Cell-Based Drug Screening for Inhibitors of Autophagy Related 4B Cysteine Peptidase
June 30th, 2023
Here, we describe a detailed protocol for the use of a luciferase-based reporter assay in a semi-automated, high-throughput screening format.
The main aim of research in my lab is to understand the regulation of autophagy and in particular of the ATG4 cysteine protean and use this knowledge to develop small molecule inhibitors that target this pathway in particular for diseases such as pancreatic cancer. We use high content, high throughput screening technologies to identify drug targets as well as drug candidates and we focus on the ATG4 cysteine protease family because we think it's a very good drug target for various forms of cancer. We have been studying the ATG4 family members for quite some time now.
We made significant discoveries into dysfunction of this protein family and cells. We've also identified novel post-translational mechanisms of regulation of the ATG4 family members and currently we are developing small molecule inhibitors and also activators of the ATG4 families for diseases such as cancer and neuro degeneration. There are not many assays to monitor ATG4 protease activity in cells.
So we were one of the first to develop a luciferase based assay to monitor this activity. And our assay is quite unusual because it uses secreted, let's say phrase, therefore we don't need to license the cells and we can adapt this protocol easily to high throughput screening methods and lab automation. We have focused on the ATG4 B protein protease for quite some time now.
We have generated knockout cell lines of the ATG4 family members. We have identified novel post-translational regulation mechanisms of ATG4, and ultimately we have also identified several novel small molecule compounds that could inhibit and even activate the ATG4 B protease. In the future, we'd like to continue our work on the ATG4 family members.
We think that's quite a lot that is currently unknown and still remains to be uncovered. For example, how these proteins regulate autophagy in neurons is currently completely not understood. We'd also like to focus our work on validation of these small molecule compounds that we've identified and potentially to use activators in neurodegenerative diseases.
View the full transcript and gain access to thousands of scientific videos
Overview
This study focuses on the regulation of autophagy, particularly the role of the ATG4 cysteine protease family in cancer and neurodegenerative diseases. The researchers developed a luciferase-based assay for monitoring ATG4 activity, adapting it for high-throughput screening, which aids in the identification of small molecule inhibitors.
Key Study Components
Research Area
- Autophagy regulation
- Cancer research
- Neurodegenerative diseases
Background
- The ATG4 protease family is believed to be a promising drug target for various cancers.
- There are limited assays to monitor ATG4 protease activity in cells.
- Understanding the post-translational regulation of ATG4 is crucial for therapeutic development.
Methods Used
- Luciferase-based reporter assays
- Cell lines with knockout mutations of ATG4 family members
- High-content, high-throughput screening technologies
Main Results
- Significant discoveries regarding the dysfunction of ATG4 family proteins in cells.
- Identification of novel small molecule compounds that inhibit or activate ATG4 B protease.
- Validated post-translational regulatory mechanisms of ATG4.
Conclusions
- This study provides a foundation for further exploration of ATG4 in regulating autophagy.
- The findings could lead to new therapeutic approaches for diseases associated with autophagy dysfunction.
Frequently Asked Questions
Executive Industry Relevance
High-throughput, cell-based screening for ATG4B inhibitors addresses a critical need in oncology drug discovery by enabling functional target validation of autophagy modulation. The luciferase-based assay provides a scalable, quantitative platform for identifying and triaging small molecule modulators of ATG4B, directly impacting early-stage portfolio decisions. This approach supports predictive confidence in target engagement and mechanistic de-risking for cancer and neurodegeneration pipelines.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct interrogation of ATG4B function in live-cell systems for target validation.
- Supports mechanistic de-risking by quantifying protease activity in disease-relevant models.
- Facilitates prioritization of autophagy-related targets based on functional readouts.
Screening & Assay Development
- Delivers a robust, luciferase-based assay adaptable to high-throughput screening platforms.
- Provides quantitative, reproducible outputs for compound triage and hit validation.
- Streamlines assay standardization and scalability for large-scale screening campaigns.
Translational & Preclinical Research
- Aligns with disease-relevant autophagy pathways implicated in cancer and neurodegeneration.
- Enables continuity from early discovery through preclinical validation of ATG4B modulators.
- Supports risk-adjusted advancement of candidates with validated mechanism of action.
Pipeline & Workflow Integration
This luciferase-based assay integrates into the discovery continuum from target validation through lead identification and preclinical evaluation of autophagy modulators.
- Discovery Biology: Quantifies ATG4B activity to support hypothesis testing and pathway clarification.
- Screening: Provides assay readiness and reproducibility for high-throughput compound evaluation.
- Analytics: Generates quantitative readouts for comparative analysis of inhibitor efficacy.
- Translational Research: Bridges discovery and preclinical studies by enabling functional validation in disease-relevant systems.
- Enterprise Reuse: Offers a reusable platform for screening both inhibitors and activators across autophagy-related targets.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in ATG4B as a therapeutic target and reduces mechanistic ambiguity.
- Operational Value: Enhances standardization, reproducibility, and scalability of screening workflows.
- Strategic Value: Improves go/no-go decisions and capital efficiency by enabling early biological de-risking.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of autophagy-targeted candidates.
Implementation Considerations
- Requires expertise in cell-based assay development and autophagy biology.
- Needs access to high-throughput screening instrumentation and luciferase detection systems.
- Demands cross-team standardization for assay protocols and data analysis.
- May require adaptation for different cell types or disease models.
- Dependent on robust controls to ensure specificity for ATG4B activity.
Biopharma FAQs
Chapters in this video
0:00
Introduction
3:18
Autophagy Protease Tag‐Compound Addition and Cellular Supernatant Harvest for Drug Screening
5:01
Luciferase Assay for the Detection of Autophagy Protease ATG4B
7:12
Image Acquisition and Analysis for the Detection of Autophagy Protease ATG4B Using Luciferase Assay
