GO:1905720 cytoplasmic microtubule bundle: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1905720 defines the cytoplasmic microtubule bundle, a cellular component consisting of any microtubule bundle located in the cytoplasm.
• Cytoplasmic microtubule bundles are dynamic arrays of parallel or anti-parallel microtubules crosslinked by motors and MAPs, essential for intracellular transport, cell polarity, and cytokinesis.
• Motor proteins such as kinesin and dynein, along with crosslinkers like anillin and tau, regulate bundle formation, stability, and function.
• Disruption of cytoplasmic microtubule bundles is linked to axonal degeneration, stem cell dysfunction, and platelet production defects.
• Key experimental approaches include live-cell imaging, CRISPR knockout/knock-in, and biochemical reconstitution to study bundle assembly and dynamics.
• EDITGENE provides CRISPR services to model bundle-related genes, enabling causal studies in disease and development.
Description
Cytoplasmic microtubule bundles (GO:1905720) are specialized cytoskeletal structures formed by the lateral association of microtubules within the cytoplasm. These bundles are distinct from other microtubule arrays because they are specifically located in the cytoplasm and often function as tracks for intracellular transport or as structural elements that maintain cell shape and polarity. The formation of these bundles is driven by motor proteins and crosslinking factors that organize microtubules into parallel or anti-parallel arrays, a process that can be reconstituted in vitro and modeled physically. Understanding cytoplasmic microtubule bundles is critical for researchers studying cell division, intracellular trafficking, and the mechanisms of diseases such as neurodegeneration and cancer.
cytoplasmic microtubule bundle At A Glance
| GO ID | GO:1905720 |
|---|---|
| GO term | cytoplasmic microtubule bundle |
| Ontology | cellular_component |
| Synonym | microtubule bundle of cytoplasm, microtubule fascicle of cytoplasm |
| Major function | Provides structural organization for intracellular transport, cell polarity, and cytokinesis |
| Location | Cytoplasm |
| Key components | Microtubules, motor proteins (kinesin, dynein), crosslinkers (anillin, tau) |
| Related processes | Microtubule organization, axonal transport, platelet formation, stem cell regeneration |
What Is GO:1905720?
According to the Gene Ontology, GO:1905720 (cytoplasmic microtubule bundle) is defined as any microtubule bundle that is part of a cytoplasm. This means it is a cellular component where multiple microtubules are held together in a bundle within the cytoplasmic compartment. Synonyms include microtubule bundle of cytoplasm and microtubule fascicle of cytoplasm. The term captures structures that are not membrane-bound but are organized by protein-protein interactions, often involving motor proteins and microtubule-associated proteins (MAPs).
Why Is cytoplasmic microtubule bundle Important in Cell Biology?
Cytoplasmic microtubule bundles are fundamental to many cellular processes, including the establishment of cell polarity, the positioning of organelles, and the mechanics of cell division. In specialized cells such as neurons and platelets, these bundles are essential for long-range transport and the elaboration of cellular extensions. Dysregulation of bundle formation or stability has been implicated in human diseases, ranging from neurodegenerative disorders to cancer and stem cell regeneration defects. Therefore, studying the molecular players that build and maintain these bundles is crucial for understanding both basic cell biology and disease mechanisms.
• Cytoplasmic microtubule bundles serve as tracks for motor-driven transport of vesicles and organelles.
• They are essential for establishing and maintaining cell polarity in processes like yeast mating and neuronal development.
• Bundles contribute to the mechanics of cytokinesis, particularly in the abscission step.
• They are involved in platelet production, where bundle coiling drives proplatelet formation.
• Disruption of bundles in axons leads to neurodegeneration, as seen in motor protein mutations.
• The TP53/TAU axis regulates microtubule bundling to control alveolar stem cell regeneration.
• Anillin crosslinks microtubules with actin, linking bundles to the contractile machinery.
• Physical models like the pivot-and-bond model help explain bundle formation principles.
• Spatial confinement can induce rotational cytoplasmic flows via bundled microtubules.
• Aurora B kinase controls microtubule stability during abscission, affecting bundle dynamics.
What Happens During cytoplasmic microtubule bundle?
Nucleation and initial bundling
In simple terms: Microtubules first form and then start to stick together.
Cytoplasmic microtubule bundles originate from the nucleation of individual microtubules, which are then brought together by crosslinking proteins and motors. In fission yeast, the organization of cytoplasmic microtubules into bundles is crucial for cell polarity and nuclear positioning. The initial bundling can be driven by motor proteins that slide microtubules relative to one another, as described by the pivot-and-bond model, which explains how bundles form through motor-driven pivoting and bond formation.
