Periodic Reporting for period 1 - synERgy (Organization and function of the axonal Endoplasmic Reticulum)
Reporting period: 2022-07-01 to 2024-12-31
The endoplasmic reticulum (ER) is a dynamic, intracellular organelle responsible for many essential subcellular processes, including the production of proteins and calcium storage. In neurons, the ER is very large and extends from the cell body all the way to the tip of long extensions known as dendrites and axons. These axons and dendrites receive and transmit signals, enabling communication between neurons at specialized junctions called synapses.
While the ER’s presence in neuronal synapses is well-established, the precise ways in which it contributes to their formation and functioning are still unclear. Disruptions in ER function have been linked to various neurological disorders and alterations in neuronal communication, underscoring the importance of gaining a deeper understanding of its role.
The primary objective of this project is to uncover the critical role of the ER in supporting neuronal communication. We aim to address the following questions: 1. What are the fundamental components and dynamic behaviors of the neuronal ER? 2. How is the degradation of the ER regulated within neurons? 3. How does the ER influence the formation and functionality of synapses?
These studies will provide innovative insights into the role of synaptic ER and thereby fill a crucial knowledge gap in neuroscience. Furthermore, they will enhance our understanding of how defects in ER and its degradation contribute to neurodegenerative diseases.
While the ER’s presence in neuronal synapses is well-established, the precise ways in which it contributes to their formation and functioning are still unclear. Disruptions in ER function have been linked to various neurological disorders and alterations in neuronal communication, underscoring the importance of gaining a deeper understanding of its role.
The primary objective of this project is to uncover the critical role of the ER in supporting neuronal communication. We aim to address the following questions: 1. What are the fundamental components and dynamic behaviors of the neuronal ER? 2. How is the degradation of the ER regulated within neurons? 3. How does the ER influence the formation and functionality of synapses?
These studies will provide innovative insights into the role of synaptic ER and thereby fill a crucial knowledge gap in neuroscience. Furthermore, they will enhance our understanding of how defects in ER and its degradation contribute to neurodegenerative diseases.
To achieve these objectives, we first focused on establishing tools for the visualization of ER and its protein composition in different neuronal compartments. We established CRISPR-Cas9 editing to visualize several endogenous ER proteins in primary neurons and designed a proximity-biotinylation approach to identify the protein composition of specific ER compartments. In addition, we can now separate axonal and somatodendritic compartments and analyze their protein content by quantitative mass spectrometry. To investigate the role of the ER in neuronal and synapse functioning, we employ viral-encoded calcium sensors to measure calcium levels in both the cytosol and the ER lumen, allowing us to assess compartment-specific calcium changes during (electrical) stimulation.
This initial phase of the project has mainly focused on creating the molecular tools to assess the role of the ER in the different neuronal compartments. With these tools, our goal is to unravel the function of (tubular) ER in neurons, particularly in synapses. These efforts not only enhance our understanding of neuronal ER organization and function, but may also provide insights into the role of ER in neurodegenerative diseases involving ER or calcium homeostasis dysfunction.