Molecular Changes in Prader-Willi Syndrome Neurons Reveals Clues About Increased Autism Susceptibility

Abstract

Background: Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by hormonal dysregulation, obesity, intellectual disability, and behavioral problems. Most PWS cases are caused by paternal interstitial deletions of 15q11.2-q13.1, while a smaller number of cases are caused by chromosome 15 maternal uniparental disomy (PW-UPD). Children with PW-UPD are at higher risk for developing autism spectrum disorder (ASD) than the neurotypical population. In this study, we used expression analysis of PW-UPD neurons to try to identify the molecular cause for increased autism risk.Methods: Dental pulp stem cells (DPSC) from neurotypical control and PWS subjects were differentiated to neurons for mRNA sequencing. Significantly differentially expressed transcripts among all groups were identified. Downstream protein analysis including immunocytochemistry and immunoblots were performed to confirm the transcript level data and pathway enrichment findings.Results: We identified 9 transcripts outside of the PWS critical region (15q11.2-q13.1) that may contribute to core PWS phenotypes. Moreover, we discovered a global reduction in mitochondrial transcripts in the PW-UPD + ASD group. We also found decreased mitochondrial abundance along with mitochondrial aggregates in the cell body and neural projections of +ASD neurons.Conclusion: The 9 transcripts we identified common to all PWS subtypes may reveal PWS specific defects during neurodevelopment. Importantly, we found a global reduction in mitochondrial transcripts in PW-UPD + ASD neurons versus control and other PWS subtypes. We then confirmed mitochondrial defects in neurons from individuals with PWS at the cellular level. Quantification of this phenotype supports our hypothesis that the increased incidence of ASD in PW-UPD subjects may arise from mitochondrial defects in developing neurons.

Identifying key underlying regulatory networks and predicting targets of orphan C/D boxSNORD116snoRNAs in Prader-Willi syndrome

“…While it has long been understood that perturbations of the chr15q11-13 region cause PWS, it is unclear if the genes included in the deletions are directly related to PWS phenotypes, if genes regulated by them are to blame, or if it is some combination of these effects. Multiple studies have atempted to address this issue by characterizing gene expression in postmortem PWS brain tissues and neurons differentiated from PWS patient-derived pluripotent stem cell lines to identify genes dysregulated in this disorder (Bochukova et al, 2018; Falaleeva et al, 2015; Huang et al, 2021; Sledziowska et al, 2023; Victor et al, 2021). While these studies indicate gene expression is indeed dysregulated in PWS patient samples, our analysis here showed few genes had consistent dysregulation across a subset of these studies (Supplemental Figure 1A).…”

“…Since the function of SNORD116 thus far has remained elusive, much effort has recently been expended to identify gene expression paterns that are dysregulated in PWS. Several studies have compared gene expression between tissue or cell lines derived from PWS patients and those from unrelated controls (Bochukova et al, 2018; Falaleeva et al, 2015; Huang et al, 2021; Sledziowska et al, 2023; Victor et al, 2021). While each of these studies identified numerous genes with distinct expression paterns in the PWS context, a coherent set of consistently dysregulated disease relevant genes has not been identified.…”

Evidence for parent-of-origin effects in autism spectrum disorder: a narrative review

“…Together, these findings suggest a real relationship between ASD and mitochondrial diseases. Interestingly, some imprinted genes also appear to affect mitochondrial function (Bressan and Kramer 2021 ; Panov et al 2020 ; Urraca et al 2013 ; Victor et al 2021 ; Yazdi et al 2013 ).…”

Analysis and comparisons of gene expression changes in patient- derived neurons from ROHHAD, CCHS, and PWS

“…Our group and others have had success modeling neurogenetic syndromes using these stem cells differentiated to neuronal cultures ( 37 – 41 ). Using this unique patient-derived stem cell model, we have observed molecular signatures and cellular phenotypes of various syndromes in primary neurons including Prader-Willi, Angelman, and Duplication 15q syndromes ( 42 – 44 ). Here we utilize this system to differentiate patient-derived DPSC lines to neuronal cultures for RNAseq in order to identify the molecular similarities and find genotype/phenotype correlations among ROHHAD, CCHS and PWS.…”