GO:0090267 positive regulation of mitotic cell cycle spindle assembly checkpoint: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0090267 describes any process that increases the rate, frequency, or extent of the mitotic spindle assembly checkpoint (SAC), which delays metaphase-to-anaphase transition until all chromosomes are correctly attached to a properly assembled spindle.
• Core SAC proteins such as MAD1, CDK1-CCNB1, BUB1, BUBR1, BUB3, and RAE1 are recruited to unattached kinetochores to amplify checkpoint signaling and block anaphase onset.
• Positive regulation of the SAC can be triggered by spindle poisons, Eg5 inhibition, or PLK1 inhibition, leading to mitotic arrest and apoptosis in cancer cells.
• Dysregulation of SAC-positive regulators is linked to tumorigenesis, including gastric cancer, colorectal cancer, and T-cell lymphoma.
• Experimental models for studying GO:0090267 include CRISPR knockout, point-mutation knock-in, and overexpression of SAC genes, combined with live-cell imaging and phosphoproteomics.
• The SAC is a promising therapeutic target: enhancing its activity can sensitize cancer cells to antimitotic agents, while its loss promotes chromosomal instability.
Description
The mitotic spindle assembly checkpoint (SAC) is a surveillance mechanism that ensures faithful chromosome segregation by delaying anaphase until every kinetochore is properly attached to the spindle. GO:0090267, positive regulation of mitotic cell cycle spindle assembly checkpoint, encompasses all molecular events that amplify or sustain this checkpoint signal, thereby increasing the duration or strength of the metaphase arrest. This regulation is critical for preventing aneuploidy and is frequently exploited or subverted in cancer. Understanding the positive regulators of the SAC is essential for researchers studying cell cycle control, chromosomal instability, and antimitotic drug responses. Recent studies have identified key kinases, scaffold proteins, and kinetochore components that positively regulate the SAC, offering new targets for therapeutic intervention.
positive regulation of mitotic cell cycle spindle assembly checkpoint At A Glance
| GO ID | GO:0090267 |
|---|---|
| GO term | positive regulation of mitotic cell cycle spindle assembly checkpoint |
| Ontology | biological_process |
| Synonym | none |
| Major function | Enhances the spindle assembly checkpoint to delay anaphase until chromosomes are properly attached |
| Related processes | Mitotic cell cycle, chromosome segregation, kinetochore signaling |
| Key regulators | MAD1, CDK1, CCNB1, BUB1, BUBR1, BUB3, RAE1, PLK1, Eg5 |
| Disease relevance | Cancer (gastric, colorectal, T-cell lymphoma), chromosomal instability |
What Is GO:0090267?
GO:0090267 is defined as any process that increases the rate, frequency, or extent of the mitotic cell cycle spindle assembly checkpoint, a cell cycle checkpoint that delays the metaphase/anaphase transition of a mitotic nuclear division until the spindle is correctly assembled and chromosomes are attached to the spindle. In practice, this term covers molecular events that enhance SAC signaling, such as kinetochore recruitment of MAD1, activation of CDK1-CCNB1, or inhibition of Eg5 that leads to checkpoint activation.
Why Is positive regulation of mitotic cell cycle spindle assembly checkpoint Important in Cell Biology?
Positive regulation of the SAC is vital for maintaining genomic stability, as it ensures that cells do not proceed to anaphase with unattached or misattached chromosomes. Its dysregulation can lead to aneuploidy, a hallmark of many cancers, and can influence sensitivity to antimitotic chemotherapies. Moreover, pathogens such as HIV-1 can manipulate SAC regulators to induce apoptosis in CD4+ T cells, highlighting its broader physiological significance.
• Prevents aneuploidy by delaying anaphase until all kinetochores are properly attached.
• Its hyperactivation by PLK1 inhibition enhances the efficacy of Brentuximab vedotin in CD30-positive T-cell lymphoma.
• Overexpression of SAC genes BUB1, BUBR1, and BUB3 is associated with gastric cancer proliferation.
• RAE1, a SAC regulator, promotes tumor growth in colorectal cancer.
• Eg5 modulation contributes to SAC activation and Tat-mediated apoptosis in CD4+ T-lymphocytes.
• CDK1-CCNB1 recruitment to kinetochores by MAD1 is essential for checkpoint signaling.
• SAC activity can be modeled computationally using relative protein abundance statistics.
• Time as a danger signal can promote G1 arrest after mitosis, linking SAC duration to cell fate.
• The EGF/hnRNP Q1 axis regulates cell cycle-related genes, including SAC components.
• SAC-positive regulators are potential targets for anticancer therapy.
What Happens During positive regulation of mitotic cell cycle spindle assembly checkpoint?
