Dissertations, Theses, and Capstone Projects

Date of Degree

9-2022

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biology

Advisor

Itzhak Mano

Committee Members

Patrizia Casaccia

Monica Driscoll

Oliver Hobert

Chris Li

Subject Categories

Bioinformatics | Molecular and Cellular Neuroscience | Molecular Biology

Keywords

Neuroscience, genetics, transcription, gene expression, neurodegeneration

Abstract

Excitotoxicity is notorious for triggering neuronal cell death in both developmental and adult-onset neurodegenerative diseases. In excitotoxicity, excessive concentrations of Glutamate in the synapse overstimulate Glutamate Receptors (GluRs) on postsynaptic neurons. While GluR mediated degenerative mechanisms remain obscure, GluR activation was surprisingly found to also have a neuroprotective effect through activation of specific transcriptional programs. To identify evolutionarily conserved transcriptional programs in neuroprotection we use a C. elegans model of excitotoxic necrosis (glt-3;nuIs5). We have identified that non-canonical activation of the transcription factor CRH-1/CREB mediates neuroprotection in our excitotoxicity model. We found the Histone Acetyl Transferase, MYS-1/KAT6, and the neuronal calcium sensor 1, NCS-1/FREQ, regulate calcium mediated neuroprotection downstream of hyperactivation of glutamate receptors in C. elegans. Our characterization of CREB-dependent neuroprotective transcriptional targets in glutamate receptor 1 (glr-1) expressing neurons revealed a potassium channel, KQT-1/KCNQ4, and a CLC chloride channel, CLH-4/CNCQ2, as mediators of neuroprotection from excitotoxicity. Genetic and pharmacological assays validated our transcriptomic data which elucidate that CREB upregulates KQT-1/KCNQ4 and CLH-4/CNCQ2 under excitotoxic conditions to provide neuroprotection. These insights could translate to novel targets for therapeutic intervention in stroke and other neurogenerative diseases where cell death is driven by excitotoxicity.

As aged neurons appear to be more vulnerable to neurodegeneration from excitotoxicity we sought to investigate neuroprotection in adult C. elegans. We previously found that IIS and DAF-16 are involved in neuroprotection and we recently identified the transcription factor PQM-1 as also involved in protection from excitotoxicity. As we found that the aging-regulating genes PQM-1 and DAF-16 are necessary for neuroprotection from excitotoxicity we decided to develop a model of inducible neurodegeneration where we have both spatial and temporal control of the induction of excitotoxicity, for the future study of excitotoxicity in aged animals. In preparation for studying neuroprotection in adults we did work towards an adult onset C. elegans excitotoxicity model. We utilized the Q systems for spatial and temporal control of transgene expression of constitutively active human G alpha S (hgGαS) specifically in adult glr-1 -expressing neurons. Taken together this work aims to provide a basic science approach to novel neuroprotective transcriptional target discovery that may lead to translational medicine to address the high unmet need in the clinic for therapeutics that provide neuroprotection from excitotoxicity.

Download

Share

COinS