GO:0005940 septin ring: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0005940 (septin ring) describes a tight ring-shaped structure that forms in the division plane at the site of cytokinesis, composed of conserved filament-forming septins and septin-associated proteins.
• Septin rings are observed at the bud neck of budding yeast, at the cleavage furrow of animal cells, at mother cell-pseudohyphal junctions, and at septation sites in filamentous fungi.
• Ring assembly proceeds through sequential recruitment, filament compaction, and splitting into a double ring, regulated by kinases, sumoylation, and F-BAR proteins.
• Key regulators include the anillin Mid2, the F-BAR protein Hof1, the SAGA subunit Spt20, and the Fir1-Skt5 complex.
• Septin ring defects are linked to cytokinesis failure, ER stress sensitivity, and age-sensitive cell-cycle re-entry, with relevance to cancer and neurodegeneration.
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal dissection of septin ring gene function in human cells and yeast.
Description
The septin ring (GO:0005940) is a conserved cellular component that assembles at the division plane during cytokinesis, forming a tight ring-shaped structure from septin filaments and associated proteins. First characterized in budding yeast at the bud neck, septin rings are now recognized across eukaryotes, including at the cleavage furrow of animal cells and at septation sites in filamentous fungi. The ring serves as a scaffold that coordinates membrane remodeling, actomyosin contractility, and cell-cycle progression. Because septin rings are essential for proper cell division and are implicated in stress responses and age-related cell-cycle re-entry, they are a focal point for researchers studying cytokinesis, cytoskeletal dynamics, and disease-associated pathways. Understanding the molecular players that build, compact, and split the septin ring is therefore critical for both basic cell biology and translational research.
septin ring At A Glance
| GO ID | GO:0005940 |
|---|---|
| GO term | septin ring |
| Ontology | cellular_component |
| Synonym | none |
| Major function | Scaffold at the division plane that coordinates cytokinesis, membrane remodeling, and cell-cycle progression |
| Cellular locations | Bud neck of budding yeast, cleavage furrow of animal cells, mother cell-pseudohyphal junction, septation sites in filamentous fungi |
| Core components | Septins (filament-forming GTP-binding proteins) and septin-associated proteins such as Mid2, Hof1, and Fir1-Skt5 |
| Assembly dynamics | Sequential recruitment, filament compaction, and splitting into a double ring |
| Regulatory inputs | Phosphorylation, sumoylation, and F-BAR protein activity |
What Is GO:0005940?
GO:0005940 (septin ring) is defined as a tight ring-shaped structure that forms in the division plane at the site of cytokinesis. It is composed of members of the conserved family of filament-forming proteins called septins as well as septin-associated proteins. This type of septin structure is observed at the bud neck of budding fungal cells, at the site of cell division in animal cells, at the junction between the mother cell and a pseudohyphal projection, and also within hyphae of filamentous fungi at sites where a septum will form.
Why Is septin ring Important in Cell Biology?
The septin ring is a central organizer of cytokinesis, acting as a spatial and temporal scaffold that recruits and regulates the machinery needed for cell division. Defects in septin ring assembly or disassembly lead to cytokinesis failure, aberrant cell-cycle re-entry, and sensitivity to ER stress, processes that are directly relevant to cancer, neurodegeneration, and aging. Because septins are conserved from yeast to humans, studies in model organisms such as Saccharomyces cerevisiae have provided mechanistic insights that translate to human cell biology. Moreover, the septin ring is a tractable model for studying how protein complexes self-organize into higher-order structures, making it a valuable system for both fundamental and applied research.
• Essential for cytokinesis and proper cell division in fungi and animals.
• Serves as a scaffold for actomyosin ring constriction and membrane remodeling.
• Regulates cell-cycle progression and age-sensitive re-entry under ER stress.
• Involved in polarized growth and pseudohyphal/hyphal septation.
• Dysregulation is linked to cytokinesis failure and genomic instability, relevant to cancer.
• Septin mutations and altered expression are associated with neurodegeneration and other diseases.
• Provides a model for studying self-assembly of filament-forming protein complexes.
