GO:0016327 apicolateral plasma membrane: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0016327 apicolateral plasma membrane is the apical end of the lateral plasma membrane of epithelial cells, a specialized membrane subdomain that coordinates cell-cell adhesion and polarity.
• It is enriched in tight junction and adherens junction proteins, including claudins, E-cadherin, and Crumbs complex components, which assemble into functional complexes at the apicolateral boundary.
• The apicolateral plasma membrane is critical for epithelial barrier function, paracellular transport, and maintenance of apical-basal polarity.
• Disruption of apicolateral membrane components is linked to cancer progression, tissue morphogenesis defects, and organ dysfunction.
• Key research methods include immunofluorescence, electron microscopy, co-immunoprecipitation, and CRISPR-based gene editing to dissect protein localization and function.
• EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression, and library screening services to study apicolateral plasma membrane biology.
Description
The apicolateral plasma membrane (GO:0016327) is a specialized subdomain of the epithelial cell plasma membrane located at the apical end of the lateral membrane, where it forms the boundary between the apical and basolateral domains. This region is characterized by the presence of tight junctions and adherens junctions, which are essential for cell-cell adhesion, barrier function, and the establishment of epithelial polarity. The apicolateral plasma membrane is not merely a passive boundary; it actively participates in signaling and cytoskeletal organization, as demonstrated by studies showing that nitric oxide modulates the apicolateral cytoskeleton in hepatocytes through a PKC-dependent mechanism. Research on the apicolateral plasma membrane has revealed its importance in epithelial morphogenesis and tissue homeostasis. The Crumbs proteins, which localize to the apicolateral membrane, play critical roles in ciliogenesis, cell migration, and actin organization. Furthermore, the secretion of E-cadherin to the apicolateral membrane is facilitated by myosin V, highlighting the dynamic nature of this domain. Understanding the molecular composition and regulation of the apicolateral plasma membrane is essential for deciphering how epithelial tissues maintain their integrity and respond to environmental cues. Given its role in cell adhesion and polarity, the apicolateral plasma membrane is implicated in various pathological conditions, including cancer and developmental disorders. This article provides a comprehensive overview of the structure, function, and research methods related to GO:0016327, based on authoritative QuickGO data and verified PubMed literature.
apicolateral plasma membrane At A Glance
| GO ID | GO:0016327 |
|---|---|
| GO term | apicolateral plasma membrane |
| Ontology | cellular_component |
| Synonym | apical lateral plasma membrane |
| Major function | Cell-cell adhesion, barrier formation, and maintenance of epithelial polarity |
| Location | Apical end of the lateral plasma membrane in epithelial cells |
| Key components | Claudins, E-cadherin, Crumbs proteins, myosin V |
| Associated junctions | Tight junctions, adherens junctions |
What Is GO:0016327?
The apicolateral plasma membrane is defined as the apical end of the lateral plasma membrane of epithelial cells. It is a specialized membrane region that sits at the junction between the apical and lateral surfaces, serving as a platform for tight junction and adherens junction assembly. This domain is critical for maintaining cell polarity and barrier function in epithelial tissues.
Why Is apicolateral plasma membrane Important in Cell Biology?
The apicolateral plasma membrane is essential for epithelial tissue function because it houses the junctional complexes that seal the paracellular space and regulate the passage of ions and molecules. Disruption of this domain leads to loss of barrier integrity, which is a hallmark of many diseases, including inflammatory bowel disease and cancer. Moreover, the apicolateral membrane serves as a signaling hub where proteins such as Crumbs and E-cadherin coordinate cell polarity and cytoskeletal dynamics. Understanding its molecular architecture is therefore fundamental to epithelial biology and disease research.
• Maintains epithelial barrier function by anchoring tight junction proteins like claudins.
• Regulates cell-cell adhesion through E-cadherin and associated catenins.
• Coordinates apical-basal polarity via the Crumbs complex.
• Modulates the actin cytoskeleton in response to signaling molecules like nitric oxide.
• Involved in ciliogenesis and cell migration during development.
• Dysregulation is linked to cancer progression and metastasis.
• Serves as a target for pathogens that disrupt epithelial barriers.
• Provides a platform for studying membrane domain specialization.
• Relevant to organ-specific functions, such as in parathyroid and hepatocyte physiology.
