Cell scientist to watch – Hana Polasek-Sedlackova Free

Hana Polasek-Sedlackova. Photo credit: Jana Mensatorova.

What inspired you to become a scientist?

I've been fascinated by nature from a very young age. Growing up in a village where my parents had a small farm, I was constantly surrounded by nature, animals and plants. During high school, I participated in the Biological Olympics science camps, which are international biology competitions. These two weeklong camps, held in beautiful mountainous locations, brought together university professors who set up laboratories and delivered lectures on various areas of biology. I vividly remember one camp where I attended a lecture on molecular biology. I was amazed by how relatively simple molecular rules could explain the complexity of life. After returning from that camp, I knew I wanted to learn more about biology – especially molecular biology. However, high school biology felt less inspiring, as it focused heavily on memorisation and writing rather than deep, conceptual thinking. I found it tedious to memorise taxonomy and plant classifications when I was eager to understand the fundamental principles of life. Around this time, I discovered a programme that allowed high school students to participate in research internships at universities. I reached out to Lumir Krejci, the head of a biochemical laboratory at Masaryk University (Brno, Czech Republic). Although I got lost on my way to the campus and arrived 1 hour late to our meeting, he patiently waited for me. That day was decisive – walking into the lab, I knew this was where I belonged. I quickly adapted to lab work and soon began contributing to small projects, which grew in significance as I gained experience. I continued working in Lumir Krejci's lab throughout my bachelor's and master's studies. In the Czech Republic, these internship programmes allow students to graduate with substantial research experience – sometimes even with published research papers. My early research experience was not only incredibly fun but also deeply formative.

How did you choose what to do and where to go for your PhD?

I love biochemistry, and in the Krejci lab, we primarily focused on purifying proteins – isolating them from cells and characterising their properties. However, while I appreciated biochemistry's clean and systematic approach, I started to miss the complexity of the cell. My project reflected this shift, as it incorporated not just biochemical methods but also complementary cell-based approaches. I realised that I wanted to learn cell biology from experts in the field. As a bachelor's student, I had the opportunity to do an internship in Professor Ian Hickson's lab at the University of Copenhagen (Denmark). That experience was eye-opening. First, it introduced me to an outstanding cell biology lab. Second, it gave me a glimpse of the wider scientific world beyond Brno. It was during this time that I fully grasped the global scale of research. That realisation was decisive – I knew I wanted to become a cell biologist. I was keen to train in a lab where I could master imaging techniques and microscopy. I sought an environment where researchers actively discussed their work, held seminars together, and fostered a collaborative rather than overly competitive atmosphere. This is exactly what I found at the University of Copenhagen, which led me to join the laboratory of Jiri Lukas (Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Denmark), known for its expertise in microscopy and cell biology. During my PhD, I studied DNA replication in human cells. In retrospect, our work contributed to understanding the minichromosome maintenance (MCM) paradox. The MCM paradox is about the excess loading of MCM helicases onto DNA in G1, despite only a subset being used in S phase. This surplus (apart from their function as backup under replication stress) acts as a speed bump on the road, helping to regulate the movement of replication forks. Replication forks that move too fast or too slowly can lead to replication stress and genome instability. However, it is important to note that my PhD project began as many PhD projects do – a senior colleague, Kumar Somyajit, my lab mentor and friend, had identified an interesting protein in a mass spectrometry screen, gathered some preliminary data, and handed the project to me to explore further. As we progressed, we realised that our tools and approach position us to address broader questions, ultimately leading to key insights into the MCM paradox.

Following your PhD at the University of Copenhagen in the laboratory of Prof. Jiri Lukas, you decided to stay as a postdoc. Why did you make this decision?

The answer is quite simple. I started in research as a high school student and quickly developed an understanding of how science works – not fully, of course, but enough to navigate the field with confidence. By the time I defended my PhD thesis in 2020, I had already begun planning my next steps as an independent researcher. After my thesis defence, Jiri Lukas offered me to stay in his lab for a year as a postdoc. That year served as a transitional period, during which I focused on securing starting grant funding and refining my research direction. It wasn't a traditional postdoc experience but rather a stepping stone toward starting my own lab. The key reason I chose this path was the incredible freedom I had in the Lukas lab. He encouraged us to fully immerse ourselves in projects and lead them independently. Even as PhD students, we were given the same level of project of ownership and responsibility as postdocs, which prepared me for the next stage of my career.