Kinetochore recruitment of MAD1 and CDK1-CCNB1
In simple terms: Proteins are recruited to chromosome attachment sites to sound the alarm.
Upon unattached kinetochores, MAD1 recruits CDK1-CCNB1 to kinetochores, which promotes spindle checkpoint signaling and delays anaphase. This recruitment is a key positive regulatory step that amplifies the checkpoint signal.
Activation of BUB and RAE1 proteins
In simple terms: Scaffold proteins at the kinetochore strengthen the stop signal.
BUB1, BUBR1, BUB3, and RAE1 are mitotic checkpoint regulators that localize to kinetochores and positively regulate SAC by inhibiting the anaphase-promoting complex. Their overexpression is linked to tumor cell proliferation.
Eg5 inhibition and spindle checkpoint activation
In simple terms: Blocking a motor protein can trigger the checkpoint.
Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation, leading to apoptosis in CD4-positive T-lymphocytes. This demonstrates that positive regulation can be induced by targeting spindle motor proteins.
PLK1 inhibition enhances SAC activation
In simple terms: Inhibiting a kinase can boost the checkpoint and improve drug efficacy.
PLK1 inhibition enhances Brentuximab vedotin efficacy in CD30-positive T-cell lymphoma via spindle assembly checkpoint activation. This highlights a therapeutic strategy to positively regulate the SAC.
Temporal control and G1 arrest after mitosis
In simple terms: The duration of the checkpoint can influence whether cells arrest later.
Time as a danger signal promoting G1 arrest after mitosis suggests that prolonged SAC activation can have downstream effects on cell cycle progression. This links positive regulation of SAC to post-mitotic checkpoints.
Key Genes Involved in GO:0090267 positive regulation of mitotic cell cycle spindle assembly checkpoint
The following genes and proteins are key positive regulators or components of the mitotic spindle assembly checkpoint, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MAD1 | Recruits CDK1-CCNB1 to kinetochores to promote SAC signaling | Essential for checkpoint amplification; knockout causes checkpoint defects |
| CDK1 | Kinase recruited by MAD1; phosphorylates substrates to delay anaphase | Central to SAC signaling; target for cell cycle studies |
| CCNB1 | Cyclin B1, partner of CDK1; regulates mitotic progression | Component of CDK1-CCNB1 complex at kinetochores |
| BUB1 | Serine/threonine kinase; scaffold for SAC proteins | Overexpressed in gastric cancer; biomarker |
| BUBR1 | Mitotic checkpoint kinase; inhibits APC/C | Overexpressed in gastric cancer; associated with proliferation |
| BUB3 | WD40 repeat protein; binds BUB1 and BUBR1 | Overexpressed in gastric cancer |
| RAE1 | mRNA export factor with mitotic checkpoint function | Promotes tumor growth in colorectal cancer |
| PLK1 | Polo-like kinase 1; regulates mitotic entry and SAC | Inhibition activates SAC and enhances drug efficacy |
| Eg5 | Kinesin motor protein; required for spindle assembly | Modulation activates SAC and induces apoptosis |
| hnRNP Q1 | RNA-binding protein regulated by EGF; affects cell cycle genes | Involved in tumorigenesis via cell cycle regulation |
| APC/C | Ubiquitin ligase; target of SAC inhibition | SAC prevents APC/C activation until chromosomes align |
| MPS1 | Kinase that recruits SAC proteins to kinetochores | Upstream activator of SAC; not directly cited but implied in |
| Aurora B | Chromosomal passenger kinase; regulates kinetochore-microtubule attachments | Modulates SAC signaling; not directly cited but context from |
| CENP-E | Kinesin required for chromosome congression | Its inhibition activates SAC; context from |
| NDC80 | Kinetochore component; monitors attachments | Part of SAC machinery; context from |
| MAD2 | Checkpoint protein; binds MAD1 and inhibits APC/C | Key effector of SAC; context from |
| TAO1 | Kinase that regulates SAC and spindle orientation | Not directly cited; omitted from citations |
| TTK | Dual-specificity kinase; essential for SAC | Not directly cited; omitted from citations |
How Is positive regulation of mitotic cell cycle spindle assembly checkpoint Regulated?
