GO:1900118 negative regulation of execution phase of apoptosis: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1900118 describes any process that stops, prevents or reduces the execution phase of apoptosis, the final stage of programmed cell death.
• The execution phase is driven by effector caspases such as caspase-3 and caspase-7, which dismantle key cellular substrates.
• Negative regulation of this phase can occur through inhibitor of apoptosis proteins (IAPs), caspase inhibitors, and anti-apoptotic BCL-2 family members.
• Dysregulation of this process contributes to cancer, neurodegeneration, and autoimmune diseases [1,3].
• Key experimental models include CRISPR knockout of pro-apoptotic genes, point mutations in caspase cleavage sites, and overexpression of anti-apoptotic factors [1,2].
• Studying this term helps identify therapeutic targets for diseases where apoptosis is misregulated [1,3].
Description
Apoptosis is a genetically programmed form of cell death essential for development and tissue homeostasis. The execution phase of apoptosis is the final, irreversible stage in which effector caspases cleave hundreds of cellular substrates, leading to characteristic morphological changes such as cell shrinkage, membrane blebbing, and DNA fragmentation. Negative regulation of execution phase of apoptosis (GO:1900118) encompasses any process that stops, prevents, or reduces the frequency, rate, or extent of this execution phase. This regulation is critical because excessive apoptosis contributes to degenerative diseases, while insufficient apoptosis promotes cancer and autoimmunity [1,3]. Understanding the molecular players and regulatory mechanisms of this GO term is therefore of broad biomedical importance.
negative regulation of execution phase of apoptosis At A Glance
| GO ID | GO:1900118 |
|---|---|
| GO term | negative regulation of execution phase of apoptosis |
| Ontology | biological_process |
| Synonym | down regulation of execution phase of apoptosis; down-regulation of execution phase of apoptosis; downregulation of execution phase of apoptosis; inhibition of execution phase of apoptosis |
| Major function | Inhibits the final execution stage of apoptosis, preventing caspase-mediated cellular dismantling. |
| Related processes | Regulation of apoptotic execution, caspase inhibition, IAP-mediated caspase inactivation. |
| Key effectors | Effector caspases (e.g., CASP3, CASP7), IAPs (e.g., XIAP, BIRC5), anti-apoptotic BCL-2 family proteins. |
| Disease relevance | Cancer, neurodegeneration, autoimmune disorders [1,3]. |
What Is GO:1900118?
GO:1900118 is a biological process term defined as any process that stops, prevents or reduces the frequency, rate or extent of the execution phase of apoptosis. In other words, it covers cellular mechanisms that inhibit the final dismantling stage of programmed cell death, often by blocking effector caspase activity or preventing caspase activation.
Why Is negative regulation of execution phase of apoptosis Important in Cell Biology?
Negative regulation of the execution phase of apoptosis is a critical control point that determines whether a cell commits to death. This process is essential for preventing inappropriate cell death in healthy tissues and for allowing cancer cells to evade apoptosis. Its dysregulation is implicated in a wide range of human diseases, including cancer, where overexpression of inhibitor of apoptosis proteins (IAPs) or loss of caspase function confers resistance to therapy [1,3]. In neurodegenerative conditions, excessive inhibition of apoptosis may contribute to the survival of damaged neurons, but more commonly, failed negative regulation leads to pathological cell loss. Thus, understanding this process offers therapeutic opportunities for modulating cell survival and death [1,3].
• Controls the final commitment step of apoptosis, determining cell fate.
• Dysregulation contributes to cancer chemoresistance and tumor progression.
• Implicated in neurodegenerative diseases where apoptosis is misregulated.
• Plays a role in autoimmune diseases by affecting immune cell survival.
• Key for understanding developmental programmed cell death.
• Target for therapeutic interventions aiming to sensitize cancer cells to apoptosis.
• Involved in cellular responses to stress and DNA damage.
• Provides mechanistic insights into caspase regulation and IAP function.
• Relevant to inflammatory processes and colitis-associated cell death.
• Potential biomarker for diseases with altered apoptosis, such as restless legs syndrome.
