Presentation Information
[P03-332]Small Molecule Hec1 Inhibitors Probe the Hec1/Nek2 Interaction: Disrupting the Complex to Reveal Stability Mechanisms
○Jiann-Jyh Huang1 (1. Institute of BioPharmaceutical Sciences, National Sun Yat-sen University (Taiwan))
Keywords:
Hec1,Nek2,proteasome-mediated degradation,drug candidate,chromosome segregation
[Purpose]
The interaction between the kinetochore protein Hec1 and Nek2 kinase is essential for chromosome segregation. However, the specific biological consequences resulting from disrupting this complex remain unclear due to the lack of specific chemical tools. We sought to address this by designing potent, selective small molecule Hec1/Nek2 protein–protein interaction inhibitors. These probes help to determine how Nek2 stability relies on its association with Hec1.
[Method]
We performed structure-based optimization on a 4-aryl-N-pyridinylcarbonyl-2-aminothiazole scaffold, targeting the Hec1 coiled-coil domain. A representative Hec1 inhibitor was selected for mechanistic characterization. Binding modes were mapped using molecular docking simulations. To validate the molecule as a specific probe, we assessed its ability to displace Nek2 in co-immunoprecipitation assays and screened it against a panel of off-target kinases to ensure selectivity.
[Results]
The lead inhibitor exhibited low nanomolar antiproliferative activity (IC50: 14.8–21.5 nM) and bound directly to Hec1. It functions by blocking the Hec1/Nek2 protein–protein interaction. Using this probe, we observed that Hec1 binding is critical for protecting Nek2 from degradation; treatment triggered rapid loss of Nek2 via the proteasome pathway. This loss resulted in severe chromosomal misalignment and mitotic catastrophe. Crucially, the inhibitor showed no significant activity against non-cancerous cells or unrelated kinases, confirming its specificity.
[Consideration]
These findings suggest that the Hec1/Nek2 interface acts as a stability switch. The data support a "death-trap" mechanism—consistent with models proposed by Lee’s group—where Nek2 displaced from Hec1 becomes vulnerable to proteasome-mediated degradation. This highlights a specific weakness in the mitotic machinery that can be exploited for biological study, distinct from the mechanism of broad-spectrum chemotherapeutic drugs.
[Conclusion]
We report a class of small molecule Hec1 inhibitors that serve as effective chemical probes for the Hec1/Nek2 interaction. By enabling precise control over this complex, these functional molecules provide new insights into kinetochore integrity and demonstrate the utility of chemical biotechnology in investigating complex protein networks.
The interaction between the kinetochore protein Hec1 and Nek2 kinase is essential for chromosome segregation. However, the specific biological consequences resulting from disrupting this complex remain unclear due to the lack of specific chemical tools. We sought to address this by designing potent, selective small molecule Hec1/Nek2 protein–protein interaction inhibitors. These probes help to determine how Nek2 stability relies on its association with Hec1.
[Method]
We performed structure-based optimization on a 4-aryl-N-pyridinylcarbonyl-2-aminothiazole scaffold, targeting the Hec1 coiled-coil domain. A representative Hec1 inhibitor was selected for mechanistic characterization. Binding modes were mapped using molecular docking simulations. To validate the molecule as a specific probe, we assessed its ability to displace Nek2 in co-immunoprecipitation assays and screened it against a panel of off-target kinases to ensure selectivity.
[Results]
The lead inhibitor exhibited low nanomolar antiproliferative activity (IC50: 14.8–21.5 nM) and bound directly to Hec1. It functions by blocking the Hec1/Nek2 protein–protein interaction. Using this probe, we observed that Hec1 binding is critical for protecting Nek2 from degradation; treatment triggered rapid loss of Nek2 via the proteasome pathway. This loss resulted in severe chromosomal misalignment and mitotic catastrophe. Crucially, the inhibitor showed no significant activity against non-cancerous cells or unrelated kinases, confirming its specificity.
[Consideration]
These findings suggest that the Hec1/Nek2 interface acts as a stability switch. The data support a "death-trap" mechanism—consistent with models proposed by Lee’s group—where Nek2 displaced from Hec1 becomes vulnerable to proteasome-mediated degradation. This highlights a specific weakness in the mitotic machinery that can be exploited for biological study, distinct from the mechanism of broad-spectrum chemotherapeutic drugs.
[Conclusion]
We report a class of small molecule Hec1 inhibitors that serve as effective chemical probes for the Hec1/Nek2 interaction. By enabling precise control over this complex, these functional molecules provide new insights into kinetochore integrity and demonstrate the utility of chemical biotechnology in investigating complex protein networks.
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