GO:0045197 establishment or maintenance of epithelial cell apical/basal polarity: Cellular Process, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045197 describes any cellular process that specifies, forms, or maintains the apicobasal polarity of an epithelial cell, a fundamental organizing principle of epithelial tissues.
• Apicobasal polarity is established by mutually antagonistic protein complexes, including the apical PAR and Crumbs complexes and the basolateral Scribble complex, which segregate to distinct membrane domains.
• The process is essential for vectorial transport, barrier function, asymmetric cell division, and tissue morphogenesis, and its disruption is a hallmark of carcinoma progression.
• Transcriptional and post-transcriptional programs, including regulation by polarity-responsive transcription factors, control the expression of core polarity regulators.
• Bacterial pathogens and host factors such as galectin-3 can modulate or co-opt apicobasal polarity during infection and neurodevelopmental gyrification, respectively.
• CRISPR-based knockout, knock-in, point-mutation, and overexpression models, combined with imaging and omics, are powerful tools to dissect polarity gene function in human cells and organoids.
Description
Epithelial cells line the surfaces and cavities of the body and must organize their plasma membrane into distinct apical and basolateral domains to perform vectorial transport, form barriers, and respond to external cues. The Gene Ontology term GO:0045197, establishment or maintenance of epithelial cell apical/basal polarity, captures the cellular processes that generate and sustain this asymmetric organization. Apicobasal polarity is not a static property but a dynamic state that is continuously reinforced by protein trafficking, cytoskeletal remodeling, and signaling feedback loops. Understanding this process is central to developmental biology, tissue homeostasis, and cancer research, because loss of polarity is associated with epithelial-to-mesenchymal transition and tumor progression. The molecular basis of apicobasal polarity has been dissected primarily in model organisms such as Drosophila melanogaster and Caenorhabditis elegans, where genetic screens identified conserved polarity complexes. In mammalian epithelia, the apical PAR complex (PAR3, PAR6, and atypical protein kinase C) and the Crumbs complex (CRB3, PALS1, PATJ) define the apical domain, while the Scribble complex (SCRIB, LLGL1/2, DLG1) and PAR1 kinases define the basolateral domain. These complexes antagonize each other, ensuring that a single apical domain forms at the free surface of the cell. Transcriptional control of polarity regulators adds another layer of regulation, linking polarity to cell fate and proliferation. Research on GO:0045197 spans multiple disciplines, from developmental genetics to infection biology and cancer cell biology. Bacterial pathogens can manipulate host polarity to breach epithelial barriers, and polarity proteins are frequently dysregulated in carcinomas. This article provides a research-grade overview of the definition, mechanisms, key genes, disease links, and experimental methods used to study establishment or maintenance of epithelial cell apical/basal polarity, with a focus on how CRISPR-based models can accelerate discovery.
establishment or maintenance of epithelial cell apical/basal polarity At A Glance
| GO ID | GO:0045197 |
|---|---|
| GO term | establishment or maintenance of epithelial cell apical/basal polarity |
| Ontology | biological_process |
| Synonym | none |
| Major function | Specification, formation, and maintenance of distinct apical and basolateral membrane domains in epithelial cells |
| Key protein complexes | Apical PAR complex (PAR3/PAR6/aPKC), Crumbs complex (CRB3/PALS1/PATJ), basolateral Scribble complex (SCRIB/LLGL/DLG) |
| Cellular structures involved | Plasma membrane domains, tight junctions, adherens junctions, cytoskeleton (actin, microtubules) |
| Representative model organisms | Drosophila melanogaster, Caenorhabditis elegans, mammalian cell lines and organoids |
| Disease relevance | Carcinoma progression, epithelial barrier dysfunction, developmental disorders |
What Is GO:0045197?
According to the Gene Ontology, GO:0045197 (establishment or maintenance of epithelial cell apical/basal polarity) refers to any cellular process that results in the specification, formation, or maintenance of the apicobasal polarity of an epithelial cell. In practice, this includes the initial symmetry-breaking events that designate one membrane domain as apical and the opposite as basolateral, the recruitment of specific protein complexes and lipids to these domains, and the ongoing mechanisms that preserve this asymmetry during cell division, migration, and tissue remodeling.
