GO:0045199 maintenance of epithelial cell apical/basal polarity: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045199 describes the biological process that preserves the asymmetric apical and basal domains of an epithelial cell once polarity has been established.
• Apical-basal polarity is maintained by conserved protein complexes including PAR, Crumbs, and Scribble modules that mutually antagonize each other at distinct membrane domains.
• Loss of maintenance of apical/basal polarity is a hallmark of epithelial cancers and is linked to tumour invasion and metastasis.
• Transcriptional programs and post-translational modifications continuously adjust polarity regulators to match tissue demands.
• Bacterial pathogens and host factors such as galectins can modulate or disrupt apical-basal polarity during infection and development.
• CRISPR-based knockout, knock-in, and overexpression models are essential to test causal roles of polarity genes in human cells and organoids.
Description
The maintenance of epithelial cell apical/basal polarity (GO:0045199) is the biological process that preserves the asymmetric distribution of proteins and lipids between the apical and basal domains of an epithelial cell after polarity has been initially established. This process is fundamental for tissue architecture, barrier function, and regulated transport, and its disruption is associated with developmental defects and cancer progression. Researchers study GO:0045199 to understand how cells continuously reinforce their polarized state despite mechanical and biochemical challenges. The QuickGO definition states that this term covers the maintenance of the apicobasal polarity of an epithelial cell, distinguishing it from the initial establishment of polarity. Because polarity maintenance is dynamically regulated by conserved protein complexes and transcriptional networks, it is a rich area for functional genomics and CRISPR screening. In this article, we integrate authoritative QuickGO annotation with real PubMed literature to provide a research-grade overview of GO:0045199, its molecular players, disease relevance, and experimental strategies.
maintenance of epithelial cell apical/basal polarity At A Glance
| GO ID | GO:0045199 |
|---|---|
| GO term | maintenance of epithelial cell apical/basal polarity |
| Ontology | biological_process |
| Synonym | None listed in QuickGO |
| Major function | Preservation of asymmetric apical and basal membrane domains in epithelial cells |
| Related processes | Establishment of apical/basal polarity, epithelial morphogenesis, cell adhesion |
| Key complexes | PAR, Crumbs, Scribble polarity modules |
| Disease relevance | Epithelial cancers, tumour invasion, developmental disorders |
What Is GO:0045199?
In our own words, GO:0045199 refers to the ongoing cellular activities that keep an epithelial cell polarized along its apical-basal axis once that polarity has been set up. It encompasses the stabilization of distinct apical and basolateral membrane domains, the continued targeting of polarity proteins to their correct locations, and the mechanisms that prevent domain mixing. This process is essential for epithelial function and is distinct from the initial establishment of polarity.
Why Is maintenance of epithelial cell apical/basal polarity Important in Cell Biology?
Maintaining apical-basal polarity is critical for epithelial tissue homeostasis, and its failure is a common event in cancer and other diseases. The process ensures that cells retain their barrier function, directional transport, and proper response to external signals, and it is continuously challenged by cell division, migration, and mechanical stress. Understanding GO:0045199 therefore has broad implications for developmental biology, cancer research, and regenerative medicine.
• Loss of apical-basal polarity maintenance is a hallmark of epithelial-to-mesenchymal transition and tumour progression.
• Polarity maintenance is required for proper gut epithelial function and barrier integrity.
• Bacterial pathogens often target polarity maintenance to disrupt host tissues.
• Transcriptional control of polarity regulators ensures tissue-specific adaptation.
• Galectin-3 has been implicated in neurodevelopmental polarity and gyrification.
• Drosophila genetics has provided foundational insights into polarity maintenance mechanisms.
• Leukocyte chemotaxis shares conserved polarity maintenance principles.
• Defects in polarity maintenance contribute to developmental disorders and cancer.
• CRISPR screens can identify novel genes required for polarity maintenance.
• Polarity maintenance is a potential therapeutic target in metastatic cancer.
What Happens During maintenance of epithelial cell apical/basal polarity?
Stabilization of apical and basolateral domains
In simple terms: The cell keeps its top and bottom sides different by continuously sorting proteins to the right place.
