Wiederhold Thorsten, Lee Ming-Fen, James Marianne, Neujahr Ralph, Smith Nicole, Murthy Anita, Hartwig John, Gusella James F, Ramesh Vijaya
Molecular Neurogenetics Unit, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Oncogene. 2004 Nov 18;23(54):8815-25. doi: 10.1038/sj.onc.1208110.
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.
神经纤维瘤病2型（NF2）是一种常染色体显性遗传病，其特征为双侧前庭神经鞘瘤和脑膜瘤。默林蛋白是神经纤维瘤病2型的肿瘤抑制蛋白，与ERM（埃兹蛋白、根蛋白、膜突蛋白）相关，并且与其家族成员一样，被认为在质膜-细胞骨架相互作用中发挥作用。我们报道了一种新的蛋白，它是默林蛋白特异性结合伴侣，我们将其命名为魔奇蛋白（默林蛋白和Grb2相互作用细胞骨架蛋白），并证明这两种蛋白在体外和体内均能相互作用，且在质膜下共定位。魔奇蛋白是一种24 kDa的蛋白，在许多细胞系和组织中均有表达。通过共分级分离、免疫荧光和电子显微镜检测发现，魔奇蛋白与肌动蛋白细胞骨架相关，与默林蛋白相似。对魔奇蛋白序列的分析揭示了其与衔接蛋白Grb2的结合基序。利用亲和结合、印迹覆盖和免疫共沉淀分析，我们证实了Grb2与魔奇蛋白之间存在相互作用。此外，默林蛋白能够与魔奇蛋白和Grb2形成三元复合物。这些结果支持了默林蛋白在细胞表面受体介导的信号传导中的作用，并且可能对细胞骨架重组的调节具有重要意义。
