GO:0120003 hinge region between urothelial plaques of apical plasma membrane: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0120003 describes the narrow rim of non-thickened membrane that separates adjacent urothelial plaques in the apical plasma membrane of umbrella cells.
• The hinge region is enriched in an 85-100 kDa glycoprotein that serves as a marker of advanced urothelial differentiation and is associated with the inter-plaque area.
• Urothelial plaques are rigid asymmetric unit membrane (AUM) domains, while the hinge region is more compliant, allowing the apical membrane to unfold during bladder filling.
• Electron tomography has revealed that fusiform vesicles deliver plaque and hinge components to the apical surface, and the hinge region is critical for membrane remodeling.
• Comparative studies in hibernators such as the American black bear show that the urothelial hinge region and plaque architecture are remodeled to withstand extreme urine storage.
• Studying GO:0120003 requires a combination of super-resolution imaging, electron tomography, and CRISPR-based models to dissect the role of hinge-specific proteins in bladder physiology and disease [1,3,4].
Description
The apical plasma membrane of urothelial umbrella cells is a highly specialized structure that must withstand large changes in surface area during bladder filling and emptying. This membrane is partitioned into rigid, thickened plaques composed of uroplakin complexes and intervening narrow rims of non-thickened membrane known as hinge regions. The Gene Ontology term GO:0120003 (hinge region between urothelial plaques of apical plasma membrane) defines this narrow rim of non-thickened membrane in between urothelial plaques. The hinge region is not merely a passive spacer; it is a distinct membrane domain that is enriched in specific proteins and is thought to provide the flexibility required for membrane unfolding and folding. Understanding the composition and regulation of the hinge region is essential for researchers studying bladder physiology, urothelial differentiation, and diseases such as bladder cancer and interstitial cystitis. The hinge region has been identified as the inter-plaque area that contains an 85-100 kDa glycoprotein, which is a marker for advanced urothelial differentiation. Electron tomography of fusiform vesicles has shown that these vesicles contain both plaque and hinge components, and their organization is critical for the delivery of membrane material to the apical surface. Moreover, biophysical studies have demonstrated that the apical membrane of umbrella cells is hypercompliant, and this property is likely conferred by the hinge regions that allow the membrane to stretch. Comparative studies in hibernating bears have further highlighted the importance of the urothelial hinge region in adapting to extreme physiological conditions. Thus, GO:0120003 represents a key structural and functional entity in urothelial biology, with implications for understanding membrane mechanics, protein trafficking, and urothelial pathology.
hinge region between urothelial plaques of apical plasma membrane At A Glance
| GO ID | GO:0120003 |
|---|---|
| GO term | hinge region between urothelial plaques of apical plasma membrane |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Provides a flexible, non-thickened membrane domain that separates rigid urothelial plaques and facilitates membrane unfolding during bladder filling. |
| Location | Apical plasma membrane of urothelial umbrella cells [1,4]. |
| Key marker | An 85-100 kDa glycoprotein associated with the inter-plaque area. |
| Related structures | Urothelial plaques (asymmetric unit membrane) and fusiform vesicles. |
| Physiological role | Contributes to the hypercompliant properties of the bladder apical membrane. |
What Is GO:0120003?
GO:0120003 is a cellular component term that refers to a narrow rim of non-thickened membrane located between urothelial plaques in the apical plasma membrane of urothelial cells. This definition is based on the QuickGO annotation, which describes the hinge region as a distinct membrane domain that separates the rigid, thickened plaques characteristic of the urothelial apical surface.
Why Is hinge region between urothelial plaques of apical plasma membrane Important in Cell Biology?
The hinge region between urothelial plaques is critical for the unique mechanical properties of the bladder epithelium. It allows the apical membrane to undergo extensive unfolding and refolding during cycles of bladder filling and emptying without rupturing. Disruption of this region can lead to compromised barrier function, which is associated with bladder pathologies such as interstitial cystitis and bladder cancer. Moreover, the hinge region serves as a marker of advanced urothelial differentiation, making it a valuable tool for studying urothelial development and regeneration. Understanding the molecular composition of the hinge region may also reveal new targets for therapeutic intervention in bladder diseases.
• Provides flexibility to the apical membrane, enabling bladder expansion and contraction.
• Serves as a docking site for specific proteins, including an 85-100 kDa glycoprotein marker.