Why Is establishment or maintenance of epithelial cell apical/basal polarity Important in Cell Biology?
Apicobasal polarity is a fundamental property of epithelial tissues and is required for normal development, organ function, and tissue homeostasis. Disruption of this process is a hallmark of epithelial cancers, where loss of polarity contributes to uncontrolled proliferation, invasion, and metastasis. Moreover, many bacterial pathogens target polarity complexes to disrupt epithelial barriers and establish infection. Understanding GO:0045197 therefore has broad implications for cancer biology, infectious disease, and regenerative medicine.
• Apicobasal polarity is essential for vectorial transport and barrier function in epithelia.
• Loss of polarity is an early event in epithelial-to-mesenchymal transition and carcinoma progression.
• Polarity complexes regulate asymmetric cell division and cell fate specification during development.
• Bacterial pathogens often modulate host polarity to breach epithelial barriers.
• Polarity proteins are implicated in neurodevelopmental processes such as gyrification.
• Transcriptional programs controlling polarity regulators link polarity to cell proliferation and differentiation.
• Polarity establishment is studied in diverse contexts, including ascidian notochord and leukocyte chemotaxis.
• Dysregulated polarity contributes to gut inflammatory diseases and barrier dysfunction.
• CRISPR screens can identify novel polarity regulators and therapeutic targets.
• Polarity is a key parameter in organoid and tissue engineering applications.
What Happens During establishment or maintenance of epithelial cell apical/basal polarity?
Initiation and symmetry breaking
In simple terms: The cell decides which side will face the outside world and which side will contact neighboring cells.
The establishment of apicobasal polarity begins with symmetry-breaking cues, such as cell-cell adhesion or extracellular matrix contacts, that designate one membrane domain as apical and the opposite as basolateral. In Drosophila epithelia, the apical PAR complex (Bazooka/PAR3, PAR6, aPKC) is recruited to the apical domain, while the basolateral Scribble complex (Scrib, Lgl, Dlg) is excluded from this region. This initial partitioning is reinforced by mutual antagonism between apical and basolateral complexes, ensuring a single apical domain per cell.
Assembly of apical and basolateral domains
In simple terms: Different protein groups gather on the top and bottom sides of the cell, forming distinct territories.
Once symmetry is broken, the apical Crumbs complex (CRB3, PALS1, PATJ) and the PAR complex accumulate at the apical membrane, where they organize the apical surface and tight junctions. Simultaneously, the Scribble complex and PAR1 kinases localize to the basolateral membrane, where they regulate adherens junctions and basolateral identity. These complexes are interconnected by trafficking pathways that deliver specific lipids and proteins to each domain, and by cytoskeletal elements that maintain domain boundaries.
Maintenance during cell division and tissue remodeling
In simple terms: Even when cells divide or move, they remember which side is up and which is down.
Maintenance of apicobasal polarity requires continuous reinforcement during cell division, migration, and tissue remodeling. In dividing epithelial cells, polarity complexes are inherited asymmetrically to daughter cells, and in migrating cells, polarity is reoriented in response to external cues. Transcriptional programs, including those controlled by polarity-responsive transcription factors, adjust the expression of core polarity regulators to meet changing demands. Disruption of these maintenance mechanisms leads to loss of tissue architecture and disease.
Regulation by external cues and pathogens
In simple terms: Outside signals, including from bacteria, can change how cells organize their surfaces.
Extracellular signals, such as growth factors and inflammatory cytokines, can modulate apicobasal polarity. Bacterial pathogens have evolved strategies to manipulate host polarity complexes, often disrupting tight junctions to invade deeper tissues. For example, some pathogens alter the localization of PAR and Crumbs complex components, leading to barrier dysfunction. These interactions highlight the dynamic and regulatable nature of apicobasal polarity.
Polarity in specialized epithelia and non-epithelial contexts
In simple terms: Similar polarity rules apply in many tissues, from the gut to the brain and even in single cells.
Apicobasal polarity is not limited to classical epithelia; it is also observed in specialized contexts such as the gut epithelium, where it regulates nutrient absorption and barrier function. In the developing brain, galectin-3 induces apicobasal polarity in neuroepithelial cells and influences gyrification. In ascidian notochord and leukocyte chemotaxis, related polarity mechanisms guide cell shape and movement. These examples underscore the evolutionary conservation and functional diversity of GO:0045197.
