GO:0000086 G2/M transition of mitotic cell cycle: Checkpoint Control, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000086 describes the commitment step where a cell in G2 phase irreversibly enters mitosis once M cyclin/CDK kinase activity crosses a threshold.
• The transition is driven by a positive feedback loop that accumulates active, unphosphorylated M cyclin/CDK complexes.
• CDC25C, CDK1, and cyclin B1 form the core regulatory module, with CDC25C alternative splicing and PUF60 emerging as a control layer.
• Mitochondrial chaperone TRAP1 and the spindle checkpoint protein MAD2 modulate CDK1 stability and G2-M progression.
• Nuclear mechanobiology and centrosome maturation are physically coupled to G2-M entry, linking cytoskeletal forces to mitotic commitment [2,6].
• The G2-M checkpoint is a validated synthetic lethal target in melanoma and a node hijacked by HIV-1 VPR [3,7].
Description
The G2/M transition of the mitotic cell cycle (GO:0000086) is the decisive regulatory step at which a cell that has completed DNA replication commits to mitosis. According to the Gene Ontology, this process begins when the kinase activity of the M cyclin/CDK complex reaches a threshold high enough for the cell cycle to proceed, accomplished by activating a positive feedback loop that accumulates unphosphorylated and active M cyclin/CDK complex. Because this switch is irreversible and tightly coupled to genome integrity, it is one of the most intensively studied cell-cycle control points in cancer biology, virology, and regenerative research [3,7]. Mechanistically, the transition integrates cyclin B1 accumulation, CDK1 activating phosphorylation, CDC25C-mediated removal of inhibitory phosphates, and spatial reorganization of organelles such as the Golgi and centrosome [1,4,6]. Recent work has shown that mitotic cyclins display plasticity in promoting the G2-M transition, meaning that the identity of the cyclin partner can be partially compensated under experimental perturbation. In parallel, nuclear mechanobiology studies have revealed that force transmission across the nuclear envelope changes markedly as cells cross G2-M, providing a physical dimension to the checkpoint. For researchers, GO:0000086 is a functional hub: perturbations in this process are read out as mitotic entry defects, checkpoint bypass, or synthetic lethality. The term is therefore central to studies of anti-mitotic drug response, viral cell-cycle manipulation, and the discovery of combination therapies that exploit G2-M vulnerabilities [3,5,7].
G2/M transition of mitotic cell cycle At A Glance
| GO ID | GO:0000086 |
|---|---|
| GO term | G2/M transition of mitotic cell cycle |
| Ontology | biological_process |
| Synonym | mitotic G2/M transition |
| Definition | The mitotic cell cycle transition by which a cell in G2 commits to M phase, beginning when M cyclin/CDK kinase activity reaches a threshold sufficient for cell cycle progression via a positive feedback loop that accumulates unphosphorylated and active M cyclin/CDK complex. |
| Major function | Irreversible commitment to mitosis through threshold activation of M cyclin/CDK |
| Core regulators | CDK1, cyclin B1, CDC25C, MAD2, TRAP1, PUF60 |
| Cellular context | Nuclear envelope remodeling, centrosome maturation, Golgi ribbon disassembly |
| Disease relevance | Cancer, viral cell-cycle manipulation, synthetic lethality in melanoma |
What Is GO:0000086?
In our own words, GO:0000086 is the biological process by which a cell in G2 phase makes the commitment to enter M phase. The defining molecular event is the kinase activity of the M cyclin/CDK complex rising above a threshold, which is achieved through a positive feedback loop that drives accumulation of the unphosphorylated, active form of the complex. This definition distinguishes the transition from upstream G2 arrest and downstream mitotic execution.
Why Is G2/M transition of mitotic cell cycle Important in Cell Biology?
GO:0000086 matters because it is the point of no return for cell division and a convergence node for DNA damage checkpoints, mitotic machinery, and organelle inheritance. Its dysregulation permits proliferation despite genomic stress, a hallmark exploited by tumors, and its pharmacological or genetic manipulation underlies anti-mitotic therapy and synthetic lethal strategies [5,7]. Because the transition is also targeted by viral effectors such as HIV-1 VPR, it sits at the interface of infection and cell-cycle control.
• Defines the commitment step for mitosis, making it a primary readout for proliferation studies.
• Integrates DNA damage and spindle assembly checkpoint signals before anaphase.
• CDC25C alternative splicing and PUF60 control G2/M timing in lung cancer progression.
• TRAP1 regulates CDK1 and MAD2 expression/ubiquitination, linking mitochondrial metabolism to G2-M.
• Nuclear mechanobiology changes at G2-M provide physical biomarkers of mitotic entry.
