and with poorer prognosis. NHERF1 colocalized with HIF1-alpha (HIF1A; 603348), and both hypoxia and serum deprivation increased NHERF1 expression in breast cancer cell lines. NHERF1 expression was highest in tumor cells of mesenchymal shape and at the leading edge pseudopodia in both breast biopsies and in 3-dimensional cultures. Overexpression of mouse Nherf1 activated invasion in 3-dimensional gels through stimulation of NHE1 Na+/H+ exchange via a PKA (see 601639)-RHOA (165390)-p38 (MAPK14; 600289) signaling cascade. Tumor cell invasion and activation and cell signaling were recapitulated by the isolated Nherf1 PDZ2 domain.
Parathyroid hormone (PTH; 168450) stimulation of the PTH receptor (PTH1R; 168468) regulates calcium homeostasis via several cell signaling pathways, including one that involves PKA and the MAP kinase pathway, characterized by ERK1 (MAPK3; 601795) and ERK2 (MAPK1; 176948). Using COS cells expressing rabbit Nherf1 and human PTH1R, Wang et al. (2008) found that Nherf1 inhibited PKA-dependent activation of Erk1/Erk2 following PTH1R stimulation. Nherf1 interrupted this signaling pathway at the level of Braf (164757) by several mechanisms: Nherf1 interacted with Akt and enhanced the inhibitory effect of Akt-dependent phosphorylation of the Braf regulatory domain; Nherf1 blocked the activating effect of PKA-dependent phosphorylation of the Braf catalytic domain; and Nherf1 displaced the activating protein 14-3-3 (see 113508) from the Braf catalytic domain.
Using synthetic derivatives of the enteropathogenic Escherichia coli guanine-nucleotide exchange factor Map, Orchard et al. (2012) found that CDC42 (116952) GTPase signal transduction was controlled by interaction between Map and the PDZ domains of EBP50 and the induction of clusters of actin-rich membrane protrusions.
Hartz (2012) mapped the SLC9A3R1 gene to chromosome 17q25.1 based on an alignment of the SLC9A3R1 sequence (GenBank AF015926) with the genomic sequence (GRCh37).
The chronic inflammatory skin disorder psoriasis (see 177900) is associated with HLA class I alleles, and linkage analysis identified a second psoriasis locus at 17q24-q25 (602723) in 3 independent sets of families. Helms et al. (2003) described 2 peaks of strong association with psoriasis on 17q25 separated by 6 Mb. Associated single-nucleotide polymorphisms (SNPs) in the proximal peak lie in or near SLC9A3R1 and NAT9 (620913), a member of the N-acetyltransferase family.
In 4 of 92 unrelated patients with calcium-containing renal stones (50 patients), bone demineralization (30), or both (12), Karim et al. (2008) identified heterozygous mutations in the SLC9A3R1 gene (604990.0001-604990.0003). Three of the patients had calcium nephrolithiasis, and 1 had decreased bone mineral density (BMD). All had significantly decreased tubular maximum for phosphate resorption per glomerular filtration rate (TmP/GFR) values compared to normal, indicating impaired proximal renal tubular phosphate absorption, as well as hypophosphatemia. Other biochemical findings included increased urinary cAMP excretion and increased serum 1,25-dihydroxyvitamin D (calcitriol). In vitro studies indicated that the mutations had no effect on basal phosphate uptake but potentiated parathyroid hormone (PTH; 168450)-induced cAMP generation and the inhibition of phosphate transport. The results demonstrated that mutations in the SLC9A3R1 gene can cause renal phosphate loss that may increase the risk of renal stone formation or bone demineralization.
