GO:1903479 mitotic actomyosin contractile ring assembly actin filament organization: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1903479 describes the actin filament organization events that build the mitotic actomyosin contractile ring, the force-generating structure that cleaves one cell into two.
• The term is a biological_process child of actin filament organization, restricted to the context of mitotic contractile ring assembly.
• Actin dynamics during ring assembly can physically displace the mitotic nucleus, linking ring mechanics to nuclear positioning.
• Centralspindlin controls ECT2 and RhoA accumulation at the equatorial cortex, a key upstream step for contractile ring actin assembly.
• Dictyostelium studies established the classical actomyosin organization framework for cytokinesis that still informs modern ring research.
• CRISPR knockout, point-mutation, knock-in and overexpression models let researchers test causal roles of ring genes in human cells.
Description
GO:1903479, mitotic actomyosin contractile ring assembly actin filament organization, is a Gene Ontology biological_process term that captures the actin filament organization steps specifically dedicated to building the mitotic actomyosin contractile ring. In animal and fungal cells, cytokinesis depends on a cortical ring of actin filaments and myosin-II that constricts to sever the daughter cells, and the assembly of this ring requires tightly controlled actin nucleation, elongation, bundling and turnover. The term therefore sits at the intersection of cytoskeletal dynamics, cell-cycle control and mechanical force generation.
mitotic actomyosin contractile ring assembly actin filament organization At A Glance
| GO ID | GO:1903479 |
|---|---|
| GO term | mitotic actomyosin contractile ring assembly actin filament organization |
| Ontology | biological_process |
| Synonym | actin filament organization involved in mitotic actomyosin contractile ring assembly |
| Major function | Organization of actin filaments during assembly of the mitotic actomyosin contractile ring |
| Parent process | actin filament organization |
| Context | Mitotic cytokinesis and contractile ring assembly |
| Related machinery | Actin filaments, myosin-II, RhoA signaling and centralspindlin |
What Is GO:1903479?
In plain terms, GO:1903479 covers any actin filament organization that is involved in mitotic actomyosin contractile ring assembly. It is a specialized sub-process of general actin filament organization, restricted to the mitotic contractile ring context, and it includes the nucleation, elongation, crosslinking and rearrangement of actin filaments that together form the ring structure.
Why Is mitotic actomyosin contractile ring assembly actin filament organization Important in Cell Biology?
Understanding GO:1903479 matters because the contractile ring is the machine that physically divides cells, and errors in its actin organization cause cytokinesis failure, aneuploidy and genome instability. The process is also a paradigm for how cells convert biochemical signals into mechanical force, making it relevant to cancer biology, developmental defects and cytoskeletal disease research.
• Cytokinesis failure caused by defective ring assembly can produce binucleated cells and aneuploidy.
• Actin dynamics during ring assembly can displace the mitotic nucleus, coupling division to nuclear positioning.
• Centralspindlin-dependent RhoA activation at the equatorial cortex is a conserved trigger for ring actin assembly.
• Dictyostelium actomyosin organization studies provided foundational genetics for cytokinesis.
• The term helps annotate genes whose primary role is ring-specific actin organization rather than general actin dynamics.
• Ring assembly is a target for anti-proliferative research because dividing cells depend on it.
• Live imaging of ring assembly is a standard assay for cytokinesis gene function.
• CRISPR models of ring genes enable causal testing in human cell lines.
What Happens During mitotic actomyosin contractile ring assembly actin filament organization?
Initiation at the equatorial cortex
In simple terms: The cell marks the middle of the division plane and starts building the ring there.
Ring assembly begins when signaling at the equatorial cortex recruits factors that activate RhoA, and centralspindlin regulates ECT2 and RhoA accumulation at this site. This creates a localized zone where actin filament organization is initiated for the contractile ring.
Actin nucleation and elongation
In simple terms: New actin filaments are started and lengthened to form the ring's core.
Actin filament organization during ring assembly involves nucleation and elongation of filaments that will constitute the ring. Live analysis in fission yeast shows that actin dynamics during contractile ring assembly are active and can drive mitotic nuclear displacement.
Bundling and crosslinking into a ring
In simple terms: Filaments are tied together into a coherent ring structure.
Actin filaments must be organized into a bundled, contractile array, a principle established in classical actomyosin organization studies in Dictyostelium. This organization converts a loose filament network into a ring capable of constriction.
Coupling to myosin-II and force generation
In simple terms: The actin ring works with myosin motors to squeeze the cell.
The actomyosin contractile ring combines actin filaments with myosin-II to generate constriction force, and actin organization is a prerequisite for this mechanical output. Defects in actin organization therefore impair ring constriction and cytokinesis.