Key Genes Involved in GO:0045197 establishment or maintenance of epithelial cell apical/basal polarity
The following genes encode core components and regulators of apicobasal polarity in epithelial cells, as identified in genetic and cell biological studies.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PARD3 (PAR3) | Apical PAR complex scaffold | Essential for apical domain formation; knockout disrupts tight junctions |
| PARD6B (PAR6) | Apical PAR complex component | Regulates aPKC activity; involved in asymmetric division |
| PRKCI (aPKC) | Apical kinase | Phosphorylates polarity substrates; key for apical identity |
| CRB3 | Apical Crumbs complex | Defines apical membrane; loss causes polarity defects |
| PALS1 (MPP5) | Apical Crumbs complex | Links Crumbs to tight junctions; mutations affect epithelial integrity |
| PATJ (INADL) | Apical Crumbs complex | Scaffold for apical proteins; regulates tight junction assembly |
| SCRIB | Basolateral Scribble complex | Tumor suppressor; loss promotes invasion |
| LLGL1/2 (Lgl) | Basolateral Scribble complex | Regulates basolateral identity; conserved from Drosophila |
| DLG1 (Dlg) | Basolateral Scribble complex | Scaffold at adherens junctions; linked to cancer |
| MARK2 (PAR1) | Basolateral kinase | Phosphorylates PAR3 to exclude it from basolateral domain |
| CDH1 (E-cadherin) | Adherens junction component | Provides adhesion cues for polarity initiation |
| TJP1 (ZO-1) | Tight junction scaffold | Connects polarity complexes to tight junctions |
| GAL3 (LGALS3) | Galectin-3 | Induces apicobasal polarity in neurodevelopment |
| RAB11A | Vesicle trafficking | Delivers apical proteins; required for polarity maintenance |
| CDC42 | Rho GTPase | Regulates actin and apical polarity complex |
| EPB41L5 | Basolateral protein | Regulates epithelial polarity and adherens junctions |
| YAP1 | Transcriptional regulator | Links polarity to proliferation; regulated by Hippo pathway |
How Is establishment or maintenance of epithelial cell apical/basal polarity Regulated?
The establishment and maintenance of apicobasal polarity are regulated at multiple levels. Transcriptional control of polarity regulators has been demonstrated, with transcription factors such as YAP1 and others modulating the expression of core polarity genes in response to growth signals. Post-translational modifications, including phosphorylation by aPKC and PAR1 kinases, control the localization and activity of polarity proteins. Vesicular trafficking, mediated by Rab GTPases and the exocyst complex, ensures the delivery of specific proteins and lipids to apical or basolateral domains. Additionally, external cues such as cell-cell adhesion, extracellular matrix stiffness, and bacterial pathogens can dynamically alter polarity. This multilayered regulation allows epithelial cells to adapt their polarity to developmental and environmental changes.
establishment or maintenance of epithelial cell apical/basal polarity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SCRIB | Epithelial cancer progression | Knockout in human epithelial cell lines; xenograft models |
| CRB3 | Barrier dysfunction, cancer | Knockout organoids; permeability assays |
| PARD3 | Tight junction defects, cancer | Point mutation knock-in in cell lines |
| LGALS3 | Neurodevelopmental gyrification | Overexpression in neuroepithelial stem cells |
| DLG1 | Epithelial cancer, infection | Knockout in gut organoids; infection models |
Cancer and loss of polarity
Disruption of apicobasal polarity is a hallmark of epithelial cancers. Loss of Scribble or other polarity proteins promotes epithelial-to-mesenchymal transition, uncontrolled proliferation, and metastasis. In many carcinomas, polarity complexes are downregulated or mislocalized, contributing to tumor progression. Restoring polarity in cancer cells can suppress malignant phenotypes, making polarity pathways attractive therapeutic targets.
Infectious diseases and barrier dysfunction
Bacterial pathogens often target host polarity complexes to disrupt epithelial barriers and establish infection. For example, some pathogens alter the localization of tight junction proteins and polarity regulators, leading to increased permeability. Understanding how pathogens modulate GO:0045197 may inform new strategies to prevent or treat infections.
