Heterochromatin and piRNAs in Fragile X mental retardation: insights from Drosophila

Fragile X syndrome is a common form of inherited intellectual disability. The mutation responsible for the disease causes the transcriptional silencing of the FMRl gene. It codes for FMRP, an RNA binding protein that is critical for the synaptic plasticity. Studies continue to shed light on the role of FMRP in the neuronal development and to uncover new functions of this protein (Santoro et al., 2012). In this context, Drosophila melanogaster plays an important role as a model for studying the Fragile-X disease and for clarifying all the molecular conserved functions of FMRP. Several studies conducted in Drosophila unveiled the role of FMRP in different small RNA pathways including miRNA and piRNA pathway (Yang et al., 2009; Bozzetti et al., 2015; Specchia et al, 2017). We will report data showing the role of FMRP in the piRNA pathway in the gonads ensuring the genome stability with a special look at an emerging link between FMRP and HP1. We also present preliminary data showing the presence of the piRNA pathway even in the nervous system suggesting a role of this pathway in the onset of the Fragile-X syndrome.