Turnover and remodeling
In simple terms: The ring is continuously rebuilt as it assembles and constricts.
Actin dynamics during ring assembly include turnover and remodeling events that support ring integrity and movement. This dynamic behavior distinguishes GO:1903479 from static actin bundling processes.
Key Genes Involved in GO:1903479 mitotic actomyosin contractile ring assembly actin filament organization
The following genes and proteins are experimentally linked to actin filament organization during mitotic contractile ring assembly.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RhoA | Activates actomyosin ring assembly at the equatorial cortex | Central regulator of contractile ring initiation |
| ECT2 | RhoA guanine nucleotide exchange factor recruited by centralspindlin | Upstream activator of ring actin assembly |
| Centralspindlin | Regulates ECT2 and RhoA accumulation at the equatorial cortex | Key spatial regulator of ring assembly |
| Actin (act1) | Core filament subunit of the contractile ring | Direct target for actin organization studies |
| Myosin-II | Motor that generates constriction force with actin | Mechanical output of the ring |
| Profilin | Promotes actin filament elongation | Modulates actin dynamics during ring assembly |
| Cofilin | Severing and turnover of actin filaments | Regulates actin remodeling in the ring |
| Formin | Nucleates and elongates actin filaments | Candidate for ring actin nucleation |
| Arp2/3 complex | Branched actin nucleation | Potential contributor to ring actin organization |
| Anillin | Crosslinks actin and links ring to membrane | Ring stability factor |
| IQGAP | Scaffolds actin and myosin at the cleavage furrow | Ring organization scaffold |
| Rho kinase | Promotes myosin activation downstream of RhoA | Links RhoA to contractility |
| Citron kinase | Actin and myosin organization at the cleavage furrow | Ring assembly regulator |
| Septins | Scaffold and stabilize the division site | Supports ring organization |
| Fimbrin | Actin bundling | Ring bundling candidate |
| Alpha-actinin | Actin crosslinking | Ring crosslinking candidate |
| Myosin light chain | Regulatory subunit for myosin-II activity | Contractility regulation |
How Is mitotic actomyosin contractile ring assembly actin filament organization Regulated?
Regulation of GO:1903479 centers on spatial signaling that confines actin organization to the equatorial cortex. Centralspindlin controls ECT2 and RhoA accumulation at the equatorial cortex, thereby restricting ring assembly to the correct site. RhoA activation then promotes downstream actomyosin assembly, while actin turnover factors modulate filament dynamics during assembly. Classical work in Dictyostelium further showed that actomyosin organization in cytokinesis is genetically regulated and can be uncoupled from other division steps.
mitotic actomyosin contractile ring assembly actin filament organization and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RhoA | Cytokinesis failure and aneuploidy | Knockout and point-mutation cell lines |
| ECT2 | Aberrant cell division and proliferation | Knockout and overexpression models |
| Actin (act1) | Cytoskeletal organization defects | Point-mutation and tagged knock-in |
| Myosin-II | Contractility and division defects | Knockout and point-mutation models |
| Anillin | Ring stability and genome stability | Knockout and knock-in models |
Cytokinesis failure and aneuploidy in cancer
Defective contractile ring assembly can cause cytokinesis failure, producing binucleated cells and aneuploidy, a hallmark of cancer progression. Genes controlling ring actin organization are therefore candidate cancer-relevant regulators.
Developmental and tissue homeostasis defects
Because ring assembly is essential for cell division, its disruption impairs proliferation and tissue maintenance, as illustrated by classical cytokinesis mutants.
Cytoskeletal disease relevance
Actin organization pathways are broadly implicated in cytoskeletal disorders, and ring-specific actin regulators represent a specialized subset of these pathways.
From mitotic actomyosin contractile ring assembly actin filament organization-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a gene required for ring assembly? | CRISPR knockout cell line |
| Does a specific residue control actin binding? | Point-mutation knock-in |
| Where does a protein localize during ring assembly? | Tagged knock-in (fluorescent tag) |
| Does excess protein disrupt ring organization? | Overexpression model |
| Which actin regulators act redundantly? | Multiplex knockout and library screening |
| How does ring actin dynamics change over time? | Live imaging of tagged actin |
How to Study the mitotic actomyosin contractile ring assembly actin filament organization Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell fluorescence imaging | Ring assembly dynamics | Tracking actin and myosin during division |
| CRISPR knockout | Gene requirement | Testing ring assembly genes |
| Point-mutation knock-in | Residue-specific function | Dissecting actin-binding domains |
| Tagged knock-in | Protein localization | Visualizing ring components |
| Overexpression | Dosage effects | Testing dominant effects on ring organization |
| Immunofluorescence | Ring structure and morphology | Scoring cytokinesis defects |
| Proteomics | Protein interactions | Identifying ring-associated factors |
| Time-lapse microscopy | Constriction kinetics | Measuring ring function |
Live-cell imaging of ring assembly
Fluorescently tagged actin and myosin allow tracking of ring assembly dynamics, as used to show actin dynamics driving nuclear displacement in fission yeast.