• Potential therapeutic target for diseases involving barrier dysfunction.
Structure and Composition of apicolateral plasma membrane
Tight Junction Assembly
In simple terms: Tight junctions are like zippers that seal the space between cells.
The apicolateral plasma membrane is the site where tight junctions form, composed of claudins and occludin. Claudins interact in a head-to-head manner to create paracellular barriers, as revealed by crystal structures. Tricellular tight junctions, specialized structures at cell corners, are also organized at this domain. These junctions are critical for selective permeability and are regulated by various signaling pathways.
Adherens Junction Formation
In simple terms: Adherens junctions are like Velcro that holds cells together.
Adherens junctions, primarily composed of E-cadherin, are localized to the apicolateral membrane. E-cadherin is delivered to this domain via myosin V-dependent secretion, ensuring proper junction formation. The cytoplasmic tail of E-cadherin binds to catenins, linking to the actin cytoskeleton and stabilizing cell-cell adhesion.
Crumbs Complex Localization
In simple terms: The Crumbs complex is a group of proteins that helps define the top side of the cell.
The Crumbs complex, consisting of Crumbs, PALS1, and PATJ, localizes to the apicolateral membrane and is essential for apical-basal polarity. It regulates actin organization and ciliogenesis, and its dysfunction leads to polarity defects.
Cytoskeletal Interactions
In simple terms: The cytoskeleton is like a scaffold that supports the membrane.
The apicolateral membrane is linked to the actin cytoskeleton through junctional proteins. Nitric oxide modulates the apicolateral cytoskeleton in hepatocytes via a PKC-dependent, cGMP-independent mechanism, indicating dynamic regulation. This interaction is crucial for maintaining membrane domain integrity and responding to mechanical stress.
Membrane Domain Specialization
In simple terms: The membrane is not uniform; it has specialized regions for specific tasks.
The apicolateral plasma membrane is a distinct domain enriched in specific lipids and proteins. Morphological studies in mammalian parathyroids have highlighted the specialization of membrane domains in epithelial cells. This specialization is maintained by targeted secretion and endocytosis, as exemplified by E-cadherin trafficking.
Key Genes Involved in GO:0016327 apicolateral plasma membrane
The following genes and proteins are key components or regulators of the apicolateral plasma membrane, based on verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CDH1 | E-cadherin, core adherens junction protein | Mutations linked to cancer; target for secretion studies |
| CLDN1 | Claudin-1, tight junction barrier protein | Crystal structure informs interaction studies |
| CLDN2 | Claudin-2, tight junction protein | Regulates paracellular permeability |
| CRB1 | Crumbs homolog 1, polarity complex | Mutations cause retinal degeneration |
| CRB2 | Crumbs homolog 2, polarity complex | Role in ciliogenesis and actin organization |
| CRB3 | Crumbs homolog 3, polarity complex | Regulates epithelial morphogenesis |
| PALS1 | Protein associated with Lin-7 1, Crumbs complex | Essential for tight junction formation |
| PATJ | PALS1-associated tight junction protein | Scaffold for polarity complex |
| MYO5B | Myosin Vb, motor protein for E-cadherin secretion | Facilitates polarized secretion |
| OCLN | Occludin, tight junction protein | Regulates barrier function |
| TJP1 | Zonula occludens-1, tight junction scaffold | Links junctions to cytoskeleton |
| TJP2 | Zonula occludens-2, tight junction scaffold | Modulates junction assembly |
| ITGA6 | Integrin alpha-6, cell-matrix adhesion | Associates with αA-crystallin in signaling |
| CRYAA | αA-crystallin, chaperone | Regulates integrin signaling at membrane |
| PRKCI | Protein kinase C iota, polarity regulator | Phosphorylates polarity proteins |
| NOS2 | Inducible nitric oxide synthase | Modulates apicolateral cytoskeleton |
| CTNNB1 | Beta-catenin, adherens junction component | Links E-cadherin to actin |
How Is apicolateral plasma membrane Regulated?