Neurodevelopmental disorders
Apicobasal polarity is critical for neuroepithelial development and cortical folding. Galectin-3 has been shown to induce apicobasal polarity in neuroepithelial cells and regulate gyrification, suggesting that polarity defects may contribute to neurodevelopmental disorders. Further research is needed to link specific polarity gene mutations to human neurodevelopmental conditions.
Gut inflammatory diseases
In the gut epithelium, apicobasal polarity is essential for barrier function and nutrient absorption. Disruption of polarity complexes can lead to increased intestinal permeability and inflammation, as seen in inflammatory bowel diseases. Studying polarity maintenance in gut organoids may reveal new therapeutic approaches.
From establishment or maintenance of epithelial cell apical/basal polarity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SCRIB disrupt apicobasal polarity and promote invasion? | SCRIB knockout in human epithelial cell lines |
| How do point mutations in PARD3 affect tight junction assembly? | PARD3 point-mutation knock-in via CRISPR |
| Can tagged CRB3 reveal dynamic trafficking to the apical membrane? | CRB3 knock-in with fluorescent tag |
| Does overexpression of GAL3 induce polarity in neuroepithelial cells? | GAL3 overexpression in stem cell-derived neuroepithelia |
| What transcriptional networks regulate polarity genes? | CRISPR library screening with RNA-seq readout |
| How do bacterial pathogens alter polarity protein localization? | Infection of polarized epithelial monolayers |
How to Study the establishment or maintenance of epithelial cell apical/basal polarity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Immunofluorescence microscopy | Localization of polarity proteins | Assessing apical/basolateral domain formation |
| Live-cell imaging | Dynamic trafficking of polarity components | Studying polarity maintenance during division |
| CRISPR knockout screens | Genes required for polarity | Identifying novel polarity regulators |
| RNA-seq | Transcriptional changes in polarity mutants | Mapping polarity gene networks |
| Proteomics | Protein composition of membrane domains | Defining apical/basolateral proteomes |
| Organoid culture | 3D epithelial polarity and barrier function | Modeling gut and kidney epithelia |
| Infection assays | Pathogen-induced polarity disruption | Studying host-pathogen interactions |
| Phosphoproteomics | Kinase signaling to polarity proteins | Dissecting regulatory phosphorylation |
Imaging-based assays for polarity
Confocal and super-resolution microscopy are used to visualize the localization of apical and basolateral markers in polarized epithelial cells. Immunofluorescence for proteins such as CRB3, PALS1, SCRIB, and DLG1 allows assessment of domain formation and maintenance. Live-cell imaging of fluorescently tagged polarity proteins can reveal dynamic trafficking and domain remodeling.
Functional genomics and CRISPR screens
CRISPR knockout and activation screens have been used to identify novel regulators of apicobasal polarity. Pooled screens with imaging or flow cytometry readouts can uncover genes whose loss or gain alters polarity domain formation. Transcriptional profiling (RNA-seq) of polarity mutants reveals downstream gene expression changes.
Biochemical and proteomic approaches
Co-immunoprecipitation and mass spectrometry can identify protein-protein interactions within polarity complexes. Proteomic analysis of apical and basolateral membrane fractions provides a comprehensive view of domain composition. Phosphoproteomics can reveal signaling events that regulate polarity protein localization.
Organoid and 3D culture models
Intestinal and kidney organoids recapitulate apicobasal polarity in a physiologically relevant context. These models allow study of polarity maintenance during differentiation and response to pathogens or drugs. CRISPR editing in organoids enables functional studies of polarity genes in human tissue-like structures.
How CRISPR Can Be Used to Study GO:0045197 establishment or maintenance of epithelial cell apical/basal polarity
Knockout
CRISPR knockout of polarity genes such as SCRIB, CRB3, or PARD3 in human epithelial cell lines or organoids can reveal their essential roles in apicobasal polarity. Knockout models are used to assess barrier function, tight junction integrity, and invasive potential.
Point Mutation
Introducing disease-associated point mutations into polarity genes (e.g., PARD3 or DLG1) via CRISPR base editing or homology-directed repair allows precise structure-function studies. Such models help determine whether specific phosphorylation sites or interaction domains are required for polarity.