Positive regulation of the SAC is controlled by phosphorylation events, protein-protein interactions, and kinetochore recruitment. MAD1-dependent recruitment of CDK1-CCNB1 to kinetochores is a critical regulatory step that promotes checkpoint signaling. PLK1 inhibition can enhance SAC activation, suggesting that PLK1 normally restrains the checkpoint. Eg5 activity modulation also contributes to SAC activation, indicating that spindle motor proteins regulate checkpoint strength. Additionally, the EGF/hnRNP Q1 axis regulates cell cycle-related genes, potentially influencing SAC components.
positive regulation of mitotic cell cycle spindle assembly checkpoint and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| BUB1 | Gastric cancer, tumor proliferation | Knockout and overexpression in gastric cancer cell lines |
| RAE1 | Colorectal cancer, tumor growth | Knockout in colorectal cancer cells and xenografts |
| PLK1 | T-cell lymphoma, drug response | Point mutation and inhibition in lymphoma models |
| Eg5 | HIV-1 pathogenesis, T-cell apoptosis | Knockdown and modulation in CD4+ T cells |
| MAD1 | Chromosomal instability, checkpoint defects | Knockout and knock-in in HeLa or RPE1 cells |
Cancer and chromosomal instability
Dysregulation of SAC-positive regulators is frequently observed in cancer. Overexpression of BUB1, BUBR1, and BUB3 is associated with gastric cancer and tumor cell proliferation. RAE1 promotes tumor growth in colorectal cancer, and its depletion reduces tumorigenicity. In CD30-positive T-cell lymphoma, PLK1 inhibition enhances Brentuximab vedotin efficacy via SAC activation, suggesting that positive regulation of SAC can be therapeutically exploited.
HIV-1 pathogenesis and T-cell apoptosis
Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation and Tat-mediated apoptosis in CD4-positive T-lymphocytes, linking SAC positive regulation to HIV-1 pathogenesis.
Cell cycle arrest and post-mitotic checkpoints
Time as a danger signal promoting G1 arrest after mitosis indicates that prolonged SAC activation can influence subsequent cell cycle phases, with implications for tissue homeostasis and disease.
From positive regulation of mitotic cell cycle spindle assembly checkpoint-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of MAD1 abolish SAC signaling? | CRISPR knockout of MAD1 in HeLa cells |
| Can a point mutation in CDK1 prevent kinetochore recruitment? | Point-mutation knock-in of CDK1 in RPE1 cells |
| Does overexpression of BUB1 increase SAC strength? | Overexpression of BUB1 in gastric cancer cells |
| Does RAE1 knockout reduce tumor growth? | Knockout of RAE1 in colorectal cancer xenografts |
| Can PLK1 inhibition enhance SAC activation? | Point mutation or knockout of PLK1 in lymphoma cells |
| Does Eg5 modulation trigger SAC and apoptosis? | Knockdown or overexpression of Eg5 in CD4+ T cells |
How to Study the positive regulation of mitotic cell cycle spindle assembly checkpoint Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Kinetochore recruitment dynamics and anaphase timing | Quantify SAC strength in knockout or knock-in cells |
| Phosphoproteomics | Phosphorylation of SAC substrates | Identify CDK1-CCNB1 targets at kinetochores |
| RNA-seq | Transcriptional changes in SAC genes | Assess PLK1 inhibition or Eg5 modulation effects |
| Proteomics | Protein abundance and interactions | Predict cell cycle network modules |
| CRISPR knockout screening | Gene essentiality for SAC function | Identify novel positive regulators |
| Flow cytometry | Cell cycle profiles and mitotic arrest | Measure SAC activation after drug treatment |
| Immunofluorescence | Kinetochore localization of SAC proteins | Validate recruitment of MAD1, BUB1, etc. |
Live-cell imaging of mitotic progression
Live-cell imaging with fluorescently tagged SAC proteins (e.g., MAD1-GFP) allows real-time monitoring of kinetochore recruitment and anaphase onset, providing quantitative measures of SAC strength.
Phosphoproteomics and proteomics
Mass spectrometry-based phosphoproteomics can identify phosphorylation events downstream of SAC activation, such as CDK1 substrates, and quantify changes in SAC protein abundance.
RNA-seq and gene expression profiling
RNA-seq can reveal transcriptional changes in SAC genes under conditions that activate the checkpoint, such as PLK1 inhibition or Eg5 modulation.
Computational modeling of cell cycle networks
Predicting network modules of cell cycle regulators using relative protein abundance statistics helps integrate SAC components into broader cell cycle models.
How CRISPR Can Be Used to Study GO:0090267 positive regulation of mitotic cell cycle spindle assembly checkpoint
Knockout
CRISPR knockout of SAC genes such as MAD1, BUB1, or RAE1 can abolish checkpoint function, leading to premature anaphase and chromosomal instability. These models are used to study the necessity of positive regulators in SAC signaling.
Point Mutation
Point mutations in CDK1 or MAD1 can disrupt specific phosphorylation or binding sites, allowing researchers to dissect the precise molecular events required for SAC positive regulation without completely removing the protein.
Knock-in
Knock-in of tagged versions of SAC proteins (e.g., GFP-MAD1) enables live-cell imaging and proteomic analysis of kinetochore recruitment and complex formation.
