GO:0001658 branching involved in ureteric bud morphogenesis: Developmental Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0001658 describes the process by which the ureteric bud, an epithelial tube growing from the metanephric duct, elongates and branches to form the ureter and kidney collecting tubules.
• Branching morphogenesis of the ureteric bud is a reciprocal signaling process between the ureteric bud epithelium and the surrounding metanephric mesenchyme.
• Key molecular regulators include RET/GFRA1 signaling, sulfated proteoglycans, and mesenchymal factors such as pleiotrophin.
• Disruption of ureteric bud branching leads to congenital kidney defects, including renal hypoplasia and nephron deficit.
• Branching morphogenesis proceeds independently of nephron formation or integration, as shown by genetic studies.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) enable precise interrogation of genes controlling ureteric bud branching.
Description
The development of the mammalian kidney depends on a highly coordinated process called branching morphogenesis of the ureteric bud, formally annotated as GO:0001658 (branching involved in ureteric bud morphogenesis). The ureteric bud is an epithelial tube that emerges from the metanephric duct and invades the metanephric mesenchyme; through iterative elongation and branching, it generates the ureter and the collecting duct system of the kidney. This process is essential for establishing the architectural blueprint of the kidney, and its disruption results in severe congenital anomalies such as renal hypoplasia and nephron deficit. Understanding the molecular and cellular mechanisms of ureteric bud branching is therefore central to developmental biology and nephrology research. At the molecular level, branching morphogenesis is driven by reciprocal inductive signals between the ureteric bud epithelium and the surrounding metanephric mesenchyme. The RET receptor tyrosine kinase and its co-receptor GFRA1, activated by GDNF from the mesenchyme, are critical for ureteric bud outgrowth and branching. Additionally, sulfated proteoglycans in the extracellular matrix modulate branching morphogenesis by regulating growth factor availability and signaling. Mesenchymal factors such as pleiotrophin have also been identified as key regulators of ureteric bud branching. These findings highlight a complex interplay of signaling pathways, extracellular matrix components, and transcriptional regulators that together orchestrate the branching program. Researchers studying GO:0001658 aim to dissect the genetic and cellular basis of kidney development and to model congenital kidney diseases. Recent work has shown that branching morphogenesis proceeds independently of nephron formation or integration, indicating that the branching program is genetically separable from other aspects of kidney development. This makes ureteric bud branching an attractive system for studying epithelial tube morphogenesis and for identifying therapeutic targets for kidney regeneration.
branching involved in ureteric bud morphogenesis At A Glance
| GO ID | GO:0001658 |
|---|---|
| GO term | branching involved in ureteric bud morphogenesis |
| Ontology | biological_process |
| Synonym | ureteric bud branching |
| Major function | Generation and organization of the branched structure of the ureteric bud, which forms the ureter and collecting duct system |
| Key signaling pathway | RET/GFRA1 signaling activated by GDNF from the metanephric mesenchyme |
| Extracellular matrix components | Sulfated proteoglycans regulate branching morphogenesis |
| Mesenchymal factors | Pleiotrophin acts as a mesenchymal factor involved in ureteric bud branching |
| Disease relevance | Disruption leads to nephron deficit and renal hypoplasia |
What Is GO:0001658?
GO:0001658, branching involved in ureteric bud morphogenesis, is the biological process in which the branching structure of the ureteric bud is generated and organized. The ureteric bud is an epithelial tube that grows out from the metanephric duct; it elongates and branches to give rise to the ureter and kidney collecting tubules.
Why Is branching involved in ureteric bud morphogenesis Important in Cell Biology?
Branching involved in ureteric bud morphogenesis is fundamental to kidney development because it establishes the collecting duct system and determines the final number of nephrons. Defects in this process cause congenital kidney malformations, including renal hypoplasia and nephron deficit, which predispose individuals to hypertension and chronic kidney disease later in life. Understanding the molecular regulation of ureteric bud branching also provides insights into epithelial tube morphogenesis and offers potential targets for regenerative medicine.
• Establishes the ureter and collecting duct system of the kidney.
• Determines nephron endowment; defects lead to nephron deficit.
