Phosphatases are proteins that play a key role in signaling pathways inside cells. “Phosphatases modify proteins, allowing them to turn signaling pathways on and off,” Professor Köhn explains. Disruption to this process can lead to malfunctions and thus to illnesses such as colorectal cancer and cardiac insufficiency. Together with her working group, Köhn is studying how phosphatases function at the molecular level in order to lay the groundwork for potential future applications in drug therapy. “Drugs are often used to block faulty proteins and thus prevent diseases,” Maja Köhn explains. “There are only very few drugs for phosphatases so far, so there’s a lot of basic research still to do in this area.”
Focusing on phosphatases in the heart muscle and in conjunction with cancer
To this end, Professor Köhn—who holds a degree in chemistry—is combining biological questions with chemical methods. “In order to study the individual functions and the regulation of phosphatases, we need special chemical tools. Some of these don’t exist yet, so we have to create them ourselves,” says Köhn, who is also a member of the Transdisciplinary Research Area “Life and Health“ at the University of Bonn. She is looking particularly closely at certain phosphatases, including one that plays important roles within heart muscle cells, for instance, where malfunctions can cause cardiac insufficiency or heart failure. This work is being funded by her ERC Consolidator Grant. Professor Köhn’s working group is also studying other phosphatases whose operations and regulation within various cellular signaling pathways play a part in carcinogenesis and the immune response to cancer cells.
Professor Walter Witke, Dean of the Faculty of Mathematics and Natural Sciences, is delighted by his new colleague’s arrival: “Maja Köhn is an exceptional researcher in her field who will inject fresh momentum into the Institute for Cell Biology.”
Making her way to the University of Bonn
Maja Köhn has held a Schlegel Professorship at the University of Bonn’s Institute for Cell Biology since October 2024. The successor to Professor Dieter Fürst, she will also serve as the institute’s Managing Director. Born in Kiel, Köhn studied chemistry to Diplom level in her home city. She completed her doctorate at TU Dortmund University and the Max Planck Institute of Molecular Physiology. She moved to Harvard University in the US in 2005 to work as a postdoc, returning to Germany two years later as a group leader at the European Molecular Biology Laboratory in Heidelberg. In 2016, Maja Köhn was appointed Professor for Integrative Signalling Studies at the University of Freiburg, where her roles also included serving as Vice Dean of the Faculty of Biology (since 2018), a Member of the Steering Committee of the Excellence Cluster CIBSS (Centre for Integrative Biological Signalling Studies) (since 2019) and Speaker for the BIOSS Centre for Biological Signalling Studies (since 2021; previously Deputy Speaker).
Essentially, I’m conducting research in biology and using chemistry to create what are known as chemical tools. When we have a biological question that I can’t answer by biological means or with what I have at hand, then we’ll think up something chemical.
I’ve always been interested in biochemistry and decided to study chemistry in Kiel. What I was most interested in back then was organic chemistry, so I did my doctorate in the subject at TU Dortmund University and the Max Planck Institute of Molecular Physiology. The chemical synthesis of tools to apply to biological research was at the center of my work there and as a postdoc at Harvard. After that, I joined EMBL, the European Molecular Biology Laboratory in Heidelberg, as a group leader. As you might guess from its name, it’s an institute that deals with molecular biology—so I had to have a biology question to answer. While I was there, I learned how biologists tackle the topics that interest them, and that left its mark on me. And I’ve been involved in biology ever since—and this includes the eight years I spent in Freiburg.
Do chemists and biologists think differently?
Here’s an example: in molecular biology, things are so complex that you find yourself discussing many hypotheses and finding various ways to interpret your findings. By contrast, if you want to use chemical synthesis to create a substance and then analyze it to check its identity, then either it will be what you think it is or it won’t. The art lies more often in devising the successful synthetic pathway and the analysis. Put another way, if you’re a synthetic chemist, you might think a bit more mathematically and analytically. A molecular cell biologist, on the other hand, will consider their results within the complex biological context and use this as a basis for drawing conclusions that can answer their biological question and will often throw up more hypotheses. So the two approaches are slightly different.
Your main area of research is phosphatases. What are they?
Our DNA, the genetic material in our cells, is essentially identical in all cells. But we have many different cells that perform very different functions. This is thanks to the proteins that are made from the DNA—but only those that are actually needed in each cell. Phosphatases are one such type of protein, which are responsible for certain modifications that other proteins undergo inside the cell. Pharmaceutical researchers often use inhibitors to block proteins in order to fight diseases. With phosphatases, however, there’s not yet much in the way of clinical research, let alone treatment, because the underlying knowledge often isn’t sufficient. So there’s still a vast amount we can find out, especially where diseases are concerned.
