14. Sept. 2022

The findings were published in the scientific journal Nature

The scientific journal NATURE has just published the discovery of the research team led by Dalibor Blazek that describes a previously unknown mechanism regulating RNA splicing – an essential process for the control of gene expression. RNA splicing is performed by spliceosome – cellular splicing machinery responsible for the removal of “junk” RNA from the newly made RNA. The scientists showed that a protein called CDK11 plays a central role in the assembly and activation of the spliceosome and in splicing regulation. Furthermore, Blazek’s research team showed that the anti-cancer compound OTS964, which selectively targets CDK11, affects the splicing process. The effect of CDK11 on spliceosome activation had until then been unknown. The research findings of Dalibor Blazek and his colleagues open up new avenues in splicing and gene expression research. Splicing modulation through CDK11 inhibition may also lead to future therapeutic applications.

CDK11 had been previously associated with a role in splicing, but the precise mechanism was unknown. One reason was that molecules that manipulate CDK11 activity were missing. A publication by Jason Sheltzer in 2019 showed that a molecule called OTS964 inhibits CDK11 and, at the same time, kills cancer cells by targeting the CDK11. But what CDK11 exactly does in cells was unknown. The discovery of OTS964 attracted the attention of Dalibor Blazek, whose lab has been studying CDK11 for many years.

First, Blazek’s research team wanted to determine whether OTS964 targets only CDK11 or whether it affects other proteins similar to CDK11, so-called kinases, in cells. The team screened the OTS964 against 412 human kinases and performed other experiments, finding that OTS964 indeed targets only CDK11. Such a strong kinase/inhibitor match is very unique since most inhibitors also have an effect on other kinases and switch them off unintentionally. One can imagine an inhibitor as a switch that can turn a kinase off to affect its activity. Kinase inhibitors block the action of particular kinases and are often used to stop the growth of cancer cells. Knowing exactly what cellular mechanism is affected by the kinase is of paramount importance for the successful identification and clinical approval of anticancer molecules. Therefore, the confirmation that OTS964 exclusively targets CDK11 and affects splicing opens up several new research directions. This complete match provided itself as the perfect tool to examine what role CDK11 plays during the splicing process.

The spliceosome plays a key role during the splicing process. One can imagine a spliceosome as a film editing machine that selectively cuts out irrelevant or incorrect material (in this case, the introns) from the initial film and sends the cleaned-up version to the director. During splicing, the junk RNA (introns) is removed from newly made RNA. This process is directed by the spliceosome and undergoes tightly controlled assembly. “We demonstrated the central role of CDK11 in spliceosome assembly and splicing regulation and that OTS964 acts as a CDK11 inhibitor that suppresses spliceosome activation and the entire splicing process,” explains Dalibor Blazek.

Spliceosome activation is crucial for the regulation of splicing. However, the mechanism of the activation is very complex and not properly understood. “We have characterised a novel mechanism and discovered a new tool that can manipulate this mechanism. Splicing modulation though CDK11 could have therapeutic potential and opens up the door for future studies on further roles of CDK11 in splicing and gene expression,” concludes Blazek.

This study is an example of meaningful interdisciplinary collaboration between colleagues across several institutes and disciplines. The experimental part of the study was led first by first authors Milan Hluchy and Pavla Gajduskova from the Dalibor Blazek Research Group, who performed genomics, biochemistry and molecular biology experiments with the help of Michal Rajecky and Zuzana Slaba. The bioinformatics analyses of the genomics data were performed by the labs of Caroline Friedel (LMU Munchen), Jernej Ule (Crick Institute, London) and Igor Ruiz de los Mozos (Crick Institute/the University of Navarra). Labs of Kamil Paruch (Department of Chemistry at Masaryk University) and Stefan Knapp (Goethe University, Frankfurt am Main) performed the chemical-biology characterisation of OTS964, and the research group of Zbynek Zdrahal (CEITEC Masaryk university) helped with analyses of proteomics data. The work was funded by a GACR standard grant, GAMU grants and by CEITEC Masaryk University.

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