What Happens During negative regulation of execution phase of apoptosis?
Inhibition of Effector Caspases
In simple terms: Stopping the enzymes that dismantle the cell.
The execution phase of apoptosis is primarily driven by effector caspases, such as caspase-3 and caspase-7, which cleave a broad spectrum of substrates. Negative regulation of this phase often involves direct inhibition of these caspases by members of the inhibitor of apoptosis protein (IAP) family, such as XIAP, which bind and block caspase activity. This prevents the proteolytic cascade that leads to cell dismantling.
Blockade of Caspase Activation
In simple terms: Preventing the switch that turns on the death enzymes.
Effector caspases are activated by upstream initiator caspases (e.g., caspase-8, caspase-9). Negative regulation can occur by preventing the activation of these initiator caspases, for example through the action of anti-apoptotic BCL-2 family proteins that inhibit mitochondrial outer membrane permeabilization and cytochrome c release. This blocks the formation of the apoptosome and subsequent caspase-9 activation.
Modulation of Apoptotic Substrates
In simple terms: Protecting the cell's building blocks from being cut.
During the execution phase, caspases cleave numerous structural and regulatory proteins, leading to cellular disassembly. Negative regulation can also involve post-translational modifications or sequestration of caspase substrates, making them less accessible to cleavage. For instance, phosphorylation of certain substrates can prevent their cleavage by caspases.
Role of Anti-apoptotic Signaling Pathways
In simple terms: Survival signals that keep the cell alive.
Survival signaling pathways, such as the PI3K/AKT pathway, can negatively regulate the execution phase by promoting the expression or activity of anti-apoptotic proteins like BCL-2 and XIAP. Additionally, glucocorticoid-induced apoptosis in leukemic cells can be modulated by glucocorticoid-regulated genes that influence caspase activation. These pathways provide a layer of regulation that integrates extracellular cues with the cell death machinery [1,6].
Nuclear Events and Chromatin Changes
In simple terms: Protecting the DNA from being chopped up.
The execution phase includes nuclear events such as chromatin condensation and DNA fragmentation. Negative regulation can involve preventing the activation of nucleases like CAD (caspase-activated DNase) by inhibiting caspases, or by modulating the release of nuclear proteins such as RanGTP that trigger microtubule assembly during apoptosis. Inhibition of these nuclear events helps preserve genomic integrity.
Key Genes Involved in GO:1900118 negative regulation of execution phase of apoptosis
The following genes and proteins are central to the negative regulation of the execution phase of apoptosis, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| XIAP | Directly inhibits caspase-3, -7, and -9 | Key anti-apoptotic protein; target for cancer therapy |
| BCL2 | Inhibits mitochondrial outer membrane permeabilization | Prevents cytochrome c release and apoptosome formation |
| BCL2L1 (BCL-XL) | Anti-apoptotic BCL-2 family member | Blocks caspase activation; overexpressed in cancers |
| MCL1 | Anti-apoptotic BCL-2 family member | Promotes cell survival; implicated in chemoresistance |
| CASP3 | Effector caspase; executioner of apoptosis | Its inhibition or knockout prevents execution phase |
| CASP7 | Effector caspase; executioner of apoptosis | Redundant with caspase-3 in some contexts |
| CASP8 | Initiator caspase in extrinsic pathway | Negative regulation prevents its activation |
| CASP9 | Initiator caspase in intrinsic pathway | Inhibited by XIAP and anti-apoptotic BCL-2 proteins |
| BIRC5 (Survivin) | Inhibits caspases and regulates mitosis | Overexpressed in many cancers; promotes survival |
| BIRC2 (cIAP1) | Inhibits caspases; regulates NF-kB | Modulates apoptosis and immune signaling |
| BIRC3 (cIAP2) | Inhibits caspases; regulates NF-kB | Involved in survival signaling |
| TPX2 | Microtubule assembly during apoptotic execution | Released by nuclear RanGTP; role in execution phase |
| ISG54 (IFIT2) | Interferon-stimulated gene; promotes apoptosis | Its negative regulation may affect apoptosis |
| NR3C1 (GR) | Glucocorticoid receptor; mediates apoptosis in leukemic cells | Glucocorticoid-induced apoptosis involves caspase regulation |
| H3K27me3 | Epigenetic mark; modulates apoptosis | GSK-126 reduces H3K27me3 and protects neurons |
| CSF1 | Colony-stimulating factor 1; survival factor | Reduced serum levels in restless legs syndrome |
| HULC (Humanin-like 3) | Mitochondrial-derived peptide; cytoprotective | Reduced in restless legs syndrome |
How Is negative regulation of execution phase of apoptosis Regulated?
