Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Cell & Molecular Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Timothy A. Evans

Committee Member

Ines Pinto

Second Committee Member

Jeffrey Lewis

Third Committee Member

Paul Adams

Fourth Committee Member

Michael Lehmann

Keywords

nervous system, neurological diseases, ligand, receptor complex

Abstract

In animals with complex nervous systems such as mammals and insects, signaling pathways are responsible for guiding axons to their appropriate synaptic targets. Importantly, when this process is not successful during the development of an organism, outcomes include catastrophes such as human neurological diseases and disorders. It is vital to determine the underlying causes of such diseases by understanding the development of the nervous system. There are many pathways that have been identified to play a role in this, however, we lack an understanding of how these pathways can promote such diverse outcomes in different populations of neurons. These pathways include conserved ligand and receptor complexes that can either synergistically or antagonistically determine the fate of axons. Among these complexes include Slit and Robo, the first ligand and receptor complex to be identified in Drosophila. Previous studies show that disrupting this complex causes ectopic midline crossing of axons in a wide range of animals. Here, to analyze the structural foundation of the diverse activities of Robo2, I examine the relative contributions of its Ig domains by generating transgenic animals expressing variant proteins. I show that Ig domains are not individually required for protein stabilization and localization in vivo. I also use a cell overlay assay to examine the structural and functional importance of all domains of Drosophila Robo2. Deleting the Ig1, Ig5, and Fn2 domains of Robo2 reduce Slit binding in cultured Drosophila cells. The other domains of Robo2 are individually dispensable in Robo2’s ability to bind to Slit in vitro.

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