GO:0097498 endothelial tube lumen extension: Angiogenic Tube Elongation, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0097498 endothelial tube lumen extension is a biological process defined as any endothelial tube morphogenesis process by which the tube is increased in length.
• It is a late step in angiogenesis, distinct from endothelial cell specification, sprouting initiation, and lumen formation; it specifically covers elongation of an already-formed endothelial tube.
• Key molecular players include VEGF-A signaling components such as Scube1 and Scube2, the endothelial junctional and extracellular matrix protein Egfl7, and matrix-dependent mechanotransduction pathways.
• Zebrafish and in vitro endothelial progenitor tubulogenesis assays are the dominant experimental systems for studying this process.
• Defects in endothelial tube lumen extension contribute to vascular malformations, impaired wound healing, retinopathies, and tumor angiogenesis.
• CRISPR knockout, point-mutation, knock-in, and overexpression models allow causal testing of candidate genes in endothelial tube lumen extension.
Description
Endothelial tube lumen extension (GO:0097498) is a biological process that describes the lengthening of an endothelial tube during vascular morphogenesis. It is a subprocess of endothelial tube morphogenesis and represents the phase in which a previously formed endothelial tube increases in length, rather than the initial specification, sprouting, or lumen creation steps. This term is therefore central to understanding how primitive vascular plexuses are remodeled into elongated, functional blood vessels. Because endothelial tube lumen extension is required for organ vascularization, its dysregulation is linked to developmental vascular defects and pathological angiogenesis. Researchers studying angiogenesis, vascular development, and endothelial cell biology need a precise ontology term to annotate genes and pathways that act specifically at the elongation step, and GO:0097498 provides that specificity. Experimental models ranging from zebrafish embryos to in vitro endothelial progenitor cultures have been used to dissect the cellular behaviors and molecular signals that drive tube extension. This article summarizes the definition, mechanism, key genes, disease relevance, and research methods for GO:0097498, with all factual claims supported by published literature.
endothelial tube lumen extension At A Glance
| GO ID | GO:0097498 |
|---|---|
| GO term | endothelial tube lumen extension |
| Ontology | biological_process |
| Synonym | none |
| Definition | Any endothelial tube morphogenesis process by which the tube is increased in length. |
| Parent process | endothelial tube morphogenesis |
| Major function | Elongation of endothelial tubes during vascular morphogenesis and angiogenesis |
| Related processes | Angiogenesis, blood vessel morphogenesis, endothelial cell migration and junctional remodeling |
| Experimental models | Zebrafish embryos, in vitro endothelial progenitor tubulogenesis assays, endothelial cell culture |
What Is GO:0097498?
GO:0097498 endothelial tube lumen extension is defined in QuickGO as any endothelial tube morphogenesis process by which the tube is increased in length. In other words, it is the elongation phase of endothelial tube morphogenesis, occurring after an endothelial tube has formed and focusing on the increase in tube length rather than on initial lumen formation or sprouting. It is a biological process and has no synonyms in the QuickGO record.
Why Is endothelial tube lumen extension Important in Cell Biology?
Endothelial tube lumen extension is important because it determines the length and reach of newly formed blood vessels, which is essential for delivering oxygen and nutrients to developing and regenerating tissues. Defects in this process can cause incomplete vascularization, vessel malformations, and impaired perfusion, contributing to developmental vascular disorders and pathological conditions such as tumor angiogenesis and retinopathies. Understanding the molecular control of tube extension also informs strategies for therapeutic angiogenesis and for targeting aberrant vessel growth in disease.
• Required for embryonic vascular development and organ vascularization.
• Distinct from initial lumen formation and sprouting, allowing precise genetic annotation.
• Regulated by VEGF-A signaling components such as Scube1 and Scube2.
• Influenced by endothelial junctional and extracellular matrix proteins such as Egfl7.
• Modulated by substrate mechanics and mechanotransduction in endothelial progenitor cells.
• Contributes to blood vessel fusion and remodeling in zebrafish embryos.
• Relevant to pathological angiogenesis, including tumor vessel growth and retinopathies.
• Provides a target for pro-angiogenic or anti-angiogenic therapeutic strategies.
• Studied using zebrafish, Ciona, and in vitro tubulogenesis models.
• Supports tissue engineering and regenerative medicine approaches requiring vascularization.
What Happens During endothelial tube lumen extension?
Initiation from a formed endothelial tube
In simple terms: The tube already exists, and now it needs to get longer.
Endothelial tube lumen extension begins after an endothelial tube has been established during vasculogenesis or angiogenesis. In zebrafish, Vegfa signaling promotes the formation and extension of endothelial tubes, and Scube1 and Scube2 cooperate to enhance Vegfa signaling during embryonic vascularization. This step is distinct from initial lumen formation and involves coordinated endothelial cell behaviors that lengthen the existing tube.
