NHE-RF, a Regulatory Cofactor for Na+-H+Exchange, Is a Common Interactor for Merlin and ERM (MERM) Proteins

Murthy, Anita E.; Gonzalez-Agosti, Charo; Cordero, Etchell; Pinney, Denise; Candia, Cecilia; Solomon, Frank; Gusella, James F.; Ramesh, Vijaya

doi:10.1074/jbc.273.3.1273

Cited by 240 publications

(182 citation statements)

References 31 publications

Supporting

Mentioning

178

Contrasting

Unclassified

Order By: Relevance

“…Negative regulation of CD44-HA interaction provides a mechanism that underlies the tumor-suppressor function of merlin Like the ERM proteins, merlin binds to several membrane-associated proteins, including CD44 (Tsukita et al, 1994;Sainio et al, 1997), NHE-RF/EBP50 (Murthy et al, 1998), and b1-integrin (Obremski et al, 1998). ERM proteins play important roles in organizing the actincytoskeleton which is essential for cell adhesion and migration.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of the hyaluronan-CD44 interaction by merlin contributes to the tumor-suppressor activity of merlin

Bai

et al. 2006

Oncogene

View full text Add to dashboard Cite

Mutation or loss of expression of merlin is responsible for neurofibromatosis type 2 (NF2), which is characterized by the development of schwannomas and other tumors of the nervous system. Like the ERM (ezrin-radixin-moesin) proteins, merlin interacts with CD44, a cell-surface receptor for hyaluronan (HA) that promotes tumorigenesis. However, the relationship between merlin and CD44 and the mechanism by which merlin exerts its tumorsuppressor function have not been elucidated. In the present study, we show that increased expression of wildtype merlin in Tr6BC1 schwannoma cells inhibits HA binding to CD44. Furthermore, we demonstrate that the residues required for this inhibitory effect and the interaction between CD44 and merlin lie within the first 50 amino acids of merlin. Overexpression of merlin inhibited subcutaneous growth of Tr6BC1 cells in immunocompromised Rag1 mice. In contrast, knocking down expression of endogenous merlin promoted tumor cell growth, as did overexpression of a merlin deletion mutant (merlinDel-1) that lacks the first 50 amino acids but not of other NH 2 -terminal deletion mutants. Together, our results demonstrate that inhibition of the CD44-HA interaction contributes to the tumor-suppressor function of merlin, and they suggest that merlin inhibits tumor growth, at least in part, by negatively regulating CD44 function.

show abstract

Section: Discussionmentioning

confidence: 99%

Inhibition of the hyaluronan-CD44 interaction by merlin contributes to the tumor-suppressor activity of merlin

Bai

et al. 2006

Oncogene

View full text Add to dashboard Cite

show abstract

“…Therefore, our findings suggest that EBP50 may contribute to the E-cadherin/b-catenindependent intercellular adhesion by acting directly on EGFR signaling output. Curto et al (2007) demonstrated that merlin/Nf2 tethers EBP50 to the cell cytoskeleton (Murthy et al, 1998) and thereby participates in the stabilization of AJs through the regulation of EGFR. The observation that EBP50, but not merlin/ Nf2, interacts directly with EGFR (Lazar et al, 2004;Takahashi et al, 2006;Curto et al, 2007), suggests that EBP50 regulates EGFR signaling per se.…”

Section: Loss Of Ebp50-egfr Interplay In Biliary Carcinomamentioning

confidence: 99%

Loss of EBP50 stimulates EGFR activity to induce EMT phenotypic features in biliary cancer cells

et al. 2011

View full text Add to dashboard Cite

Scaffold proteins form multiprotein complexes that are central to the regulation of intracellular signaling. The scaffold protein ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) is highly expressed at the plasma membrane of normal biliary epithelial cells and binds epidermal growth factor receptor (EGFR), a tyrosine kinase receptor with oncogenic properties. This study investigated EBP50-EGFR interplay in biliary cancer. We report that in a collection of 106 cholangiocarcinomas, EBP50 was delocalized to the cytoplasm of tumor cells in 66% of the cases. Ectopic expression of EBP50 was correlated with the presence of satellite nodules and with the expression of EGFR, which was at the plasma membrane, implying a loss of interaction with EBP50 in these cases. In vitro, loss of interaction between EBP50 and EGFR was mimicked by EBP50 depletion using a small interfering RNA approach in human biliary carcinoma cells co-expressing the two proteins at their plasma membrane, and in which interaction between EBP50 and EGFR was validated. EBP50 depletion caused an increase in EGFR expression at their surface, and a sustained activation of the receptor and of its downstream effectors (extracellular signal-regulated kinase 1/2, signal transducer and activator of transcription 3) in both basal and EGF-stimulated conditions. Cells lacking EBP50 showed epithelial-to-mesenchymal transition-associated features, including reduction in E-cadherin and cytokeratin-19 expression, induction of S100A4 and of the E-cadherin transcriptional repressor, Slug, and loss of cell polarity. Accordingly, depletion of EBP50 induced the disruption of adherens junctional complexes, the development of lamellipodia structures and the subsequent acquisition of motility properties. All these phenotypic changes were prevented upon inhibition of EGFR tyrosine kinase by gefitinib. These findings indicate that loss of EBP50 at the plasma membrane in tumor cells may contribute to biliary carcinogenesis through EGFR activation.