Can you give me some examples of medical conditions that this could be exciting news for?
One of the models we’re using is colorectal cancer, while we’re also studying phosphatases in the immune defense mechanism against cancer. We’ve been working for a few years on heart muscle cells too, where malfunctioning phosphatases can cause cardiac insufficiency or heart failure, for instance.
What questions are you looking at right now?
We’re studying a specific phosphatase inside heart muscle cells. We’re attempting to understand what kind of tasks it performs within the cell and how these are regulated, and are also creating some specific chemical tools to address the issue in a targeted way. Because this particular phosphatase is active throughout the cell, we have to try and control it in a modulated fashion so that we can turn it off or on in certain parts of the cell. This allows us to study the phosphatase in precisely this part of the cell, something that we need chemical methods for. It’s a question that we’re also tackling with bioinformatics in order to find out what other kinds of proteins are affected by this phosphatase.
In addition, we’re also working with T cells, i.e. those immune cells that are currently attracting a lot of attention because of immunotherapy. We’re looking at the phosphatases in these cells and their mode of operation and regulation along various cellular signaling pathways in order to learn as much as we can about how they work.
Together with colleagues, we’re also looking at other biological processes such as identifying phosphatases involved in the cell’s response to mechanical stress. We’re working on this with Professor Höhfeld from the University of Bonn as part of a research group.
You’ve actually been collaborating with researchers from the University of Bonn since 2018. Did that influence your decision to come here?
Professor Jörg Höhfeld from the Institute for Cell Biology heads up the research group that’s looking at the mechanisms in play when a cell is subject to mechanical stress. I’ve been a member of his group since 2018. So I already knew a bit about the University of Bonn and had already scientific connections. I’d also met some fellow researchers from the University before. Needless to say, that always helps you make a decision like this, although other personal and professional factors are also very important, of course.
You worked in a Cluster of Excellence in Freiburg. Was it a wrench to leave?
For me personally, moving to Bonn meant joining a new academic and scientific community as well. I really like new scientific input, stimulation and a new environment—it lets you create new things and gives you new scientific freedom. Being part of a Cluster of Excellence is great, of course, but I think it’s exciting to have another change of scene.
You worked as a postdoc at Harvard University. What made a lasting impression on you during your time there?
What I noticed was that there’s a different spirit in the US when it comes to exchanging opinions, to academic debate—people are a lot more open and inquisitive. You don’t get that as much in Germany, where people are often focused more on their own research. I’d say there’s room for improvement as far as this culture goes.
What are your first impressions of the University of Bonn?
I can’t praise the onboarding service enough. Heike Rauer and Corinna Rütten were both incredibly helpful and are still people I can go to with anything. Heike Rauer even viewed our apartment for us because we couldn’t be there in person.
It was a shame that the construction work for my lab was delayed, but the situation has now been resolved, fortunately, and it can get going. I have the impression that people here are keen to find a solution for everything.
And everyone I’ve met so far, whether it’s been in the Life and Health Transdisciplinary Research Area or in the biology, chemistry or biomedicine groups, has been helpful and super nice. I’ve had a genuinely friendly welcome across the board.
How are you finding the city?
Bonn has more of an international flavor than Freiburg, and there’s more going on. Not a weekend seems to go by without some festivity somewhere. And Cologne is just down the road. That was one of the first things we did, as it happens. My daughter really wanted to go to gamescom. And it never takes long to travel from place to place in Bonn, even though it’s a fairly big city. It’s very easy to get around by bike and public transport, which I find really great.
If you could switch research fields with another professor for a day, what area would you choose?
I met a historian once who was researching the space exploration during and after the Second World War and what people back then thought about outer space, aliens, rockets and all that. Something like that must be fascinating, I think, because these are developments that have shaped humanity and science. And it’s a different point of view for me as well. There are certainly some interesting subjects out there that people are tackling where I could also learn different approaches to the ones I use as a scientist.
Where do you get your best ideas?
The best ones come just before a deadline. Why, I don’t know. Sometimes, you’re browsing a specialist journal or a professional society’s periodical and find you’re able to link something that actually has nothing to do with your research to your own situation. This has genuinely produced some ideas in the past. Apart from that, though, I don’t have a secret—usually, the idea comes when I’m not consciously thinking about it.