Date of Award

5-2024

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology/Molecular, Cellular, and Organismal Biology

First Advisor

Alexey Veraksa

Second Advisor

Kristin White

Third Advisor

Catherine McCusker, Linda Huang, Jens Rister

Abstract

Determining the mechanisms behind developmental diseases of the nervous system can provide insight into advancing treatments. The human kinase DYRK1A plays a role in Down syndrome, microcephaly, and cancer; however the exact mechanism through which it functions is unknown. By studying its Drosophila melanogaster homolog, Minibrain (Mnb), we can learn more about DYRK1A function. Neural stem cells (called neuroblasts in flies) give rise to differentiated cells and the adult brain structure. In this dissertation I uncover novel functions of Mnb in development, identify novel protein interactions between Mnb and endocytic proteins, and characterize additional mutation-specific proteomes of the developmentally important GTPase Neurofibromin 1 (NF1). During development, the proper number of neuroblasts must be formed from neuroepithelial cells, and this transition is a carefully regulated process. Molecular marker analysis of mnb null mutants has revealed alterations in the neuroepithelium and neuroblast regions of developing larval brains. To determine how Mnb regulates brain development, I performed affinity purification-mass spectrometry (AP-MS) on embryos expressing an endogenously tagged form of Mnb. I identified novel Mnb binding partners Ral interacting protein (Rlip) and RALBP1 associated Eps domain containing (Reps) that work together with Mnb to regulate Drosophila development. I also showed that Mnb interacts with the GTPase Ras-like protein A (Rala) to regulate brain development within the neuroepithelium. I also characterize a novel role for Mnb in early Drosophila development. In this work I show that Mnb is required for proper closure of the embryo on the dorsal side. Without Mnb, embryos do not fully close and the viability of embryos is reduced. In this dissertation I also characterize the differences in interactomes between wild type and mutant NF1. I have identified several protein interactions that are gained in mutant NF1 and are not present or present at reduced intensities in wild type NF1. This work sets the foundation for further characterization of these interactions and opens avenues for investigating the mechanisms through which mutant NF1 may regulate tumor formation. My work expands our knowledge of the Mnb signaling network and how it regulates Drosophila development as well as the NF1 interactome and how mutations may affect protein interactions. This work may suggest new approaches to developing therapies for Neurofibromatosis and DYRK1A-related diseases in humans.

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