• Plays a role in the delivery and organization of fusiform vesicles to the apical surface.
• Its disruption may compromise the urothelial barrier, leading to inflammation and infection.
• Alterations in hinge region components are observed in bladder cancer and other urothelial disorders.
• Comparative studies in hibernators highlight its adaptive significance in extreme urine storage.
• The hinge region is a target for studying membrane domain assembly and protein sorting.
• It is essential for maintaining the asymmetric unit membrane structure and function.
• Understanding hinge region biology can inform tissue engineering of urothelial substitutes.
• It provides a model for studying how cells regulate membrane mechanics and curvature.
Structure and Composition of hinge region between urothelial plaques of apical plasma membrane
Membrane Architecture and Plaque Organization
In simple terms: The hinge region is the flexible gap between rigid patches on the surface of bladder cells.
The apical plasma membrane of urothelial umbrella cells is organized into rigid, thickened plaques that are composed of uroplakin complexes and are separated by narrow hinge regions. These plaques are part of the asymmetric unit membrane (AUM), which is characterized by an outer leaflet that is thicker than the inner leaflet. The hinge region is a non-thickened membrane domain that lacks the characteristic plaque structure and is thought to be enriched in specific lipids and proteins that confer flexibility. Electron tomography has revealed that the hinge regions are narrow and that the plaques are arranged in a mosaic pattern, allowing the membrane to unfold like an accordion during bladder filling.
Protein Components of the Hinge Region
In simple terms: The hinge region contains a specific protein that is a marker for mature bladder cells.
The hinge region is characterized by the presence of an 85-100 kDa glycoprotein that is recognized by specific antibodies and is associated with the inter-plaque area. This glycoprotein is a marker for an advanced stage of urothelial differentiation and is not found in the plaques themselves. In addition to this glycoprotein, the hinge region may contain other proteins that are involved in membrane trafficking and cytoskeletal anchoring, although their identities remain to be fully elucidated. The unique protein composition of the hinge region distinguishes it from the plaque domains and suggests specialized functions in membrane dynamics.
Fusiform Vesicles and Delivery to the Apical Surface
In simple terms: Special vesicles carry building blocks to the cell surface, and the hinge region is where they insert.
Fusiform vesicles are cytoplasmic organelles that contain both plaque and hinge components. Electron tomography has shown that these vesicles are elongated and that their membranes are organized similarly to the apical membrane, with plaque and hinge domains. Upon fusion with the apical plasma membrane, fusiform vesicles deliver their contents to the surface, contributing to the expansion of the apical membrane during bladder filling. The hinge regions within these vesicles are thought to be important for the proper folding and insertion of the vesicles into the apical membrane, ensuring that the plaque and hinge domains are correctly positioned.
Biophysical Properties and Membrane Compliance
In simple terms: The hinge region makes the bladder surface stretchy, like a rubber band between stiff tiles.
The apical membrane of umbrella cells is hypercompliant, meaning it can undergo large deformations without breaking. This property is largely attributed to the hinge regions, which are more flexible than the rigid plaques. Biophysical measurements have shown that the apical membrane has a low elastic modulus, allowing it to stretch significantly during bladder filling. The hinge regions act as hinges that permit the plaques to move relative to one another, thereby accommodating changes in surface area. This mechanical behavior is essential for the bladder's function as a storage organ.
Comparative and Evolutionary Aspects
In simple terms: Animals that hold urine for long periods have special adaptations in their bladder lining.
Studies of hibernating animals, such as the American black bear, have provided insights into the adaptive significance of the urothelial hinge region. During hibernation, bears do not urinate for months, and their urothelium must withstand prolonged exposure to urine. The urothelium of hibernators exhibits structural adaptations, including changes in plaque and hinge organization, that help maintain barrier function under extreme conditions. These comparative studies highlight the evolutionary importance of the hinge region in enabling urine storage and may inform research on human bladder disorders.
