Andrea Cerase, PhD
University of London,
Department of Biology,
Università di Pisa, Pisa, Italy
Rett syndrome (RTT) and CDKL5 deficiency (CDD) syndromes are two severe neurodevelopmental disorders caused by mutations in the X-linked genes MeCP2 and Cdkl5, respectively. While MeCP2 mutations are lethal in most males, females survive birth but show severe neurological defects. Similarly, CDD shows a highly skewed 12:1 female-to-male ratio.
Females silence one of the two X chromosomes at random in a process called X-chromosome inactivation (XCI). Approximately 50% of the cells silence the wild-type (WT) copy of the MeCP2/Cdkl5 genes. Thus, reactivating the silent WT copy of MeCP2/Cdkl5 could provide therapeutic intervention for RTT and CDD. Toward this goal, we screened ~ 28,000 small-molecule compounds from several libraries using a MeCP2-luciferase reporter cell line and cortical neurons from a MeCP2-EGFP mouse model. We used the gain/increase of luminescence or fluorescence as a readout of MeCP2 reactivation and tested the efficacy of these drugs under different drug regimens, conditions, and cellular contexts. We identified the JAK/STAT pathway inhibitors as XCI-reactivating agents, both by in vitro and ex vivo assays. In particular, we showed that AG-490, a Janus Kinase 2 (JAK2) kinase inhibitor, and Jaki, a pan JAK/STAT inhibitor, can reactivate MeCP2 from the inactive X chromosome in different cellular contexts. Recently we set up a second-generation double-reporter screening system to screen for the reactivation of MeCP2 and Cdkl5 genes, using dedicated peptidomimetic libraries. We will present preliminary results from this screen.