ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Rachael Norris is first author on ‘Gap junction internalization and processing in vivo: a 3D immuno-electron microscopy study’, published in JCS. Rachael is a postdoctoral fellow in the lab of Mark Terasaki at UConn Health, Farmington, CT, where she is investigating the functional significance of gap junction internalization using immuno-electron microscopy techniques to study protein localization.
Rachael Norris
How would you explain the main findings of your paper in lay terms?
Nearly all of our cells connect to their neighboring cells by specialized structures called gap junctions. Once formed, gap junctions do not easily separate, so during their internalization, one cell engulfs the whole junction and part of the cell it was connected to. To figure out what happens to the double membrane vesicles that form, we marked a gap junction protein, connexin 43, and imaged thin sections of tissue using electron microscopy. Electron microscopy allows us to see all the main parts of a cell with a great level of detail, and we can detect proteins of interest by labeling them with tiny gold particles. However, one thin slice does not provide a full picture of what each part really looks like, so we used a new method for collecting, labeling and imaging several serial sections of tissue attached to strips of tape in order to get a three-dimensional perspective. With this approach, we were able to see the complete structures of gap junctions connecting cells, gap junctions that were internalized and internalized gap junctions that were getting broken down within cells.
Were there any specific challenges associated with this project? If so, how did you overcome them?
One main challenge was to figure out what vesicles could be causing the modifications to the internalized gap junctions. After unsuccessful attempts with various antibodies against markers for endosomes or lysosomes, we finally succeeded with an antibody to the enzyme cathepsin B that serves as a lysosome marker. Seeing cathepsin B localized to modified internalized gap junctions was an important step forward.
When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?
After seeing connexin 43 localized to intracellular structures that were not easily recognizable, it started to sink in that these must be intermediates in the breakdown of internalized gap junctions. Since many of the structures resembled multi-vesicular endosomes, a ‘eureka’ moment was realizing that some portion of ‘multivesicular endosomes’ within cells of other tissues might also form from similar instances of partial cell engulfment (trogocytosis) followed by subdivision of the donor cell's contents.
Why did you choose Journal of Cell Science for your paper?
Journal of Cell Science is a highly reputable journal, and I have always admired the quality of articles published here.
Have you had any significant mentors who have helped you beyond supervision in the lab? How was their guidance special?
My PhD mentor, Rindy Jaffe, set up many opportunities for me to thrive, and I cannot imagine what course my science training would have taken without her guidance. Outside the lab, she taught me the importance of going for walks and swims, and how to prepare some delicious food. My current supervisor, Mark Terasaki, has also played a large role in helping me to meet a broad network of other scientists and to apply my skills to new sets of problems. Both Rindy and Mark also encouraged me to spend ample time at the Marine Biological Laboratory (MBL) in Woods Hole, which has led to some wonderful memories.
What motivated you to pursue a career in science, and what have been the most interesting moments on the path that led you to where you are now?
I have always been curious about how things work, and by growing up in Maine, I was fortunate to have a forest in my backyard to explore and have frequent visits to the ocean to see the variety of creatures there. In my senior year of high school, I took a class in histology, which has come in really useful to this day! There have been so many other interesting moments, but another highlight is having had the chance to take the Embryology course at the MBL in Woods Hole while I was in graduate school.
Images showing the different stages after a gap junction is internalized. Connexin 43 is labeled by 10 nm gold particles. Scale bars: 250 nm.
What's next for you?
One way or another, I hope to continue working on projects that use electron microscopy to answer questions about membrane trafficking and intercellular communication. Time will tell!
Tell us something interesting about yourself that wouldn't be on your CV
When I have the time and inspiration, I really enjoy carving inserts for paper lanterns, which I learned how to do from friends in Seattle.
Footnotes
Rachael Norris's contact details: UConn Health, 263 Farmington Ave., Farmington, CT 06030, USA.
E-mail: norris{at}uchc.edu
- © 2021. Published by The Company of Biologists Ltd
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