How did you then decide what direction you wanted to go in, and where to go, when making the transition to setting up your own research group

First, I realised that my research was progressing well and raising interesting questions, so I decided to continue working on DNA replication. Second, I knew Lukas was moving away from this field, and it would have felt like a missed opportunity to abandon my work. Third, I recognised that finding another postdoc position with the same level of independence and collaborative atmosphere would be challenging. For these reasons, I decided then to take the leap and establish my own research group. I had always known that I wanted to return to the Czech Republic. Even during my master's studies, I told myself that one day I would come back, inspired by the previous generation of scientists who returned and brought fresh perspectives to the Czech scientific community. I wanted to give back to the system that had invested in my education and training. However, returning so soon was not part of my initial plan. Two key factors influenced this decision: my personal life and COVID-19. I chose Denmark for my PhD because it was relatively close to the Czech Republic, allowing me to stay connected to my family. Throughout my PhD and postdoc, I was in a long-distance relationship with my partner, now my husband. As I was finishing my PhD, I realised I could no longer manage a long-distance relationship – I needed us to be together. Then, the COVID-19 lockdowns made it even more difficult for us to see each other, reinforcing my decision to return sooner rather than later.

In 2022, you started your own lab at the Institute of Biophysics, CAS. What challenges did you face when starting your own lab that you didn't expect?

There were many, many challenges. But part of my personality is that I try not to overthink things too much. I also knew from colleagues who had been through the same experience that this would be one of the most difficult periods of a scientific career. So, I managed my expectations and took things as they came. I told myself: “these are the cards I have; I'll play with them and see what I can achieve”. One of the first challenges I faced was realising that I had to build the lab, buy all the equipment, and smartly organise it so that everything could be fitted in a relatively small space. I was given an empty room that needed to be renovated, and I had to figure out how to set everything up from scratch. Another crucial part of this process was finding the right people to support me at different levels. My husband was tremendously helpful with the practical aspects – he's a construction project manager, so managing people and overseeing renovations are his areas of expertise. He helped me plan the space so that it would be functional and include everything the lab needed. In many ways, running a lab is like running a company, and his advice was invaluable. Right now, we are a team of six, which is a good size. One of the best decisions I made was hiring a lab manager. She was already at the institute and knew how everything worked, which saved me a great deal of time and effort in navigating administrative and logistical details. Through open calls, I was able to recruit a highly talented and motivated postdoc and PhD students.

Did you have any mentors that helped you in your career?

From an early age, I was fortunate to have great mentors. Even in elementary school, I had an excellent biology teacher who nurtured my curiosity. Later, as a high school student, I was lucky to have Lumir Krejci as a supervisor. He was incredibly patient and supportive, guiding me through my first research experience in his lab. During my PhD, Kumar Somyajit's enthusiasm for science was contagious, and he introduced me to the fascinating field of DNA replication. The days we spent together in the lab – discussing science and life, conducting experiments, and simply having fun – were priceless. Of course, I must also mention my PhD supervisor, Jiri Lukas, who truly shaped my scientific perspective and took my understanding of scientific research to the next level. I am particularly grateful of my ongoing scientific relationship with him – he is always willing to discuss science, read my manuscripts, provide feedback, and offer advice whenever I face challenges. His continued support is truly exceptional, and I deeply appreciate it.

What is the best science-related advice you ever received?

In science, we are constantly arguing and debating, whether in manuscripts, revisions or grant applications. We construct clear and bold arguments to support our ideas. But I've come to realise that sometimes, when working in the lab, an inner voice – a gut instinct – can guide you. In those moments, you might not have strong evidence or a solid argument to justify your intuition, but it's worth paying attention to. Of course, science is built on data, evidence and rational thinking. But sometimes, your subconscious mind is processing information in ways you don't immediately understand, and that instinct might be pointing you in the right direction. I believe it's important to listen to that instinct – not blindly, but as part of your decision-making process.

And what advice would you give to someone seeking independence?

The best advice I can pass on is the same advice I once received from Jiri Lukas: surround yourself with positive people who share a similar mindset. I don't mean people with the same background – diverse perspectives and approaches are valuable – but rather those who bring motivation, enthusiasm and a proactive attitude. Being around people with this kind of energy is key to staying inspired and pushing forward. In addition, having good mentors has been essential to my career, and I always emphasise this when speaking to students, especially first year bachelor's students. In my lectures, I make a point to include a final slide reminding them how important it is to find a good supervisor or mentor – someone who will truly support their development. Taking the time to find the right mentor can make all the difference.