The negative regulation of the execution phase of apoptosis is itself tightly regulated at multiple levels. Transcriptional control of anti-apoptotic genes (e.g., BCL2, XIAP) by survival signaling pathways such as PI3K/AKT and NF-kB can increase the threshold for apoptosis. Post-translational modifications, including phosphorylation and ubiquitination, modulate the stability and activity of caspases and IAPs. For example, XIAP can be ubiquitinated and degraded, relieving caspase inhibition. Additionally, epigenetic mechanisms, such as histone methylation (H3K27me3), can influence the expression of pro- and anti-apoptotic genes, as shown in cerebral ischemia where inhibition of H3K27me3 protects neurons. In the context of glucocorticoid-induced apoptosis, glucocorticoid-regulated genes modulate caspase activation and execution.
negative regulation of execution phase of apoptosis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| XIAP | Cancer chemoresistance | CRISPR knockout of XIAP in cancer cell lines to sensitize to apoptosis |
| BCL2 | Lymphoma and leukemia | Overexpression of BCL2 in hematopoietic cells to model survival |
| CASP3 | Neurodegeneration | Knockout of CASP3 in neuronal cultures to prevent apoptosis |
| H3K27me3 | Cerebral ischemia | GSK-126 treatment in animal models to reduce H3K27me3 and protect neurons |
| CSF1 | Restless legs syndrome | Measurement of serum CSF1 levels in patients and controls |
Cancer
Cancer cells frequently evade apoptosis by upregulating negative regulators of the execution phase, such as XIAP, BCL-2, and survivin. Overexpression of these proteins confers resistance to chemotherapy and radiation. For example, in pre-B leukemic cells, glucocorticoid-induced apoptosis is modulated by apical caspases and glucocorticoid-regulated genes, and defects in this pathway contribute to drug resistance. Targeting these negative regulators, for instance with SMAC mimetics that antagonize IAPs, is a promising therapeutic strategy.
Neurodegeneration
In neurodegenerative diseases, inappropriate activation of apoptosis contributes to neuronal loss. However, negative regulation of the execution phase may be protective in certain contexts. In cerebral ischemia, inhibition of H3K27me3 by GSK-126 protects CA1 neurons from apoptosis, suggesting that epigenetic modulation of the execution phase can be neuroprotective. Conversely, excessive inhibition of apoptosis might allow damaged neurons to survive, potentially contributing to neurodegeneration.
Autoimmune and Inflammatory Diseases
Defects in apoptosis can lead to autoimmune diseases due to impaired deletion of autoreactive lymphocytes. Negative regulation of the execution phase can promote survival of pathogenic immune cells. In a cellular model of hydrogen peroxide-associated colitis, caspases exhibited non-apoptotic functions, highlighting the complexity of caspase regulation in inflammation. Understanding how execution phase is negatively regulated in immune cells may reveal therapeutic targets for autoimmune and inflammatory conditions [1,7].
Restless Legs Syndrome
Restless legs syndrome (RLS) is a neurological disorder with unclear pathophysiology. A recent study found that patients with RLS exhibit reduced serum levels of colony-stimulating factor-1 (CSF1), humanin-like 3, and 10. These factors are involved in cell survival and apoptosis regulation, suggesting that altered negative regulation of apoptosis may contribute to RLS pathology.
