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Updated: Oct 1, 2025
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
The MYC oncoprotein directly interacts with its chromatin cofactor PNUTS to recruit PP1 phosphatase
Yong Wei1,2,3, Cornelia Redel1,4, Alexandra Ahlner5
1Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.
Abstract:
Despite MYC dysregulation in most human cancers, strategies to target this potent oncogenic driver remain an urgent unmet need. Recent evidence shows the PP1 phosphatase and its regulatory subunit PNUTS control MYC phosphorylation, chromatin occupancy, and stability, however the molecular basis remains unclear. Here we demonstrate that MYC interacts directly with PNUTS through the MYC homology Box 0 (MB0), a highly conserved region recently shown to be important for MYC oncogenic activity. By NMR we identified a distinct peptide motif within MB0 that interacts with PNUTS residues 1-148, a functional unit, here termed PNUTS amino-terminal domain (PAD). Using NMR spectroscopy we determined the solution structure of PAD, and characterised its MYC-binding patch. Point mutations of residues at the MYC-PNUTS interface significantly weaken their interaction both in vitro and in vivo, leading to elevated MYC phosphorylation. These data demonstrate that the MB0 region of MYC directly interacts with the PAD of PNUTS, which provides new insight into the control mechanisms of MYC as a regulator of gene transcription and a pervasive cancer driver.
Insights
Researchers discovered how the MYC protein interacts with PNUTS, a key regulator. This finding sheds light on MYC
Area of Science:
- Molecular Biology
- Cancer Research
- Structural Biology
Background:
- MYC is a crucial oncogenic driver frequently dysregulated in human cancers.
- Targeting MYC remains a significant challenge in cancer therapy.
- The PP1 phosphatase and its regulatory subunit PNUTS influence MYC phosphorylation, chromatin binding, and stability.
Purpose of the Study:
- To elucidate the molecular mechanism underlying the interaction between MYC and PNUTS.
- To identify the specific regions and residues involved in MYC-PNUTS binding.
- To understand how this interaction impacts MYC's function and oncogenic activity.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy to determine protein structures and interactions.
- In vitro binding assays to characterize the MYC-PNUTS interface.
- In vivo studies using point mutations to assess the functional consequences of disrupted interaction.
Main Results:
- MYC directly interacts with PNUTS via its MYC homology Box 0 (MB0) region.
- A specific peptide motif within MB0 binds to the PNUTS amino-terminal domain (PAD).
- Mutations at the MYC-PNUTS interface weaken the interaction, leading to increased MYC phosphorylation and altered function.
Conclusions:
- The MB0 region of MYC directly binds to the PAD of PNUTS, defining a novel interaction interface.
- This interaction is critical for regulating MYC phosphorylation, stability, and oncogenic activity.
- Understanding this interaction provides new avenues for targeting MYC in cancer treatment.
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