Cloning and characterization of SCHIP-1, a novel protein interacting specifically with spliced isoforms and naturally occurring mutant NF2 proteins.
The neurofibromatosis type 2 (NF2) protein, known as schwannomin or merlin, is a tumor suppressor involved in NF2-associated and sporadic schwannomas and meningiomas. It is closely related to the ezrin-radixin-moesin family members, implicated in linking membrane proteins to the cytoskeleton. The molecular mechanism allowing schwannomin to function as a tumor suppressor is unknown. In attempt to shed light on schwannomin function, we have identified a novel coiled-coil protein, SCHIP-1, that specifically associates with schwannomin in vitro and in vivo. Within its coiled-coil region, this protein is homologous to human FEZ proteins and the related Caenorhabditis elegans gene product UNC-76. Immunofluorescent staining of transiently transfected cells shows a partial colocalization of SCHIP-1 and schwannomin, beneath the cytoplasmic membrane. Surprisingly, immunoprecipitation assays reveal that in a cellular context, association with SCHIP-1 can be observed only with some naturally occurring mutants of schwannomin, or a schwannomin spliced isoform lacking exons 2 and 3, but not with the schwannomin isoform exhibiting growth-suppressive activity. Our observations suggest that SCHIP-1 interaction with schwannomin is regulated by conformational changes in schwannomin, possibly induced by posttranslational modifications, alternative splicing, or mutations.
Goutebroze
L
L
U434, INSERM-Institut Curie, 75005 Paris, France. goutebroze@cephb.fr
Brault
E
E
Muchardt
C
C
Camonis
J
J
Thomas
G
G
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D025581:Neurofibromin 2; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D012326:RNA Splicing; D016415:Sequence Alignment
D002352:Carrier Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D025581:Neurofibromin 2; D020033:Protein Isoforms; D011506:Proteins; C405019:SCHIP1 protein, human