Once polarity is established, the apical and basolateral membrane domains must be actively maintained to prevent mixing. Conserved polarity complexes, including the PAR and Crumbs modules, reinforce the apical domain, while the Scribble module defines the basolateral domain. These complexes mutually antagonize each other, ensuring that each domain retains its identity.
Vesicle trafficking and targeted delivery
In simple terms: The cell uses internal transport to deliver the right proteins to the top or bottom.
Maintenance of polarity relies on continuous vesicle trafficking that delivers newly synthesized and recycled proteins to the correct membrane domain. This process is regulated by small GTPases and adaptor proteins that ensure apical and basolateral cargoes are sorted correctly.
Cytoskeletal organization and junctional complexes
In simple terms: The cell's skeleton and the junctions between cells help hold the polarized structure in place.
The actin cytoskeleton and microtubule networks provide structural support for polarity maintenance. Tight junctions and adherens junctions act as barriers that prevent diffusion of membrane proteins between apical and basolateral domains, and they are dynamically regulated during tissue remodeling.
Transcriptional and post-translational regulation
In simple terms: The cell adjusts polarity gene activity to meet changing needs.
Transcriptional programs control the expression levels of polarity regulators, allowing cells to adapt to developmental and environmental cues. Post-translational modifications such as phosphorylation also modulate the activity and localization of polarity proteins.
Response to external cues and stress
In simple terms: Outside signals can strengthen or weaken the cell's polarity.
Bacterial pathogens can modulate epithelial polarity to promote infection, while host factors such as galectin-3 influence polarity during neurodevelopment. These examples illustrate that polarity maintenance is responsive to external stimuli and can be disrupted in disease.
Key Genes Involved in GO:0045199 maintenance of epithelial cell apical/basal polarity
The following genes and proteins are central to the maintenance of epithelial cell apical/basal polarity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PARD3 | Apical polarity complex component | Knockout studies in epithelial cells |
| PARD6B | Apical polarity complex component | CRISPR models for polarity maintenance |
| PRKCI | Atypical protein kinase C, apical polarity | Point mutations to test kinase activity |
| CRB3 | Crumbs complex, apical domain | Overexpression and knockout in organoids |
| PALS1 | Crumbs complex scaffold | Knock-in tagging for imaging |
| PATJ | Crumbs complex, tight junction | Knockout in cancer cell lines |
| LLGL1 | Scribble complex, basolateral | Loss-of-function in polarity studies |
| LLGL2 | Scribble complex, basolateral | CRISPR screens for polarity |
| SCRIB | Basolateral polarity module | Tumour suppressor studies |
| DLG1 | Scribble complex, basolateral | Knockout in epithelial models |
| AMOTL2 | Angiomotin-like 2, polarity disruption | Overexpression in cancer invasion |
| LGALS3 | Galectin-3, neurodevelopmental polarity | Knockout in neurodevelopmental models |
| CDH1 | E-cadherin, adherens junctions | Point mutations in cancer |
| CTNNB1 | Beta-catenin, junctional signaling | Knock-in for reporter assays |
| TJP1 | Tight junction protein ZO-1 | Tagged knock-in for live imaging |
| RAB11A | Vesicle trafficking to apical membrane | Knockout in epithelial cells |
| RAB8A | Vesicle trafficking to basolateral membrane | Overexpression studies |
How Is maintenance of epithelial cell apical/basal polarity Regulated?
The maintenance of apical-basal polarity is regulated at multiple levels. Transcriptional control of polarity regulators ensures appropriate expression in different tissues. Post-translational modifications, including phosphorylation by aPKC, modulate the localization and activity of polarity proteins. Additionally, external cues such as bacterial pathogens can disrupt polarity maintenance through secreted effectors, and host factors like galectin-3 can influence polarity during development. These regulatory layers allow epithelial cells to dynamically maintain polarity in response to changing environments.
maintenance of epithelial cell apical/basal polarity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| AMOTL2 | Tumour invasion and metastasis | Overexpression in cancer cell lines |
| LGALS3 | Neurodevelopmental polarity and gyrification | Knockout in neural organoids |
| SCRIB | Epithelial cancer and tumour suppression | Knockout in epithelial cells |
| CRB3 | Cancer and developmental defects | Knock-in tagging in organoids |
| PARD3 | Epithelial cancer and polarity loss | Point mutations in cancer models |
Cancer and tumour invasion
Disruption of apical-basal polarity maintenance is a key step in epithelial-to-mesenchymal transition and tumour progression. AmotL2 has been shown to disrupt polarity and promote tumour invasion. Loss of polarity maintenance is associated with poor prognosis in several epithelial cancers.
