The Novel Large Deletion Mouse Model of AS: How Can it Help us in Drug Development for Angelman Syndrome?

Quick Overview

Dr. Xiaona Lu from Yale University presented a talk on the novel large deletion mouse model of Angelman Syndrome and its potential in drug development. The model was generated using CRISPR genome editing to insert two FRT sites, resulting in a clean large deletion mice. The expression of UBE3A, a gene associated with Angelman Syndrome, was significantly reduced in the neurons of the large deletion mice. The mice were subjected to various behavior tests, which revealed similarities in cognitive and motor deficiencies between the large deletion mice and UBE3A mutant mice. However, the large deletion mice showed unique behaviors and increased seizure sensitivity compared to the mutant mice. The study also generated five companion lines for further research.

Introduction

Dr. Xiaona Lu from Yale University presented her research on the novel large deletion mouse model of Angelman Syndrome (AS) and its potential in drug development. This mouse model aims to better represent the majority of AS patients who lack the maternal contribution from chromosome 15q11-q13, about 6 megabase. Dr. Lu discussed the process of generating this mouse model using CRISPR genome editing and highlighted the importance of studying the large deletion mice in comparison to the classic UBE3A exon 2 deletion mouse model.

Generating the Large Deletion Mouse Model

Dr. Lu explained the process of generating the large deletion mouse model. The first step involved inserting the first FRT on the upstream of the large deletion region using CRISPR genome editing. Then, a second FRT was inserted using the same strategy. By crossing the founder mice carrying both FRTs with an active flat male, the genes between the two FRTs were removed, resulting in a large deletion mice in the next generation.

Challenges and Successes

Dr. Lu shared the challenges she faced during the generation of the large deletion mouse model. The procedure required a significant number of mice, with approximately 450 mice needed to obtain just one large deletion founder. However, through careful planning and optimization, Dr. Lu was able to achieve success and obtain a clean large deletion mice after four generations.

Confirmation of the Large Deletion Mouse Model

To confirm the successful generation of the large deletion mouse model, Dr. Lu performed RT-qPCR using mouse brain tissue. The results showed a remarkable reduction in the expression level of UBE3A, which is only maternally expressed in neurons. The non-neuronal cells still had a small amount of UBE3A expression. Additionally, the expression level of paternal expressed genes was not impacted by the large deletion. These findings confirmed the successful generation of the large deletion mouse model.

Companion Lines and Further Studies

In addition to the large deletion mouse model, Dr. Lu and her team generated five companion lines using the CRISPR genome editing strategy. These lines had intact imprinting centers and UBE3A, making them valuable for further study. Dr. Lu emphasized the importance of these lines, especially the E line, for future gene therapy studies. They will serve as positive controls for comparison with the large deletion mice without gene therapy.

Behavioural and Molecular Studies

Dr. Lu discussed the ongoing behavioural and molecular studies being conducted on the large deletion mouse model and other companion lines. These studies include cognitive function tests, motor function tests, natural behaviour assessments, fluoride-induced seizure tests, LTP (long-term potentiation) analysis, and EEG (electroencephalogram) recordings. The large deletion mice showed similar deficiencies to the UBE3A mutant mice in various tests, indicating hyperactivity, hypersensitivity, and increased seizure susceptibility in Angelman Syndrome.

Conclusion

In conclusion, Dr. Lu’s research successfully generated a novel large deletion mouse model of Angelman Syndrome. The comparison between the large deletion mice and the UBE3A protein mutation mice provided valuable insights into the hyperactivity, hypersensitivity, and increased seizure susceptibility observed in Angelman Syndrome. The large deletion mouse model, along with the companion lines, will contribute to further studies and drug development for Angelman Syndrome. Dr. Lu expressed her gratitude to her mentor, Dr. Yong-Hui Jiang, and the FAST Foundation for providing her with the fellowship to conduct this research.