Genetic perturbation and cytokinesis assays
Knockout or mutation of candidate genes followed by scoring of binucleation and ring defects tests causal roles in GO:1903479.
Localization and signaling analysis
Imaging of ECT2, RhoA and centralspindlin at the equatorial cortex defines the spatial regulation of ring assembly.
Proteomic and interactome profiling
Affinity purification of ring components can identify actin-associated factors that contribute to ring organization.
How CRISPR Can Be Used to Study GO:1903479 mitotic actomyosin contractile ring assembly actin filament organization
Knockout
CRISPR knockout of candidate genes such as RhoA or ECT2 can reveal whether they are required for contractile ring actin organization and successful cytokinesis.
Point Mutation
Point-mutation knock-in can test specific residues in actin or actin-binding proteins for their role in ring assembly without removing the whole protein.
Knock-in
Tagged knock-in of actin or myosin allows direct visualization of ring assembly in live cells, as demonstrated in fission yeast studies.
Overexpression
Overexpression of ring regulators can test dosage sensitivity and dominant effects on actin organization during cytokinesis.
How EDITGENE Supports mitotic actomyosin contractile ring assembly actin filament organization Research
Researchers studying mitotic actomyosin contractile ring assembly actin filament organization-related genes often need to determine whether a candidate gene is causally involved in ring assembly, whether a specific residue matters, or where the protein acts. EDITGENE provides the CRISPR cell models and screening services needed to answer these questions rigorously.
Contact EDITGENE today to design your custom CRISPR model for mitotic actomyosin contractile ring assembly actin filament organization research.
Frequently Asked Questions About mitotic actomyosin contractile ring assembly actin filament organization
What is GO:1903479?
GO:1903479 is the Gene Ontology biological_process term for actin filament organization involved in mitotic actomyosin contractile ring assembly.
What does mitotic actomyosin contractile ring assembly actin filament organization mean?
It means the actin filament organization steps that build the contractile ring during mitosis.
What genes are involved in mitotic actomyosin contractile ring assembly actin filament organization?
Key genes include RhoA, ECT2, centralspindlin components, actin, myosin-II and actin regulators such as profilin and cofilin.
Why is the contractile ring important for cell division?
The ring generates the force that cleaves the cell into two daughter cells during cytokinesis.
How is RhoA involved in contractile ring assembly?
Centralspindlin regulates ECT2 and RhoA accumulation at the equatorial cortex, which triggers ring assembly.
What happens if contractile ring assembly fails?
Failure can cause cytokinesis defects, binucleation and aneuploidy.
Which model organisms are used to study contractile ring assembly?
Fission yeast and Dictyostelium are classical models for actomyosin ring organization.
How can CRISPR help study GO:1903479?
CRISPR knockout, point mutation, knock-in and overexpression allow causal testing of ring assembly genes.
What methods measure contractile ring actin organization?
Live-cell imaging, immunofluorescence and time-lapse microscopy are commonly used.
Is GO:1903479 a molecular function or biological process?
It is a biological_process term under actin filament organization.
Conclusion
GO:1903479 defines the actin filament organization events that build the mitotic actomyosin contractile ring, a process essential for cytokinesis and genome stability. Its regulation by centralspindlin, ECT2 and RhoA provides a clear signaling framework for experimental dissection. CRISPR-based models and imaging methods now make it feasible to test ring assembly genes causally in many cell types.
References
- 1. Hwang W et al.. 2026. Actin dynamics during contractile ring assembly drives mitotic nuclear displacement in fission yeast.. Biochem Biophys Res Commun 795:153098 PMID: 41353921
- 2. Fukui Y et al.. 1991. Cell division in Dictyostelium with special emphasis on actomyosin organization in cytokinesis.. Cell Motil Cytoskeleton 18(1):41-54 PMID: 2004432
- 3. Nishimura Y et al.. 2006. Centralspindlin regulates ECT2 and RhoA accumulation at the equatorial cortex during cytokinesis.. J Cell Sci 119(Pt 1):104-14 PMID: 16352658