Developmental disorders
Proper polarity maintenance is essential for normal development. Galectin-3 regulates neurodevelopmental apical-basal polarity and gyrification, and its dysregulation may contribute to cortical malformations. Drosophila studies have revealed conserved genetic requirements for polarity maintenance in development.
Infectious diseases
Bacterial pathogens often target epithelial polarity to breach host barriers. Modulation of polarity by bacterial effectors can lead to tissue damage and facilitate infection.
Gut and barrier diseases
In the gut, maintenance of apical-basal polarity is critical for barrier function and nutrient absorption. Defects in polarity maintenance have been linked to inflammatory bowel diseases and other gut disorders.
From maintenance of epithelial cell apical/basal polarity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X maintain apical-basal polarity? | CRISPR knockout in epithelial cell lines |
| Does a specific mutation affect polarity maintenance? | Point mutation knock-in |
| Where does protein X localize during polarity maintenance? | Tagged knock-in with fluorescent tag |
| Does overexpression of gene Y disrupt polarity? | Overexpression cell model |
| Which genes are essential for polarity maintenance? | CRISPR library screening |
| How does gene Z affect polarity in 3D tissue? | Organoid knockout or knock-in |
How to Study the maintenance of epithelial cell apical/basal polarity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Immunofluorescence | Localization of polarity proteins | Assessing polarity maintenance in monolayers |
| Live-cell imaging | Dynamic changes in polarity | Tracking tagged proteins in real time |
| CRISPR knockout screening | Genes required for polarity | Unbiased discovery of polarity regulators |
| RNA-seq | Transcriptional changes | Identifying polarity-associated gene networks |
| Proteomics | Protein interactions and abundance | Mapping polarity complex components |
| Organoid culture | 3D tissue architecture | Modeling epithelial polarity in vitro |
| Point mutation knock-in | Effect of specific mutations | Testing disease-associated variants |
Imaging-based polarity assays
Immunofluorescence and live-cell imaging with markers for apical (e.g., ZO-1) and basolateral (e.g., E-cadherin) proteins are standard to assess polarity maintenance. Tagged knock-in cell lines allow dynamic tracking of polarity proteins.
CRISPR knockout and point mutation screens
Pooled CRISPR knockout screens can identify genes required for polarity maintenance, while point mutations can test specific residues in polarity regulators. These approaches are powerful for unbiased discovery.
Transcriptomics and proteomics
RNA-seq and proteomics can reveal changes in polarity gene expression and protein interactions under conditions that challenge polarity maintenance. These methods help identify regulatory networks.
Organoid and 3D culture models
3D organoid cultures recapitulate tissue architecture and are ideal for studying polarity maintenance in a physiologically relevant context. CRISPR-edited organoids can model disease-associated mutations.
How CRISPR Can Be Used to Study GO:0045199 maintenance of epithelial cell apical/basal polarity
Knockout
CRISPR knockout of polarity genes such as PARD3 or SCRIB in epithelial cell lines can reveal their requirement for maintaining apical-basal polarity. Knockout organoids can model tissue-level consequences.
Point Mutation
Introducing point mutations in polarity regulators (e.g., PRKCI kinase-dead mutants) allows precise testing of domain-specific functions in polarity maintenance. This approach is useful for dissecting signaling pathways.
Knock-in
Tagged knock-in of polarity proteins with fluorescent or epitope tags enables live imaging and biochemical isolation of protein complexes. Knock-in of disease-associated mutations can model human disorders.
Overexpression
Overexpression of genes like AMOTL2 can disrupt polarity and promote invasion, providing gain-of-function models to study polarity maintenance in cancer.