• Target for antifungal and anticancer strategies aimed at cell division machinery.
• Enables quantitative superresolution imaging of nanoscopic ring structures.
• Offers a platform for CRISPR-based functional genomics of cytokinesis genes.
What Happens During septin ring?
Initiation and Recruitment at the Division Plane
In simple terms: The cell marks where it will divide and starts gathering septin proteins there.
Septin ring formation begins with the recruitment of septin complexes to the future division site, a process that is spatially and temporally controlled. In budding yeast, septins assemble at the bud neck, while in animal cells they localize to the cleavage furrow. The initial recruitment step is regulated by upstream signals including the SAGA complex subunit Spt20, which is required for proper septin ring assembly. This early phase establishes the ring's position and sets the stage for subsequent compaction and maturation.
Filament Compaction and Ring Maturation
In simple terms: The loose septin filaments tighten into a compact ring.
After recruitment, septin filaments undergo compaction into a tight ring structure, a step that requires the anillin Mid2 and is coupled to contractile ring constriction. This compaction is essential for the ring to function as a stable scaffold. The process is also influenced by the F-BAR protein Hof1, whose phosphorylation drives septin ring splitting. Together, these events convert an initially diffuse septin assembly into a mature, functional ring.
Ring Splitting and Double Ring Formation
In simple terms: The single ring splits into two rings to help the cell divide.
A hallmark of septin ring dynamics is the splitting of the initial ring into a double ring, which occurs during cytokinesis. This splitting is regulated by transient sumoylation that steers a Fir1-Skt5 protein complex between the split septin ring. Phosphorylation of Hof1 also drives septin ring splitting in budding yeast. The double ring then coordinates with the actomyosin contractile ring to complete cell division.
Disassembly and Transfer to Cytokinetic Remnants
In simple terms: After division, the ring is dismantled or passed on to leftover structures.
Following cytokinesis, the septin ring is disassembled or transferred to cytokinetic remnants, a process that can direct age-sensitive cell-cycle re-entry under ER stress. This transfer links septin ring dynamics to stress responses and aging. The disassembly step is tightly regulated to ensure proper completion of division and to prevent aberrant re-entry. Defects in this stage can lead to persistent septin structures and cell-cycle defects.
Size Control and Quantitative Dynamics
In simple terms: The cell controls how big the ring gets.
The size of the septin ring is precisely controlled, and recent work has begun to uncover the origin of septin ring size control in budding yeast. Quantitative superresolution microscopy has enabled precise measurement of nanoscopic septin ring structures, revealing dynamic changes in ring dimensions. These studies show that ring size is not arbitrary but is regulated by the availability of septin subunits and associated factors. Understanding size control is key to linking ring architecture to function.
Key Genes Involved in GO:0005940 septin ring
The following genes and proteins are central to septin ring assembly, regulation, and function, as supported by the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SEPT1-SEPT14 (septins) | Core filament-forming GTP-binding proteins of the septin ring | Conserved from yeast to humans; mutations linked to disease |
| MID2 | Anillin-like protein required for septin filament compaction into rings | Key regulator of ring maturation and contractile ring coupling |
| HOF1 | F-BAR protein whose phosphorylation drives septin ring splitting | Links membrane remodeling to ring splitting |
| FIR1 | Part of Fir1-Skt5 complex steered by sumoylation between split rings | Regulates ring splitting via sumoylation |
| SKT5 | Part of Fir1-Skt5 complex involved in septin ring dynamics | Sumoylation target in ring splitting |
| SPT20 | Structural subunit of SAGA complex regulating septin ring assembly | Connects transcription regulation to ring assembly |
| CDC3 | Septin in budding yeast essential for bud neck ring | Model for septin assembly |
| CDC10 | Septin in budding yeast required for ring formation | Core component of the ring |
| CDC11 | Septin in budding yeast involved in ring assembly | Core component of the ring |
| CDC12 | Septin in budding yeast essential for ring integrity | Core component of the ring |
| GIN4 | Kinase regulating septin ring assembly and disassembly | Phosphorylation-dependent regulation |
| CLA4 | Kinase involved in septin ring dynamics | Regulates ring assembly |
| ELM1 | Kinase implicated in septin ring regulation | Modulates ring formation |
| BUD3 | Protein involved in septin ring positioning | Spatial control of ring |
| BUD4 | Protein involved in septin ring positioning | Spatial control of ring |
| RHO1 | Small GTPase regulating septin ring and cell wall integrity | Signaling to ring |
| MYO1 | Myosin II heavy chain coordinating with septin ring | Contractile ring coupling |
| IQG1 | IQGAP-like protein linking septin ring to actomyosin ring | Scaffold for cytokinesis |
How Is septin ring Regulated?
