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Detection of Signaling Effector-Complexes Downstream of BMP4 Using in situ PLA, a Proximity Ligation Assay
Published on: March 3, 2011
A multiplexed time-resolved fluorescence resonance energy transfer ultrahigh-throughput screening assay for targeting
Abstract:
The signaling pathway of transforming growth factor-beta (TGFβ) plays crucial roles in the establishment of an immunosuppressive tumor microenvironment, making anti-TGFβ agents a significant area of interest in cancer immunotherapy. However, the clinical translation of current anti-TGFβ agents that target upstream cytokines and receptors remains challenging. Therefore, the development of small molecule inhibitors specifically targeting SMAD4, the downstream master regulator of TGFβ pathway, would offer an alternative approach with significant therapeutic potential for anti-TGF-β signaling. In this study, we present the development of a cell lysate-based multiplexed time-resolved fluorescence resonance energy transfer (TR-FRET) assay in an ultrahigh-throughput screening (uHTS) 1536-well plate format. This assay enables simultaneous monitoring of the protein-protein interaction (PPI) between SMAD4 and SMAD3, as well as the protein-DNA interaction (PDI) between SMADs and their consensus DNA binding motif. The multiplexed TR-FRET assay exhibits high sensitivity, allowing the dynamic analysis of the SMAD4-SMAD3-DNA complex at single amino acid resolution. Moreover, the multiplexed uHTS assay demonstrates robustness for screening small molecule inhibitors. Through a pilot screening of an FDA-approved and bioactive compound library, we identified gambogic acid and gambogenic acid as potential hit compounds. These proof-of-concept findings underscore the utility of our optimized multiplexed TR-FRET platform for large-scale screening to discover small molecule inhibitors that target the SMAD4-SMAD3-DNA complex as novel anti-TGFβ signaling agents.
Insights
We developed a novel assay to screen for small molecules targeting the SMAD4 protein, a key regulator in TGFβ signaling. This approach identified potential new cancer immunotherapy agents by analyzing protein interactions.
Area of Science:
- Molecular Biology and Biochemistry
- Cancer Immunotherapy
- Drug Discovery
Background:
- The transforming growth factor-beta (TGFβ) pathway is critical in creating an immunosuppressive tumor microenvironment, making it a target for cancer immunotherapy.
- Current anti-TGFβ therapies face clinical translation challenges, necessitating alternative strategies like targeting downstream regulators.
- SMAD4 is a master regulator of the TGFβ pathway, making it a promising target for small molecule inhibitors.
Approach:
- Developed a cell lysate-based multiplexed time-resolved fluorescence resonance energy transfer (TR-FRET) assay for ultrahigh-throughput screening (uHTS) in a 1536-well format.
- The assay simultaneously monitors protein-protein interactions (SMAD4-SMAD3) and protein-DNA interactions (SMADs-DNA motif).
- Enabled dynamic analysis of the SMAD4-SMAD3-DNA complex with high sensitivity and single amino acid resolution.
Key Points:
- The multiplexed TR-FRET assay is sensitive and robust for screening small molecule inhibitors.
- Successfully performed a pilot screen using an FDA-approved and bioactive compound library.
- Identified gambogic acid and gambogenic acid as potential hit compounds targeting the SMAD4-SMAD3-DNA complex.
Conclusions:
- The developed multiplexed uHTS TR-FRET platform is effective for large-scale screening.
- This platform can discover novel small molecule inhibitors targeting the SMAD4-SMAD3-DNA complex.
- These inhibitors represent a new class of anti-TGFβ signaling agents with therapeutic potential in cancer immunotherapy.
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