Mariam Gachechiladze
Program: Neurosciences
Current advisor: Joseph D. Dougherty, PhD
Undergraduate university: Georgetown University
Research summary
Normal brain development requires tight control of gene expression in space and time. Mutations that lead to dysregulation in the amount, localization, or timing of gene expression can cause neurodevelopmental disorders (NDDs). NDDs often affect multiple brain circuits, each of which has distinct critical periods for gene expression. These circuit-specific critical periods shape both the emergence and reversibility of NDD phenotypes. Investigation of therapeutics for individuals with NDDs necessitates determining the developmental windows at which interventions are likely to be effective. My work addresses approaches to genetic rescue for NDDs, centered on MYT1L syndrome, an NDD caused by loss-of-function mutations in the MYT1L gene. Through four interconnected studies, I explore genetic rescue, both as a proof-of-principle and via translational approaches, and investigate novel methodology for identifying therapeutic targets through profiling of noncoding elements.
First, I helped develop a MYT1L conditional knock-in mouse model to investigate the consequences of rescuing MYT1L expression in different spatiotemporal contexts. We demonstrate the ability of this tool to successfully restore MYT1L levels in the brain and set up experimental paradigms for testing the effectiveness of MYT1L rescue at different postnatal timepoints in both brain-wide and specific cellular contexts. Next, I worked on development of an antisense oligonucleotide (ASO) to upregulate MYT1L levels as a more translational approach for investigating therapeutics for MYT1L syndrome. Next, I build on the Inferred Stability Optimized Massively Parallel Reporter Assay (ISOMPRA) method by using a tiling design to systematically study 3’ untranslated region (UTR) sequence effects on RNA stability in a high-throughput, unbiased manner for a set of neuropsychiatric disease genes. We demonstrate the ability of the tiled ISOMPRA approach to rediscover previously known 3’UTR regulatory regions and respond to external manipulations of RNA stability. We also demonstrate that we can uncover cell-type-specific differences in regulation of RNA stability. Finally, we test the effectiveness of this approach to identify novel ASO targets for neuropsychiatric haploinsufficiency genes. Finally, I apply Calling Cards, a genomic recording technology, to identify novel enhancer loci that predict severity of seizures in an acute induced seizure mouse model. We identify over 200 enhancers whose activity predicted seizure severity and show that we could pharmacologically manipulate two genes associated with these enhancers to modify seizure severity.
Together, this body of work advances our understanding of gene regulation in the brain and how to leverage it for therapeutic applications for various neuropsychiatric disease genes. This work also presents and validates valuable tools for future studies, including genetic rescue studies of MYT1L syndrome, identification of therapeutic targets for genetic rescue of any genes of interest, and linking enhancer usage to future neurobehavioral phenotypes.
Graduate publications
Gachechiladze MA, Dougherty JD. 2024 Neurodevelopmental Genetic Associations Across the Translational Space-Time Continuum. Biol Psychiatry, 95(9):825-27.
Yen A, Mateusiak C, Sarafinovska S, Gachechiladze MA, Guo J, Chen X, Moudgil A, Cammack AJ, Hoisington-Lopez J, Crosby M, Brent MR, Mitra RD, Dougherty JD. 2023 Calling Cards: A Customizable Platform to Longitudinally Record Protein-DNA Interactions Over Time in Cells and Tissues. Curr Protoc, 3(9)::e883.