Key Genes Involved in GO:0120003 hinge region between urothelial plaques of apical plasma membrane
The following genes and proteins are key components or markers associated with the hinge region between urothelial plaques and related urothelial structures.
| Gene | Major Role | Research Relevance |
|---|---|---|
| UPK1A | Uroplakin 1A, a tetraspanin component of urothelial plaques | Mutations or knockout affect plaque formation and hinge integrity. |
| UPK1B | Uroplakin 1B, another tetraspanin in plaques | Essential for plaque assembly and apical membrane structure. |
| UPK2 | Uroplakin 2, a major plaque protein | Knockout leads to plaque defects and compromised barrier. |
| UPK3A | Uroplakin 3A, a plaque protein | Involved in plaque formation and hinge region organization. |
| UPK3B | Uroplakin 3B, a plaque protein | May interact with hinge components. |
| KRT20 | Cytokeratin 20, a marker of urothelial differentiation | Expressed in umbrella cells and may be associated with hinge region. |
| KRT13 | Cytokeratin 13, a marker of urothelial differentiation | Used to identify differentiated urothelial cells. |
| TUBB | Beta-tubulin, component of microtubules | Involved in vesicle trafficking to the apical surface. |
| ACTB | Beta-actin, cytoskeletal protein | Important for membrane dynamics and vesicle transport. |
| RAB8A | Rab8a, a small GTPase | Regulates vesicle trafficking to the apical membrane. |
| RAB11A | Rab11a, a small GTPase | Involved in recycling of apical membrane components. |
| SNAP23 | Synaptosomal-associated protein 23 | Mediates vesicle fusion with the apical membrane. |
| VAMP3 | Vesicle-associated membrane protein 3 | Participates in vesicle fusion events. |
| CDH1 | E-cadherin, cell adhesion molecule | Maintains urothelial integrity and may influence hinge region. |
| ITGB1 | Integrin beta 1 | Mediates cell-matrix adhesion and signaling. |
| EGFR | Epidermal growth factor receptor | Regulates urothelial proliferation and differentiation. |
| PPARG | Peroxisome proliferator-activated receptor gamma | Transcription factor involved in urothelial differentiation. |
| FOXA1 | Forkhead box A1 | Regulates urothelial gene expression. |
How Is hinge region between urothelial plaques of apical plasma membrane Regulated?
The formation and maintenance of the hinge region are regulated at multiple levels, including transcriptional control of urothelial differentiation genes, post-translational modifications of membrane proteins, and vesicle trafficking pathways. Transcription factors such as PPARG and FOXA1 are known to regulate urothelial differentiation and may influence the expression of hinge-specific components. Additionally, small GTPases like Rab8a and Rab11a are involved in the trafficking of fusiform vesicles to the apical membrane, ensuring that hinge and plaque domains are correctly delivered. The mechanical properties of the hinge region may also be modulated by changes in lipid composition and by interactions with the underlying cytoskeleton.
hinge region between urothelial plaques of apical plasma membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| UPK1A | Bladder cancer, urothelial barrier defects | UPK1A knockout mouse or bladder cancer cell lines. |
| UPK2 | Congenital urinary tract anomalies | UPK2 knockout mouse. |
| UPK3A | Bladder cancer, interstitial cystitis | UPK3A knockout or knockdown in urothelial cells. |
| KRT20 | Bladder cancer differentiation marker | KRT20 knockout or overexpression in bladder cancer cells. |
| PPARG | Bladder cancer, urothelial differentiation | PPARG knockout or agonist treatment in urothelial cells. |
Bladder Cancer
Disruption of the urothelial apical membrane and its hinge regions is a hallmark of bladder cancer. Loss of urothelial differentiation markers, including the 85-100 kDa glycoprotein associated with the hinge region, is observed in high-grade bladder tumors. Alterations in uroplakin expression and plaque organization can lead to compromised barrier function and increased susceptibility to carcinogens. Understanding the role of hinge region components in bladder cancer may provide new diagnostic and therapeutic targets.
Interstitial Cystitis/Bladder Pain Syndrome
Interstitial cystitis is a chronic condition characterized by bladder pain and urinary urgency. Defects in the urothelial barrier, including the apical membrane and hinge regions, are thought to contribute to the pathogenesis of this disease. Disruption of the hinge region may lead to increased permeability to urinary solutes, triggering inflammation and pain. Studies on the mechanical properties of the apical membrane may shed light on the pathophysiology of interstitial cystitis.
Urinary Tract Infections
Uropathogenic bacteria such as Escherichia coli attach to the urothelial surface and can invade umbrella cells. The hinge region may serve as a site for bacterial adhesion or entry, as it is a distinct membrane domain. Disruption of the hinge region could affect the ability of the urothelium to resist infection. Research into the interaction between pathogens and hinge region components may lead to new strategies for preventing urinary tract infections.
