In a collaboration between the team of Pascal Genschik and several international partners, an important step has been made toward understanding the mechanisms that control the plant cell cycle.
This study, published in the journal Science Advances, reveals the central role of a protein called FBL17. This protein belongs to the F-box family, which is involved in the ubiquitination system – a key cellular mechanism that regulates protein stability by targeting proteins for controlled degradation. Although FBL17 was already known to participate in plant development, its precise role in cell cycle control had remained poorly understood until now.
The researchers show that FBL17 acts as a key regulator of a central transcriptional module of the cell cycle, the RBR1–E2F/DP complex, which controls the expression of many genes required for DNA replication and cell cycle progression. By modulating the stability of specific E2F transcription factors, FBL17 helps maintain a fine balance between activation and repression of cell cycle genes.
When FBL17 is absent, this balance is disrupted: some transcription factors accumulate abnormally, leading to a massive deregulation of genes involved in cell cycle control and DNA damage responses. As a consequence, plants display severe developmental defects and altered cellular organization.
One particularly striking result of the study concerns the transcription factor E2Fc. In the absence of FBL17, E2Fc accumulates but loses its ability to function properly within the RBR1–E2F/DP complex. Remarkably, genetic inactivation of E2Fc largely restores near-normal development in plants lacking FBL17, revealing a novel combinatorial regulatory mechanism linking ubiquitination and transcriptional control.
In summary, this study highlights the key role of FBL17 in the fine coordination of the plant cell cycle. By ensuring precise control of the stability of major cell cycle regulators, this work led by Pascal Genschik’s team provides new insights into plant development and genome integrity maintenance.
