Mutation of orthologous prickle genes causes a similar epilepsy syndrome in flies and humans

Abstract

ObjectiveGenetically tractable fruit flies have been used for decades to study seizure disorders. However, there is a paucity of data specifically correlating fly and human seizure phenotypes. We have previously shown that mutation of orthologous PRICKLE genes from flies to humans produce seizures. This study aimed to determine whether the prickle‐mediated seizure phenotypes in flies closely parallel the epilepsy syndrome found in PRICKLE patients.MethodsVirtually all fly seizure studies have relied upon characterizing seizures that are evoked. We have developed two novel approaches to more precisely characterize seizure‐related phenotypes in their native state in prickle mutant flies. First, we used high‐resolution videography to document spontaneous, unprovoked seizure events. Second, we developed a locomotion coordination assay to assess whether the prickle mutant flies were ataxic. Third, we treated the mutant flies with levetiracetam to determine whether the behavioral phenotypes could be suppressed by a common antiepileptic drug.ResultsWe find that the prickle mutant flies exhibit myoclonic‐like spontaneous seizure events and are severely ataxic. Both these phenotypes are found in human patients with PRICKLE mutations, and can be suppressed by levetiracetam, providing evidence that the phenotypes are due to neurological dysfunction. These results document for the first time spontaneous, unprovoked seizure events at high resolution in a fly human seizure disorder model, capturing seizures in their native state.InterpretationCollectively, these data underscore the striking similarities between the fly and human PRICKLE‐mediated epilepsy syndromes, and provide a genetically tractable model for dissecting the underlying causes of the human syndromic phenotypes.

Hub connectivity, neuronal diversity, and gene expression in theC. elegansconnectome

“…Genes encoding cell adhesion molecules related to axon outgrowth and guidance, cell migration and locomotion (sax-3, cam-1, unc-6, rig-1, unc-5 ), learning (casy-1 ) [57,96,97,98,99], as well as genes involved in determining cell polarity (vang-1, prkl-1 ) [100,101] were also amongst the top scoring genes for connectivity. These genes have been implicated in neuronal connectivity in both flies and humans [102,103,104], with our results predicting that they may play a similar role in C. elegans. In addition, transcription factors regulating neuronal development, fate specification (lin-11, unc-3, unc-42, ceh-14, ast-1, cfi-1 ) [105,106,107,108,109,110], and locomotion (unc-3 ) [106]) were also implicated in driving increased CGE amongst connected pairs of neurons.…”

Pervasive genetic interactions modulate neurodevelopmental defects of the autism-associated 16p11.2 deletion in Drosophila melanogaster

“…2a ) knockdown flies throughout the testing period. Since about 24% of individuals with 16p11.2 deletion manifest seizures 27 , we next used a recently developed spontaneous seizure assay that assesses unprovoked seizures in their native state, which better recapitulates human seizures in Drosophila 28 . We found that MAPK3 rl , PPP4C pp4-19C , and KCTD13 CG10465 knockdown flies were more likely to show seizure phenotypes compared to controls (Fig.…”

“…Fly behavior was recorded at 30 frames/s for 5 min using a Canon High Definition Vixia HFM31 Camcorder (resolution 1920 × 1080). Each fly’s behavior during the viewing window was then assessed for abrupt, involuntary seizure-associated movements, which manifest as rapid repositioning of the flies within the chamber as previously described 28 . The total number of flies that exhibited spontaneous seizure events and the number of seizing events per seizing fly was initially assessed in 10–20 flies with each knockdown genotype (Supplementary Fig.…”

Pervasive epistasis modulates neurodevelopmental defects of the autism-associated 16p11.2 deletion

“…We performed negative geotaxis experiments to measure locomotor function and identified dramatic reductions in the climbing ability of ALDOA ald and MAPK3 rl knockdown flies throughout the testing period ( Figure 2B, Figure S2A). Since about 20% of individuals with 16p11.2 deletion manifest seizures 35 , we next used a recently developed spontaneous seizure assay that assesses unprovoked seizures in their native state, which better recapitulates human seizures in Drosophila 36 . We found that MAPK3 rl , PPP4C pp4-19C , and KCTD13 CG10465 knockdown flies were more likely to show seizure phenotypes compared to controls ( Figure 2C, Figure S2B).…”

“…Fly behavior was recorded at 30 frames/sec for 5 min using a Canon High Definition Vixia HFM31 Camcorder (resolution 1920 x 1080). Each fly's behavior during the viewing window was then assessed for abrupt, involuntary seizure-associated movements, which manifest as rapid repositioning of the flies within the chamber as previously described 36 . The total number of flies that exhibited spontaneous seizure events and the number of seizing events per seizing fly was initially assessed in 10-20 flies with each knockdown genotype ( Figure S2B (Table S11).…”