We have a new paper out! This post is to describe what our paper is about. The paper is free to read, so please take a look if you are interested.
Gabrielle Larocque, Daniel J. Moore, Méghane Sittewelle, Cansu Kuey, Joseph H.R. Hetmanski, Penelope J. La-Borde, Beverley J. Wilson, Nicholas I. Clarke, Patrick T. Caswell & Stephen J. Royle
Intracellular nanovesicles mediate α5β1 integrin trafficking during cell migration
J Cell Biol 220 (10): e202009028. doi: 10.1083/jcb.202009028
A quick guide to the paper
The paper in a nutshell: We show that normal cell migration and invasion in a cancer context depend on TPD54. The mechanism involves the recycling of integrins, which we demonstrate occurs via intracellular nanovesicles.
Huh? What is cell migration? Cells move a lot and this movement (migration) is needed in the body for all kinds of normal, healthy things, such as the immune response.
That sounds good, so what about cancer? There are times when you don’t want cells to move, such as in cancer. Tumour cells that move away are said to “metastasise”. This means they can make new tumours in different places in the body. This can make the cancer more difficult to treat and can mean a bad outcome for the patient. Previous work had found that patients with certain cancers, e.g. breast cancer, had high levels of Tumor Protein D52 (TPD52) and Tumor Protein D54 (TPD54). Not only that, but these patients tended to do worse because their cancer was more aggressive and migratory.
Our lab had previously found that TPD54 is on tiny vesicles inside cells and we call them intracellular nanovesicles, or INVs for short.
TPD54 is the link between INVs and cell migration
We can watch cells move around (migrating) under the microscope. We noticed that if we decrease the amount of TPD54 in cells the cells migrate less. This is shown in the video below. Notice how the cells on the right move slower and less far than the normal cells on the left. Not only that but if we make the cells express more TPD54, like in cancer, the cells migrate more. Their speed is higher.
This result is the main finding in the paper, but there is a lot of other information in there and lots of experiments. A few other highlights:
- We found that TPD52 and TPD53 (other members of the family) behave in the same way
- The changes in migration are due to altered integrin recycling
Integrin recycling? When cells move, they need to break and remake their attachment with the surface they are moving on. These attachments are made by integrins on the cell’s surface, binding to “extracellular matrix” proteins. One matrix protein is fibronectin and it is bound by an integrin named alpha5/beta1. The integrin’s connection with matrix is broken by it being taken up into the cell and moved in vesicles and then it is recycled to the cell surface to make a new connection. We found that alpha5/beta1 integrins were recycled differently in cells with less TPD54. This suggests that the recycling of this integrin type happens in INVs.
As well as watching cells move on a flat surface – like in the movie above – we imaged cells invading a 3D matrix. This is more similar to the way that cancer cells would move in the body. We saw similar results with these experiments suggesting that integrin recycling in INVs is important here too. This part of the paper was contributed by Pat Caswell’s group at University of Manchester.
The paper is mainly the work of Gabrielle Larocque but there were a bunch of other people who made important contributions, particularly during the revision stage. The invasion experiments were in collaboration with Joe Hetmanski, Bev Wilson, and Pat Caswell at University of Manchester. Nick Clarke did the correlative light-electron microscopy imaging of INVs. Penny La-Borde figured out how to test if TPD54 binds direct to vesicles. Daniel Moore extended this analysis during the revisions as well as doing proteomic analysis of INVs. Méghane Sittewelle did many cell migration experiments and integrin imaging for the revisions. Cansu Kuey imaged INVs wiggling around and she quantified mitochondrial aggregation. You can meet the folks in our lab here.
Path to publication
This was a pandemic paper. Although some of this work dates back to 2014, Gabrielle wrote the first draft of the paper during the first UK national lockdown in 2020. We posted it to bioRxiv in summer 2020 and sent it to J Cell Biol for consideration. As always, the review process was robust and a number of suggestions came back. Unfortunately they required a lot of experimental work to answer at a time when we had only limited access to the lab due to the pandemic. Not only that but many authors, including Gabrielle, had moved on to other jobs. Other scientists were drafted in to do the work here and in Manchester. Eventually we sent the revised paper back. J Cell Biol waived their normal time allowance for revisions which was great. It was a tough situation and the contributors, particularly Daniel and Méghane put in so much work to complete everything. The paper was accepted at the end of June 2021.
The work was funded by UKRI MRC and the money for publishing the paper Open Access came from the University’s UKRI block grant. Did I mention it’s free to read? Here is the link.
The post title is taken from “Culture Move” by Asian Dub Foundation from their album Rafi’s Revenge. If you are having some déjà vu, this is an updated version of an earlier post.