Endothelial cell rearrangement and junctional remodeling
In simple terms: Cells in the tube rearrange and adjust their connections to let the tube stretch.
During extension, endothelial cells within the tube rearrange and remodel their junctions. Egfl7 knockdown in zebrafish causes defects in the extension and junctional arrangements of endothelial cells during vasculogenesis, indicating that Egfl7 is required for normal tube extension and junctional organization. These junctional changes allow the tube to elongate while maintaining barrier integrity.
Migration and directed elongation
In simple terms: Cells move in a coordinated direction to push the tube longer.
Endothelial tube extension requires directed endothelial cell migration and coordinated cell movements. In zebrafish, distinct cellular mechanisms of blood vessel fusion have been described, including cell rearrangement and junctional resolution that contribute to tube remodeling and extension. In vitro, endothelial progenitor cells form tubes in response to VEGF and substrate mechanics, demonstrating that migration and matrix interactions drive tubulogenesis.
Matrix and mechanical regulation
In simple terms: The stiffness and composition of the surrounding matrix tell the tube how to grow.
Substrate mechanics regulate in vitro tubulogenesis of endothelial progenitor cells, with VEGF and matrix stiffness acting together to control tube formation and extension. Computational analyses of blood-wall transport also highlight the importance of physical forces in vessel wall biology, although direct evidence for tube extension in that model is limited. These findings indicate that mechanical cues are integrated with growth factor signaling during endothelial tube lumen extension.
Fusion and connection to neighboring tubes
In simple terms: The growing tube connects with other tubes to form a network.
Endothelial tube extension is often accompanied by fusion with neighboring tubes to form a vascular network. In zebrafish, blood vessel fusion occurs through distinct cellular mechanisms that involve cell rearrangement and junctional changes, which are essential for building a connected vascular plexus. This fusion step ensures that extended tubes become part of a functional circulatory network.
Key Genes Involved in GO:0097498 endothelial tube lumen extension
The following genes and proteins have been experimentally implicated in endothelial tube lumen extension or closely related endothelial tube morphogenesis processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| VEGFA | Primary pro-angiogenic growth factor driving endothelial tube formation and extension | Central regulator of tubulogenesis in vitro and in vivo |
| SCUBE1 | Cooperates with Scube2 to promote Vegfa signaling during embryonic vascularization | Modulates Vegfa availability and signaling in zebrafish |
| SCUBE2 | Cooperates with Scube1 to promote Vegfa signaling during embryonic vascularization | Modulates Vegfa availability and signaling in zebrafish |
| EGFL7 | Endothelial junctional and extracellular matrix protein required for tube extension and junctional arrangement | Knockdown causes defects in endothelial cell extension and junctions in zebrafish |
| CDH5 | Endothelial adherens junction protein involved in junctional remodeling during tube extension | Junctional rearrangements are required for tube elongation |
| PECAM1 | Endothelial junctional molecule involved in cell-cell interactions during vessel fusion | Participates in endothelial cell rearrangements during fusion |
| KDR | VEGF receptor mediating pro-angiogenic signaling for tube extension | Key receptor for VEGF-driven tubulogenesis |
| FLT1 | VEGF receptor modulating VEGF signaling availability | Regulates VEGF signaling during vascularization |
| NRP1 | VEGF co-receptor enhancing signaling during endothelial tube formation | Modulates VEGF pathway activity |
| ITGB1 | Integrin mediating matrix adhesion and mechanotransduction | Required for matrix-dependent tubulogenesis |
| ITAVB3 | Integrin involved in endothelial matrix interactions during angiogenesis | Contributes to matrix-dependent tube formation |
| MMP2 | Matrix metalloproteinase remodeling extracellular matrix during tube extension | Facilitates matrix remodeling for tube elongation |
| MMP9 | Matrix metalloproteinase involved in matrix degradation during angiogenesis | Supports endothelial tube extension |
| TIE2 | Endothelial receptor tyrosine kinase regulating vessel stabilization and remodeling | Modulates tube extension and stabilization |
| ANGPT2 | Angiopoietin ligand regulating endothelial remodeling | Influences vessel remodeling during extension |
| NOTCH1 | Signaling receptor regulating endothelial cell fate and sprouting | Modulates endothelial cell behavior during tube extension |
| DLL4 | Notch ligand regulating endothelial sprouting and tube formation | Controls endothelial cell rearrangement during extension |
How Is endothelial tube lumen extension Regulated?
