Charlotte Aumeier is an Assistant Professor of Biochemistry at the University of Geneva, Switzerland. After completing her PhD at the University of Bonn, Germany, studying the cytoskeleton of diatoms, Charlotte moved to the University of Grenoble, France, for a postdoc, where she became hooked on microtubules. In 2018, she established her own lab in Geneva, where she and her team work to uncover the dynamics and regulatory mechanisms of microtubule networks using a variety of approaches, including synthetic biology and non-standard model organisms. We spoke with Charlotte over Zoom to learn more about her work, her love of diatoms and how she views some of the biggest challenges of her career as her biggest advantages as a scientist.
What inspired you to become a scientist?
I always wanted to be a scientist, even before primary school. I think what really inspired me is nature itself: its beauty and its complexity. As a small kid, my parents saw me sitting in front of ants; I observed them for hours and hours, just watching how they move and how they organise themselves. But I'm from a non-scientific family background, so it may have been tougher for me to plan a scientific career because I didn't have the knowledge of how things work in academia. I definitely made some ‘wrong’ career decisions, which have turned out to be perfect decisions after all, even though they weren't in a straight line. But my parents and family were always super supportive and proud of me going in this direction, so that was a big plus.
During your PhD at the University of Bonn in Dr Diedrik Menzel's lab, you studied cytoskeletal networks in diatoms, an unconventional model organism in cell biology. What is your favourite thing about working with diatoms?
I have so many favourite things about diatoms; it is really hard to pin one down. Diatoms are unicellular algae enclosed by a highly structured cell wall made out of silica, and they are responsible for fixing up to 25% of global CO2. The way they are structured and organised is amazing. The cytoskeleton, which is by itself very dynamic, defines the shape and structure of the diatoms. Beauty, regulation, organisation, ecological importance: you name it, it's all there. So for me, this was a great thing to work on. But on the other hand, it's not as straightforward as working with yeast or Drosophila. It's a non-model organism, and your output is definitely much lower than when you work with mammalian cells, where everything is already established and you can just focus on your scientific question. With diatoms, whatever tool you want to use to answer your scientific question, you have to develop for yourself. So it challenges you, but it pays off.
How did your unconventional research and non-linear career decisions end up helping you progress?
I actually started my research in gravity biology for my master’s degree. For my PhD, I then went to work with Diedrik Menzel, who was close to retiring. I love my PhD supervisor, and the lab was great, but it was not the typical career move to a large or well-known research institute. I was the first one working on diatoms in the lab, so I had nobody to show me how things worked, and I had to figure that all out as I went. But it meant that I matured a lot during my PhD, which prepared me to work independently as a postdoc. Even so, at the end of my PhD, I thought ‘okay, you screwed it up. You didn't choose the best starting point. Science is over for you.’ However, I wanted to pursue an academic career, so I chose to take the initiative to go to some carefully selected conferences to present my PhD work. At one conference, I captured Laurent Blanchoin, who co-leads a lab with Manuel Théry in France, in front of my poster to tell him about my work. He asked what I wanted to do next, and I said ‘I want to do a postdoc in your lab!’ He said maybe try writing an application, and I replied that I already did, but he never answered. He apologised and asked if we should have lunch, and I said ‘yes, please!’ That's how I ended up here; I had to take the initiative. I'm so thankful to Laurent because he gave me the boost I needed. Laurent and Manuel's lab was the perfect environment to move forward in.
For your postdoc, you moved to France to work with Laurent Blanchoin at the University of Grenoble. How was your experience moving to a new country, and what do you think are the benefits of international training experiences for early career researchers?
I love to live in other countries, to have input from different cultures and experience different approaches. I have to say, it's very important for people to experience living abroad sometimes, because then you actually realise how difficult it can be to be a foreigner or to learn a new language, and that makes you appreciate much more the difficulties other people go through. It can be so lonely if everybody's speaking a different language and you're the only one who can't. This is really underestimated by people who have never lived abroad.
