[Neurofibromatosis type 2 (NF2)]

Neurofibromatosis type 2 (NF2) is an autosomal dominantly inherited disorder, strongly associated with development of benign intracranial tumors, including bilateral vestibular schwannomas and meningiomas. The NF2 gene located on the human chromosome 22q12 was recently cloned, and the protein it encodes (termed merlin/schwannomin) was found to be strikingly similar to the moesin-ezrin-radixin (MER) family of cytoskeleton-associated proteins. Mutations of NF2 gene have been found not only in the NF2 patient but also in NF2-related sporadic tumors such as acoustic schwannomas and meningiomas, suggesting that the NF2 gene functionally acts as a tumor suppressor gene. To elucidate the biological function of merlin, we have detected five merlin binding cellular proteins. The N-terminal region of merlin, the entire merlin-ezrin-radixin-moesin (MERM) homology domain, was found to be essential for binding to all five proteins. Since most reported NF2 mutations in the region were determined to be necessary for binding, the mutations probably impair binding. The majority of NF2 mutations are nonsense mutations or frameshifts that resulted in premature termination of merlin. The lack of these interactions caused by such mutations of NF2 gene may affect the cellular signals, resulting in benign intracranial tumors in NF2 patients.