Hyperactive locomotion in a Drosophila model is a functional readout for the synaptic abnormalities underlying fragile X syndrome

Sci Signal. 2017 May 2;10(477):eaai8133. doi: 10.1126/scisignal.aai8133.

Abstract

Fragile X syndrome (FXS) is the most common cause of heritable intellectual disability and autism and affects ~1 in 4000 males and 1 in 8000 females. The discovery of effective treatments for FXS has been hampered by the lack of effective animal models and phenotypic readouts for drug screening. FXS ensues from the epigenetic silencing or loss-of-function mutation of the fragile X mental retardation 1 (FMR1) gene, which encodes an RNA binding protein that associates with and represses the translation of target mRNAs. We previously found that the activation of LIM kinase 1 (LIMK1) downstream of augmented synthesis of bone morphogenetic protein (BMP) type 2 receptor (BMPR2) promotes aberrant synaptic development in mouse and Drosophila models of FXS and that these molecular and cellular markers were correlated in patients with FXS. We report that larval locomotion is augmented in a Drosophila FXS model. Genetic or pharmacological intervention on the BMPR2-LIMK pathway ameliorated the synaptic abnormality and locomotion phenotypes of FXS larvae, as well as hyperactivity in an FXS mouse model. Our study demonstrates that (i) the BMPR2-LIMK pathway is a promising therapeutic target for FXS and (ii) the locomotion phenotype of FXS larvae is a quantitative functional readout for the neuromorphological phenotype associated with FXS and is amenable to the screening novel FXS therapeutics.

MeSH terms

  • Algorithms
  • Animals
  • Animals, Genetically Modified / genetics
  • Animals, Genetically Modified / physiology
  • Behavior, Animal / drug effects
  • Bone Morphogenetic Protein Receptors, Type II / genetics
  • Bone Morphogenetic Protein Receptors, Type II / metabolism
  • Disease Models, Animal*
  • Drosophila / drug effects
  • Drosophila / genetics
  • Drosophila / growth & development
  • Drosophila / physiology*
  • Drosophila Proteins / antagonists & inhibitors
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Female
  • Fragile X Mental Retardation Protein / genetics
  • Fragile X Mental Retardation Protein / metabolism*
  • Fragile X Syndrome / physiopathology*
  • High-Throughput Screening Assays
  • Larva / drug effects
  • Larva / physiology
  • Lim Kinases / antagonists & inhibitors
  • Lim Kinases / genetics
  • Lim Kinases / metabolism
  • Locomotion / physiology*
  • Male
  • Mice
  • Mice, Knockout
  • Small Molecule Libraries / pharmacology
  • Synapses / drug effects
  • Synapses / metabolism
  • Synapses / pathology*

Substances

  • Drosophila Proteins
  • FMR1 protein, Drosophila
  • Small Molecule Libraries
  • Fragile X Mental Retardation Protein
  • Lim Kinases
  • limk1 protein, Drosophila
  • Bone Morphogenetic Protein Receptors, Type II