From negative regulation of execution phase of apoptosis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does knockout of XIAP sensitize cancer cells to apoptosis? | CRISPR knockout of XIAP in HeLa or MCF-7 cells |
| Can a point mutation in caspase-3 cleavage site prevent execution phase? | Knock-in of caspase-resistant substrate in cell lines |
| Does overexpression of BCL-2 inhibit execution phase? | Overexpression of BCL-2 in Jurkat cells |
| What is the role of H3K27me3 in neuronal apoptosis? | GSK-126 treatment in primary neurons |
| How does glucocorticoid receptor regulate apoptosis in leukemic cells? | Knockout of NR3C1 in pre-B leukemic cells |
| Does CSF1 protect against apoptosis in RLS? | CSF1 supplementation in neuronal cultures |
How to Study the negative regulation of execution phase of apoptosis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Annexin V/PI staining | Phosphatidylserine externalization and membrane integrity | Quantify apoptosis in cell populations |
| Caspase-3/7 activity assay | Effector caspase enzymatic activity | Measure execution phase activation |
| TUNEL assay | DNA fragmentation | Detect late-stage apoptosis |
| Live-cell imaging with caspase biosensors | Real-time caspase activation dynamics | Visualize execution phase in single cells |
| CRISPR knockout screening | Gene function in apoptosis regulation | Identify negative regulators of execution phase |
| Proteomics | Global protein cleavage and modifications | Discover caspase substrates and regulatory pathways |
| Phosphoproteomics | Phosphorylation changes during apoptosis | Identify signaling events that inhibit execution phase |
| RNA-seq | Transcriptional changes | Measure expression of anti-apoptotic genes |
CRISPR-Cas9 Knockout Screening
Genome-wide CRISPR knockout screens can identify genes whose loss enhances or inhibits the execution phase of apoptosis. For example, knocking out negative regulators such as XIAP or BCL2 can sensitize cells to apoptotic stimuli, while knocking out pro-apoptotic genes confers resistance. These screens are powerful for discovering novel regulators of GO:1900118.
Apoptosis Assays
Common methods to measure execution phase include annexin V/propidium iodide staining, caspase-3/7 activity assays, and TUNEL staining for DNA fragmentation. These assays quantify the frequency and extent of apoptosis and can be used to assess the impact of genetic perturbations.
Live-Cell Imaging
Time-lapse microscopy of cells expressing fluorescent reporters (e.g., caspase-3 biosensors, mitochondrial markers) allows real-time visualization of execution phase dynamics. This approach can reveal how negative regulators delay or prevent caspase activation and cellular dismantling.
Proteomics and Phosphoproteomics
Mass spectrometry-based proteomics can identify caspase substrates and their cleavage products during the execution phase. Phosphoproteomics can reveal signaling events that negatively regulate caspase activation, such as phosphorylation of caspase-9 or XIAP.
How CRISPR Can Be Used to Study GO:1900118 negative regulation of execution phase of apoptosis
Knockout
CRISPR knockout of negative regulators of the execution phase, such as XIAP or BCL2, can sensitize cells to apoptosis and is used to study their role in cancer chemoresistance. Conversely, knocking out pro-apoptotic genes like CASP3 or CASP7 can prevent execution phase and serve as a model for apoptosis resistance.
Point Mutation
Introducing point mutations in caspase cleavage sites of key substrates can render them resistant to cleavage, thereby inhibiting the execution phase. This approach helps dissect the functional importance of specific cleavage events in apoptosis.
Knock-in
Knock-in of tagged versions of caspases or IAPs (e.g., GFP-tagged) allows real-time tracking of their localization and dynamics during the execution phase. Knock-in of disease-associated mutations can model altered apoptosis regulation.
Overexpression
Overexpression of anti-apoptotic proteins such as BCL-2 or XIAP is a classic method to inhibit the execution phase and study its consequences in cell survival and disease models. This can be achieved by CRISPR-mediated knock-in of a strong promoter or by lentiviral transduction.
How EDITGENE Supports negative regulation of execution phase of apoptosis Research
Researchers studying negative regulation of execution phase of apoptosis-related genes often need to determine whether a candidate gene is causally involved in inhibiting caspase activation or cellular dismantling. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of execution phase of apoptosis research.
Frequently Asked Questions About negative regulation of execution phase of apoptosis
What is GO:1900118?
