Advance Development of a Cell-Based Test for Screening of Drugs to Correct Circadian Rhythm Defects in PWS

Funding Summary

The purpose of this project is to develop a cellular assay specific to circadian rhythm defects identified by the Reiter laboratory. The eventual goal is to use this assay to screen for compounds that can normalize these circadian defects, potentially identifying drugs that would address developmental and metabolic changes that accompany circadian rhythm defects in Prader-Willi (PWS) and Schaaf-Yang (SYS) syndromes.

Research Outcomes: Public Summary

Our laboratory has been constructing a repository of PWS dental pulp stem cells (DPSC) to better understand the cellular and molecular changes occurring in neurons from individuals with PWS deletion as well as PWS UPD and Schaaf-Yang syndromes. We can do this by stimulating the DPSC to develop into neurons in culture dishes. Here we used a viral construct that expresses luciferase under the control of the circadian gene promoter for Per2. This construct emits light when Per2 is normally expressed during the 24-hour circadian cycle. We hope that by rescuing the mitochondrial defects we can also rescue the autism phenotype in PWS-UPD individuals. Using control dental pulp derived stem cells and stem cells from PWS subjects, we were able to design and implement an assay that allowed us to measure the normal circadian rhythm in differentiated neurons from multiple individuals. We found that PWS Deletion neuronal cultures showed either a shorter than control or longer than control period length – indicative of a defect in circadian rhythm. We also tested some Schaaf-Yang lines and found the rhythm to be completely disrupted. Finally, we were able to partially rescue these defective short period rhythms in the PWS Deletion neurons by treating the cells with a drug called Longdaysin. Many children with PWS suffer from so called “daytime sleepiness” which could be the result of these defects in normal circadian rhythm – i.e. the cells and the brain are signaling sleep cycles at the wrong time. Identifying this phenotype and the drugs that are effective at rescuing the circadian defect will benefit individuals with both PWS and SYS who suffer from sleep issues.