The ubiquitin proteasome system as a regulator of neuronal function

The accumulation of damaged and misfolded proteins is toxic to cells and is believed to play a major role in neuronal ageing and neurodegenerative disorders such as Alzheimer’s disease and Amyotrophic Lateral Sclerosis. In order to maintain protein homeostasis cells have protein degradation pathways which serve to repair or remove damaged proteins. The targeting of damaged proteins for degradation is primarily mediated by the Ubiquitin Proteasome System (UPS). Importantly, specific isoforms of the E3 ligases, which comprise a key part of the UPS, are known to localise within neurons.

The loss of E3 ligase efficacy and the resultant perturbation of protein homeostasis is believed to contribute to neuronal ageing and neurodegeneration. Intriguingly, there is mounting evidence that these proteins also serve as key modulators of neuronal function in the healthy nervous system. For example, the UPS has been shown to regulate the grown of axons, the formation of synapses and the release of neurotransmitter. However, we know relatively about how E3 ligases influence vertebrate neurons in vivo. This project will use zebrafish, a powerful vertebrate model for in vivo neuroscience research, to understand how molecular and pharmacological perturbation of the UPS influences the physiology function, morphology, connectivity and output of neural tissue.

The overarching aim is to determine how short and long term changes in UPS function affect vertebrate nervous tissue in vivo. Specifically, the project has the following three aims:

Aim 1 will investigate the effects UPS disruption on neuronal function. First we will use in vivo patch clamp electrophysiology to monitor effects on the firing properties and synaptic efficacy of single neurons. This will be complimented with in vivo calcium imaging approaches to monitor effects on population of neurons within the central nervous system.

Aim 2 will investigate the effects of UPS perturbation on neuronal morphology and connectivity. Here we will fish that express green fluorescent protein within different neuronal subtypes to monitor the branching and synaptic connectivity of neurons in which the UPS is perturbed.

Aim 3 seeks to understand how UPS-mediated changes in neuronal properties affect central nervous system output. To do this we will challenged fish with a range of sensory stimuli and monitor their behavioural responses.
The project will draw upon McDearmid’s extensive expertise in applying patch clamp electrophysiology and imaging methods to the zebrafish nervous system with Norton’s extensive experience with zebrafish molecular biology.