• Centrosome maturation requires a cell-cycle-dependent acetylation-to-phosphorylation switch.
• Golgi ribbon disassembly is a morphological marker of G2-M transition.
• G2-M checkpoint targeting enables synthetic lethality in melanoma.
• HIV-1 VPR modulates G2/M through non-classic mechanisms, informing viral pathogenesis.
• Mitotic cyclin plasticity affects interpretation of cyclin perturbation experiments.
What Happens During G2/M transition of mitotic cell cycle?
Threshold activation of M cyclin/CDK
In simple terms: The cell waits until a molecular engine called M cyclin/CDK is running fast enough, then flips a switch to start mitosis.
The transition begins when the kinase activity of the M cyclin/CDK complex reaches a threshold high enough for the cell cycle to proceed. This threshold is achieved by a positive feedback loop that results in accumulation of unphosphorylated and active M cyclin/CDK complex. Cyclin availability and CDK1 post-translational modifications are therefore rate-limiting for entry [5,8].
CDC25C-dependent dephosphorylation and feedback
In simple terms: A phosphatase removes inhibitory marks from the engine, and the engine then activates more of that phosphatase, creating a self-reinforcing loop.
CDC25C is a key phosphatase that removes inhibitory phosphates from CDK1, and its alternative splicing is regulated by PUF60 to promote cell cycle progression and lung cancer progression. This creates the positive feedback that locks in the active state described in the GO definition [1,8].
Checkpoint surveillance and MAD2 control
In simple terms: Quality-control proteins make sure the engine does not start until the cell is ready, and they are themselves kept in check.
TRAP1 controls G2-M transition through regulation of CDK1 and MAD2 expression and ubiquitination. MAD2 is a spindle assembly checkpoint component, so its abundance influences whether the transition proceeds or is delayed.
Organelle and structural remodeling
In simple terms: As the switch flips, the cell reshapes its internal compartments and skeleton to prepare for division.
The Golgi ribbon disassembles during the G2-M transition, providing a measurable morphological event. Nuclear mechanobiology also changes during G2-M, reflecting altered force transmission across the nuclear envelope. Centrosome maturation requires a cell-cycle-dependent transition from acetylation to phosphorylation for timely execution.
Cyclin plasticity and robustness
In simple terms: The engine can sometimes swap one fuel line for another, so blocking one cyclin does not always stop the switch.
Mitotic cyclins display plasticity in promoting the G2-M transition, meaning that loss of one cyclin can be partially compensated by another under experimental conditions. This plasticity is important when interpreting knockout or knockdown phenotypes.
Key Genes Involved in GO:0000086 G2/M transition of mitotic cell cycle
The following genes and proteins are experimentally implicated in GO:0000086, based on the verified literature cited in this article.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CDK1 | Catalytic kinase of M cyclin/CDK complex; threshold activity defines transition | Core target for G2-M arrest and anti-mitotic studies [5,8] |
| CCNB1 (cyclin B1) | Regulatory cyclin partner of CDK1 | Accumulation and plasticity determine transition timing |
| CDC25C | Phosphatase activating CDK1 by removing inhibitory phosphates | Alternative splicing regulated by PUF60 in lung cancer |
| PUF60 | RNA-binding regulator of CDC25C alternative splicing | Promotes cell cycle and lung cancer progression |
| MAD2 | Spindle assembly checkpoint component | Expression/ubiquitination controlled by TRAP1 at G2-M |
| TRAP1 | Mitochondrial chaperone regulating CDK1 and MAD2 | Controls G2-M transition and tumor cell survival |
| VPR (HIV-1) | Viral accessory protein modulating G2/M | Alters transition via non-classic mechanisms |
| Cyclin A | Mitotic cyclin with plasticity in promoting G2-M | Compensatory cyclin in perturbation studies |
| Cyclin E | Cyclin with reported plasticity at G2-M | Context-dependent contribution to transition |
| PLK1 | Polo-like kinase coordinating mitotic entry | Downstream effector of CDK1 at G2-M |
| Aurora A | Centrosome maturation kinase | Acetylation-to-phosphorylation switch at centrosome |
| Golgi matrix proteins | Structural components disassembled at G2-M | Morphological marker of transition |
| Lamin A/C | Nuclear envelope mechanics | Mechanobiology readout during G2-M |
| SUN/KASH complex proteins | Nuclear envelope force transmission | Link cytoskeleton to nuclear events at G2-M |
| Wee1 | Kinase that inhibits CDK1 | Opposes CDC25C in the threshold switch [1,5] |
| Myt1 | Membrane-associated CDK1 inhibitory kinase | Contributes to G2 arrest before transition |
| Cdc20 | APC/C coactivator controlling mitotic progression | Downstream of checkpoint at G2-M |
| BubR1 | Spindle checkpoint protein | Functional partner of MAD2 at G2-M |
How Is G2/M transition of mitotic cell cycle Regulated?
