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

Abstract

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.

The NF2 Tumor Suppressor Merlin and the ERM Proteins Interact with N-WASP and Regulate Its Actin Polymerization Function

“…The anti-WAVE, anti-N-WASP, and anti-WIP antibodies have been described (13,16,17). Anti-NHE-RF IC270 and anti-merlin antibodies 1C4 and C26H were described previously (18,19). Anti-Nck and anti-Myc 9E10 antibodies were purchased from BD Transduction Laboratories and Developmental Studies Hybridoma Bank, respectively.…”

MED28 (mediator complex subunit 28)

“…Affinity-binding assays demonstrated that MED28 interacted with the SH3 domains of Grb2 (Wiederhold et al, 2004). Accordingly, MED28 was also named as magicin, merlin and Grb2 interacting cytoskeletal protein (Wiederhold et al, 2004).…”

“…MED28 was also identified as a merlin-interacting protein by yeast two-hybrid screen (Wiederhold et al, 2004), where merlin, the neurofibromatosis 2 (NF2) tumor suppressor protein, belongs to the ezrin-radixinmoesin (ERM) family members. Affinity-binding assays demonstrated that MED28 interacted with the SH3 domains of Grb2 (Wiederhold et al, 2004).…”

“…The full-length MED28 protein consists of 178 amino acids with a predicted molecular weight ~20 kDa (Wiederhold et al, 2004). MED28, an evolutionaly conserved protein, was identified as an endothelialderived gene, EG-1 (Liu et al, 2002).…”

Clinical course of vestibular schwannoma in pediatric neurofibromatosis Type 2

“…Recently, understanding of the molecular biology and genetic mutations of NF2 has been increasing. 8,25,30,34,40 Drugs targeting the pathways involved in the molecular pathogenesis of NF2 are now under investigation. Potential treatments for NF2 are expected to emerge in the near future.…”