• Involves reciprocal signaling between ureteric bud epithelium and metanephric mesenchyme.
• Regulated by RET/GFRA1 signaling, sulfated proteoglycans, and pleiotrophin.
• Proceeds independently of nephron formation or integration.
• Provides a model for studying epithelial branching morphogenesis.
• Disruption is linked to congenital anomalies of the kidney and urinary tract.
• Offers potential targets for kidney regeneration and tissue engineering.
• Key genes are conserved between mouse and human, facilitating translational research.
• CRISPR screening can identify novel regulators of ureteric bud branching.
What Happens During branching involved in ureteric bud morphogenesis?
Initiation and Outgrowth of the Ureteric Bud
In simple terms: The ureteric bud starts as a small bump on the metanephric duct and grows outward toward the kidney mesenchyme.
The ureteric bud emerges from the metanephric duct (also called the Wolffian duct) as an epithelial outgrowth that invades the surrounding metanephric mesenchyme. This initial outgrowth is induced by signals from the mesenchyme, including GDNF, which activates RET/GFRA1 signaling in the ureteric bud epithelium. The bud elongates and begins to branch, forming the first bifurcation that will give rise to the renal pelvis and major calyces.
Iterative Branching and Elongation
In simple terms: The bud keeps splitting into new branches, like a tree growing new limbs, to create the collecting duct network.
Following initiation, the ureteric bud undergoes iterative rounds of branching and elongation. Each branch tip induces the surrounding mesenchyme to form nephrons, while the branch itself will become a collecting duct. This process is regulated by a combination of growth factors, extracellular matrix components, and transcription factors. Sulfated proteoglycans in the extracellular matrix modulate the availability and activity of growth factors such as GDNF and FGF, thereby influencing branching patterns. Mesenchymal factor pleiotrophin also promotes ureteric bud branching.
Reciprocal Signaling with the Metanephric Mesenchyme
In simple terms: The growing bud and the surrounding kidney tissue talk to each other to coordinate their development.
Branching morphogenesis relies on reciprocal inductive signaling between the ureteric bud epithelium and the metanephric mesenchyme. The mesenchyme secretes GDNF, which binds to RET/GFRA1 on the ureteric bud, promoting growth and branching. In turn, the ureteric bud secretes factors such as FGF2 and BMP7 that signal back to the mesenchyme to promote nephron formation. This crosstalk ensures that branching and nephron formation are spatially and temporally coordinated, although branching can proceed independently of nephron formation.
Regulation by Transcriptional and Epigenetic Factors
In simple terms: Special proteins inside the cell control which genes are turned on or off to guide branching.
Transcriptional regulators and epigenetic modifiers control the expression of genes involved in ureteric bud branching. For example, ASH2L, a component of the COMPASS-like histone methyltransferase complex, regulates RET/GFRA1 signaling activity and is required for ureteric bud morphogenesis in mice. Other transcription factors such as PAX2, EYA1, and SIX1 are also critical for ureteric bud outgrowth and branching. These factors coordinate the expression of signaling molecules and structural components needed for branching.
Termination and Differentiation into Collecting Ducts
In simple terms: Once enough branches are made, they stop growing and mature into the kidney's collecting tubes.
After a defined number of branching events, the ureteric bud derivatives differentiate into the collecting duct system, including the ureter, renal pelvis, calyces, and collecting tubules. This differentiation involves changes in gene expression that promote epithelial maturation and functional specialization. The final architecture of the collecting system is essential for urine concentration and transport.
