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Dissertation Defense: Molecular Mechanisms of Neuronal mRNA Localization in an Animal Model of Fragile X Syndrome

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Renesa Tarannum
Dissertation Defense

Molecular Mechanisms of Neuronal mRNA Localization in an Animal Model of Fragile X Syndrome

Renesa Tarannum

Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Farris Lab, Fralin Biomedical Research Institute at VTC
April 28, 2026, at 12 p.m.
Room 1101, 4 Riverside Circle
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About this Dissertation

Neurons localize thousands of mRNAs to axons and dendrites for fine-tuned gene expression that supports activity-induced synaptic modifications. Synaptic activity induced nascent protein synthesis from the locally available pool of mRNAs is requiredfor synaptic plasticity underlying learning and memory. While the diversity of mRNA species that are localized to the dendrites are known, it remains elusive what post-transcriptional mechanisms are in place to coordinate their targeted delivery at steady-state and after synaptic activity. Using a well-studied RNA-binding protein FMRP and a dozen of its mRNA targets, Tarannum, mentored by Shannon Farris, attempted to systematically map the spatial organization of localized mRNAs in multiple cell types of the hippocampus. Taking advantage of high-resolution microscopy, multiplex smFISH and computational tools, Tarannum discovered that FMRP target mRNAs in the hippocampal neuropil are localized in various copy number states and are co-packaged as mRNPs that is best explained by the stochastic RNA-RNA interaction-driven assembly predicted based on the abundance of the localized mRNAs. This model of mRNA localization is consistent with the principles of energy minimization. Subsequently, Tarannum visualized a subset of these mRNAs in the presence and absence of FMRP using environmental enrichment as a model for synaptic activity to understand if the loss of FMRP impacts its targets similarly or selectively. She found that loss of FMRP does not impact steady state abundance of its targets. Rather, selective targets are downregulated after synaptic activity in the FMRP knock-out mice indicating specific mRNAs, probably due to their functional role in synaptic plasticity, are dysregulated in the absence of FMRP. Taken together, these data suggest a biological model for neuronal mRNA localization that is consistent with global principles of cost-efficiency and energy minimization to achieve spatiotemporally controlled gene expression- an indispensable feature for the neurons.

More About the Candidate and Project

Education

Virginia Tech, Translational Biology, Medicine, and Health, Ph.D. Candidate

Dhaka University, MBBS

Training

Graduate Research Assistant, Farris Lab, Fralin Biomedical Research Institute at VTC

Mentor

Shannon Farris, Ph.D., Assistant Professor, Fralin Biomedical Research Institute at VTC

Committee Members

Publications

Tarannum, R., Sappa, M., Farris S. Evidence for dysregulated localized mRNA abundance & ribosomal protein post-translational modifications after synaptic activity in Fmr1 KO mice. (In preparation)

Alsalman, M., Turner, L., Pannoni, K., Tarannum, R., Desai, R., Swanger, S. A., & Farris, S. (2025). Hippocampal cell- and circuit-specific differences in mitochondrial form and function. bioRxiv : the preprint server for biology, 2025.12.16.694759. https://doi.org/10.64898/2025.12.16.694759. (in review)

Tarannum, R., Mun, G., Quddos, F., Swanger, S.A., Steward, O., & Farris, S. (2024). Multiplexed smFISH reveals the spatial organization of neuropil localized mRNAs is linked to abundance. eNeuro, 12(12), ENEURO.0184-25.2025.

Pannoni, K.E., Fischer, Q.S., Tarannum, R., Cawley, M.L., Alsalman, M.A., Acosta, N., Ezigbo, C., Gil, D.V., Campbell, L.A., & Farris, S. (2025). MCU expression in hippocampal CA2 neurons modulates dendritic mitochondrial morphology and synaptic plasticity.Scientific Reports, 15 (1), 4540.

Oral Presentations

mRNA localization in neurons: is it a numbers game? Research in progress seminar (2025). Fralin Biomedical Research Institute. Roanoke, VA. Apr 2025

Quantitatively mapping the colocalization of dendritic RNAs in mouse hippocampus: insights from highly multiplexed imaging. FASEB Science Research Conference “RNA Localization and Local Translation” (2024). Melbourne, Florida. Jul 2024

Deciphering the molecular logic of dendritic RNA transport in the hippocampus. Research in progress seminar (2024). Fralin Biomedical Research Institute. Roanoke, VA. Apr 2024

Studying mechanisms of dendritic RNA transport in the hippocampus. Center for Neurobiology Research symposium (2023). Fralin Biomedical Research Institute. Roanoke, VA. Aug 2023

Posters

Renesa Tarannum, Maanya Sappa, Shannon Farris. Multiplexed smFISH to study cell-specific RNA dysregulation in a mouse model of Fragile X Syndrome. AMA Research Challenge (2025). (virtual) Oct 2025

Renesa Tarannum, Grace Mun, Sharon A. Swanger, Shannon Farris. Mapping the colocalization of dendritic RNA cargoes in the hippocampus. Society for Neuroscience. (2024) Annual meeting, Chicago, Illinois. Oct 2024

Renesa Tarannum, Grace Mun, Shannon Farris. Unraveling the molecular logic: Mapping dendritic RNA localization in Hippocampus. Central Virginia Chapter for Society for Neuroscience (CVCSN). (2024) Blacksburg, VA. Apr 2024

  • FASEB RNA Localization Conference Young Investigator Award 
  • Ray Gaskin Health Sciences Graduate Fellowship
  • Graduate Research Development Program Scholarship
  • TBMH Hokie Pitch (2nd Place)
  • TBMH Peer Mentor (2022-2024)
  • Science Fair Judge (Roanoke Valley Governor School Science Fair, Western Virginia Regional Science Fair) (2023-2025)
  • Center for Neurobiology Research Data Jam Coordinator (2025-2026)
  • Volunteer, VTC Bodies and bites program (2023-2026)