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RNF43
ring finger protein 43
The RNF43 gene provides instructions for a protein that is involved in regulating cell signalling pathways, particularly the Wnt signalling pathway, and has implications for various cancers. The RNF43 gene encodes the ring finger protein 43, which functions as an E3 ubiquitin ligase.
RNF43 is located on the long (q) arm of chromosome 17, at band 17q22. Arm ratio per GRCh38 - banding schematic.
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Overview
The RNF43 gene, or ring finger protein 43, is an important component of cellular regulatory mechanisms. It is primarily known for its role in modifying Wnt signalling, a fundamental pathway crucial for embryonic development and tissue homeostasis in adults. By acting as a negative regulator, RNF43 helps to control the intensity and duration of Wnt signals, ensuring proper cell behaviour.
Variations within the RNF43 gene have been linked to an increased susceptibility to various types of cancer, particularly those affecting the gastrointestinal tract. Understanding the function of RNF43 provides insights into the molecular basis of certain inherited cancer syndromes and contributes to strategies for early detection and potential therapeutic interventions.
What the gene does
The RNF43 gene encodes a protein that acts as an E3 ubiquitin ligase, a type of enzyme central to the ubiquitin-proteasome system. This system is responsible for labelling unwanted or damaged proteins for degradation. In the context of RNF43, its ligase activity is crucial for regulating the Wnt signalling pathway.
Specifically, RNF43 targets Frizzled receptors, which are key components that initiate Wnt signalling at the cell surface. By modifying these receptors through ubiquitination, RNF43 promotes their degradation, thereby reducing the cellular response to Wnt signals. This negative regulatory role is vital because uncontrolled Wnt signalling can lead to excessive cell proliferation and, consequently, tumour development. The protein's function as a ubiquitin ligase allows it to fine-tune the signalling process, maintaining cellular balance and preventing aberrant growth.
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Chromosome location
The RNF43 gene is situated on chromosome 17 at position q22, meaning it is found on the long arm of chromosome 17. The precise location, 17q22, indicates its specific band on the chromosome, contributing to the overall organisation of the human genome. This gene spans a region of DNA that provides the genetic blueprint for a protein composed of 783 amino acids.
Protein structure
The RNF43 protein, consisting of 783 amino acids, exhibits a defined domain architecture essential for its function. A key feature is the RING-type atypical (Zinc finger) domain, located from amino acid positions 272 to 313. This domain is characteristic of E3 ubiquitin ligases and is crucial for interacting with E2 ubiquitin-conjugating enzymes, facilitating the transfer of ubiquitin to target proteins. Additionally, the protein contains several Disordered (Region) segments. These include regions from amino acids 363-406, 421-477, 514-673, and 731-760. Such disordered regions typically lack a fixed three-dimensional structure and can be flexible, often playing roles in molecular recognition, signalling, and protein-protein interactions. This structural composition allows RNF43 to effectively mediate its regulatory roles within the Wnt signalling pathway.
Key variants
Variants within the RNF43 gene can alter the protein's structure or function, potentially impacting its ability to regulate cellular processes. These genetic changes can range from single nucleotide substitutions to larger deletions or duplications. Pathogenic variants can disrupt the important role RNF43 plays in Wnt signalling. Research indicates that certain variants may either lead to a loss of RNF43's negative regulatory function or result in a protein that is less effective at targeting and degrading Wnt receptors. The inheritance pattern for conditions associated with RNF43 is autosomal dominant, meaning a single copy of a pathogenic variant is sufficient to increase disease susceptibility.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1009C>T | p.Arg337Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Sessile serrated polyposis cancer syndrome |
c.1976del | p.Gly659fs | Pathogenic/Likely pathogenic | ★★☆☆ | Sessile serrated polyposis cancer syndrome |
c.394C>T | p.Arg132Ter | Pathogenic | ★★☆☆ | Sessile serrated polyposis cancer syndrome |
c.1016_1017del | p.Leu339fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.1131_1134del | p.Ser378fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.1207_1210dup | p.Arg404fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.1252_1255dup | p.Ser419fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.127G>T | p.Glu43Ter | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.1308_1449del | p.Arg437fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
c.1383del | p.Pro462fs | Pathogenic | ★☆☆☆ | Sessile serrated polyposis cancer syndrome |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Variants in the RNF43 gene are primarily associated with an increased predisposition to certain types of cancer. The role of RNF43 in negatively regulating the Wnt signalling pathway means that perturbations can lead to uncontrolled cell growth characteristic of tumour formation. Genetic alterations in RNF43 have been identified in various cancers, particularly those linked to the gastrointestinal tract, and are often considered in the context of hereditary cancer predisposition syndromes. This gene's involvement highlights its significance in cancer biology.
No disease links recorded for this gene in our reference set.
Inheritance pattern
Conditions caused by pathogenic RNF43 variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
In the UK, the RNF43 gene is integrated into clinical genomic testing pathways, reflecting its recognised role in inherited conditions. It is included in the 'Inherited polyposis and early onset colorectal cancer - germline testing' panel (R211) within PanelApp, the NHS Genomic Medicine Service's knowledge base. This inclusion means that RNF43 is routinely analysed when individuals are assessed for a predisposition to inherited colorectal cancer and related polyposis syndromes, facilitating genetic diagnosis and risk management for affected families.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Maintaining a healthy lifestyle is a general recommendation for overall wellbeing, and research suggests it may play a role in managing general health risks. For example, a balanced diet rich in fruits, vegetables, and whole grains, coupled with regular physical activity, is commonly associated with a reduced risk of various conditions. Limiting consumption of processed foods, red and processed meats, and sugary drinks may also contribute to better health outcomes in the general population. However, these are general population observations and do not specifically mitigate the genetic risk posed by RNF43 variants.
Supplement considerations
There is no conclusive scientific evidence to suggest that specific supplements can prevent or treat conditions associated with RNF43 gene variants. While some supplements are marketed for general health benefits, individuals should exercise caution and consult with a healthcare professional before taking any new supplements, particularly if they have a known genetic predisposition. A healthcare provider can offer personalised advice based on individual health needs and potential interactions with other medications.
Frequently asked questions
What is the RNF43 gene?
The RNF43 gene provides instructions for making the ring finger protein 43, which acts as an E3 ubiquitin ligase. This protein is a key negative regulator of the Wnt signalling pathway, influencing cell growth and development.
How does RNF43 relate to cancer?
RNF43 plays a critical role in controlling the Wnt signalling pathway, which when overactive, can lead to uncontrolled cell proliferation. Pathogenic variants in RNF43 can disrupt this regulatory function, increasing susceptibility to certain cancers, particularly those of the gastrointestinal tract.
What is the inheritance pattern for RNF43 variants?
Conditions associated with RNF43 variants typically follow an autosomal dominant inheritance pattern. This means that an individual only needs to inherit one copy of a pathogenic RNF43 variant to have an increased risk of developing the associated condition.
Is RNF43 testing available in the UK?
Yes, RNF43 is included in germline testing panels within the NHS Genomic Medicine Service, specifically for 'Inherited polyposis and early onset colorectal cancer'. This ensures its analysis for relevant clinical indications.
What is the Wnt signalling pathway?
The Wnt signalling pathway is a fundamental cell communication system involved in processes like embryonic development, tissue regeneration, and maintaining cell homeostasis. RNF43 helps to negatively regulate this pathway to prevent excessive cell growth.