Merlin/NF2-loss Driven Tumorigenesis Linked to CRL4(DCAF1)-Mediated Inhibition of the Hippo Pathway Components Lats1 and 2

Studies in drosophila have suggested that Merlin/NF2 suppresses tumorigenesis by activating upstream components of the Hippo pathway at or near the plasma membrane. In contrast, studies of Merlin-deficient tumor cells have indicated that Merlin suppresses tumorigenesis by entering into the nucleus where it inhibits the E3 ubiquitin ligase CRL4DCAF1. We found that CRL4DCAF1 promotes YAP and TEAD-dependent transcription by ubiquitylating and thereby inhibiting Lats1 and 2 in the nucleus. Genetic epistasis experiments and analysis of tumor-derived missense mutations indicate that this signaling connection sustains the oncogenicity of Merlin-deficient tumor cells. Analysis of clinical samples confirms that this pathway operates in NF2 mutant mesotheliomas, schwannomas and meningiomas. We conclude that de-repressed CRL4DCAF1 controls the output of the Hippo pathway by inhibiting Lats1 and 2 in the nucleus. To generate a gene expression signature reflective of CRL4(DCAF1)-dependent YAP activity, we used DNA microarray analysis to compare the effect of inactivation of CRL4(DCAF1) and simultaneous inactivation of YAP and TAZ on gene expression in Meso-33 human mesothelioma cells