Key Genes Involved in GO:0001658 branching involved in ureteric bud morphogenesis
The following genes and proteins are key regulators of branching involved in ureteric bud morphogenesis, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RET | Receptor tyrosine kinase activated by GDNF; essential for ureteric bud outgrowth and branching | Mutations cause renal agenesis or hypoplasia; target for CRISPR knockout studies |
| GFRA1 | Co-receptor for GDNF; forms complex with RET to transduce signals | Modulates RET signaling; knockout leads to severe kidney defects |
| GDNF | Mesenchymal-derived ligand that activates RET/GFRA1 | Overexpression or knockout alters branching patterns |
| ASH2L | Epigenetic regulator; controls RET/GFRA1 signaling activity | Knockout in mice impairs ureteric bud morphogenesis |
| Pleiotrophin (PTN) | Mesenchymal factor that promotes ureteric bud branching | Exogenous addition or knockdown affects branching in culture |
| Sulfated proteoglycans (e.g., syndecans, glypicans) | Extracellular matrix components that modulate growth factor signaling | Enzymatic removal or genetic modification alters branching |
| PAX2 | Transcription factor required for ureteric bud outgrowth | Mutations linked to renal coloboma syndrome |
| EYA1 | Transcriptional co-activator essential for ureteric bud initiation | Mutations cause branchio-oto-renal syndrome |
| SIX1 | Homeodomain transcription factor cooperating with EYA1 | Mutations associated with branchio-oto-renal syndrome |
| BMP7 | Signaling molecule that promotes ureteric bud branching and nephron formation | Knockout mice show severe kidney defects |
| FGF2 | Growth factor that modulates ureteric bud branching | Exogenous FGF2 affects branching in organ culture |
| WNT9B | Secreted signal from ureteric bud that induces nephron formation | Conditional knockout affects branching and nephrogenesis |
| WNT11 | Secreted signal involved in ureteric bud branching | Knockout leads to reduced branching |
| GATA3 | Transcription factor required for ureteric bud elongation and branching | Haploinsufficiency causes renal defects |
| LHX1 | Lim-homeodomain transcription factor essential for ureteric bud outgrowth | Knockout mice lack ureteric bud |
| EMX2 | Transcription factor expressed in ureteric bud epithelium | Knockout affects branching and collecting duct patterning |
| SALL1 | Transcription factor regulating ureteric bud branching | Mutations cause Townes-Brocks syndrome with renal anomalies |
| HNF1B | Transcription factor required for ureteric bud branching and collecting duct differentiation | Mutations cause renal cysts and diabetes syndrome |
How Is branching involved in ureteric bud morphogenesis Regulated?
Branching involved in ureteric bud morphogenesis is regulated by a complex network of signaling pathways, transcription factors, and epigenetic modifiers. The RET/GFRA1 signaling pathway, activated by GDNF from the metanephric mesenchyme, is a central regulator of ureteric bud outgrowth and branching. Sulfated proteoglycans in the extracellular matrix modulate the distribution and activity of growth factors such as GDNF and FGF, thereby influencing branching patterns. Mesenchymal factors like pleiotrophin also promote branching. Epigenetic regulation by the COMPASS-like complex component ASH2L controls RET/GFRA1 signaling activity, highlighting the role of chromatin modifications in this process. Additionally, transcription factors such as PAX2, EYA1, SIX1, GATA3, and LHX1 are essential for proper ureteric bud morphogenesis. The process can proceed independently of nephron formation, indicating that branching and nephrogenesis are genetically separable.
branching involved in ureteric bud morphogenesis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RET | Renal agenesis, Hirschsprung disease, CAKUT | CRISPR knockout in mouse ureteric bud cells; point mutation to mimic patient variants |
| GDNF | Renal hypoplasia, CAKUT | Overexpression or knockout in metanephric mesenchyme; organ culture |
| PAX2 | Renal coloboma syndrome, CAKUT | Knockout mouse models; patient-derived iPSCs |
| HNF1B | Renal cysts and diabetes syndrome, CAKUT | Conditional knockout in ureteric bud; knock-in of patient mutations |
| ASH2L | Ureteric bud morphogenesis defects in mice | CRISPR knockout in mouse embryos; overexpression studies |
Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)
Disruption of branching involved in ureteric bud morphogenesis leads to congenital anomalies of the kidney and urinary tract, including renal hypoplasia, renal agenesis, and nephron deficit. Mutations in genes such as RET, GDNF, PAX2, EYA1, SIX1, and HNF1B are associated with CAKUT in humans. These conditions often present with reduced nephron number, which predisposes to hypertension and chronic kidney disease later in life.