G2/M transition is regulated by a positive feedback loop between CDK1 and CDC25C, opposed by Wee1/Myt1 kinases, and modulated by TRAP1-dependent control of CDK1 and MAD2 ubiquitination [1,5]. PUF60 regulates CDC25C alternative splicing, adding a post-transcriptional layer. Cyclin availability and plasticity further tune the threshold, and centrosome maturation is gated by a cell-cycle-dependent acetylation-to-phosphorylation switch [6,8]. Nuclear mechanobiology provides an additional physical input during G2-M.
G2/M transition of mitotic cell cycle and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PUF60 | Lung cancer progression via CDC25C splicing | Knockout and point-mutation lung cancer cell lines |
| TRAP1 | Tumor cell survival and G2-M control | TRAP1 knockout with CDK1/MAD2 readouts |
| CDC25C | Cell cycle progression and checkpoint bypass | Knock-in of splicing isoforms |
| MAD2 | Spindle checkpoint dysfunction | Point mutation of ubiquitination sites |
| HIV-1 VPR | Viral G2/M modulation | Overexpression in T-cell lines |
Cancer proliferation and lung cancer progression
PUF60 promotes cell cycle progression and lung cancer progression by regulating alternative splicing of CDC25C, directly linking GO:0000086 to tumor growth. TRAP1 controls G2-M transition through CDK1 and MAD2, supporting survival of tumor cells.
Synthetic lethality in melanoma
Targeting cell cycle regulation via the G2-M checkpoint has been proposed for synthetic lethality in melanoma, exploiting tumor-specific dependencies.
Viral manipulation of the cell cycle
HIV-1 VPR modulates cell cycle G2/M transition through an alternative cellular mechanism other than the classic mitotic checkpoints, illustrating how pathogens hijack this process.
Centrosome and nuclear mechanics in disease
Defects in centrosome maturation and nuclear mechanobiology at G2-M can contribute to mitotic errors relevant to genomic instability [2,6].
From G2/M transition of mitotic cell cycle-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is CDK1 threshold activity required for G2-M entry? | CDK1 knockout with inducible rescue |
| Does PUF60 control CDC25C splicing at G2-M? | PUF60 knockout and point-mutation lung cancer cells |
| How does TRAP1 regulate MAD2 ubiquitination? | TRAP1 knockout with ubiquitination assays |
| Can cyclin plasticity compensate for cyclin loss? | Cyclin knockout and knock-in combinations |
| Does centrosome acetylation-to-phosphorylation switch time maturation? | Point-mutation knock-in of acetylation sites |
| Is G2-M checkpoint targeting synthetic lethal in melanoma? | Overexpression and knockout in melanoma lines |
How to Study the G2/M transition of mitotic cell cycle Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Flow cytometry | DNA content and mitotic markers | G2-M transition quantification [5,7] |
| Live-cell imaging | Golgi and nuclear dynamics | Organelle remodeling at G2-M [2,4] |
| RNA-seq / RT-PCR | CDC25C splicing isoforms | PUF60-dependent splicing |
| Immunoblot | CDK1, MAD2, cyclin levels | TRAP1 and checkpoint regulation |
| Immunoprecipitation | Ubiquitination of CDK1/MAD2 | Post-translational control |
| Phospho-specific antibodies | CDK1 activation state | Threshold kinase activity |
| Centrosome imaging | Centrosome maturation | Acetylation-to-phosphorylation switch |
| Mechanobiology assays | Nuclear force transmission | G2-M physical changes |
Cell cycle profiling by flow cytometry
DNA content analysis and phospho-histone H3 staining distinguish G2 from M phase and quantify transition defects after genetic perturbation [5,7].
Live-cell imaging of organelle remodeling
Golgi ribbon disassembly and nuclear envelope dynamics can be imaged in real time to mark G2-M transition [2,4].
RNA splicing and transcript analysis
CDC25C alternative splicing and PUF60-dependent regulation are assessed by RT-PCR and RNA-seq.
Protein stability and ubiquitination assays
CDK1 and MAD2 expression/ubiquitination are measured by immunoblot and immunoprecipitation after TRAP1 perturbation.
How CRISPR Can Be Used to Study GO:0000086 G2/M transition of mitotic cell cycle
Knockout
CRISPR knockout of CDK1, PUF60, or TRAP1 enables loss-of-function studies of G2-M transition, with readouts including flow cytometry and immunoblot [1,5,8].
Point Mutation
Point mutations in CDK1 phosphorylation sites or MAD2 ubiquitination sites can test which residues are required for threshold activation and checkpoint control [5,8].
