Cyclic Adenosine Monophosphate (cAMP) and Fragile X Mental Retardation Protein (FMRP) Mediate Avoidance Behaviour in Drosophila

• Author / Creator

  Androschuk, Alaura MA

• Fragile X Syndrome (FXS) is neurodevelopmental disorder caused by a trinucleotide CGG repeat expansion that leads to the methylation and transcriptional silencing of the Fragile X mental retardation 1 (fmr1) gene. This results in the loss of Fragile X mental retardation protein (FMRP), an mRNA-binding protein that functions in neuronal mRNA metabolism, namely in the translation of neuronal mRNAs involved in synaptic structure and function. FXS is the most common form of inherited intellectual disability and the largest single genetic cause of autism, affecting 1 in 4000 males and 1 in 8000 females. FMRP plays a crucial role in neural circuit patterning/formation and the regulation of key signalling pathways. FXS is a syndrome is characterized by misregulation of protein synthesis and dysfunction within multiple signalling pathways. Here we implicate two signalling pathways underlying Fragile X Syndrome neuropathology, the cAMP signalling pathway and the Wnt signalling pathway, in cognitive defects. In chapter 2 and 3, we show that FMRP is required for Drosophila stress odour (dSO) avoidance behaviour; dSO is an odour emitted when flies are subjected to electrical or mechanical stress, elicits an innate avoidance behavioural response by Drosophila. Our results suggest that FMRP is required developmentally, specifically in the mushroom body for higher-order processing, in the establishment of neuronal networks and in the regulation of the cAMP signalling cascade that mediates Drosophila stress odour (dSO) sensory processing and avoidance behaviour in Drosophila. Furthermore we show that cyclic adenosine monophosphate (cAMP) is required for avoidance and identify the cAMP cascade as a key signalling pathway underlying avoidance behaviour dysfunction in FXS. Through pharmacological intervention targeting the misregulated cAMP pathway we show that avoidance behaviour can be rescued in FXS flies, demonstrating the ability to ameliorate a developmental abnormality. In chapter 4 we show that over-expression of armadillo/β-catenin results in learning and long-term memory defects and likely contributes to FXS pathology. Furthermore we demonstrate that FXS flies exhibit a learning reversal and long-term memory reversal defect, which may be a result of abnormal armadillo/β-catenin expression resulting in synaptic function and remodeling defects.

• Subjects / Keywords

  • Long-term memory reversal
  • Drosophila
  • Fragile X Syndrome
  • Learning reversal
  • Sensory processing
  • Armadillo
  • Cyclic adenosine monophosphate
  • Avoidance
  • Fragile X mental retardation protein
  • Beta-catenin

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R35718339

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.