Congenital Anomalies of the Urinary Tract
Congenital anomalies such as ureteropelvic junction obstruction and bladder exstrophy can affect urothelial development and function. Mutations in genes involved in urothelial plaque and hinge formation, such as uroplakins, have been linked to these conditions. Studying the hinge region in model organisms may help elucidate the genetic basis of these anomalies.
From hinge region between urothelial plaques of apical plasma membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of UPK1A in hinge region formation? | UPK1A knockout mouse or CRISPR knockout in urothelial cell lines. |
| How does the 85-100 kDa glycoprotein contribute to hinge function? | Knock-in of tagged glycoprotein or knockout of its gene in urothelial cells. |
| What are the trafficking pathways that deliver hinge components? | CRISPR knockout of Rab8a or Rab11a in urothelial cells. |
| How does the hinge region adapt to mechanical stress? | Overexpression of mechanosensitive proteins in urothelial cells. |
| What is the role of PPARG in hinge region gene expression? | Point mutation or knockout of PPARG in urothelial organoids. |
| Can we visualize hinge region dynamics in live cells? | Knock-in of fluorescent tags into hinge-specific proteins. |
How to Study the hinge region between urothelial plaques of apical plasma membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Electron tomography | 3D ultrastructure of membrane domains | Visualizing hinge regions and fusiform vesicles. |
| Super-resolution microscopy | Localization of specific proteins | Mapping the 85-100 kDa glycoprotein to the hinge region. |
| Atomic force microscopy | Membrane stiffness and elasticity | Measuring hypercompliance of apical membrane. |
| Proteomics | Protein composition of membrane fractions | Identifying hinge-specific proteins. |
| Glycoproteomics | Glycosylation patterns | Characterizing the 85-100 kDa glycoprotein. |
| CRISPR knockout | Gene function | Testing the role of candidate genes in hinge formation. |
| Live-cell imaging | Dynamic trafficking of vesicles | Tracking fusiform vesicle delivery to the apical surface. |
| RNA-seq | Transcriptional profiles | Comparing gene expression in differentiated urothelial cells. |
Electron Tomography
Electron tomography is a powerful technique for visualizing the three-dimensional organization of the urothelial apical membrane and fusiform vesicles. It has been used to reveal the narrow hinge regions between plaques and the organization of vesicles. This method provides high-resolution structural information that is essential for understanding the architecture of the hinge region.
Super-Resolution Microscopy
Super-resolution microscopy techniques, such as STORM and STED, can be used to localize specific proteins within the hinge region and plaques. By labeling the 85-100 kDa glycoprotein or uroplakins with fluorescent antibodies, researchers can determine their precise distribution relative to the hinge region. This approach allows for the study of protein dynamics and interactions in fixed and live cells.
Biophysical Measurements
Atomic force microscopy (AFM) and micropipette aspiration can measure the mechanical properties of the apical membrane, including its compliance and elasticity. These techniques have demonstrated that the apical membrane is hypercompliant, and that the hinge regions contribute to this property. Such measurements are crucial for understanding how the hinge region functions under mechanical stress.
Proteomics and Glycoproteomics
Mass spectrometry-based proteomics can identify proteins enriched in the hinge region. By isolating apical membrane fractions and comparing plaque versus hinge domains, researchers can discover novel hinge-specific proteins. The 85-100 kDa glycoprotein was identified using biochemical and immunological methods. Glycoproteomics can further characterize the glycosylation patterns of hinge proteins.
How CRISPR Can Be Used to Study GO:0120003 hinge region between urothelial plaques of apical plasma membrane
Knockout
CRISPR knockout of genes encoding uroplakins or hinge-specific proteins can be used to study their role in hinge region formation and function. For example, knockout of UPK1A or UPK2 in urothelial cell lines or mouse models leads to defects in plaque assembly and apical membrane structure. These models help determine whether a gene is essential for hinge region integrity.
Point Mutation
Point mutations can be introduced into genes to mimic human disease-associated variants or to dissect specific protein domains. For instance, point mutations in the 85-100 kDa glycoprotein gene could reveal its role in hinge region function. CRISPR-based base editing allows precise introduction of such mutations without creating double-strand breaks.