Septin ring assembly and disassembly are regulated by multiple post-translational modifications and signaling pathways. Phosphorylation of the F-BAR protein Hof1 drives septin ring splitting in budding yeast. Transient sumoylation steers a Fir1-Skt5 protein complex between the split septin ring, highlighting a role for SUMO modification in ring dynamics. The SAGA complex subunit Spt20 regulates septin ring assembly, linking transcriptional regulation to ring formation. Additionally, the anillin Mid2 and contractile ring constriction are required for septin filament compaction into rings. ER stress can direct the transfer of the septin ring to cytokinetic remnants, influencing age-sensitive cell-cycle re-entry. These regulatory inputs ensure that the septin ring is assembled, remodeled, and disassembled at the correct time and place.
septin ring and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SEPT9 | Cancer (colorectal, breast); cytokinesis defects | CRISPR knockout in human cancer cell lines |
| SEPT2 | Neurodegeneration; hereditary neuralgic amyotrophy | Knock-in of patient mutations in iPSC-derived neurons |
| SEPT7 | Cancer; genomic instability | Overexpression and knockout in HeLa cells |
| SEPT12 | Male infertility; cytokinesis failure | Point mutation knock-in in mouse models |
| MID2 | Cytokinesis defects; potential cancer relevance | Knockout in yeast and human cells |
Septin Ring Defects and Cancer
Dysregulation of septin ring components can lead to cytokinesis failure, resulting in aneuploidy and genomic instability, which are hallmarks of cancer. Septins are frequently altered in human cancers, and their role in cell division makes them potential therapeutic targets. Understanding how septin ring assembly is controlled may reveal vulnerabilities in cancer cells that divide rapidly.
Septin Ring and Neurodegeneration
Septins are abundant in the nervous system, and mutations in septin genes have been linked to neurodegenerative conditions such as hereditary neuralgic amyotrophy and Parkinson's disease. The septin ring's role in maintaining cellular architecture and division may be relevant to neuronal function and survival. Studies in model organisms have begun to uncover how septin ring dynamics contribute to age-related cellular decline.
Septin Ring in ER Stress and Aging
ER stress can direct the transfer of the septin ring to cytokinetic remnants, which in turn influences age-sensitive cell-cycle re-entry. This connection suggests that septin ring regulation is part of the cellular stress response and may contribute to aging-related phenotypes. Targeting this pathway could have implications for age-related diseases.
From septin ring-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene essential for septin ring assembly? | CRISPR knockout in Saccharomyces cerevisiae or human cells |
| Does a specific phosphorylation site regulate ring splitting? | Point mutation (phospho-null or phospho-mimetic) knock-in |
| How does a disease-associated mutation affect ring dynamics? | Knock-in of patient mutation in cell lines |
| Where and when is a septin protein localized? | Tagged knock-in with fluorescent protein |
| Does overexpression of a septin disrupt ring formation? | Overexpression cell model |
| What genes modulate septin ring size? | CRISPR library screening in budding yeast |
How to Study the septin ring Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Superresolution microscopy | Nanoscopic ring structure and size | Quantifying septin ring dimensions |
| Live-cell fluorescence imaging | Real-time ring dynamics | Tracking assembly and splitting |
| Co-immunoprecipitation | Protein-protein interactions | Identifying septin-associated proteins |
| Mass spectrometry | Post-translational modifications | Detecting sumoylation and phosphorylation |
| CRISPR knockout screening | Gene essentiality for ring formation | Discovering novel regulators |
| CRISPR point mutation knock-in | Effect of specific residues | Testing phosphorylation sites |
| Overexpression | Dosage effects on ring integrity | Modeling septin overexpression |
| Deep learning image analysis | Automated ring measurements | High-throughput phenotyping |
Quantitative Superresolution Microscopy
Deep learning-assisted quantitative superresolution microscopy enables precise measurement of nanoscopic septin ring structures, revealing dynamic changes in ring dimensions and architecture. This method is essential for studying ring size control and splitting.
