Related Experiment Video
Updated: Sep 7, 2025
Identifying PD-1/PD-L1 Inhibitors with Surface Plasmon Resonance Technology
Published on: May 2, 2025
A degron system targeting endogenous PD-1 inhibits the growth of tumor cells in mice
Chie Naruse1, Kazushi Sugihara1, Tatsuhiko Miyazaki2
1Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Abstract:
Recently, targeted protein degradation systems have been developed using the ubiquitin-proteasome system. Here, we established Programmed cell death-1 (PD-1) knockdown mice as a model system for subjecting endogenous mouse proteins to the small molecule-assisted shutoff (SMASh) degron system. SMASh degron-tagged PD-1-mCherry in Jurkat cells and CD3+ splenocytes were degraded by the NS3/4A protease inhibitors, asunaprevir (ASV) or grazoprevir (GRV). Growth of MC-38 colon adenocarcinoma cells injected in Pdcd1-mCherry-SMASh homozygous knock-in (KI) mice was repressed by ASV or GRV. Moreover, growth of MC-38 cells was suppressed in wild-type mice transplanted with KI bone marrow cells after GRV treatment. This is the first study to use a degron tag targeting an endogenous mouse protein in vivo. Our experimental system using the SMASh degron may be employed for treating diseases and characterizing the cellular functions of essential proteins.
Insights
Researchers developed a novel system to degrade endogenous mouse proteins using small molecule-assisted shutoff (SMASh) technology. This targeted protein degradation approach successfully repressed tumor growth in mouse models, offering new therapeutic and research possibilities.
Area of Science:
- Biochemistry
- Molecular Biology
- Immunology
Background:
- Targeted protein degradation leverages the ubiquitin-proteasome system.
- Novel degron systems are needed for precise control of endogenous protein levels.
Purpose of the Study:
- To establish a mouse model for endogenous protein degradation using the SMASh system.
- To validate the efficacy of SMASh-mediated degradation of Programmed cell death-1 (PD-1) in vivo.
- To assess the therapeutic potential of SMASh for cancer treatment.
Main Methods:
- Generated Programmed cell death-1 (PD-1) knockdown mice with a SMASh degron tag.
- Utilized asunaprevir (ASV) or grazoprevir (GRV) to induce PD-1 degradation in cell lines and mouse models.
- Administered MC-38 colon adenocarcinoma cells to assess tumor growth inhibition.
- Employed bone marrow transplantation experiments to confirm cell-specific degradation.
Main Results:
- SMASh degron-tagged PD-1-mCherry was effectively degraded in Jurkat cells and CD3+ splenocytes by protease inhibitors.
- Tumor growth of MC-38 cells was significantly repressed in knock-in mice treated with ASV or GRV.
- Tumor growth suppression was also observed in wild-type mice receiving knock-in bone marrow cells followed by GRV treatment.
- This study represents the first in vivo application of a degron tag for endogenous mouse protein degradation.
Conclusions:
- The developed SMASh degron system provides a powerful tool for targeted degradation of endogenous mouse proteins in vivo.
- This system holds promise for developing novel therapeutic strategies for diseases.
- It also offers a valuable method for characterizing the functions of essential proteins in cellular processes.
