Parasite cell division cycles decoded

A team from the Wellcome Centre for Anti-Infectives Research (WCAIR) at the University of Dundee has used a high-throughput genetic screen to decode mechanisms underpinning the trypanosome cell cycle.

In a paper just published in Nature Communications the Horn lab describe hundreds of proteins that impact the cell division cycle in trypanosomes.

These important parasites cause lethal disease in both humans and livestock and display a mix of conserved and divergent features relative to human cells. Notably, proteins that impact cell cycle progression are typically required for survival and growth, and a number of these parasite proteins are therefore also promising potential drug targets.

Before cells divide, they must copy their DNA and segregate their chromosomes. They must also replicate and segregate many other cellular components, and these steps must be completed with fidelity and coordinated. Unsurprisingly then, the cell cycle is subject to elaborate mechanisms of regulation and control.

The Dundee team often uses genome-scale genetic screening in Trypanosoma brucei to explore biological questions. These screens can yield large datasets and often also yield unanticipated insights. One prior dataset, that has been particularly widely exploited by the research community, reports parasite loss-of-fitness following knockdown of each individual protein.

David Horn said “Given the impact of our prior ‘fitness profiling’ dataset, we felt that a parallel ‘cell cycle profiling’ dataset would be a great asset. This came with some technical and bioinformatics challenges, in terms of both running the screen, and in data analysis, but Catarina Marques (now a post-doc in Glasgow), Melanie Ridgway and Michele Tinti overcame these challenges and are all recognised as equal contributing authors on the paper as a result.”

Melanie Ridgway said “These genetic screens are incredibly powerful, and several new and interesting hypotheses have emerged. One area that I will explore further is the role of ‘redox’ signalling, which can impact protein structure and folding, in coordinating the replication and segregation of cellular compartments. Trypanosomes present a great model system in which to investigate these processes, in terms of both molecular and cell biology.”

Michele said: “Genome-scale genetic screens present some interesting challenges in terms of data quantification and visualisation. In this case, we were able to digitally reconstructed >10,000 cell cycle profiles following genome-wide knockdown. Some of the resulting visualisations can be seen in the paper and we’ve also made all outputs available via an online interactive database, making this large dataset readily accessible and exploitable.”

David added: “Although cell cycle controls in nucleated cells have been subject to intensive study, we still have much to learn. We hope that this work helps to accelerate discovery in this area and, since trypanosomes have been evolving on a different path relative to the animals, plants, and yeasts for over a billion years, some novel mechanisms may emerge”.

17th September 2022