Live-Cell Imaging of Ring Dynamics
Time-lapse fluorescence microscopy of fluorescently tagged septins allows real-time visualization of ring assembly, compaction, splitting, and disassembly. This approach has been used to track septin ring and collar formation in Saccharomyces cerevisiae.
Genetic and Biochemical Assays
Genetic screens and biochemical assays identify regulators of septin ring assembly, such as Spt20 and the Fir1-Skt5 complex. Co-immunoprecipitation and mass spectrometry can reveal septin-associated proteins and post-translational modifications.
CRISPR-Based Functional Genomics
CRISPR knockout and library screening enable systematic dissection of genes required for septin ring formation and function. These methods can identify novel regulators and potential therapeutic targets.
How CRISPR Can Be Used to Study GO:0005940 septin ring
Knockout
CRISPR knockout of septin genes or regulators such as MID2, HOF1, or SPT20 in yeast and human cells can reveal their essential roles in septin ring assembly and cytokinesis. Knockout models are used to assess defects in ring formation, cell division, and stress responses.
Point Mutation
Point mutation knock-in of phosphorylation sites in HOF1 or sumoylation sites in FIR1/SKT5 allows precise testing of their role in septin ring splitting. Phospho-null or phospho-mimetic mutations can clarify the contribution of specific residues to ring dynamics.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) into endogenous septin genes enables real-time visualization of ring assembly and disassembly in live cells. Disease-associated mutations can also be knocked in to model their impact on ring function.
Overexpression
Overexpression of septins or associated proteins can disrupt ring stoichiometry and function, providing insights into dosage sensitivity and dominant-negative effects. This approach is useful for modeling septin overexpression observed in cancer.
How EDITGENE Supports septin ring Research
Researchers studying septin ring-related genes often need to determine whether a candidate gene is causally involved in ring assembly, dynamics, or disease. EDITGENE provides end-to-end CRISPR services to generate precisely engineered cell models for such functional studies.
Contact EDITGENE today to design your custom CRISPR model for septin ring research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SEPTIN7 Knockout HEK293 Cell Line | EDJ-KQ3540 | Human | 989 | Details Get a Quote |
| SEPTIN1 Knockout HEK293 Cell Line | EDJ-KQ4444 | Human | 1731 | Details Get a Quote |
| SEPTIN2 Knockout HEK293 Cell Line | EDJ-KQ5327 | Human | 4735 | Details Get a Quote |
| SEPTIN5 Knockout HEK293 Cell Line | EDJ-KQ5500 | Human | 5413 | Details Get a Quote |
| SEPTIN4 Knockout HEK293 Cell Line | EDJ-KQ5501 | Human | 5414 | Details Get a Quote |
| SEPTIN9 Knockout HEK293 Cell Line | EDJ-KQ6541 | Human | 10801 | Details Get a Quote |
| SEPTIN6 Knockout HEK293 Cell Line | EDJ-KQ7858 | Human | 23157 | Details Get a Quote |
| SEPTIN8 Knockout HEK293 Cell Line | EDJ-KQ7865 | Human | 23176 | Details Get a Quote |
| SEPTIN12 Knockout HEK293 Cell Line | EDJ-KQ8540 | Human | 124404 | Details Get a Quote |
| SEPTIN10 Knockout HEK293 Cell Line | EDJ-KQ11317 | Human | 151011 | Details Get a Quote |
| SEPTIN3 Knockout HEK293 Cell Line | EDJ-KQ15225 | Human | 55964 | Details Get a Quote |
| SEPTIN11 Knockout HEK293 Cell Line | EDJ-KQ15226 | Human | 55752 | Details Get a Quote |
| SEPTIN14 Knockout HEK293 Cell Line | EDJ-KQ15227 | Human | 346288 | Details Get a Quote |
| SEPTIN9 Knockout A-549 Cell Line | EDJ-KQ32095 | Human | 10801 | Details Get a Quote |
| SEPTIN9 Knockout HCT 116 Cell Line | EDJ-KQ32096 | Human | 10801 | Details Get a Quote |
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Frequently Asked Questions About septin ring
What is the septin ring (GO:0005940)?
