Organization and function of the axonal Endoplasmic Reticulum

Introduction

Brain function relies on neurotransmission at synapses, where local increases in calcium trigger the fusion of synaptic vesicles and the release of their neurotransmitters. Decades of research yielded detailed knowledge on synaptic vesicles and the individual proteins that mediate neurotransmission. Conversely, we know surprisingly little about the synaptic contribution of the largest organelle in neurons: the Endoplasmic Reticulum (ER).

Importance of the Endoplasmic Reticulum

Aberrant alterations in ER shape are, however, associated with many neurologic disorders, highlighting the importance of understanding the role this organelle plays in the neuron. Taking into consideration the mere quantity and range of specialized ER functions such as calcium signaling and lipid synthesis, the neuronal ER has received very little attention.

Research Objectives

I therefore strive to shed light on the major, unresolved questions of the field, namely:

1. What is the ER protein composition in synapses?
2. How does the ER contribute to important neuronal functions such as neurotransmission?

Methodology

To dissect ER function in neurons, I will:

1. Characterize the composition of neuronal ER proteins and identify the key players that regulate ER degradation.
2. Manipulate ER content, localization, and degradation to understand how the ER contributes to neurotransmission and development.
3. Investigate the importance of ER and ER degradation for physiological and pathophysiological processes in vivo.

Proposed Approach

To this end, I propose a multidisciplinary approach using:

• Advanced imaging techniques
• Endogenous protein tagging
• Proteomics

These methods will be employed to study ER function and its regulated degradation in neurons.

Expected Outcomes

These studies will yield innovative fundamental insights into the role of synaptic ER and thereby fill a crucial knowledge gap in neuroscience. Furthermore, they will provide a better understanding and explanation of how defects in ER and ER degradation cause neurodegenerative diseases.