Shenolikar et al. (2002) found that targeted disruption of the mouse Nherf1 gene eliminated Nherf1 expression in kidney and other tissues of the mutant mice without altering Nherf2 levels in these tissues. Heterozygous and homozygous deficient male mice maintained normal blood electrolytes but showed increased urinary excretion of phosphate when compared with homozygous wildtype animals. Although the overall levels of renal Nherf1 targets, Slc9a3 and sodium-phosphate transport-2 (Npt2; 182309), were unchanged in the mutant mice, immunocytochemistry showed that the Npt2 protein was aberrantly localized at internal sites in the renal proximal tubule cells. The mislocalization of Npt2 paralleled a reduction in the transporter protein in renal brush-border membranes isolated from the mutant mice. In contrast, Slc9a3 was appropriately localized at the apical surface of proximal tubules in both wildtype and mutant mice. These data suggested that NHERF1 plays a unique role in the apical targeting and/or trafficking of NPT2 in the mammalian kidney, a function not shared by NHERF2 or other renal PDZ proteins. Phosphate wasting seen in the Nherf1 homozygous-null mice provided a novel experimental system for defining the role of PDZ adaptors in the hormonal control of ion transport and renal disease.
Weinman et al. (2003) found that the Na+/H+ exchanger Nhe3 (SLC9A3; 182307) was expressed and targeted correctly in brush border membranes prepared from Nherf1 -/- renal proximal tubules and that basal Na+/H+ exchange was indistinguishable from wildtype. However, Nherf1 -/- membranes were defective in PKA-mediated cAMP-dependent phosphorylation and inhibition of Nhe3 transport activity.
Using isolated wildtype and Nherf1 -/- mouse kidney cortex and ileum, Murtazina et al. (2007) found that Nherf1 was required for all cAMP inhibition of Nhe3 in kidney, which occurred through both Epac (RAPGEF3; 606057)-dependent and PKA-dependent mechanisms. In contrast, cAMP inhibition of Nhe3 in ileum occurred only by a PKA-dependent pathway that was independent of Nherf1.
In 2 unrelated patients with impaired renal phosphate absorption resulting in calcium nephrolithiasis and decreased BMD (612287), respectively, Karim et al. (2008) identified a heterozygous 328C-G transversion in exon 1 of the SLC9A3R1 gene, resulting in a leu110-to-val (L110V) substitution. A third unrelated individual with decreased TmP/GFR was also found to be heterozygous for the mutation. The mutation was not identified in 112 patients with normal TmP/GFR values.
In a 44-year-old woman with impaired renal phosphate resorption resulting in calcium nephrolithiasis (612287), Karim et al. (2008) identified a heterozygous 458G-A transition in exon 2 of the SLC9A3R1 gene, resulting in an arg153-to-gln (R153Q) substitution. The patient's sister and niece, who both had a history of recurrent renal lithiasis and low TmP/GFR values, carried the same mutation. Another sister of the proband, who had no history of renal lithiasis and a normal TmP/GFR value, did not carry the mutation. The mutation was not identified in 112 patients with normal TmP/GFR values.
In a 57-year-old woman with impaired renal phosphate resorption resulting in calcium nephrolithiasis (612287), Karim et al. (2008) identified a heterozygous 673G-A transition in exon 3 of the SLC9A3R1 gene, resulting in a glu225-to-lys (E225K) substitution. The mutation was not identified in 112 patients with normal TmP/GFR values.
Bonilha, V. L., Rodriguez-Boulan, E. Polarity and developmental regulation of two PDZ proteins in the retinal pigment epithelium. Invest. Ophthal. Vis. Sci. 42: 3274-3282, 2001. [PubMed: 11726633]
Cardone, R. A., Bellizzi, A., Busco, G., Weinman, E. J., Dell'Aquila, M. E., Casavola, V., Azzariti, A., Mangia, A., Paradiso, A., Reshkin, S. J. The NHERF1 PDZ2 domain regulates PKA-RhoA-p38-mediated NHE1 activation and invasion in breast tumor cells. Molec. Biol. Cell 18: 1768-1780, 2007. [PubMed: 17332506] [Full Text: https://doi.org/10.1091/mbc.e06-07-0617]
Hartz, P. A. Personal Communication. Baltimore, Md. 1/25/2012.