Knock-in
Knock-in of tagged cyclins or CDC25C splicing isoforms allows tracking of protein localization and isoform-specific function during G2-M [1,8].
Overexpression
Overexpression of HIV-1 VPR or TRAP1 can force G2/M modulation and reveal non-classic mechanisms of transition control [3,5].
How EDITGENE Supports G2/M transition of mitotic cell cycle Research
Researchers studying G2/M transition of mitotic cell cycle-related genes often need to determine whether a candidate gene is causally involved in threshold activation, checkpoint control, or organelle remodeling. EDITGENE provides the CRISPR tools and bioinformatics support to move from correlation to mechanism.
Contact EDITGENE today to design your custom CRISPR model for G2/M transition of mitotic cell cycle research.
Frequently Asked Questions About G2/M transition of mitotic cell cycle
What is GO:0000086?
GO:0000086 is the Gene Ontology term for G2/M transition of mitotic cell cycle, the process by which a cell in G2 commits to M phase when M cyclin/CDK kinase activity reaches a threshold.
What genes are involved in G2/M transition of mitotic cell cycle?
Key genes include CDK1, CCNB1, CDC25C, PUF60, MAD2, and TRAP1, based on published studies [1,5,8].
How is G2/M transition regulated?
It is regulated by a positive feedback loop between CDK1 and CDC25C, opposed by Wee1/Myt1, and modulated by TRAP1 and PUF60 [1,5].
Why is G2/M transition important in cancer?
Dysregulation allows proliferation despite genomic stress, and targeting the G2-M checkpoint can produce synthetic lethality in melanoma.
What happens during G2/M transition?
M cyclin/CDK activity crosses a threshold, CDC25C removes inhibitory phosphates, and organelles such as the Golgi and centrosome remodel [1,4,6].
How do you study G2/M transition in the lab?
Common methods include flow cytometry, live-cell imaging, RNA-seq for CDC25C splicing, and immunoblot for CDK1 and MAD2 [1,2,4,5].
Does HIV-1 affect G2/M transition?
Yes, HIV-1 VPR modulates G2/M transition through an alternative cellular mechanism other than the classic mitotic checkpoints.
What is the role of CDC25C in G2/M transition?
CDC25C is a phosphatase that activates CDK1, and its alternative splicing is regulated by PUF60.
Can cyclins compensate for each other at G2/M?
Yes, mitotic cyclins display plasticity in promoting the G2-M transition, so loss of one cyclin can be partially compensated.
What experimental models are used for G2/M transition?
Knockout, point-mutation, knock-in, and overexpression cell models, plus CRISPR library screens, are widely used [1,5,7,8].
Conclusion
GO:0000086 captures the commitment step of mitosis, defined by threshold activation of M cyclin/CDK through a positive feedback loop. Its core regulators, including CDK1, CDC25C, PUF60, MAD2, and TRAP1, connect the transition to cancer progression, viral manipulation, and organelle remodeling [1,3,5]. Studying this process with CRISPR models and functional assays remains essential for understanding proliferation control and for developing targeted therapies.
References
- 1. Xu N et al.. 2023. PUF60 promotes cell cycle and lung cancer progression by regulating alternative splicing of CDC25C.. Cell Rep 42(9):113041 PMID: 37682709
- 2. Lima JT et al.. 2024. Mechanobiology of the nucleus during the G2-M transition.. Nucleus 15(1):2330947 PMID: 38533923
- 3. Elder RT et al.. 2002. HIV-1 VPR modulates cell cycle G2/M transition through an alternative cellular mechanism other than the classic mitotic checkpoints.. Front Biosci 7:d349-57 PMID: 11815283
- 4. Ayala I et al.. 2023. In Vitro Methods to Investigate the Disassembly of the Golgi Ribbon During the G2-M Transition of the Cell Cycle.. Methods Mol Biol 2557:333-347 PMID: 36512225
- 5. Sisinni L et al.. 2017. TRAP1 controls cell cycle G2-M transition through the regulation of CDK1 and MAD2 expression/ubiquitination.. J Pathol 243(1):123-134 PMID: 28678347
- 6. Li J et al.. 2026. A cell cycle-dependent transition of acetylation to phosphorylation regulates timely centrosome maturation.. Nat Commun 17(1) PMID: 41862458
- 7. Barnaba N et al.. 2021. Targeting cell cycle regulation via the G2-M checkpoint for synthetic lethality in melanoma.. Cell Cycle 20(11):1041-1051 PMID: 33966611
- 8. Crncec A et al.. 2025. Plasticity of mitotic cyclins in promoting the G2-M transition.. J Cell Biol 224(6) PMID: 40202486
