title: Universal absence of merlin, but not other ERM family members, in schwannomas.
abstract: NF2 (neurofibromatosis 2, encoding the merlin protein) gene mutations and chromosome 22q loss have been demonstrated in the majority of sporadic and NF2-associated schwannomas, but many schwannomas fail to demonstrate genetic evidence of biallelic NF2 gene inactivation. In addition, the role of the merlin-related ERM family members (ezrin, radixin, and moesin) remains unclear in these tumors. We therefore studied expression of NF2-encoded merlin as well as ezrin, radixin, and moesin in 22 vestibular and peripheral schwannomas that had been evaluated for NF2 mutations and chromosome 22q loss. Western blotting and immunohistochemistry with antibodies directed against the amino and carboxy termini of merlin demonstrated loss of merlin expression in all studied schwannomas, including 12 tumors lacking genetic evidence of biallelic NF2 gene inactivation. Western blotting with antibodies directed against ezrin, radixin, and moesin, however, showed expression of these proteins in all schwannomas. In addition, immunohistochemistry with an antibody to moesin revealed widespread expression in tumor and endothelial cells. These data indicate that the specific loss of merlin is universal to schwannomas and is not linked to loss of ezrin, radixin, or moesin expression.
authors.affiliation: Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, USA.
authors.forename: A O
authors.initials: AO
authors.lastname: Stemmer-Rachamimov
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.forename: C
authors.initials: C
authors.lastname: Gonzalez-Agosti
authors.forename: J A
authors.initials: JA
authors.lastname: Burwick
authors.forename: D
authors.initials: D
authors.lastname: Pinney
authors.forename: R
authors.initials: R
authors.lastname: Beauchamp
authors.forename: L B
authors.initials: LB
authors.lastname: Jacoby
authors.forename: J F
authors.initials: JF
authors.lastname: Gusella
authors.forename: V
authors.initials: V
authors.lastname: Ramesh
authors.forename: D N
authors.initials: DN
authors.lastname: Louis
mesh_terms: D001798:Blood Proteins / Q000378:metabolism; D015153:Blotting, Western; D003390:Cranial Nerve Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003598:Cytoskeletal Proteins; D016515:Genes, Neurofibromatosis 2 / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D008840:Microfilament Proteins; D009363:Neoplasm Proteins / Q000276:immunology / Q000378:metabolism*; D009442:Neurilemmoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D025581:Neurofibromin 2; D010524:Peripheral Nervous System Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010750:Phosphoproteins / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D014725:Vestibular Nerve / Q000378:metabolism* / Q000473:pathology; D000099149:Ezrin
chemical_list: D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D025581:Neurofibromin 2; D010750:Phosphoproteins; D011506:Proteins; D000099149:Ezrin; C071058:moesin; C071776:radixin