What are the main research questions that your lab addresses?

Our lab studies DNA replication – the precise process by which the genome is duplicated. This process fascinates me because it is so fundamental to life. Consider human development: it begins with a single cell, and for the body to form, that cell's genetic material must be copied with extraordinary accuracy before each division. This remarkable process is made possible by a complex network of molecular mechanisms that ensure replication fidelity. Any errors can lead to severe diseases, including cancer, highlighting the crucial need for tight regulation. Our research focuses on understanding how DNA replication achieves such high fidelity. We study the earliest steps of replication, specifically a process called origin licensing, which is the first step that ensures replication begins correctly. Although much is known about the factors involved, we aim to investigate an even earlier stage: how cells prepare for origin licensing. What mechanisms regulate the availability and timing of essential proteins required for DNA replication? How do cells ensure that the right proteins are present in the right amounts at the right time? A major focus in our lab is the development of new imaging techniques. Microscopy and imaging technologies are crucial tools for answering complex biological questions, an interest I developed during my time in Jiri Lukas' lab. There, I worked closely with Claudia Lukas – an exceptional microscopist – who shared my enthusiasm for imaging innovations. I have carried that enthusiasm into my own lab, where we aim to push the boundaries of what can be visualised and measured in live cells. By developing novel imaging approaches, we hope to gain unprecedented insights into DNA replication and its regulation.

Are you still doing experiments yourself?

When I first started my lab, I worked at the bench full time. Now, as my team has grown, I focus more on supportive tasks. I try to spend time in the lab to set up new techniques, train new team members and conduct exploratory experiments when I need a break from administrative work. Sometimes, these small experiments yield unexpected results, which is always rewarding.

What is your advice on establishing good collaborations?

This is a very important question. In my lab, we engage in multiple collaborations, which can generally be divided into two types: short-term and long-term. Short-term collaborations usually involve making a specific contribution or delivering a particular result and are simpler. On the other hand, long-term collaborations, where individuals work together on joint projects over an extended period, are more complex. For such collaborations to be successful, it's essential that the people involved complement each other's skills, share a similar mindset, and, above all, have mutual respect.

What do you think is needed to help more women and underrepresented researchers take up leadership positions in science?

This is an extremely important topic. Going to Denmark was an eye-opening experience. The social system there is fantastic, and it taught me that it is possible to have both a family and a career in science. In the Czech Republic, we now offer dedicated support for scientists with families, including grant schemes and various implementation tools. One of the reasons I chose our institute is because we offer a dedicated children's corner with childcare services – an initiative established by our director, Eva Bartova. This kind of support is essential, and I hope it will continue and expand.

If you could change one thing in academia, what would it be?

It would be wonderful to see equal opportunities for all scientists, regardless of their background or geographical location. When I was a student and later a postdoc, I thought ‘equal opportunities’ was just a phrase, something people said. However, now that I have my own lab, I can clearly see that these inequalities still exist. I recently read a book by Katalin Karikó (University of Szeged, Hungary), whom I had the privilege of meeting at a European Molecular Biology Organization (EMBO) conference. In her book, she recounts her career and the challenges she faced 50 years ago. I was struck by how many of the obstacles she encountered still resonate today. It made me realise that, even after five decades, the struggles persist. This is where it would be great to see change. For instance, EMBO is a great example of an organisation supporting science across a broad scientific research scope and geographical reach. I also admire Journal of Cell Science for its Cell Scientists to Watch series. When I looked through the list of interviewees, I found many exceptional researchers who shared similar experiences to mine.

Could you tell us an interesting fact about yourself that people wouldn't know by looking at your CV?

I live a peaceful village life. I commute to Brno every day for my lab, but once I'm home, it's all about village life. I really enjoy gardening. We have a small garden, and right now, we have paprika seeds growing behind our window. We also have a greenhouse, which I take care of. In addition to gardening, I love reading Nordic crime stories, a hobby I picked up during my time in Denmark. I also enjoy engineering work. We have a 3D printer, and I've learned how to design objects for 3D printing. From time to time, I create new items for our lab – preferably colourful ones. For example, I've made microtube racks, agarose gel trays and combs, and even designed an insert for a microscope stage.

Hana Polasek-Sedlackova was interviewed by Sara Morais da Silva, Reviews Editor at Journal of Cell Science. This piece has been edited and condensed with approval from the interviewee.