1. 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, UK
2. 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