Helms, C., Cao, L., Krueger, J. G., Wijsman, E. M., Chamian, F., Gordon, D., Heffernan, M., Daw, J. A. W., Robarge, J., Ott, J., Kwok, P.-Y., Menter, A., Bowcock, A. M. A putative RUNX1 binding site variant between SLC9A3R1 and NAT9 is associated with susceptibility to psoriasis. Nature Genet. 35: 349-356, 2003. [PubMed: 14608357] [Full Text: https://doi.org/10.1038/ng1268]
Karim, Z., Gerard, B., Bakouh, N., Alili, R., Leroy, C., Beck, L., Silve, C., Planelles, F., Urena-Torres, P., Grandchamp, B., Friedlander, G., Prie, D. NHERF1 mutations and responsiveness of renal parathyroid hormone. New Eng. J. Med. 359: 1128-1135, 2008. [PubMed: 18784102] [Full Text: https://doi.org/10.1056/NEJMoa0802836]
Murtazina, R., Kovbasnjuk, O., Zachos, N. C., Li, X., Chen, Y., Hubbard, A., Hogema, B. M., Steplock, D., Seidler, U., Hoque, K. M., Tse, C. M., De Jonge, H. R., Weinman, E. J., Donowitz, M. Tissue-specific regulation of sodium/proton exchanger isoform 3 activity in Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) null mice: cAMP inhibition is differentially dependent on NHERF1 and exchange protein directly activated by cAMP in ileum versus proximal tubule. J. Biol. Chem. 282: 25141-25151, 2007. [PubMed: 17580307] [Full Text: https://doi.org/10.1074/jbc.M701910200]
Murthy, A., Gonzalez-Agosti, C., Cordero, E., Pinney, D., Candia, C., Solomon, F., Gusella, J., Ramesh, V. NHE-RF, a regulatory cofactor for Na(+)-H(+) exchange, is a common interactor for merlin and ERM (MERM) proteins. J. Biol. Chem. 273: 1273-1276, 1998. [PubMed: 9430655] [Full Text: https://doi.org/10.1074/jbc.273.3.1273]
Orchard, R. C., Kittisopikul, M., Altschuler, S. J., Wu, L. F., Suel, G. M., Alto, N. M. Identification of F-actin as the dynamic hub in a microbial-induced GTPase polarity circuit. Cell 148: 803-815, 2012. [PubMed: 22341450] [Full Text: https://doi.org/10.1016/j.cell.2011.11.063]
Reczek, D., Berryman, M., Bretscher, A. Identification of EBP50: a PDZ-containing phosphoprotein that associates with members of the ezrin-radixin-moesin family. J. Cell Biol. 139: 169-179, 1997. [PubMed: 9314537] [Full Text: https://doi.org/10.1083/jcb.139.1.169]
Shenolikar, S., Voltz, J. W., Minkoff, C. M., Wade, J. B., Weinman, E. J. Targeted disruption of the mouse NHERF-1 gene promotes internalization of proximal tubule sodium-phosphate cotransporter type IIa and renal phosphate wasting. Proc. Nat. Acad. Sci. 99: 11470-11475, 2002. [PubMed: 12169661] [Full Text: https://doi.org/10.1073/pnas.162232699]
Takahashi, Y., Morales, F. C., Kreimann, E. L., Georgescu, M.-M. PTEN tumor suppressor associates with NHERF proteins to attenuate PDGF receptor signaling. EMBO J. 25: 910-920, 2006. [PubMed: 16456542] [Full Text: https://doi.org/10.1038/sj.emboj.7600979]
Wang, B., Yang, Y., Friedman, P. A. Na/H exchange regulatory factor 1, a novel AKT-associating protein, regulates extracellular signal-regulated kinase signaling through a B-Raf-mediated pathway. Molec. Biol. Cell 19: 1637-1645, 2008. [PubMed: 18272783] [Full Text: https://doi.org/10.1091/mbc.e07-11-1114]
Weinman, E. J., Steplock, D., Shenolikar, S. NHERF-1 uniquely transduces the cAMP signals that inhibit sodium-hydrogen exchange in mouse renal apical membranes. FEBS Lett. 536: 141-144, 2003. [PubMed: 12586353] [Full Text: https://doi.org/10.1016/s0014-5793(03)00043-7]