Date of Award
Fall 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Molecular Biophysics and Biochemistry
First Advisor
Koleske, Anthony
Abstract
There is a critical need to elucidate the biochemical events that control dendrite and synapse function to develop better targeted therapeutic strategies for neurodevelopmental disorders. Functionally damaging mutations in TRIO are enriched in individuals with neurodevelopmental disorders. TRIO encodes a synaptic regulatory protein with three catalytic domains (Hence the name, TRIO) - two guanine nucleotide exchange factor domains, GEF1 (Rac1 and RhoG) and GEF2 (RhoA), and a putative kinase domain. Broadly speaking, Trio serves as a signaling hub to integrate signals from cell surface receptors and coordinate cytoskeletal rearrangements by activating small GTPases. However, the mechanistic details of how Trio GEF1 and GEF2 are regulated in cells and how these processes become disrupted in neurodevelopmental disorders remains largely unclear. Therefore, the goal of my thesis was to answer one fundamental signaling question, which is how Trio GEF activity is regulated in vitro and in cells.In Chapter One of my thesis, I begin by providing a general overview of the genetic, biochemical, and model organism studies that indicate that disrupted function of the TRIO gene is a risk factor for neurodevelopmental disorders. Next, I detail the extensive toolkit I generated to probe the regulatory mechanisms and binding partners of Trio in vitro. I conclude Chapter One by briefly describing applications of this toolkit. Chapter Two covers my co-first author work with former graduate student Josie Bircher, where we discovered a novel mechanism wherein Trio spectrin repeats autoinhibit GEF1 activity. In this work, I leveraged the recombinant Trio constructs and in vitro GEF assay from Chapter One to show that when spectrin repeats 6-9 are appended to GEF1 (SR6-GEF1), GEF activity is significantly inhibited in vitro, that disease variants relieve this autoinhibition, and that this phenotype is also observed in cells. Based on my finding that the spectrin repeats autoinhibit GEF1 activity in vitro and in cells, the next question I sought to answer was how Trio GEF1 activity is regulated spatiotemporally in cells. More specifically, I hypothesized that tails of cellular receptors engage and activate Trio SR6-GEF1 or post-translational modifications (PTMs) activate Trio SR6-GEF1 in a tightly coordinated manner. In Chapter Three, I detail my unpublished work in this project. In Chapter Four, I conclude my thesis with a brief overview of future directions of this project and the current scope of the field.
Recommended Citation
Corcoran, Ellen Elizabeth, "Disruption of Trio GEF Function and Regulation in Neurodevelopmental Disorders" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1211.
https://elischolar.library.yale.edu/gsas_dissertations/1211