Renal Hypoplasia and Nephron Deficit
Experimental models have shown that early defects in ureteric bud branching morphogenesis lead to a reduced number of nephrons, a condition known as nephron deficit. This deficit is a risk factor for the development of hypertension and progressive renal failure. Studies in animal models have identified critical roles for RET/GFRA1 signaling and epigenetic regulators like ASH2L in maintaining adequate branching and nephron endowment.
Kidney Cancer and Wilms Tumor
Aberrant activation of developmental pathways involved in ureteric bud branching, such as RET and WNT signaling, has been implicated in pediatric kidney tumors like Wilms tumor. Although direct evidence linking GO:0001658 to Wilms tumor is limited, the genes and pathways that regulate branching are frequently dysregulated in renal malignancies. Further research is needed to establish causal relationships.
From branching involved in ureteric bud morphogenesis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate ureteric bud branching? | CRISPR knockout in mouse embryonic kidney explants or cell lines |
| How does a patient-specific mutation affect branching? | Point mutation knock-in in mouse or human iPSCs |
| What is the role of a specific protein domain in branching? | Knock-in of tagged or mutant protein |
| Can overexpression of gene Y rescue branching defects? | Overexpression via transgenesis or viral vectors |
| What are the downstream targets of RET/GFRA1 signaling? | RNA-seq and ChIP-seq in knockout vs. wild-type ureteric bud cells |
| How do epigenetic regulators control branching? | Conditional knockout of epigenetic modifiers (e.g., ASH2L) in mouse ureteric bud |
How to Study the branching involved in ureteric bud morphogenesis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Organ culture | Branching morphogenesis in real time | Testing gene function or drug effects |
| RNA-seq | Transcriptional changes during branching | Identifying novel regulators |
| CRISPR screening | Genes required for branching | High-throughput discovery |
| Immunofluorescence | Protein localization and tissue architecture | Validating gene expression patterns |
| Live imaging | Dynamic branching events | Quantifying branch number and length |
| In situ hybridization | mRNA localization | Mapping gene expression in developing kidney |
| Western blot | Protein expression and signaling activity | Assessing RET/GFRA1 pathway activation |
| ChIP-seq | Chromatin binding of transcription factors | Identifying direct targets of regulators |
Organ Culture and Live Imaging
Embryonic kidney organ culture combined with live imaging allows real-time visualization of ureteric bud branching. This method is used to assess the effects of genetic manipulations or pharmacological treatments on branching dynamics.
RNA Sequencing and Transcriptomics
RNA-seq of ureteric bud cells or whole embryonic kidneys can identify genes differentially expressed during branching morphogenesis. This approach helps uncover novel regulators and downstream targets of key signaling pathways.
CRISPR Screening
Genome-wide CRISPR knockout or activation screens in ureteric bud cell lines or organoids can systematically identify genes that promote or inhibit branching. Such screens have the potential to reveal new therapeutic targets.
Immunofluorescence and Confocal Microscopy
Immunofluorescence staining for markers of ureteric bud epithelium (e.g., cytokeratin, RET) and basement membrane components allows visualization of branching structures and protein localization in tissue sections.
How CRISPR Can Be Used to Study GO:0001658 branching involved in ureteric bud morphogenesis
Knockout
CRISPR knockout of candidate genes in mouse embryonic kidney explants or ureteric bud cell lines can determine whether a gene is required for branching morphogenesis. For example, knockout of ASH2L in mice impairs ureteric bud morphogenesis through dysregulation of RET/GFRA1 signaling.
Point Mutation
Introducing patient-specific point mutations into genes such as RET or HNF1B using CRISPR base editing or homology-directed repair allows researchers to study how these variants affect ureteric bud branching and contribute to CAKUT.
Knock-in
Knock-in of fluorescent tags or reporter genes (e.g., GFP) into endogenous loci enables live imaging of ureteric bud branching and tracking of specific cell populations. This approach can also be used to express mutant proteins under native regulatory elements.
Overexpression
CRISPR activation (CRISPRa) or transgenic overexpression can be used to test whether increasing the level of a gene product enhances or disrupts ureteric bud branching. For instance, overexpression of pleiotrophin promotes branching in cultured kidneys.