The septin ring is a tight ring-shaped structure that forms in the division plane at the site of cytokinesis, composed of septins and septin-associated proteins.
What genes are involved in septin ring assembly?
Key genes include septins (CDC3, CDC10, CDC11, CDC12), MID2, HOF1, FIR1, SKT5, and SPT20.
Where is the septin ring located?
It is found at the bud neck of budding yeast, the cleavage furrow of animal cells, the mother cell-pseudohyphal junction, and septation sites in filamentous fungi.
How is the septin ring regulated?
It is regulated by phosphorylation (e.g., Hof1), sumoylation (Fir1-Skt5), and the SAGA complex subunit Spt20.
What is the function of the septin ring?
It acts as a scaffold for cytokinesis, coordinating actomyosin ring constriction, membrane remodeling, and cell-cycle progression.
How can I study septin ring dynamics?
Quantitative superresolution microscopy and live-cell imaging of fluorescently tagged septins are commonly used.
What diseases are associated with septin ring defects?
Septin ring defects are linked to cancer, neurodegeneration, and age-related cell-cycle re-entry.
What model organisms are used to study the septin ring?
Saccharomyces cerevisiae is a primary model, but human cell lines and filamentous fungi are also used.
Can CRISPR be used to study septin ring genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable functional dissection of septin ring genes.
What is the role of Mid2 in the septin ring?
Mid2 is an anillin-like protein required for septin filament compaction into rings and coupling to contractile ring constriction.
Conclusion
The septin ring (GO:0005940) is a conserved and dynamic cellular component essential for cytokinesis and cell-cycle coordination. Its assembly, compaction, splitting, and disassembly are controlled by a network of septins and associated regulators such as Mid2, Hof1, Fir1-Skt5, and Spt20. Defects in septin ring function are linked to cancer, neurodegeneration, and aging, making it a compelling target for both basic and translational research. Advances in quantitative imaging and CRISPR-based models continue to illuminate the molecular principles of septin ring biology.
References
- 1. Kukhtevich IV et al.. 2025. The origin of septin ring size control in budding yeast.. EMBO J 44(22):6466-6498 PMID: 41039155
- 2. Müller J et al.. 2024. Transient septin sumoylation steers a Fir1-Skt5 protein complex between the split septin ring.. J Cell Biol 223(1) PMID: 37938157
- 3. Varela Salgado M et al.. 2024. Phosphorylation of the F-BAR protein Hof1 drives septin ring splitting in budding yeast.. Nat Commun 15(1):3383 PMID: 38649354
- 4. Arbizzani F et al.. 2022. Septin filament compaction into rings requires the anillin Mid2 and contractile ring constriction.. Cell Rep 39(3):110722 PMID: 35443188
- 5. Chen H et al.. 2011. Dynamics of septin ring and collar formation in Saccharomyces cerevisiae.. Biol Chem 392(8-9):689-97 PMID: 21736496
- 6. Lei B et al.. 2014. Septin ring assembly is regulated by Spt20, a structural subunit of the SAGA complex.. J Cell Sci 127(Pt 18):4024-36 PMID: 25015293
- 7. Zehtabian A et al.. 2022. Precise measurement of nanoscopic septin ring structures with deep learning-assisted quantitative superresolution microscopy.. Mol Biol Cell 33(8):ar76 PMID: 35594179
- 8. Chao JT et al.. 2019. Transfer of the Septin Ring to Cytokinetic Remnants in ER Stress Directs Age-Sensitive Cell-Cycle Re-entry.. Dev Cell 51(2):173-191.e5 PMID: 31564614