Endothelial tube lumen extension is regulated by a combination of growth factor signaling, junctional remodeling, and mechanical cues. VEGF-A signaling, enhanced by Scube1 and Scube2, is a major positive regulator of endothelial tube formation and extension during embryonic vascularization. Egfl7 is required for proper extension and junctional arrangement of endothelial cells, indicating that extracellular matrix and junctional proteins regulate this process. Substrate mechanics and integrin-mediated mechanotransduction also modulate in vitro tubulogenesis of endothelial progenitor cells, showing that physical forces are integrated with biochemical signals. Blood vessel fusion mechanisms further regulate how extended tubes connect into networks.
endothelial tube lumen extension and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| EGFL7 | Vascular malformations and junctional defects | Zebrafish egfl7 knockdown |
| SCUBE1/SCUBE2 | Impaired embryonic vascularization | Zebrafish scube1/scube2 loss-of-function |
| VEGFA | Tumor angiogenesis and retinopathies | Endothelial progenitor tubulogenesis assay |
| ITGB1 | Matrix-dependent angiogenesis defects | In vitro endothelial progenitor culture |
| CDH5 | Vascular barrier and junctional disorders | Zebrafish vascular fusion assays |
Vascular malformations and developmental vascular defects
Defects in endothelial tube lumen extension can lead to incomplete or malformed vascular networks. Egfl7 knockdown in zebrafish causes defects in endothelial cell extension and junctional arrangements during vasculogenesis, demonstrating that disruption of tube extension machinery produces vascular malformations. Similarly, impaired Vegfa signaling due to loss of Scube1/Scube2 function affects embryonic vascularization.
Tumor angiogenesis and retinopathies
Pathological angiogenesis, including tumor vessel growth and proliferative retinopathies, depends on endothelial tube extension. VEGF-A and matrix-dependent tubulogenesis pathways that drive tube extension are also central to tumor angiogenesis and retinal neovascularization. Targeting these pathways is a therapeutic strategy in anti-angiogenic therapy.
Impaired wound healing and tissue regeneration
Adequate endothelial tube extension is required for revascularization of wounded or ischemic tissues. In vitro models using endothelial progenitor cells show that VEGF and substrate mechanics regulate tubulogenesis, which is relevant to therapeutic angiogenesis for wound healing and regenerative medicine.
From endothelial tube lumen extension-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for endothelial tube extension? | CRISPR knockout in zebrafish or endothelial cells |
| Does a specific point mutation alter tube extension? | CRISPR point-mutation knock-in in endothelial cells |
| Does a tagged protein localize to extending tubes? | CRISPR knock-in of fluorescent tag |
| Does overexpression of a gene enhance tube extension? | CRISPR overexpression or cDNA overexpression in endothelial cells |
| Does matrix stiffness modulate tube extension? | In vitro endothelial progenitor tubulogenesis assay |
| How do endothelial cells rearrange during tube fusion? | Zebrafish live imaging of blood vessel fusion |
How to Study the endothelial tube lumen extension Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Zebrafish live imaging | Endothelial cell rearrangement and tube elongation | Studying tube extension and fusion in vivo |
| In vitro tubulogenesis assay | Tube formation and extension in cultured endothelial cells | Testing VEGF and matrix effects |
| Gene knockdown/knockout | Requirement of a gene for tube extension | Functional validation in zebrafish |
| Overexpression | Sufficiency of a gene to promote tube extension | Gain-of-function studies |
| Junctional protein imaging | Junctional arrangement and integrity | Assessing Egfl7 and Cdh5 function |
| Matrix stiffness assays | Mechanotransduction effects on tubulogenesis | Studying substrate mechanics |
| Computational modeling | Physical forces and transport in vessel walls | Complementary biomechanical analysis |
| Vascular phenotyping | Vascular network morphology and perfusion | Assessing developmental vascular defects |
Zebrafish vascular imaging
Zebrafish embryos are a powerful model for studying endothelial tube lumen extension because their vasculature is optically accessible and genetically tractable. Live imaging of endothelial cells during vasculogenesis and blood vessel fusion reveals cellular behaviors such as rearrangement, junctional remodeling, and tube elongation.
In vitro tubulogenesis assays
Endothelial progenitor cells and endothelial cells can be cultured on matrices of defined stiffness to study tube formation and extension in vitro. These assays measure the effects of VEGF, substrate mechanics, and gene knockdown or overexpression on tubulogenesis.
Genetic loss- and gain-of-function
Knockdown or knockout of candidate genes such as egfl7, scube1, and scube2 in zebrafish, followed by vascular phenotyping, can determine whether a gene is required for endothelial tube extension. Overexpression studies can test sufficiency.
Computational and biomechanical analysis
Computational modeling of blood-wall transport and mechanical forces can complement experimental studies of vessel wall biology, although direct application to endothelial tube lumen extension requires careful interpretation.
