Disease relevance of NF2

• We have identified a candidate gene for the NF2 tumor suppressor that has suffered nonoverlapping deletions in DNA from two independent NF2 families and alterations in meningiomas from two unrelated NF2 patients [1].
• Neurofibromatosis 2 (NF2) is a dominantly inherited disorder characterized by the occurrence of bilateral vestibular schwannomas and other central nervous system tumors including multiple meningiomas [1].
• The NF2 protein, called schwannomin or merlin, is absent in virtually all schwannomas, and many meningiomas and ependymomas [2].
• We show that the activation of ERK and the proliferation of human schwannoma cells bearing a loss-of-function mutation in the neurofibromatosis 2 (NF2) gene require MLK3 [3].
• Mutations in the NF2 tumor suppressor gene encoding merlin induce the development of tumors of the nervous system [4].
• The results show that merlin plays a key role in the regulation of the Schwann cell microtubule cytoskeleton and suggest a mechanism by which loss of merlin leads to cytoskeletal defects observed in human schwannomas [5].

Psychiatry related information on NF2

• A single high i.v. dose of SCH 58500 (1.1 x 10(12) pfu/kg) was associated with lethargy, soft feces, a ruffled-hair coat, and death within 1 h postdose [6].
• These findings extend to the behavioural parameters the protective effects of SCH 58261 in the QA model of Huntington's disease [7].
• The effects of SCH 72788 suggest that M2 receptor antagonists may be useful for treating the cognitive decline observed in AD and other dementias [8].

High impact information on NF2

• The tumor suppressors Merlin, expanded, hippo, salvador and mob as tumor suppressor also share multiple Fat pathway phenotypes but regulate Warts activity independently [9].
• This interaction mediates the membrane localization of schwannomin to the plasma membrane, where it associates with beta 1 integrin and erbB2 [10].
• Pathogenic mutations that result in production of defective schwannomin include in-frame deletions of exon 2 and three independent missense mutations within this same exon [10].
• Thus, alternative splicing of NF2 may regulate betaII-spectrin binding [2].
• Neurofibromatosis 2 tumour suppressor schwannomin interacts with betaII-spectrin [2].

Chemical compound and disease context of NF2

• NHE-RF, a merlin-interacting protein, is primarily expressed in luminal epithelia, proliferative endometrium, and estrogen receptor-positive breast carcinomas [11].
• The enhanced proliferation of merlin-deficient NF2 schwannoma cells could be reduced in the presence of quinidine, a K(+) channel blocker, whereas the proliferation of normal Schwann cells is not affected [12].
• Effects of the antiestrogen EM-800 (SCH 57050) and cyclophosphamide alone and in combination on growth of human ZR-75-1 breast cancer xenografts in nude mice [13].
• Bronchial hyperreactivity to histamine and methacholine in asthmatic children after inhalation of SCH 1000 and chlorpheniramine maleate [14].
• Comparison of aerosolized atropine sulfate and SCH 1000 on exercise-induced bronchospasm in children [15].

Biological context of NF2

• The NF2 gene may therefore constitute a novel class of tumor suppressor gene [1].
• Three naturally occurring NF2 missense mutations showed reduced, but not absent, betaII-spectrin binding, suggesting an explanation for the milder phenotypes seen in patients with missense mutations [2].
• Genetic linkage studies and investigations of both sporadic and familial tumors suggest that NF2 is caused by inactivation of a tumor suppressor gene in chromosome 22q12 [1].
• Nucleocytoplasmic transfer of the NF2 tumor suppressor protein merlin is regulated by exon 2 and a CRM1-dependent nuclear export signal in exon 15 [16].
• Serine 518 phosphorylation modulates merlin intramolecular association and binding to critical effectors important for NF2 growth suppression [17].

Anatomical context of NF2

• Interaction between NF2 protein and the actin-containing cytoskeleton was indicated by partial colocalization, by cytochalasin B-induced coclustering, and by retention of NF2 protein in the detergent-insoluble fraction [18].
• Both transfected and endogenous NF2 protein localized underneath the plasma membrane in a pattern typical of an ERM protein [18].
• The cells contained restructured membrane extensions and blebs, and CHO cells expressing NF2 protein were more elongated than control transfectants [18].
• In COS-1 transfectants, NF2 protein typically codistributed with ezrin but, in cells with poorly developed actin cytoskeleton, it replaced ezrin in filopodia and ruffling edges [18].
• Merlin is also expressed in reactive astrocytes and in the astrocytes of NF2-associated glial hamartomas [19].

