State of the art: The Fragile X Syndrome (FXS) is the most frequent form of inherited intellectual disability and genetic form of Autism Spectrum Disorder (ASD). FXS, is caused by the absence or mutation of a single gene, FMR1, encoding for the RNA binding protein FMRP. FMRP, together with its cytoplasmic interactor CYFIP1, regulates, in an activity-dependent manner, the synthesis of key synaptic proteins. In the brain, CYFIP1 has a dual function: it is able to repress translation of FMRP-targeted mRNAs and regulate the actin cytoskeleton. CYFIP1 gene maps on 15q11.2, a highly unstable chromosomal region (BP1-BP2), close to a region, critical for two ASD syndromes (Angelman and Prader-Willi). Microdeletions or microduplications encompassing the CYFIP1 gene predispose to intellectulal dissabilities, autism spectrum disorder, idiopathic generalized epilepsies, schizophrenia and Alzheimer’s disease, making the study of this molecule extremely challenging and relevant for several human brain pathologies. Goals of the proposed project:1)To investigate the role of CYFIP in aging using the fly model and examine the lifespan of a CYFIP Drosophila mutant.2)To determine the role of CYFIP in different types of behavior such as negative geotaxis, locomotor activity and social

interaction (aggression).3)To study the effect of CYFIP deficiency on the Amyloid Precursor Protein (APP) production.Results: In this study, we investigated how loss of CYFIP (the homolog of CYFIP1 in flies) affects lifespan, social interaction and motor defects in Drosophila. Climbing assay analysis revealed that CYFIP heterozygous flies bearing a complete loss of CYFIP in specific brain regions, show late onset motor reflex defects throughout adulthood. Furthermore, aggression assays in flies used as measurement of social interaction, reveal that Cyfip85.1/+ flies present an early-onset deficit. Finally, we provide evidence that Cyfip85.1/+ flies have an increased level of Amyloid Precursor Protein (APP), a protein associated with neurodegenerative diseases, such as Alzheimer’s disease.These findings highlight the basis of the neurodevelopmental disorders raised by the absence of CYFIP1 and lay the ground for further research on the amelioration of these phenotypes observed in patients.

Dimitrios Gerasoudis1, Alexandros K. Kanellopoulos2 and Claudia Bagni2

 1. University of Glasgow, MSc Medical Genetics 2013-2014, UK2. Center for the Biology of Disease, Vlaams Institut voor Biotechnologie Leuven, Belgium; Center for Human Genetics, Leuven Institute for Neuroscience and Disease, KU Leuven Leuven, Belgium.

Characterization of CYFIP heterozygous mutant flies

A. Life Span

B. Real Time (quantitative) PCR

Negative Geotaxis

Motor reflex in CYFIP mutant flies

CONCLUSIONS: FUTURE PLANS:• Determine the neuronal population where CYFIP is required for these behavioral

processes• Monitor possible cell death (i.e.immunohistochemistry) in brain different areas and

investigate possible neurodegeneration or neuronal loss• Investigate the role of CYFIP1 in cognitive processes during aging, such as associative

learning and memory • Identification of compounds able to ameliorate the CYFIP deficits

The role of CYFIP1/Sra-1 in aging using the Drosophila melanogaster as a model

The model of the two CYFIP1 complexes in neurons. The brain-derived neurotrophic factor (BDNF) activates Rac1 and the GTP-Rac1 releases the CYFIP1 from the complex of translation and is moved to WAVE regulatory complex. GTP-Rac1 changes the conformation of CYFIP1 resulting in alteration of the equilibrium between the two complexes. CYFIP1 coordinates two molecular processes, actin remodeling and translation, both of which are necessary for the proper and correct spine morphology. Reproduced from De Rubeis et al, 2013.

Locomotor activity of CYFIP mutant flies

Social Interactions in CYFIP mutant flies

APP levels in CYFIP mutant fly brains

• Cyfip85.1/+ flies have reduced dCyfip mRNA levels• CYFIP deficiency increases the mortality rate in Drosophila• Negative geotaxis assay reveals that CYFIP mutant flies have age-dependent behavioural

deficits • Loss of CYFIP in dopaminergic neurons reveals an age-dependent phenotype in

locomotion• Aging does not worsen the social interaction deficit observed in young CYFIP mutant flies• Young CYFIP mutant flies exhibit elevated APP levels