How EDITGENE Supports branching involved in ureteric bud morphogenesis Research
Researchers studying branching involved in ureteric bud morphogenesis-related genes often need to determine whether a candidate gene is causally involved in this process. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic manipulation and functional validation in relevant cell models and organoids.
Contact EDITGENE today to design your custom CRISPR model for branching involved in ureteric bud morphogenesis research.
Frequently Asked Questions About branching involved in ureteric bud morphogenesis
What is GO:0001658?
GO:0001658 is the Gene Ontology term for branching involved in ureteric bud morphogenesis, the process by which the ureteric bud forms a branched structure that gives rise to the ureter and kidney collecting tubules.
What genes are involved in branching involved in ureteric bud morphogenesis?
Key genes include RET, GFRA1, GDNF, ASH2L, pleiotrophin, PAX2, EYA1, SIX1, and HNF1B, among others.
Why is ureteric bud branching important for kidney development?
It establishes the collecting duct system and determines nephron number; defects lead to renal hypoplasia and nephron deficit.
What signaling pathways regulate ureteric bud branching?
The RET/GFRA1 pathway activated by GDNF is central, along with modulation by sulfated proteoglycans and mesenchymal factors like pleiotrophin.
How can CRISPR be used to study ureteric bud branching?
CRISPR knockout, point mutation, knock-in, and overexpression models allow precise manipulation of candidate genes in cell lines and organoids to assess their roles in branching.
What diseases are associated with defects in ureteric bud branching?
Congenital anomalies of the kidney and urinary tract (CAKUT), including renal hypoplasia and nephron deficit, are linked to disrupted branching.
Is branching morphogenesis independent of nephron formation?
Yes, studies have shown that branching morphogenesis in the developing kidney is not impacted by nephron formation or integration.
What model systems are used to study ureteric bud branching?
Mouse embryonic kidney organ culture, genetically modified mice, and human iPSC-derived kidney organoids are commonly used.
What is the role of ASH2L in ureteric bud morphogenesis?
ASH2L, a component of the COMPASS-like complex, controls ureteric bud morphogenesis by regulating RET/GFRA1 signaling activity in mice.
How does pleiotrophin affect ureteric bud branching?
Pleiotrophin is a mesenchymal factor that promotes ureteric bud branching in the developing kidney.
Conclusion
Branching involved in ureteric bud morphogenesis (GO:0001658) is a fundamental developmental process that builds the kidney collecting system and determines nephron endowment. Its regulation involves a complex interplay of signaling pathways, extracellular matrix components, and transcriptional/epigenetic regulators. Disruption of this process leads to congenital kidney anomalies, making it a critical area of research. CRISPR-based tools now enable precise genetic interrogation of this process, offering new opportunities for understanding kidney development and disease.
References
- 1. Sariola H. 2002. Nephron induction.. Nephrol Dial Transplant 17 Suppl 9:88-90 PMID: 12386301
- 2. Steer DL et al.. 2004. Regulation of ureteric bud branching morphogenesis by sulfated proteoglycans in the developing kidney.. Dev Biol 272(2):310-27 PMID: 15282150
- 3. Gilbert T et al.. 1996. Early defect in branching morphogenesis of the ureteric bud in induced nephron deficit.. Kidney Int 50(3):783-95 PMID: 8872952
- 4. al-Awqati Q et al.. 1998. Architectural patterns in branching morphogenesis in the kidney.. Kidney Int 54(6):1832-42 PMID: 9853247
- 5. Zhao Z et al.. 2023. ASH2L Controls Ureteric Bud Morphogenesis through the Regulation of RET/GFRA1 Signaling Activity in a Mouse Model.. J Am Soc Nephrol 34(6):988-1002 PMID: 36758123
- 6. Short KM et al.. 2018. Branching morphogenesis in the developing kidney is not impacted by nephron formation or integration.. Elife 7 PMID: 30063208
- 7. Davies JA et al.. 1999. Collecting duct morphogenesis.. Pediatr Nephrol 13(6):535-41 PMID: 10452285
- 8. Sakurai H et al.. 2001. Identification of pleiotrophin as a mesenchymal factor involved in ureteric bud branching morphogenesis.. Development 128(17):3283-93 PMID: 11546745
