Role of Merlin in the Growth and Transformation of Arachnoidal Cells

Abstract

Abstract : This proposal is concerned with the functional role of merlin in arachnoidal and meningioma cells. The focus of year 1 was to characterize and develop meningioma-specific NF2 model systems. We have successfully generated three additional meningioma cell lines. The expression of merlin was quantitated at the transcript and protein level in these and arachnoidal cells. The KT21MG1 cell line is merlin-deficient and contains a novel splice site mutation between exon 14 and 15. This alternative splicing results in a 79 bp insertion that encodes for truncated merlin. We have used a tetracycline inducible system, to express wild type merlin and the L64P, S518A and S518D mutant forms of merlin in KT21MG1. Additionally, we have tested the ability of three NF2-specific short interfering RNA (siRNA) to silence merlin. Two siRNAs significantly reduced transcript and protein levels of merlin in arachnoidal cells and the SF6717 meningioma cell line. Stable suppression of merlin in these cell lines has been achieved using the pSUPER retroviral RNAi system. In summary, we have successfully developed three meningioma-specific NF2 model systems. In the subsequent 2 years, we will use these systems to understand the mechanistic role of merlin and to investigate meningioma cell type specific functions.