ORCID
https://orcid.org/0000-0002-5086-7409
Date of Award
11-28-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Improvements to models of age-associated neurodegenerative diseases are increasingly important as our population ages and their prevalence increases. Overexpression of microRNAs-9/9* and 124 (miR-9/9*-124) convert human adult fibroblasts into neurons (miNs) by silencing non-neuronal networks, allowing the neuronal program to take over. However, improvements to this paradigm are still necessary to bring this system as close to in vivo investigation as possible. Structure equals function is one of the core tenants of molecular and cellular biology, and it applies to the morphology of neurons more so than most cells in the body. To identify drivers of morphometric reprogramming of miNs, we turned to signaling pathways important to neuronal development in vivo. We identified that inhibiting Notch signaling has a dramatic effect on improving neurite outgrowth and density. We identified that the first seven days of reprogramming are necessary and sufficient for this phenotype, and that the most likely genetic culprit is MYLIP, an E3 ubiquitin ligase previously identified to inhibit neurite outgrowth in neural progenitor cells. This week of importance indicates that erasure of fibroblast fate is the likely target of Notch inhibition, which is supported by transcriptomics showing erasure of non-neuronal terms at PID7. Additionally, we find that at PID21 this results in a dramatic increase in neuronal identity. We hoped to use this improved reprogramming paradigm to investigate the epigenetics of Alzheimer's Disease (AD). Existing epigenetic experiments of neurodegenerative disease suffer numerous setbacks, from relying on degraded post-mortem samples to artificial models derived from human iPSCs or mouse models. miNs offer a solution to this problem, as they recapitulate the cell types of interest displaying disease phenotypes, circumventing the problems of existing models. With the advent of CUT&Tag lowering the material threshold required to perform these types of experiments, cell culture is no longer a roadblock. By taking samples from a family which carries an autosomal dominant mutation causing AD and comparing them to healthy age and sex matched controls, we hoped to identify known and novel drivers of AD. Of particular interest, one of these novel mechanisms may be fAD associated hyperacetylation of H4K¬16 on genes containing Olduvai domains, an integral part of neurodevelopment.
Language
English (en)
Chair and Committee
Andrew Yoo
Committee Members
Jim Skeath
Recommended Citation
Burbach, Kyle Foster, "Inhibiting Notch Signaling in miNs Improves Neurite Extension & Investigating the Epigenome of Alzheimer’s Disease" (2023). Arts & Sciences Electronic Theses and Dissertations. 3194.
https://openscholarship.wustl.edu/art_sci_etds/3194