Date of Award
Spring 5-4-2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Dr. Ashok Hegde
Second Advisor
Dr. Ellen France
Third Advisor
Dr. Matthew Milnes
Abstract
Synaptic plasticity refers to the changing of synaptic strength and underlies the ability of the nervous system to store information. A cellular process of increasing synaptic strength is long-term potentiation (LTP) which is thought to be critical for long-term memory consolidation. Many molecular processes such as new gene transcription and translation as well as protein degradation play a role in LTP. Regulated protein degradation occurs through the ubiquitin-proteasome pathway (UPP) in which ubiquitin-tagged substrate proteins are degraded by the 26S proteasome, a structure containing a 20S catalytic core and two 19S regulatory subunits. The UPP has also been shown to have a non-proteolytic role by participating in gene transcription, which is required for LTP. While previous work suggests a role of the proteasome regulatory particle Rpt1 in gene transcription, the precise amino acids within this subunit that are targets for cellular signaling that enable it to travel to the nucleus for transcriptional regulation have not been previously revealed. Chemical long-term potentiation (cLTP) on mouse hippocampal slices was used to induce synaptic strengthening. cLTP experiments were performed in the absence or presence of exogenous peptides. Each peptide was specifically designed to contain a different sequence that mutated amino acids that are targets for attachment of a Small Ubiquitin-like Modifier (sumoylation) or phosphorylation, both of which are hypothesized to regulate LTP. Immunohistochemistry was then performed with antibodies against a specific amino-acid sequence called an HA tag that was included in the Rpt1 peptides. By visualizing nuclear translocation of these mutants with immunofluorescence, efforts were made to determine what specific amino acids are required within Rpt1 to regulate transcription of memory-related genes. It was concluded that sumoylation and phosphorylation are likely necessary for nuclear translocation of Rpt1 as revealed by the experiments on mutant peptides. The results from the present study broadly suggest that the proteasome, specifically Rpt1, is likely to have a non-proteolytic role in long-term synaptic plasticity.
Recommended Citation
Timm, Logan, "Mechanisms Underlying Novel Roles of Rpt-1 in Long-term Synaptic Plasticity" (2024). Biology Theses. 36.
https://kb.gcsu.edu/biology/36