Scientifically, it is always highly recommended to change your lab between PhD and postdoc to learn different working cultures. I'm not sure it's necessary to change countries, but I think you should definitely change your location in order to experience different working environments. If you go from a German university to a Max Planck Institute, you're very often under the leadership of a non-German scientist, so you'll already get different leadership styles and different dynamics. Additionally, you'll also see different organisational structures between universities and research centres. I personally think it's very good for self-development to be exposed to new environments. Career-wise, it is useful for later job searches to change countries, because you better understand the different systems. For example, the French scientific system works differently from the German one, and there are different academic positions in each.
… it's very important for people to experience living abroad sometimes, because then you actually realise how difficult it can be to be a foreigner or to learn a new language, and that makes you appreciate much more the difficulties other people go through.
In 2018, you started your own lab at the University of Geneva, Switzerland. What did you feel was the biggest challenge to overcome as a new group leader?
Everything! The first year was just incredibly tough. I think I have never learned so much in my life as I did in this first year of being a PI. The biggest difficulty I faced was that I had no clue what people expected from me. Suddenly I was a PI, but I had no idea what it really was. I thought I was well prepared, and then when I started, I was like ‘okay, what am I supposed to do now?’ Figuring that out took a lot of energy and time. Learning to fit in with other existing groups, establishing your lab, writing grants, starting financial calculations, learning accounting, learning how to guide people and hire people, dealing with companies and negotiating prices. I'm quite German, and I'm used to there being a set market price – I pay that and I'm done. This is not how it works in science; you need to negotiate. To overcome these challenges, I got advice from senior PIs in my department. In addition, what was incredibly helpful was a ‘young PI club’, where young PIs clustered and had regular lunches together. This was the perfect opportunity to share information and experiences, learn from each other, or just give each other mental support.
What are the main questions your lab is currently trying to answer?
The main question is how such a dense and dynamic cytoskeletal network in the cell organises in space and time to fulfil so many different biological functions. We address that on several different levels in my group. We focus on microtubules in particular, but I don't fully exclude actin. Actually, for my postdoc, I started out working on actin, but I somehow stumbled across microtubules, and I got hooked, though I certainly like actin a lot. Maybe one day I will push myself a little bit out of this niche again, but I don't know. Microtubules are just great!
An important focus of your work, and of the microtubule field in general, is interpreting the many posttranslational modifications that make up the ‘tubulin code’. What new methods have your group adapted to tackle this challenge?
Posttranslational modifications of tubulin play a crucial role in fine-tuning microtubule properties. A general problem is that all these posttranslational modifications are heterogeneous along microtubules and differ between cell types. You can purify tubulin out of, for example, a cow brain, but then you have a range of different modifications. Another possibility is to purify tubulin that has very few modifications from cultured cells. Then you can enzymatically treat the protein, for example with polyglutamylases, but you still have no idea how many glutamates you have and no control over where they are positioned. So, although you are super precise in one aspect, you are imprecise in another. This is where we teamed up with the lab of Beat Fierz at the Swiss Federal Institute of Technology in Lausanne (EPFL). We developed a system of semi-synthetic tubulins, where we purify the core of the tubulin, then take a synthesised tail and click them together. The synthesised tail carries exactly our precise modifications, which allows us 100% control over what modifications we have. We can control position and length of the modifications, and combinations are possible.
Your current work utilises a range of approaches, including reconstitution of microtubules, mammalian cell culture and, once again, diatoms. Would you encourage more cell and molecular biologists to adopt the use of non-standard model organisms in their research?
The advantage of non-model organisms is that they are an open box of great discovery options. With non-model organisms, you might see different directions and possibilities you have not thought about before, because we've never looked at a particular biological process from this angle or on this level of complexity. I see this as a big benefit, as it helps us to think more broadly. Different organisms find different solutions to fulfil similar tasks. As for diatoms, they have a really reduced set of proteins that regulate the microtubule or actin networks. Often when we study very important microtubule or actin regulators in mammalian cell lines, they are not present in diatoms. For example, some of the most studied actin regulators in other systems are profilin, α-actinin and Arp2/3, but they are not present in diatoms. By looking at different model organisms, one can discover different functionalities or other proteins that take over those functions, which are overlooked in the standard model organisms. In mammalian neurons and standard cell lines, the microtubule network is very dense and it's super tricky, if not sometimes impossible, to discern one microtubule from another, especially at the centre of the cell. Diatoms have a reduced, clearer network, but still a lot more than yeast, which has very few microtubules, so they might be a nice intermediate organism to study cytoskeletal complexity. I think these opportunities are very rewarding and exciting.