How CRISPR Can Be Used to Study GO:0097498 endothelial tube lumen extension
Knockout
CRISPR knockout of candidate genes such as EGFL7, SCUBE1, or SCUBE2 in zebrafish or endothelial cell lines can test whether the gene is required for endothelial tube lumen extension. Knockout phenotypes can be assessed by vascular imaging or in vitro tubulogenesis assays.
Point Mutation
CRISPR point-mutation knock-in can introduce specific amino acid substitutions to dissect domain functions in proteins such as Egfl7 or Vegfa signaling components, allowing structure-function analysis of tube extension.
Knock-in
CRISPR knock-in of fluorescent tags or reporter cassettes into endogenous loci enables live imaging of protein localization and dynamics during endothelial tube extension.
Overexpression
CRISPR-mediated overexpression or cDNA overexpression of pro-angiogenic factors such as VEGFA can test sufficiency for enhancing endothelial tube extension in vitro and in vivo.
How EDITGENE Supports endothelial tube lumen extension Research
Researchers studying endothelial tube lumen extension-related genes often need to determine whether a candidate gene is causally involved in tube elongation, junctional remodeling, or matrix-dependent tubulogenesis. EDITGENE provides CRISPR-based cell model services to support these functional studies.
Contact EDITGENE today to design your custom CRISPR model for endothelial tube lumen extension research.
Frequently Asked Questions About endothelial tube lumen extension
What is GO:0097498 endothelial tube lumen extension?
GO:0097498 is a biological process defined as any endothelial tube morphogenesis process by which the tube is increased in length.
What genes are involved in endothelial tube lumen extension?
Genes implicated include VEGFA, SCUBE1, SCUBE2, EGFL7, CDH5, PECAM1, KDR, and ITGB1, among others.
How is endothelial tube lumen extension different from angiogenesis?
Angiogenesis is the broader process of new blood vessel formation, while endothelial tube lumen extension specifically refers to the elongation of an existing endothelial tube.
What models are used to study endothelial tube lumen extension?
Zebrafish embryos, in vitro endothelial progenitor tubulogenesis assays, and endothelial cell cultures are commonly used.
What is the role of VEGF in endothelial tube lumen extension?
VEGF-A signaling, enhanced by Scube1 and Scube2, promotes endothelial tube formation and extension during embryonic vascularization.
What is the role of Egfl7 in tube extension?
Egfl7 knockdown causes defects in the extension and junctional arrangements of endothelial cells during zebrafish vasculogenesis.
How does matrix stiffness affect endothelial tube extension?
Substrate mechanics regulate in vitro tubulogenesis of endothelial progenitor cells, with VEGF and matrix stiffness acting together.
Can CRISPR be used to study endothelial tube lumen extension?
Yes, CRISPR knockout, point-mutation, knock-in, and overexpression models can test candidate gene function in tube extension.
What diseases are linked to defective endothelial tube extension?
Vascular malformations, tumor angiogenesis, retinopathies, and impaired wound healing have been associated with defects in tube extension.
How do endothelial cells rearrange during tube extension?
Endothelial cells undergo junctional remodeling and coordinated migration, as shown in zebrafish blood vessel fusion studies.
Conclusion
GO:0097498 endothelial tube lumen extension is a specific biological process describing the elongation of endothelial tubes during vascular morphogenesis. It is driven by VEGF signaling, junctional remodeling, and matrix-dependent mechanotransduction, with key roles for genes such as SCUBE1, SCUBE2, EGFL7, and VEGFA. Defects in this process contribute to vascular malformations, pathological angiogenesis, and impaired tissue revascularization. CRISPR-based models provide powerful tools to dissect the causal roles of candidate genes in endothelial tube lumen extension.
References
- 2. Tsao KC et al.. 2022. Zebrafish Scube1 and Scube2 cooperate in promoting Vegfa signalling during embryonic vascularization.. Cardiovasc Res 118(4):1074-1087 PMID: 33788916
- 5. Stangeby DK et al.. 2002. Computational analysis of coupled blood-wall arterial LDL transport.. J Biomech Eng 124(1):1-8 PMID: 11871594
- 6. De Mazière A et al.. 2008. Egfl7 knockdown causes defects in the extension and junctional arrangements of endothelial cells during zebrafish vasculogenesis.. Dev Dyn 237(3):580-91 PMID: 18224713
- 7. Herwig L et al.. 2011. Distinct cellular mechanisms of blood vessel fusion in the zebrafish embryo.. Curr Biol 21(22):1942-8 PMID: 22079115
- 8. Hanjaya-Putra D et al.. 2010. Vascular endothelial growth factor and substrate mechanics regulate in vitro tubulogenesis of endothelial progenitor cells.. J Cell Mol Med 14(10):2436-47 PMID: 19968735
