THE RNA-BINDING PROTEIN, IMP, GENERATES NEURAL DIVERSITY IN THE DROSOPHILA TYPE 2 NEUROBLAST LINEAGE
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Date
2024-08-07
Authors
Munroe, Jordan
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Publisher
University of Oregon
Abstract
Neural diversity generated during development is required to produce a fully functioning nervous system. Thousands of neurons precisely target their axons to the relevant post-synaptic partners to create neural circuits that generate proper sensory and motor behavior at the organismal level. A lack of neural diversity can cause improper circuit formation. In Drosophila, temporal patterning within neural stem cells aids in the correct regulation and generation of neurons. Drosophila neural stem cells, or neuroblasts (NBs), within the central brain express opposing temporal gradients of the RNA-binding proteins, Imp and Syp. Here I show that a subset of central brain NBs, known as type 2 NBs (T2NBs) all express Imp in a high-to-low expression pattern early in Drosophila neurogenesis, while Syp expression is dependent upon the T2NB lineage. Unique to T2NBs, compared to other Drosophila neuroblasts, is the generation of intermediate neural progenitors (INPs) which are necessary for expansion of neural number and diversity in the Drosophila central complex (CX), an adult brain structure required for celestial navigation. Upon their generation, I have shown that newborn INPs express equivalent Imp and Syp levels as T2NBs and form high-to-low expression gradients throughout the INP lineage. However, Imp levels increase in old INPs where I show it is required for the proper generation of E-PG and PF-R neurons in the CX. Loss of Imp in old INPs causes morphological defects while Imp overexpression causes abnormal neurite morphology. Finally, I highlight Imp’s minor role in post-mitotic morphogenesis of PF-R and P-FN neurons in the adult CX. Loss or overexpression of post-mitotic Imp causes only minor changes in PF-R and P-FN neuropil volume.
This dissertation includes previously published co-authored material.
Supplemental Video 3.1 Imaris reconstruction of T2NBs in larval brain
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Keywords
Central complex, Drosophila, Imp, Syp, Type 2 neuroblasts