The apicolateral plasma membrane is dynamically regulated by signaling pathways and trafficking mechanisms. Nitric oxide modulates the apicolateral cytoskeleton in hepatocytes through a PKC-dependent, cGMP-independent pathway, highlighting post-translational regulation. Myosin V facilitates the polarized secretion of E-cadherin to the apicolateral membrane, ensuring junction assembly. The Crumbs complex is regulated by phosphorylation and interactions with other polarity proteins, influencing its localization and function. Additionally, claudin assembly into tight junctions is regulated by phosphorylation and lipid environment.
apicolateral plasma membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CDH1 | Cancer, EMT | Knockout in epithelial cell lines |
| CRB1 | Retinal degeneration | Knock-in of patient mutations in iPSCs |
| CLDN1 | Barrier dysfunction | Point mutation to alter barrier properties |
| CRYAA | Cataract | Overexpression of mutant in lens cells |
| MYO5B | Microvillus inclusion disease | Knockout in intestinal organoids |
Cancer and Metastasis
Loss of apicolateral membrane integrity is a hallmark of epithelial-to-mesenchymal transition (EMT) in cancer. Downregulation of E-cadherin (CDH1) and claudins disrupts cell-cell adhesion, promoting metastasis. Crumbs complex dysregulation has been linked to tumor progression and loss of polarity.
Retinal Degeneration
Mutations in CRB1, a Crumbs homolog, cause retinal degeneration by disrupting apicolateral membrane organization in photoreceptors. This highlights the importance of the apicolateral domain in sensory epithelia.
Inflammatory Bowel Disease
Altered tight junction composition at the apicolateral membrane, including changes in claudin expression, contributes to barrier dysfunction in inflammatory bowel disease.
Cataract and Lens Biology
αA-crystallin (CRYAA) associates with α6 integrin at the apicolateral membrane in lens epithelial cells, regulating signaling; mutations in CRYAA lead to cataract.
From apicolateral plasma membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X localize to apicolateral membrane? | Tagged knock-in with fluorescent protein |
| Is gene X required for barrier function? | Knockout in epithelial monolayers |
| Does mutation Y affect junction assembly? | Point mutation knock-in |
| Can overexpression rescue polarity defects? | Overexpression in mutant background |
| What proteins interact with component Z? | Knock-in with affinity tag for proteomics |
| How does gene X affect E-cadherin secretion? | Knockout of MYO5B and rescue |
How to Study the apicolateral plasma membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Immunofluorescence | Protein localization and co-localization | Visualize apicolateral markers |
| Electron microscopy | Ultrastructure of junctions | Analyze tight junction strands |
| Co-immunoprecipitation | Protein-protein interactions | Identify Crumbs complex partners |
| CRISPR knockout | Gene function | Test requirement for barrier formation |
| CRISPR knock-in | Tagged protein localization | Track E-cadherin secretion |
| Proteomics | Protein composition | Define apicolateral membrane proteome |
| Live-cell imaging | Dynamic trafficking | Follow myosin V-dependent transport |
Immunofluorescence Microscopy
Immunofluorescence is used to visualize the localization of apicolateral membrane proteins such as E-cadherin, claudins, and Crumbs proteins. This method reveals domain-specific distribution and co-localization with junctional markers.
Electron Microscopy
Electron microscopy, including freeze-fracture, provides ultrastructural details of tight junction strands and membrane domain organization at the apicolateral region.
Co-immunoprecipitation and Proteomics
Co-immunoprecipitation coupled with mass spectrometry identifies protein complexes associated with the apicolateral membrane, such as the Crumbs complex and adherens junction components.
CRISPR-Cas9 Gene Editing
CRISPR-Cas9 enables knockout, knock-in, or point mutation of genes encoding apicolateral membrane proteins to study their function in epithelial cells.
How CRISPR Can Be Used to Study GO:0016327 apicolateral plasma membrane
Knockout
CRISPR knockout of genes such as CDH1, CLDN1, or CRB3 in epithelial cell lines abolishes apicolateral membrane protein expression, leading to loss of barrier function and polarity defects. These models are used to assess the requirement of specific components for junction assembly.
Point Mutation
Point mutations can be introduced into genes like CLDN1 to mimic disease-associated variants or to disrupt specific phosphorylation sites. Such models help dissect the molecular mechanisms of tight junction regulation.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) into endogenous loci such as CDH1 allows real-time tracking of protein trafficking to the apicolateral membrane. This approach has revealed myosin V-dependent E-cadherin secretion.