Knock-in
Knock-in of fluorescent tags or epitope tags into hinge-specific genes enables live-cell imaging and biochemical purification. Tagging the 85-100 kDa glycoprotein with GFP, for example, allows visualization of its trafficking to the hinge region. Knock-in models are also useful for studying protein interactions and dynamics.
Overexpression
Overexpression of hinge region proteins can be achieved by CRISPR activation (CRISPRa) or by introducing a transgene. Overexpressing uroplakins or the 85-100 kDa glycoprotein may lead to altered membrane architecture and provide insights into their roles in hinge formation. Overexpression models are valuable for gain-of-function studies.
How EDITGENE Supports hinge region between urothelial plaques of apical plasma membrane Research
Researchers studying hinge region between urothelial plaques of apical plasma membrane-related genes often need to determine whether a candidate gene is causally involved in hinge region formation, maintenance, or function. EDITGENE provides a comprehensive suite of CRISPR-based 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 hinge region between urothelial plaques of apical plasma membrane research.
Frequently Asked Questions About hinge region between urothelial plaques of apical plasma membrane
What is GO:0120003?
GO:0120003 is a Gene Ontology cellular component term that describes the hinge region between urothelial plaques of apical plasma membrane, a narrow rim of non-thickened membrane in urothelial cells.
What genes are involved in the hinge region between urothelial plaques?
Genes encoding uroplakins (UPK1A, UPK1B, UPK2, UPK3A, UPK3B) and markers such as KRT20 are associated with urothelial plaques and hinge regions [1,4].
What is the function of the hinge region in urothelial cells?
The hinge region provides flexibility between rigid plaques, allowing the apical membrane to unfold during bladder filling.
How is the hinge region related to bladder cancer?
Loss of hinge region markers, such as the 85-100 kDa glycoprotein, is observed in high-grade bladder cancer, suggesting a role in differentiation and tumor suppression.
What proteins are enriched in the hinge region?
An 85-100 kDa glycoprotein is a known marker of the inter-plaque hinge area in urothelial cells.
How can I study the hinge region using CRISPR?
CRISPR knockout, knock-in, and overexpression models can be used to dissect the function of hinge-specific genes in urothelial cell lines [1,3].
What is the relationship between fusiform vesicles and the hinge region?
Fusiform vesicles contain both plaque and hinge components and deliver them to the apical membrane during bladder filling.
Why is the apical membrane of umbrella cells hypercompliant?
The hypercompliance is due to the presence of flexible hinge regions between rigid plaques, which allow the membrane to stretch.
Are there animal models for studying the hinge region?
Yes, knockout mouse models for uroplakins and comparative studies in hibernators like bears have been used to study hinge region biology [1,2].
What methods are used to visualize the hinge region?
Electron tomography and super-resolution microscopy are key techniques for visualizing the hinge region and its components [3,4].
Conclusion
The hinge region between urothelial plaques (GO:0120003) is a specialized membrane domain that is essential for the unique mechanical properties of the bladder epithelium. Its distinct protein composition, including the 85-100 kDa glycoprotein, and its role in vesicle trafficking and membrane compliance make it a fascinating subject for researchers in cell biology, physiology, and urology. Disruption of the hinge region is associated with bladder diseases such as cancer and interstitial cystitis, highlighting its clinical relevance. Advances in CRISPR-based models and imaging technologies will continue to unravel the molecular mechanisms governing hinge region formation and function, potentially leading to new therapeutic strategies.
References
- 1. Mathai JC et al.. 2014. Hypercompliant apical membranes of bladder umbrella cells.. Biophys J 107(6):1273-9 PMID: 25229135
- 2. Spector DA et al.. 2015. The urothelium of a hibernator: the American black bear.. Physiol Rep 3(6) PMID: 26109187
- 3. Hudoklin S et al.. 2012. Electron tomography of fusiform vesicles and their organization in urothelial cells.. PLoS One 7(3):e32935 PMID: 22427911
- 4. Yu J et al.. 1992. Identification of an 85-100 kDa glycoprotein as a cell surface marker for an advanced stage of urothelial differentiation: association with the inter-plaque ('hinge') area.. Epithelial Cell Biol 1(1):4-12 PMID: 1307937