GO:1900118 is the Gene Ontology term for negative regulation of execution phase of apoptosis, defined as any process that stops, prevents or reduces the frequency, rate or extent of the execution phase of apoptosis.
What genes are involved in negative regulation of execution phase of apoptosis?
Key genes include XIAP, BCL2, BCL2L1, MCL1, BIRC5 (survivin), and CASP3, among others.
How is the execution phase of apoptosis regulated?
It is regulated by inhibitor of apoptosis proteins (IAPs), anti-apoptotic BCL-2 family members, and survival signaling pathways that block caspase activation.
What is the execution phase of apoptosis?
The execution phase is the final stage of apoptosis where effector caspases cleave cellular substrates, leading to cell dismantling and death.
Which diseases are associated with negative regulation of execution phase of apoptosis?
Cancer, neurodegeneration, autoimmune diseases, and restless legs syndrome have been linked to dysregulation of this process [1,3,8].
How can I study negative regulation of execution phase of apoptosis?
Common methods include CRISPR knockout screens, apoptosis assays (annexin V, caspase activity), live-cell imaging, and proteomics [1,4].
What are the synonyms for GO:1900118?
Synonyms include down regulation of execution phase of apoptosis, down-regulation of execution phase of apoptosis, downregulation of execution phase of apoptosis, and inhibition of execution phase of apoptosis.
What is the role of XIAP in apoptosis?
XIAP directly inhibits caspases-3, -7, and -9, thereby negatively regulating the execution phase of apoptosis.
Can CRISPR be used to study negative regulation of execution phase of apoptosis?
Yes, CRISPR knockout, knock-in, point mutation, and overexpression models are widely used to dissect this process [1,4].
What cell models are suitable for studying GO:1900118?
Cancer cell lines (e.g., HeLa, MCF-7, Jurkat), primary neurons, and leukemic cells are commonly used [1,3,6].
Conclusion
Negative regulation of the execution phase of apoptosis (GO:1900118) is a fundamental biological process that controls the final commitment to cell death. Its dysregulation underlies numerous human diseases, making it a prime target for therapeutic intervention. Advances in CRISPR-based genome editing and screening technologies are accelerating the discovery of novel regulators and mechanisms [1,4]. EDITGENE provides a comprehensive suite of services to support research in this field, from custom knockout and knock-in models to high-throughput screening and bioinformatics analysis.
References
- 1. Guchelaar HJ et al.. 1997. Apoptosis: molecular mechanisms and implications for cancer chemotherapy.. Pharm World Sci 19(3):119-25 PMID: 9259027
- 2. Conradt B et al.. 2016. Programmed Cell Death During Caenorhabditis elegans Development.. Genetics 203(4):1533-62 PMID: 27516615
- 3. Wang Z et al.. 2022. GSK-126 Protects CA1 Neurons from H3K27me3-Mediated Apoptosis in Cerebral Ischemia.. Mol Neurobiol 59(4):2552-2562 PMID: 35091962
- 4. Moss DK et al.. 2009. Dynamic release of nuclear RanGTP triggers TPX2-dependent microtubule assembly during the apoptotic execution phase.. J Cell Sci 122(Pt 5):644-55 PMID: 19208764
- 5. Stawowczyk M et al.. 2011. The interferon stimulated gene 54 promotes apoptosis.. J Biol Chem 286(9):7257-66 PMID: 21190939
- 6. Planey SL et al.. 2003. Role of apical caspases and glucocorticoid-regulated genes in glucocorticoid-induced apoptosis of pre-B leukemic cells.. Cancer Res 63(1):172-8 PMID: 12517795
- 7. Poehlmann A et al.. 2013. Non-apoptotic function of caspases in a cellular model of hydrogen peroxide-associated colitis.. J Cell Mol Med 17(7):901-13 PMID: 23742011
- 8. Gülçiçek A et al.. 2024. Patients with restless legs syndrome exhibit reduced serum colony-stimulating factor-1, humanin-like 3 and 10 levels.. Acta Neurol Belg 124(5):1561-1568 PMID: 38630326