Overexpression
Overexpression of wild-type or mutant forms of apicolateral membrane proteins, such as CRB2 or CRYAA, can rescue or exacerbate phenotypes in knockout backgrounds, providing insights into gain-of-function mechanisms.
How EDITGENE Supports apicolateral plasma membrane Research
Researchers studying apicolateral plasma membrane-related genes often need to determine whether a candidate gene is causally involved in junction assembly, barrier function, or polarity. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for apicolateral plasma membrane research.
Frequently Asked Questions About apicolateral plasma membrane
What is the apicolateral plasma membrane?
The apicolateral plasma membrane (GO:0016327) is the apical end of the lateral plasma membrane of epithelial cells, where tight junctions and adherens junctions form to regulate cell-cell adhesion and polarity.
What genes are involved in the apicolateral plasma membrane?
Key genes include CDH1 (E-cadherin), CLDN1 (claudin-1), CRB1/2/3 (Crumbs homologs), PALS1, PATJ, and MYO5B (myosin Vb).
How is the apicolateral plasma membrane studied?
Common methods include immunofluorescence, electron microscopy, co-immunoprecipitation, and CRISPR-Cas9 gene editing.
What is the role of E-cadherin at the apicolateral membrane?
E-cadherin is a core adherens junction protein that mediates cell-cell adhesion and is secreted to the apicolateral membrane via myosin V.
What diseases are linked to apicolateral plasma membrane dysfunction?
Dysfunction is linked to cancer metastasis, retinal degeneration, inflammatory bowel disease, and cataract.
What are tight junctions at the apicolateral membrane?
Tight junctions are protein complexes composed of claudins and occludin that seal the paracellular space and regulate permeability.
How does the Crumbs complex function at the apicolateral membrane?
The Crumbs complex (Crumbs, PALS1, PATJ) regulates apical-basal polarity, actin organization, and ciliogenesis.
Can CRISPR be used to study apicolateral plasma membrane genes?
Yes, CRISPR knockout, knock-in, and point mutation models are widely used to dissect gene function in this domain.
What is the difference between apical and apicolateral membrane?
The apical membrane faces the lumen, while the apicolateral membrane is the apical portion of the lateral membrane, enriched in junctional complexes.
How does nitric oxide affect the apicolateral membrane?
Nitric oxide modulates the apicolateral cytoskeleton in hepatocytes via a PKC-dependent, cGMP-independent mechanism.
Conclusion
The apicolateral plasma membrane (GO:0016327) is a specialized membrane domain critical for epithelial cell adhesion, barrier function, and polarity. Its molecular composition, including claudins, E-cadherin, and Crumbs proteins, is tightly regulated and essential for tissue homeostasis. Dysregulation of this domain contributes to cancer, retinal degeneration, and other diseases. Advances in CRISPR-based gene editing and imaging technologies continue to unravel the dynamic nature of this membrane region, offering potential therapeutic targets.
References
- 1. Tanasic D et al.. 2022. Myosin V facilitates polarised E-cadherin secretion.. Traffic 23(7):374-390 PMID: 35575181
- 2. Furuse M et al.. 2014. Molecular organization of tricellular tight junctions.. Tissue Barriers 2:e28960 PMID: 25097825
- 3. Burgstahler AD et al.. 1995. NO modulates the apicolateral cytoskeleton of isolated hepatocytes by a PKC-dependent, cGMP-independent mechanism.. Am J Physiol 269(5 Pt 1):G789-99 PMID: 7491972
- 4. Suzuki H et al.. 2017. Crystal structures of claudins: insights into their intermolecular interactions.. Ann N Y Acad Sci 1397(1):25-34 PMID: 28605828
- 5. Bazellières E et al.. 2018. Role of the Crumbs proteins in ciliogenesis, cell migration and actin organization.. Semin Cell Dev Biol 81:13-20 PMID: 29056580
- 6. Wild P et al.. 1995. Mammalian parathyroids: morphological and functional implications.. Microsc Res Tech 32(2):120-8 PMID: 8580507
- 7. Bazellieres E et al.. 2009. Crumbs proteins in epithelial morphogenesis.. Front Biosci (Landmark Ed) 14(6):2149-69 PMID: 19273190
- 8. Menko AS et al.. 2010. αA-Crystallin associates with α6 integrin receptor complexes and regulates cellular signaling.. Exp Eye Res 91(5):640-51 PMID: 20709056
