Institut Curie attends ASCB EMBO meeting in Washington
Among all the presentations from Institut Curie researchers, three of them will be particularly key.
Saturday, December, 7th - 8.30-11.30am
Thomas Walter will present a new artificial intelligence technique to analyze the distribution of RNA in the cell.
MRNA (m stands for messengers) are small intermediate molecules between the DNA that are present in the core of our cells and proteins. Each of these mRNA carry the "recipe" for making a protein. It was long thought that mRNA were distributed randomly in the cell.
But this is not the case; in some cases mRNA form agglomerations in the cytoplasm - the liquid medium that fills the cells - which may serve as "translation factories", where their message will be translated into proteins. This represents a new spatial control mechanism that has been discovered thanks to a productive collaboration between researchers from Institut Curie and Mines ParisTech (Thomas Walter), Institut Pasteur (Florian Müller) and the Institute of Molecular Genetics of Montpellier (Edouard Bertrand). The precise role and the mechanism for locating RNA remain poorly understood and their study requires large-scale imaging approaches, involving thousands of microscopy experiments. It is impossible for researchers to analyze thousands or millions of cell images manually, to deduce the distribution profiles of these RNA. Machine learning techniques however can help here, in particular "artificial neuron networks", a particularly powerful technique for image classification: they apply a series of transformation of images, one after the other, leading from the image to the prediction. The parameters of these transformations are adapted to minimize the prediction error.
But these deep neuron networks still need to base their own analysis on a large number of images already interpreted, which they can use for "inspiration".
To resolve the issue, Thomas Walter, an image analysis specialist at Institut Curie and Mines ParisTech, developed a new innovative machine learning strategy: "rather than using real images of cells analyzed by humans, images of RNA distribution were simulated electronically, showing the most interesting known patterns. The computer can then base its analysis on all these configurations and learn to recognize them in new images," he explains. The algorithms also developed by Thomas Walter's team allow the computer systems to classify the images in different categories corresponding to different RNA distributions. Biologists have already noticed that mRNA often accumulate in protrusions, outgrowths that play precise roles in the cell. They think that this distribution of RNA would allow the cell to rapidly produce proteins required at this specific location.
The technique developed by Thomas Walter will allow the scientific community to rigourously analyze a large variety of localization patterns in order to understand the many facets of RNA localization in cells. He will be presenting this new tool at the next ASCB Meeting where these machine learning strategies play an increasingly important role. Since last year they have had a dedicated session.
Monday, December, 9th 1.00pm
Manuela Dezi unveils the mysteries of membrane contact sites.
Membrane contact sites (MCS) were discovered in the 1950s. Researchers have explored them gradually within cells and have updated their roles. These contact areas allow various organelles to come together; these are structures inside the cell that fulfill different functions, such as signaling or transport of lipids and maturation of proteins. But the structure of these MCS - assemblies of several proteins - remained a mystery. On December 7, at the annual meeting of the ASCB - American Society for Cell Biology - Manuela Dezi will present her latest discoveries in the area.
"Most of the teams that work on MCS do so on living cells, which lets us explore their function, but not their structural organization. And we managed to recreate MCS in vitro, using purified proteins," Lennon explains. This first step was already a real challenge because it is more difficult to create the right conditions to assemble these proteins - which are more "comfortable" on contact with lipids - than with classic proteins which are soluble in water. "Once these MCS were recreated, we were able to study them using different electronic microscopy techniques. And this is how we found out that they could be of different lengths. We present the hypothesis that this allows them to affect a remote organelle before getting close to it, or that it helps them to be more flexible and adapt their structure to different environments," Manuela Dezi tells us. Dezi is delighted to share these discoveries with the international community: "We are the first to use these electronic microscopy techniques with MCS recreated in vitro. And our information is valuable since these MCS are involved in anomalies of cholesterol transport, in a neuro-degenerative disease, and may also be involved in cancer."
Tuesday, December, 10th, 8-9.30am
Ana-Maria Lennon will present her latest discoveries on the sentinel cells of our immune system.
Dendritic cells are the sentinels of our immune system. They are tasked with "patrolling" the tissues and detecting the presence of foreign cells or molecules. When they recognize an intruder, they communicate information to identify other immune cells, the T lymphocytes that will eliminate the threat at hand.
In December, at the annual meeting of the ASCB - American Society for Cell Biology - Ana-Maria Lennon will present her latest discoveries on the movements of dendritic cells. Director of research at Institut Curie, she works at the interface between cellular biology, immunology and bio-physics and is particularly interested in these dendritic cells. She recently deciphered the role played by the actomyosin cytoskeleton (architecture of the cell made up of two complementary proteins, actin and myosin) in this process. "The space and time dynamic of actomyosin defines the type of trajectory of the dendritic cells in various tissues, and couples their migratory mode with their function as sentinels of the immune system," she explains. Thus the dynamic of the actomyosin cytoskeleton optimizes the ability of the dendritic cells to explore their environment, collect information to send to the T lymphocytes and handle the constraints of their environment. Lastly, during her presentation Ana-Maria Lennon will address her team's recent work showing that by controlling the location of dendritic cells inside tissues, the actomyosin cytoskeleton determines the signals to which they are exposed, their differentiation and their functional specialization.