SciTech

Understanding Atlastin-1 and its dynamics

In the above diagram of a cell, the region in red represents the endoplasmic reticulum. (credit: Courtesy of Courtesy of Mariana Ruiz via Wikimedia Commons) In the above diagram of a cell, the region in red represents the endoplasmic reticulum. (credit: Courtesy of Courtesy of Mariana Ruiz via Wikimedia Commons)

It’s no secret that the endoplasmic reticulum (ER) is a crucial organelle. In most cells, the ER is involved in post-translational modification of proteins, calcium homeostasis, lipid synthesis, and other important functions. Recently, an enzyme localized in the ER, a GTPase known as Atlastin-1, gained prominence as a necessary component for mediating proper ER structure.

In terms of clinical applications of ER fusion, prior research has linked impairments in ER function — possibly caused by improper formation of networks — to Hereditary Spastic Paraplegia, a neurological disorder characterized by spasms and weakness/stiffness in the legs.

On Feb. 16, at the weekly Department of Biological Sciences Research Club meeting, first-year Ph.D. student Ellie Lai presented her research during her rotation in the Lee lab about visualizing atlastin (ATL) dynamics during ER fusion. (In this context, fusion refers to the joining of tubules to form networks that make up the endoplasmic reticulum.)

Lai hypothesized that if ATL is specifically localized to fusion sites, it should be possible to visualize "hot spots" at presumptive fusion sites within the ER. If not, there should be an even distribution of ATL within the cell, regardless of where ER fusion is occurring.

For her experimental methods, Lai transiently transfected a red fluorescently tagged Atlastin-1 and a green fluorescently tagged general ER marker into tissue culture cells. Lai imaged the cells with confocal microscopy to gain five- to seven-minute long movie clips that showed the complete process within the ER networks.

The analysis of the clips showed instances in which Atlastin-1 did indeed localize at fusion sites before and during fusion, but disappeared afterwards. However, there were also instances within the ER that did not seem to have ATL enrichment during fusion.

Building upon these findings, Lai plans to investigate further into the visualization of fusion events using optimized methods. Potential routes could involve finding ways to increase the number of cells that can be imaged for a more robust assessment or to identify more fusion events within the cell.