Technische Universität München
Genetically encoded nano-barcodes
TECHNICAL UNIVERSITY OF MUNICH
NEWS RELEASE
Electron microscopy: Nano-reporter proteins make invisible processes visible
Genetically encoded nano-barcodes
- New gene reporter system for electron microscopy
- Uses barcodes to identify cellular states and structures that would otherwise remain unidentified
- Important step to better elucidate cellular structural changes also in disease
How do the nerve cells in our brain communicate with each other? What processes take place when T cells render cancer cells harmless? Details of the mechanisms at the cellular level remain hidden from view. Now, special reporter proteins developed by a research team led by the Technical University of Munich (TUM) may help unveil these mechanisms.
Peering through an electron microscope provides scientists the deepest view into cellular structures – the resolution lies in the sub-nanometer range. Even cell components like mitochondria or connections between nerve cells can be discerned. Nonetheless, many important structures and processes remain invisible. "This is somewhat like looking at a city map," explains Gil Gregor Westmeyer, Professor of Neurobiological Engineering at TUM and Director of the Institute for Synthetic Biomedicine at Helmholtz Munich. "It is sufficient to get a visual impression of the surroundings and see where the roads are. But it doesn't tell us how often traffic lights are switched, how much traffic there is at any given point, and when or where something is currently under reconstruction."
But the ability to intervene in faulty processes, or to recreate them in artificial tissues and organs, absolutely requires an understanding of the processes within and between cells. Westmeyer and his colleagues have thus developed a so-called genetic reporter system that does the reconnaissance work within the cells for them. The gene reporters are protein capsules just large enough to be resolved by an electron microscope.
Identification by barcodes
The capsules are produced by the cells themselves. Their genetic blueprints are attached to specific target genes. The reporter proteins are produced when the target genes become active. The basic principle behind this method is already a standard procedure in light microscopy. There, researchers work with fluorescent proteins. However, this method is not suitable for electron microscopy, because rather than colors, different shapes are distinguished based on their electron densities, for example.
The researchers exploited this by incorporating metal-binding proteins into differently-sized capsules. These "EMcapsulins" appear as variously sized concentric circles under the electron microscope and can be quickly identified and assigned like barcodes using artificial intelligence.
Making invisible structures visible
So, how exactly can the researchers utilize these reporter proteins? On the one hand, they can use them to indicate the activity of certain genes, but also to discover structures that would otherwise not be visible under an electron microscope – e.g. electrical synapses between nerve cells or receptors that influence the interaction between cancer cells and T cells.
"If we also give the EMcapsulins fluorescent properties, this will allow us to initially examine structures in living tissue using light microscopy," says Felix Sigmund, first author of the study. In the process, striking dynamics and structures could be observed, which in a next step can then be highly resolved under an electron microscope.
"It is also conceivable to in the future deploy the reporter proteins as sensors that change their structure, for example, when a cell becomes active. In this way, the relationships between cell function and cell structure can be better elucidated, which is also pertinent to understanding disease processes, as well as to produce therapeutic cells and tissues," adds Westmeyer.
To this end, the researchers will also use the new Electron Microscopy Facility at TUM and collaborate with the new TUM Center for Organoid Systems (COS).
Publications
- F. Sigmund, O. Berezin, S. Beliakova, B. Magerl, M. Drawitsch, A. Piovesan, F. Gonçalves, S.-V. Bodea, S. Winkler, Z. Bousraou, M. Grosshauser, E. Samara, J. Pujol-Martí, S. Schädler, C. So, S. Irsen, A. Walch, F. Kofler, M. Piraud, J. Kornfeld, K. Briggman, G. G. Westmeyer: Genetically encoded barcodes for correlative volume electron microscopy, Nature Biotechnology (2023), DOI: https://doi.org/10.1038/s41587-023-01713-y
- Augmenting electron microscopy with barcoded gene reporters, Nature Biotechnology Research Briefing (2023), DOI: https://doi.org/10.1038/s41587-023-01731-w
Further information
- Prof. Gil Westmeyer is Principal Investigator at the Munich Institute of Biomedical Engineering (MIBE). MIBE is an Integrative Research Institute (IRI) within the Technical University of Munich (TUM) that fosters interdisciplinary cooperation and synergies between researchers from the broad field of Biomedical Engineering. At MIBE, researchers specializing in medicine, the natural sciences, and engineering join forces to develop new methods for preventing, diagnosing or treating diseases. The activities cover the entire development process – from the study of basic scientific principles through to their application in new medical devices, medicines and software. https://www.bioengineering.tum.de/en/
- Researchers from the following universities and institutions were involved in the research: Technical University of Munich (TUM); Helmholtz Munich; Max Planck Institute for Biological Intelligence; Max Planck Institute for Multidisciplinary Sciences; Max Planck Institute for Neurobiology of Behavior – Caesar; Carl Zeiss Microscopy GmbH.
- The research was funded by the Consolidator Grant "EMcapsulins" of the European Research Council.
Additional information for editors
High-resolution pictures: https://mediatum.ub.tum.de/1705691
Expert contact
Prof. Dr. Gil WestmeyerTechnical University of Munich
Professor of Neurobiological Engineering
Phone: +49 (89) 289 10953
gil.westmeyer@tum.de
Media Contact
Carolin Lerch
Media Relations
Tel. +49 89 289 10808
presse@tum.de
The Technical University of Munich (TUM) is one of Europe’s leading research universities, with more than 600 professors, 50,000 students, and 11,000 academic and non-academic staff. Its focus areas are the engineering sciences, natural sciences, life sciences and medicine, combined with economic and social sciences. TUM acts as an entrepreneurial university that promotes talents and creates value for society. In that it profits from having strong partners in science and industry. It is represented worldwide with the TUM Asia campus in Singapore as well as offices in Beijing, Brussels, Mumbai, San Francisco, and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel, Carl von Linde, and Rudolf Mößbauer have done research at TUM. In 2006, 2012, and 2019 it won recognition as a German "Excellence University." In international rankings, TUM regularly places among the best universities in Germany.