show abstract

“…Merlin constructs representing full-length (aa 1-595), amino terminus (aa 1-340) and carboxy terminus (aa 341-595) of isoform 1 were used as baits to screen a human fetal frontal cortex interaction library as previously described (Murthy et al, 1998). The cDNA clone obtained (aa 13-178) from this screen was referred to as MerIntA.…”

Section: Molecular Cloning Of Magicinmentioning

confidence: 99%

“…Full-length (aa 1-577), amino terminus (aa 1-332) and carboxy terminus (aa 307-577) of human moesin were expressed as GST fusion proteins using the vector pGEX4T1 (Amersham Biosciences). Expression and purification of all the GST fusion proteins were performed as described previously (Murthy et al, 1998). To generate GST-magicin fusion protein, magicin (aa 13-178) was cloned into pGEX-4T1, expressed and purified as for merlin.…”

Section: Dna Constructs and Expression In Escherichia Colimentioning

confidence: 99%

“…Merlin interacts with F-actin through actin binding sites within the FERM domain (Xu and Gutmann, 1998;Brault et al, 2001;James et al, 2001). In addition to actin, several other merlin interacting proteins have been identified, which include b-fodrin/bII-spectrin (Scoles et al, 1998;Neill and Crompton, 2001), SCHIP-1 (Goutebroze et al, 2000), NHE-RF (Murthy et al, 1998), b1-integrin (Obremski et al, 1998), CD44 (Sainio et al, 1997;Morrison et al, 2001), HRS (Scoles et al, 2000), RhoGDI (Maeda et al, 1999), syntenin (Jannatipour et al, 2001), paxillin (Fernandez-Valle et al, 2002) and RIb subunit of the cAMP-protein kinase A (Gronholm et al, 2003). Among these proteins, NHE-RF, CD44 and RhoGDI have been independently identified as ERM binding partners (Tsukita et al, 1994;Reczek et al, 1997;Takahashi et al, 1997), while HRS and syntenin appear to be specific for merlin.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magicin, a novel cytoskeletal protein associates with the NF2 tumor suppressor merlin and Grb2

et al. 2004

Self Cite

View full text Add to dashboard Cite

Neurofibromatosis 2 (NF2) is a dominantly inherited disorder characterized by bilateral vestibular schwannomas and meningiomas. Merlin, the neurofibromatosis 2 tumor suppressor protein, is related to the ERM (ezrin, radixin, moesin) proteins and, like its family members, is thought to play a role in plasma membrane-cytoskeletal interactions. We report a novel protein as a merlin-specific binding partner that we have named magicin (merlin and Grb2 interacting cytoskeletal protein) and show that the two proteins interact in vitro and in vivo as well as colocalize beneath the plasma membrane. Magicin is a 24 kDa protein that is expressed in many cell lines and tissues. Magicin, similar to merlin, associates with the actin cytoskeleton as determined by cofractionation, immunofluorescence and electron microscopy. Analysis of the magicin sequence reveals binding motifs for the adaptor protein Grb2. Employing affinity binding, blot overlay and co-immunoprecipitation assays, we demonstrate an interaction between Grb2 and magicin. In addition, merlin is capable of forming a ternary complex with magicin and Grb2. These results support a role for merlin in receptor-mediated signaling at the cell surface, and may have implications in the regulation of cytoskeletal reorganization.

show abstract

NHE-RF, a Regulatory Cofactor for Na+-H+Exchange, Is a Common Interactor for Merlin and ERM (MERM) Proteins

Cited by 240 publications

References 31 publications

Inhibition of the hyaluronan-CD44 interaction by merlin contributes to the tumor-suppressor activity of merlin

Inhibition of the hyaluronan-CD44 interaction by merlin contributes to the tumor-suppressor activity of merlin

Loss of EBP50 stimulates EGFR activity to induce EMT phenotypic features in biliary cancer cells

Magicin, a novel cytoskeletal protein associates with the NF2 tumor suppressor merlin and Grb2

Contact Info

Product

Resources

About