What is your approach to mentoring and establishing a good lab culture?
My approach to mentoring is to acknowledge that it's actually quite tricky to mentor people, because every person is different. You cannot have one mentoring strategy because everybody needs something different. You need time to understand their characters and where the difficulties are. At a certain point, you need to understand their limitations to enable them to mature. For me, this maturation is important. Very often you have to put your finger on the weak spot of the student to make that thing better, which is sometimes difficult. I always try to make those discussions very positive, but it's not always easy. A PhD is not only a super exciting time; it's also a lot of frustration, a lot of failure. But it shows you how much intrinsic desire and motivation you have. You can also get motivation from stepping outside the lab. Sometimes it helps for refocusing when you step away to do something else between assays that aren't working to remotivate yourself a little. When I recruit new lab members, they definitely need to have intrinsic excitement about science, so I try to keep a good lab team spirit. My team is really close, and they interact very well. It's really important for me and for the lab culture that they collaborate a lot and that they help each other out continuously; that they interact and share things, and that they are honest.
It's really important for me and for the lab culture that [my team] collaborate a lot and that they help each other out continuously; that they interact and share things, and that they are honest.
What elements, inside or outside the lab, have been key to your success so far?
There are several things. One is that I really love what I'm doing. A key part of this is that my family has always been so incredibly supportive. I'm married and I have four kids – and it is actually not that difficult to have four kids and a scientific career – it's actually one reason why I think I was successful. I had my third child in the first year of my PhD; I did my PhD during the day, and in the evenings and mornings I was a full-time mum. While handling three kids, I had no time to think about my experiments; I had to think about how to build Lego, or how to get stains out of the carpet again, which somehow gave me the necessary distance to be fresher the next day. Having kids allowed me to do this, and I think that actually helped me to advance in science. Another thing is that my husband and I agreed that the weekend is the weekend. I always try to keep it free, and I am sometimes not that successful, especially when grant applications come up. But I think you need to disconnect sometimes and come back to the lab fresher and more creative.
What is the best science-related advice you ever received?
One thing that has stuck with me comes from Laurent Blanchoin, my postdoc supervisor. He told me ‘When you start your own group, get your science done first and then go to meetings.’ If you're a young female scientist, you can get a lot of invitations to meetings. If you run around at conferences talking about your postdoc, you're visible, but you don't produce anything, and you have no time to advance as a PI. And being in a tenure track position is super exhausting – much tougher than your postdoc – so focus on it. I absolutely followed his advice; I did not go to conferences before I had my first publication out. Then, after the first publication came, COVID-19 struck... But at the time that was really excellent advice, because it's very easy to lose yourself in meetings and conferences and not get your lab started. I'm now tenured; I just passed my tenure evaluation. For researchers on the tenure track: don't lose your mind while going through the tenure process. It's not an easy path. I think it's important that people know it's sometimes quite tough to get yourself and the lab going. Another piece of advice I got here in Geneva from another PI is something quite simple: just do it. If you find it exciting, go for it!
Finally, could you tell us an interesting fact about yourself that people wouldn't know by looking at your CV?
I love everything connected to water. I swim all the time, and I love sailing and snorkelling. I do quite a bit of sport in general, as I also dance ballet. This is something I didn't do in the first two years of being a young group leader because I was always too busy and had no time. Now I have managed to reinforce having time to do sports four times a week, and that really is good for me. I like to be outdoors a lot. I also love food, and good cooking is definitely my sweet spot. I love to have my family and friends around me; hosting and cooking for twenty people around our table is my idea of the perfect evening.
Charlotte Aumeier's contact details: Department of Biochemistry, University of Geneva, Science II, 30 Quai Ernest-Ansermet, 1205 Genève, Switzerland
Charlotte Aumeier was interviewed by Amelia Glazier, Features & Reviews Editor for Journal of Cell Science. This piece has been edited and condensed with approval from the interviewee.