How EDITGENE Supports maintenance of epithelial cell apical/basal polarity Research
Researchers studying maintenance of epithelial cell apical/basal polarity-related genes often need to determine whether a candidate gene is causally involved in polarity maintenance or is merely correlated with it. EDITGENE provides a comprehensive suite of CRISPR services to enable such functional studies in relevant cell models.
Contact EDITGENE today to design your custom CRISPR model for maintenance of epithelial cell apical/basal polarity research.
Frequently Asked Questions About maintenance of epithelial cell apical/basal polarity
What is GO:0045199?
GO:0045199 is the Gene Ontology term for the maintenance of epithelial cell apical/basal polarity, a biological process that preserves the asymmetric apical and basal domains of epithelial cells.
What genes are involved in maintenance of epithelial cell apical/basal polarity?
Key genes include PARD3, PARD6B, PRKCI, CRB3, PALS1, PATJ, LLGL1, LLGL2, SCRIB, DLG1, AMOTL2, and LGALS3, among others.
Why is apical-basal polarity maintenance important?
It is essential for epithelial barrier function, tissue architecture, and prevention of cancer progression.
How is apical-basal polarity maintained?
Through conserved polarity complexes, vesicle trafficking, cytoskeletal organization, and transcriptional regulation.
What diseases are linked to defects in apical-basal polarity maintenance?
Epithelial cancers, developmental disorders, and infectious diseases are associated with disrupted polarity maintenance.
How can I study maintenance of epithelial cell apical/basal polarity?
Using CRISPR knockout, knock-in, overexpression models, imaging, and organoid cultures.
What is the role of AMOTL2 in polarity?
AMOTL2 disrupts apical-basal polarity and promotes tumour invasion.
Does galectin-3 affect polarity?
Yes, galectin-3 induces neurodevelopmental apical-basal polarity and regulates gyrification.
What are the main polarity complexes?
The PAR, Crumbs, and Scribble complexes are the main conserved polarity modules.
Can CRISPR screens identify new polarity genes?
Yes, pooled CRISPR screens are powerful for discovering novel regulators of polarity maintenance.
Conclusion
The maintenance of epithelial cell apical/basal polarity (GO:0045199) is a dynamic and essential process that safeguards epithelial tissue organization and function. Its disruption is a common theme in cancer, developmental disorders, and infections, making it a critical area of research. By leveraging CRISPR-based models and advanced imaging, researchers can uncover the molecular mechanisms that maintain polarity and translate these findings into therapeutic strategies. EDITGENE offers comprehensive services to support such studies, from knockout and knock-in models to library screening and bioinformatics.
References
- 1. Buckley CE et al.. 2022. Apical-basal polarity and the control of epithelial form and function.. Nat Rev Mol Cell Biol 23(8):559-577 PMID: 35440694
- 2. Rust K et al.. 2021. Transcriptional Control of Apical-Basal Polarity Regulators.. Int J Mol Sci 22(22) PMID: 34830224
- 3. Thottacherry JJ et al.. 2023. Apical-basal polarity in the gut.. Semin Cell Dev Biol 150-151:15-22 PMID: 36670034
- 4. Tapia R et al.. 2017. Modulation of epithelial cell polarity by bacterial pathogens.. Ann N Y Acad Sci 1405(1):16-24 PMID: 28628193
- 5. Gómez-Moutón C et al.. 2007. Establishment and maintenance of cell polarity during leukocyte chemotaxis.. Cell Adh Migr 1(2):69-76 PMID: 19329880
- 6. Müller HA. 2000. Genetic control of epithelial cell polarity: lessons from Drosophila.. Dev Dyn 218(1):52-67 PMID: 10822259
- 7. Soares LC et al.. 2025. Galectin-3 induces neurodevelopmental apical-basal polarity and regulates gyrification.. Sci Adv 11(36):eadt5859 PMID: 40901969
- 8. Mojallal M et al.. 2014. AmotL2 disrupts apical-basal cell polarity and promotes tumour invasion.. Nat Commun 5:4557 PMID: 25080976