Knock-in
Knock-in of fluorescent or epitope tags into endogenous polarity genes (e.g., CRB3, PALS1) enables real-time tracking of protein localization and dynamics in living cells. Tagged knock-in models are valuable for studying trafficking and domain maintenance.
Overexpression
CRISPR activation or lentiviral overexpression of polarity regulators (e.g., GAL3, YAP1) can test sufficiency for inducing or disrupting polarity. Overexpression models are useful for studying gain-of-function effects in neurodevelopment and cancer.
How EDITGENE Supports establishment or maintenance of epithelial cell apical/basal polarity Research
Researchers studying establishment or maintenance of epithelial cell apical/basal polarity-related genes often need to determine whether a candidate gene is causally involved in polarity establishment, maintenance, or disease progression. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling functional validation of polarity genes in relevant epithelial and organoid systems.
Contact EDITGENE today to design your custom CRISPR model for establishment or maintenance of epithelial cell apical/basal polarity research.
Frequently Asked Questions About establishment or maintenance of epithelial cell apical/basal polarity
What is GO:0045197?
GO:0045197 is a Gene Ontology biological process term defined as any cellular process that results in the specification, formation, or maintenance of the apicobasal polarity of an epithelial cell.
What genes are involved in establishment or maintenance of epithelial cell apical/basal polarity?
Key genes include PARD3, PARD6B, PRKCI, CRB3, PALS1, PATJ, SCRIB, LLGL1/2, DLG1, and MARK2, which encode core polarity complex components.
Why is apicobasal polarity important?
Apicobasal polarity is essential for epithelial barrier function, vectorial transport, asymmetric cell division, and tissue morphogenesis; its loss is linked to cancer and other diseases.
How is apicobasal polarity established?
It is established through symmetry-breaking cues that recruit apical PAR and Crumbs complexes and basolateral Scribble complexes to distinct membrane domains, reinforced by mutual antagonism and trafficking.
What diseases are associated with defects in epithelial cell polarity?
Defects in apicobasal polarity are associated with epithelial cancers, barrier dysfunction in infections, gut inflammatory diseases, and neurodevelopmental disorders.
Can CRISPR be used to study apicobasal polarity?
Yes, CRISPR knockout, knock-in, point mutation, and overexpression models are widely used to dissect polarity gene function in epithelial cells and organoids.
What are the main protein complexes in apicobasal polarity?
The apical PAR complex (PAR3/PAR6/aPKC), the apical Crumbs complex (CRB3/PALS1/PATJ), and the basolateral Scribble complex (SCRIB/LLGL/DLG) are the main polarity complexes.
How do bacterial pathogens affect epithelial polarity?
Some bacterial pathogens manipulate host polarity complexes to disrupt tight junctions and breach epithelial barriers.
What model organisms are used to study apicobasal polarity?
Drosophila melanogaster and Caenorhabditis elegans are classic genetic models, while mammalian cell lines and organoids are used for human-relevant studies.
What methods are used to study establishment or maintenance of epithelial cell apical/basal polarity?
Common methods include immunofluorescence microscopy, live-cell imaging, CRISPR screens, RNA-seq, proteomics, and organoid culture.
Conclusion
GO:0045197, establishment or maintenance of epithelial cell apical/basal polarity, is a fundamental biological process that governs epithelial architecture and function. Its disruption contributes to cancer, infectious diseases, and developmental disorders, making it a critical area of research. Advances in CRISPR-based models and imaging technologies are accelerating the discovery of new polarity regulators and therapeutic targets. EDITGENE offers comprehensive services to support functional studies of polarity genes in relevant cell and organoid models.
References
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- 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. Soares LC et al.. 2025. Galectin-3 induces neurodevelopmental apical-basal polarity and regulates gyrification.. Sci Adv 11(36):eadt5859 PMID: 40901969
- 7. Peng H et al.. 2020. Polarity Establishment and Maintenance in Ascidian Notochord.. Front Cell Dev Biol 8:597446 PMID: 33195278
- 8. Müller HA. 2000. Genetic control of epithelial cell polarity: lessons from Drosophila.. Dev Dyn 218(1):52-67 PMID: 10822259