Overexpression
Overexpression of BUB1, BUBR1, or BUB3 can enhance SAC signaling and is associated with tumor cell proliferation, providing models to study SAC hyperactivation in cancer.
How EDITGENE Supports positive regulation of mitotic cell cycle spindle assembly checkpoint Research
Researchers studying positive regulation of mitotic cell cycle spindle assembly checkpoint-related genes often need to determine whether a candidate gene is causally involved in checkpoint control, chromosomal stability, or drug response. 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 positive regulation of mitotic cell cycle spindle assembly checkpoint research.
Frequently Asked Questions About positive regulation of mitotic cell cycle spindle assembly checkpoint
What is GO:0090267?
GO:0090267 is a Gene Ontology term for positive regulation of the mitotic cell cycle spindle assembly checkpoint, describing processes that increase the rate or extent of the SAC, which delays anaphase until chromosomes are properly attached.
What genes are involved in positive regulation of the spindle assembly checkpoint?
Key genes include MAD1, CDK1, CCNB1, BUB1, BUBR1, BUB3, RAE1, PLK1, and Eg5, as shown in studies of kinetochore recruitment and checkpoint activation.
How is the spindle assembly checkpoint positively regulated?
It is positively regulated by kinetochore recruitment of MAD1 and CDK1-CCNB1, activation of BUB proteins, and inhibition of Eg5 or PLK1, which amplify the checkpoint signal.
What diseases are associated with dysregulation of the spindle assembly checkpoint?
Dysregulation is linked to gastric cancer, colorectal cancer, T-cell lymphoma, and chromosomal instability, with SAC gene overexpression promoting tumor growth.
How can I study positive regulation of the SAC using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection of SAC genes in cell lines, combined with live-cell imaging and proteomics.
What is the role of MAD1 in the spindle assembly checkpoint?
MAD1 recruits CDK1-CCNB1 to kinetochores, which promotes spindle checkpoint signaling and delays anaphase.
Does PLK1 inhibition activate the spindle assembly checkpoint?
Yes, PLK1 inhibition enhances Brentuximab vedotin efficacy in CD30-positive T-cell lymphoma via spindle assembly checkpoint activation.
What is the connection between RAE1 and colorectal cancer?
RAE1, a mitotic checkpoint regulator, promotes tumor growth in colorectal cancer, and its targeting may reduce tumorigenicity.
How does Eg5 modulation affect the SAC?
Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation and Tat-mediated apoptosis in CD4-positive T-lymphocytes.
What experimental models are suitable for studying SAC positive regulators?
CRISPR knockout, point-mutation knock-in, tagged knock-in, and overexpression cell models, along with live-cell imaging and phosphoproteomics, are suitable.
Conclusion
GO:0090267, positive regulation of the mitotic cell cycle spindle assembly checkpoint, is a critical biological process that ensures genomic stability by delaying anaphase until chromosomes are properly attached. Its dysregulation contributes to cancer and other diseases, and its modulation offers therapeutic opportunities. Researchers can leverage CRISPR-based models and advanced omics to dissect the molecular players and develop targeted interventions.
References
- 1. Mori Y et al.. 2026. PLK1 inhibition enhances Brentuximab vedotin efficacy in CD30-positive T-cell lymphoma via spindle assembly checkpoint activation.. Leukemia PMID: 42443409
- 2. Fulcher LJ et al.. 2026. Time as a danger signal promoting G1 arrest after mitosis.. Trends Cell Biol 36(2):142-153 PMID: 40628545
- 3. Liu M et al.. 2014. Modulation of Eg5 activity contributes to mitotic spindle checkpoint activation and Tat-mediated apoptosis in CD4-positive T-lymphocytes.. J Pathol 233(2):138-47 PMID: 24488929
- 4. Wang YC et al.. 2018. The EGF/hnRNP Q1 axis is involved in tumorigenesis via the regulation of cell cycle-related genes.. Exp Mol Med 50(6):1-14 PMID: 29884818
- 5. Alfonso-Pérez T et al.. 2019. MAD1-dependent recruitment of CDK1-CCNB1 to kinetochores promotes spindle checkpoint signaling.. J Cell Biol 218(4):1108-1117 PMID: 30674583
- 6. Oguz C et al.. 2017. Predicting network modules of cell cycle regulators using relative protein abundance statistics.. BMC Syst Biol 11(1):30 PMID: 28241833
- 7. Kobayashi Y et al.. 2021. Mitotic checkpoint regulator RAE1 promotes tumor growth in colorectal cancer.. Cancer Sci 112(8):3173-3189 PMID: 34008277
- 8. Grabsch H et al.. 2003. Overexpression of the mitotic checkpoint genes BUB1, BUBR1, and BUB3 in gastric cancer--association with tumour cell proliferation.. J Pathol 200(1):16-22 PMID: 12692836
