Like most genetic disorders, no specific therapeutic intervention targets the specific molecular defect of Prader- Willi syndrome (PWS), a genomic imprinting and neurobehavioral disorder. PWS is caused by paternal deficiency of genes in the chromosome 15q11-q13 region. The corresponding genes in the maternal chromosome are structurally intact, but their transcription is repressed epigenetically. The involvement of epigenetic repression renders PWS as one of the best opportunities to explore molecular therapy. Recent reports indicate SnoRNA, clusters including HBII-85 (SNORD116) between the SNRPN and UBE3A genes, is responsible for key features of PWS including childhood obesity, hypogonadism, hyperphagia, and developmental delay. Epigenetic mechanisms, including DNA methylation and chromatin modifications at the PWS imprinting center region (PWS-ICR), are involved in regulating the paternal-specific expression of genes including SNRPN and SnoRNAs in the 15q11-q13 region. The imprinting domain in the 15q11-q13 region is highly conserved in mice. The expression of SnoRNA clusters is processed from continuous transcripts initiated from the PWS-ICR/promoter bound CpG island of SNRPN. DNA methylation can activate the expression of the SNRPN gene from the silent maternal chromosome in cultured cells of PWS patients and mouse models, but its clinical utility is limited by the concern of the genome wide effect of these drugs. These observations, however, strongly support a approach to unsilence/activate the expression of SnoRNAs from maternal chromosome through an epigenetic mechanism. Because the SnoRNAs are non-coding, we propose to use embryonic fibroblasts (MEFs) from mice carrying Snrpn-EGFP fusion protein as screening tool. Drugs that activate the Snrpn-EGFP are expected to have the same impact on the SnoRNAs. In collaboration with Dr. Bryan Roth (Director of NIMH Psychoactive Drug Screening Program), we have completed the first phase screen and identified several candidate drugs. We have showed that a histone methyltransferase inhibitor activated the expression of Snrpn and SnoRNAs from the maternal chromosome in cultured PWS cells. Using the same strategy, Dr. Roth's team also identified a FDA approved drug that activates the Angelman syndrome Ube3a gene from paternal chromosome in vivo. The long term goal of our project is to develop a therapeutic intervention targeted to the specific epigenetic defects of PWS. The central hypothesis is that a small molecule can modulate the epigenetic modification in the PWS-ICR and lead to the activation of the silenced PWS candidate genes from the maternal chromosome. The specific objective is to identify and characterize small molecules that activate the expression of Snrpn and SnoRNAs from the maternal chromosome by performing high-content small molecule screening using maternal Snrpn-EGFP as a marker. The proposed study is significant because it will lead to the development of a therapeutic intervention in PWS and provide the novel insight for molecular mechanism underlying the genomic imprinting.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21HD077197-02
Application #
8860216
Study Section
Therapeutic Approaches to Genetic Diseases Study Section (TAG)
Program Officer
King, Tracy
Project Start
2014-06-15
Project End
2017-05-31
Budget Start
2015-06-01
Budget End
2017-05-31
Support Year
2
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Duke University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
Cheng, Ying; Li, Ziyi; Manupipatpong, Sasicha et al. (2018) 5-Hydroxymethylcytosine alterations in the human postmortem brains of autism spectrum disorder. Hum Mol Genet 27:2955-2964
Duffney, Lara J; Valdez, Purnima; Tremblay, Martine W et al. (2018) Epigenetics and autism spectrum disorder: A report of an autism case with mutation in H1 linker histone HIST1H1E and literature review. Am J Med Genet B Neuropsychiatr Genet 177:426-433
Chung, Leeyup; Bey, Alexandra L; Towers, Aaron J et al. (2018) Lovastatin suppresses hyperexcitability and seizure in Angelman syndrome model. Neurobiol Dis 110:12-19
Chung, Changuk; Ha, Seungmin; Kang, Hyojin et al. (2018) Early Correction of N-Methyl-D-Aspartate Receptor Function Improves Autistic-like Social Behaviors in Adult Shank2-/- Mice. Biol Psychiatry :
Hulbert, Samuel W; Jiang, Yong-Hui (2017) Cellular and Circuitry Bases of Autism: Lessons Learned from the Temporospatial Manipulation of Autism Genes in the Brain. Neurosci Bull 33:205-218
Kim, Yuna; Lee, Hyeong-Min; Xiong, Yan et al. (2017) Targeting the histone methyltransferase G9a activates imprinted genes and improves survival of a mouse model of Prader-Willi syndrome. Nat Med 23:213-222
Hulbert, S W; Jiang, Y-H (2016) Monogenic mouse models of autism spectrum disorders: Common mechanisms and missing links. Neuroscience 321:3-23
Wang, Xiaoming; Bey, Alexandra L; Katz, Brittany M et al. (2016) Altered mGluR5-Homer scaffolds and corticostriatal connectivity in a Shank3 complete knockout model of autism. Nat Commun 7:11459
Xu, Qiong; Goldstein, Jennifer; Wang, Ping et al. (2016) Chromosomal microarray analysis in clinical evaluation of neurodevelopmental disorders-reporting a novel deletion of SETDB1 and illustration of counseling challenge. Pediatr Res 80:371-81
Chung, Leeyup; Wang, Xiaoming; Zhu, Li et al. (2015) Parental origin impairment of synaptic functions and behaviors in cytoplasmic FMRP interacting protein 1 (Cyfip1) deficient mice. Brain Res 1629:340-50