Motor-driven organization and dynamics
In simple terms: Motor proteins push and pull microtubules to shape the bundle.
Motor proteins such as kinesins and dynein play a central role in organizing microtubule bundles. In Drosophila axons, loss or gain of motor protein function causes microtubule bundle damage, highlighting the importance of motor activity in maintaining bundle integrity. These motors generate forces that slide microtubules, leading to bundle compaction or extension, and can also transport cargo along the bundle.
Crosslinking and stabilization
In simple terms: Other proteins glue microtubules together to keep the bundle stable.
Crosslinking proteins, including anillin and tau, stabilize microtubule bundles by physically linking microtubules to each other or to actin filaments. Anillin directly crosslinks microtubules with actin filaments, providing mechanical coupling that is important for cytokinesis. The TP53/TAU axis regulates microtubule bundling in alveolar stem cells, where tau promotes bundling to control regeneration. These crosslinkers ensure bundle stability and function.
Regulation by kinases and signaling
In simple terms: Enzymes can add chemical tags to bundle proteins to change their behavior.
Kinases such as Aurora B regulate microtubule stability and dynamics during abscission, thereby influencing bundle behavior. Phosphorylation of motor proteins and MAPs can alter their activity, leading to changes in bundle organization. For example, Aurora B controls microtubule stability to regulate abscission dynamics in stem cells. This regulation ensures proper timing and location of bundle assembly and disassembly.
Functional outputs: transport and mechanics
In simple terms: Once formed, bundles help move things around and give the cell shape.
Cytoplasmic microtubule bundles function as tracks for intracellular transport and as mechanical elements. In platelets, microtubule bundles coil to drive proplatelet elaboration, a process essential for platelet production. Spatial confinement of active microtubule networks can induce large-scale rotational cytoplasmic flow, demonstrating how bundles can generate fluid dynamics. These functions are critical for cell physiology and development.
Key Genes Involved in GO:1905720 cytoplasmic microtubule bundle
The following genes and proteins are key players in the formation, regulation, and function of cytoplasmic microtubule bundles.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TUBB | Beta-tubulin, core microtubule subunit | Mutations affect microtubule stability and bundle formation |
| TUBA | Alpha-tubulin, core microtubule subunit | Post-translational modifications regulate bundle dynamics |
| KIF5B | Kinesin-1 motor, transports cargo along microtubules | Motor dysfunction causes bundle damage in axons |
| DYNC1H1 | Dynein heavy chain, retrograde transport | Mutations linked to neurodegeneration and bundle defects |
| ANLN | Anillin, crosslinks microtubules with actin | Essential for cytokinesis and bundle stability |
| MAPT | Tau, microtubule-associated protein | Regulates bundling in stem cells and neurons |
| TP53 | Tumor suppressor, regulates TAU axis | Controls microtubule bundling in alveolar regeneration |
| AURKB | Aurora B kinase, regulates microtubule stability | Controls abscission dynamics and bundle behavior |
| CLASP1 | Microtubule plus-end tracking protein | Regulates microtubule dynamics and bundling |
| MAPRE1 | EB1, plus-end tracking protein | Influences bundle formation and polarity |
| PRC1 | Protein regulator of cytokinesis 1 | Crosslinks anti-parallel microtubules in bundles |
| KIF11 | Eg5 kinesin, slides anti-parallel microtubules | Essential for spindle and bundle organization |
| KIF4A | Kinesin-4, regulates microtubule length | Affects bundle dynamics in interphase |
| STMN1 | Stathmin, sequesters tubulin dimers | Regulates microtubule catastrophe and bundle turnover |
| TACC3 | Transforming acidic coiled-coil protein 3 | Stabilizes microtubules in bundles |
| CLIP1 | CLIP-170, links microtubules to organelles | Facilitates bundle interactions with cargo |
| DCTN1 | Dynactin subunit, cofactor for dynein | Required for dynein-mediated transport along bundles |
How Is cytoplasmic microtubule bundle Regulated?