Associations of NF2 with chemical compounds

• Deletion of this NES or treatment with the CRM1-specific inhibitor leptomycin B leads to overall nuclear accumulation of merlin isoforms missing exon 2 [16].
• Furthermore, both in vitro and in vivo phosphorylation studies of the wild-type and mutated C termini demonstrated that PKA can phosphorylate merlin at serine 518, a site that is phosphorylated also by p21-activated kinases (PAKs) [4].
• The interaction between TRBP and merlin was confirmed by glutathione S-transferase pull-down assays, co-immunoprecipitation, and co-localization experiments [20].
• Schwannomin and Pak phosphorylation levels are not reduced in response to lowering Rac-GTP levels with NSC23766 [21].
• The three major proteins of mammalian neurofilaments of molecular weights 179,000 (NF1), 129,000 (NF2), and 66,500 (NF3) have been purified to homogeneity by multiple anion-exchange and hydroxylapatite absorption chromatography in 8 M urea [22].

Physical interactions of NF2

• Mixed-lineage kinase 3 regulates B-Raf through maintenance of the B-Raf/Raf-1 complex and inhibition by the NF2 tumor suppressor protein [3].
• Previously we demonstrated that the hepatocyte growth factor-regulated tyrosine kinase substrate (HRS) strongly interacts with schwannomin [23].
• Ezrin was coimmunoprecipitated with merlin from lysates of human U251 glioma cells and from COS-1 cells transfected with cDNA encoding for merlin isoform I. The interaction was further studied and the association domains were mapped with the yeast two-hybrid system and with blot overlay and affinity precipitation experiments [24].
• Here, we report in SCs that schwannomin S518 phosphorylation requires binding to paxillin and targeting to the plasma membrane [21].
• Both the ezrin and merlin N-ERMAD bind EBP50 [25].

Co-localisations of NF2

• NF2 protein colocalized with CD44, which in transfected cells accumulated into restructured cell membrane protrusions [18].

Regulatory relationships of NF2

• Overexpression of the NF2 gene inhibits schwannoma cell proliferation through promoting PDGFR degradation [26].
• Therefore, we hypothesized that schwannomin inhibits STAT activation through interaction with HRS [23].
• Merlin regulates the activity of extracellular signal-regulated kinase 2 (ERK2) and nuclear localization of both proteins was induced by cell adhesion [27].
• Furthermore, PAK1-specific inhibitors CEP-1347 and WR-PAK18 selectively inhibit the growth of NF2-deficient cancer cells, but not NF2-positive cells [28].
• In this report, we investigated how merlin inhibits the oncogenic activity of TRBP in association with cell growth conditions [29].

Other interactions of NF2

• Analogous to merlin, we show that DAL-1 loss is an early event in meningioma tumorigenesis, suggesting that these two protein 4.1 family members are critical growth regulators in the pathogenesis of meningiomas [30].
• These results point to kinesin-1 as a common denominator between NF1 and NF2 [31].
• Both in vitro and in vivo interaction studies indicated that phosphorylation of serine 518 promotes heterodimerization between merlin and ezrin, an event suggested to convert merlin from a growth-suppressive to a growth-permissive state [4].
• We directly demonstrate that PAK2 phosphorylation impairs merlin N-term/C-term binding in vitro and in vivo [17].
• In addition, merlin is capable of forming a ternary complex with magicin and Grb2 [32].

Analytical, diagnostic and therapeutic context of NF2

• Using monoclonal and polyclonal anti-merlin antibodies for Western blotting and immunohistochemistry, we evaluated the cellular pattern of merlin expression in the normal human central nervous system (CNS), reactive gliosis; and NF2-associated glial hamartomas [19].
• To determine the pattern of NF2 gene expression in mouse embryos, we sequenced the mouse NF2 gene and used in situ hybridization and antischwannomin antibodies to determine the developmental expression of the NF2 gene [33].
• Furthermore, using an adenoviral vector mediated gene transfer technique, changes in the phenotypic characteristics after NF2 gene restoration in a newly established NF2 gene-mutated human schwannoma cell line (HEI 193) were investigated [26].
• Magicin, similar to merlin, associates with the actin cytoskeleton as determined by cofractionation, immunofluorescence and electron microscopy [32].
• Using indirect immunofluorescence we have for the first time visualized endogenous merlin and localized it to the motile regions, such as leading or ruffling edges, in human fibroblast and meningioma cells [34].

References