The formation and stability of cytoplasmic microtubule bundles are regulated by a variety of signaling pathways and post-translational modifications. Aurora B kinase controls microtubule stability to regulate abscission dynamics, thereby affecting bundle behavior during cytokinesis. The TP53/TAU axis regulates microtubule bundling in alveolar stem cells, linking cell cycle and stress signals to bundle formation. Motor protein activity is also regulated by phosphorylation, which can alter the force generation and directionality of kinesins and dynein, impacting bundle organization. Additionally, spatial confinement and mechanical cues can influence bundle formation and dynamics, as shown by the induction of rotational cytoplasmic flow in confined microtubule networks.
cytoplasmic microtubule bundle and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| KIF5B | Neurodegeneration, axonal transport defects | Knockout or point mutation in neurons |
| MAPT | Tauopathies, Alzheimer's disease | Knock-in of mutant tau in stem cells |
| TP53 | Lung cancer, impaired regeneration | Knockout in alveolar stem cells |
| AURKB | Cancer, cytokinesis failure | Overexpression or knockout in cancer cell lines |
| ANLN | Cytokinesis defects, cancer | Knockout in HeLa cells |
Neurodegeneration and axonal transport defects
Disruption of cytoplasmic microtubule bundles in axons leads to impaired transport and neurodegeneration. In Drosophila, loss or gain of motor protein function causes microtubule bundle damage in axons, providing a model for human diseases linked to motor protein mutations. Tau, a microtubule-associated protein, regulates bundling, and its dysfunction is implicated in Alzheimer's disease and other tauopathies.
Cancer and stem cell regeneration
The TP53/TAU axis regulates microtubule bundling to control alveolar stem cell-mediated regeneration, suggesting that dysregulation of bundling contributes to lung diseases and cancer. Aurora B, a key regulator of mitosis, controls microtubule stability during abscission; its overexpression is common in cancers and can lead to genomic instability.
Platelet disorders
Cytoplasmic microtubule bundles are essential for proplatelet elaboration, the process by which platelets are formed from megakaryocytes. Defects in bundle mechanics can lead to thrombocytopenia or platelet function disorders.
From cytoplasmic microtubule bundle-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of KIF5B disrupt axonal microtubule bundles? | CRISPR knockout in Drosophila or mouse neurons |
| How does tau phosphorylation affect bundling? | Point mutation (phospho-mimetic) knock-in in stem cells |
| Can anillin crosslink microtubules to actin? | Tagged knock-in (GFP) in epithelial cells |
| Does Aurora B overexpression cause bundle instability? | Overexpression in cancer cell lines |
| What is the role of TP53 in alveolar regeneration? | Knockout in lung organoids |
| How do motor proteins organize bundles? | In vitro reconstitution with purified proteins |
How to Study the cytoplasmic microtubule bundle Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Dynamics of fluorescently tagged microtubules | Bundle formation and movement in real time |
| In vitro reconstitution | Bundle formation from purified components | Mechanistic studies of crosslinkers and motors |
| CRISPR knockout screens | Gene requirement for bundle formation | Discovery of novel regulators |
| Proximity labeling (BioID) | Protein-protein interactions in bundles | Mapping the bundle interactome |
| Phosphoproteomics | Signaling changes affecting bundles | Identifying kinase substrates |
| Electron microscopy | Ultrastructure of bundles | High-resolution bundle architecture |
| TIRF microscopy | Single-molecule dynamics | Motor stepping and crosslinker binding |
Live-cell imaging of microtubule bundles
Fluorescently labeled tubulin or microtubule-binding proteins (e.g., GFP-tubulin, EB1-GFP) allow real-time visualization of bundle dynamics in living cells. This method reveals how bundles form, move, and disassemble, and can be combined with motor protein mutants to assess their roles.
Biochemical reconstitution and crosslinking assays
Purified microtubules, motors, and crosslinkers can be mixed in vitro to reconstitute bundle formation. Crosslinking assays, such as co-sedimentation or microscopy, measure the ability of proteins like anillin to bundle microtubules. This approach provides mechanistic insights into bundle assembly.
CRISPR-based genetic screens
Genome-wide CRISPR knockout or activation screens can identify genes that regulate microtubule bundling. For example, screens in cells expressing a bundle reporter can uncover novel regulators. This method is powerful for discovering new components and pathways.
Proteomics and interactomics
Mass spectrometry-based proteomics can identify proteins that co-purify with microtubule bundles, revealing the bundle proteome. Proximity labeling (e.g., BioID) can map interactions in living cells, providing a comprehensive view of bundle composition and regulation.
How CRISPR Can Be Used to Study GO:1905720 cytoplasmic microtubule bundle
Knockout
CRISPR knockout of genes such as KIF5B, ANLN, or MAPT can abolish or disrupt cytoplasmic microtubule bundles, allowing researchers to assess their necessity for bundle formation and function. For example, knockout of motor proteins in Drosophila causes bundle damage in axons. Knockout of anillin impairs cytokinesis and bundle stability.
Point Mutation
Introducing specific point mutations (e.g., phospho-mimetic or phospho-deficient) in genes like MAPT or AURKB can reveal how post-translational modifications regulate bundle dynamics. Point mutations in motor domains of kinesins can dissect their roles in bundle organization.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) or epitope tags into endogenous loci enables real-time tracking of bundle proteins at physiological levels. Tagged knock-in of tubulin or MAPs allows visualization of bundle dynamics without overexpression artifacts.
Overexpression
Overexpression of bundling proteins such as tau or anillin can induce ectopic bundle formation or stabilize existing bundles, providing gain-of-function models. Overexpression of Aurora B can disrupt bundle stability and abscission.
How EDITGENE Supports cytoplasmic microtubule bundle Research
Researchers studying cytoplasmic microtubule bundle-related genes often need to determine whether a candidate gene is causally involved in bundle formation, maintenance, or function. This requires precise genetic manipulation to avoid confounding effects, and CRISPR-based models are the gold standard for such studies.
Contact EDITGENE today to design your custom CRISPR model for cytoplasmic microtubule bundle research.
Frequently Asked Questions About cytoplasmic microtubule bundle
What is GO:1905720 cytoplasmic microtubule bundle?
GO:1905720 is a Gene Ontology term for any microtubule bundle that is part of the cytoplasm. It describes a cellular component where multiple microtubules are organized into a bundle within the cytoplasm, often by motor proteins and crosslinkers.
What genes are involved in cytoplasmic microtubule bundle formation?
Key genes include tubulins (TUBB, TUBA), motor proteins (KIF5B, DYNC1H1), crosslinkers (ANLN, MAPT), and regulators like AURKB and TP53.
How are cytoplasmic microtubule bundles studied?
Common methods include live-cell imaging with fluorescent tubulin, in vitro reconstitution, CRISPR knockout screens, and proteomics.
What diseases are linked to cytoplasmic microtubule bundle defects?
Defects are linked to neurodegeneration (e.g., motor protein mutations), cancer (Aurora B dysregulation), and platelet disorders (proplatelet formation defects).
What is the role of tau in microtubule bundling?
Tau promotes microtubule bundling, and the TP53/TAU axis regulates bundling in alveolar stem cells to control regeneration.
How does anillin contribute to microtubule bundles?
Anillin directly crosslinks microtubules with actin filaments, providing mechanical stability to bundles during cytokinesis.
Can CRISPR be used to study cytoplasmic microtubule bundles?
Yes, CRISPR knockout, knock-in, and overexpression models are powerful tools to dissect gene function in bundle formation and dynamics.
What is the pivot-and-bond model of bundle formation?
It is a physical model explaining how motor proteins pivot and bond microtubules to form bundles, providing insights into self-organization.
How do motor proteins affect axonal microtubule bundles?
Loss or gain of motor protein function causes microtubule bundle damage in Drosophila axons, leading to transport defects.
What is the clinical relevance of cytoplasmic microtubule bundles?
They are relevant to neurodegenerative diseases, cancer, and regenerative medicine, making them targets for therapeutic development.
Conclusion
Cytoplasmic microtubule bundles (GO:1905720) are dynamic cytoskeletal structures essential for intracellular transport, cell polarity, and cytokinesis. Their formation and function rely on a complex interplay of tubulins, motor proteins, and crosslinkers, and their dysregulation contributes to human diseases including neurodegeneration and cancer. Continued research using advanced CRISPR models and imaging techniques will further illuminate their roles and therapeutic potential.
References
- 1. Sawin KE et al.. 2006. Cytoplasmic microtubule organization in fission yeast.. Yeast 23(13):1001-14 PMID: 17072892
- 2. Prelogović M et al.. 2019. Pivot-and-bond model explains microtubule bundle formation.. Phys Rev E 100(1-1):012403 PMID: 31499770
- 3. Liew YT et al.. 2026. Loss and gain of motor protein function cause microtubule bundle damage in Drosophila axons.. Curr Biol 36(3):707-722.e6 PMID: 41558478
- 4. Kodba S et al.. 2025. Aurora B controls microtubule stability to regulate abscission dynamics in stem cells.. Cell Rep 44(2):115238 PMID: 39854207
- 5. Suzuki K et al.. 2017. Spatial confinement of active microtubule networks induces large-scale rotational cytoplasmic flow.. Proc Natl Acad Sci U S A 114(11):2922-2927 PMID: 28265076
- 6. Bareja I et al.. 2025. Anillin directly crosslinks microtubules with actin filaments.. EMBO J 44(17):4803-4824 PMID: 40691415
- 7. Konishi S et al.. 2026. TP53/TAU axis regulates microtubule bundling to control alveolar stem cell-mediated regeneration.. J Clin Invest 136(7) PMID: 41642658
- 8. Italiano JE Jr et al.. 2007. Mechanics of proplatelet elaboration.. J Thromb Haemost 5 Suppl 1:18-23 PMID: 17635704
