Recombinant Human Uncharacterized protein C3orf18 (C3orf18)

What is C3orf18 and what is known about its genomic context?

C3orf18 (chromosome 3 open reading frame 18) is a protein-coding gene located on chromosome 3p21.31. The gene consists of 8 exons spanning from position 50,558,025 to 50,574,700 on the complement strand (NC_000003.12) . It is also known as G20 and encodes what is currently classified as an "uncharacterized protein." According to the Alliance of Genome Resources (March 2025 update), C3orf18 is predicted to be located in the membrane .

The gene's classification as an "open reading frame" indicates it was initially identified based solely on the presence of an open reading frame. According to human gene nomenclature guidelines, such designations are applied when "genes of unknown function fit none of the [standard naming] criteria" and are "designated by the chromosome of origin, the letters 'orf' for open reading frame, and a number in a series" .

What is currently understood about C3orf18 protein structure and characteristics?

While C3orf18 remains largely uncharacterized, some preliminary data suggests it may have important cellular functions. The protein has been implicated in various cellular processes including cell growth, differentiation, and apoptosis . Recombinant forms of the protein have been produced for research purposes, with one variant described as "Recombinant Full Length Human Uncharacterized Protein C3Orf18 Protein, His-Tagged" produced in E. coli .

What expression patterns has C3orf18 shown in human tissues?

Expression data for C3orf18 is available through resources like The Human Protein Atlas, though the specific expression patterns were not detailed in the provided search results . According to other research sources, C3orf18 has been studied in various tissue and cell contexts including:

• Brain tissue in the context of PTSD and cardiovascular disease research

• Triple-negative breast cancer cell lines

• Multiple tissue types in genomic studies

From one of the commercial antibody descriptions, it's suggested that C3orf18 may be involved in multiple biological processes with potential implications in diseases such as cancer, neurological disorders, and metabolic conditions .

What experimental tools are available for studying C3orf18?

Several research tools have been developed to study C3orf18:

Antibodies:

• Polyclonal antibodies such as Anti-C3orf18 Antibody (PACO42546) validated for Western blot (WB), immunohistochemistry (IHC), and immunofluorescence (IF) applications

Recombinant Proteins:

• Recombinant Human C3orf18 293 Cell Lysate (HEK293-derived)

• Recombinant Full Length Human Uncharacterized Protein C3orf18 Protein with His-Tag (E. coli-derived)

Genetic Tools:

• C3orf18 CRISPR/Cas9 KO Plasmid for gene knockout studies

• C3orf18 CRISPR Activation Plasmid for gene upregulation using deactivated Cas9 (dCas9) with VP64 activation domain

How can researchers effectively detect and analyze C3orf18 in experimental samples?

For detection and analysis of C3orf18, researchers can employ several methodological approaches:

Protein Detection:

• Western blot using validated antibodies (recommended dilution 1:500-1:2000)

• Immunohistochemistry for tissue samples (recommended dilution 1:20-1:200)

• Immunofluorescence for cellular localization studies (recommended dilution 1:50-1:200)

• ELISA for quantitative analysis (recommended dilution 1:2000-1:10000)

Genetic Expression Analysis:

• RT-PCR or qPCR for mRNA expression

• RNA-seq for transcriptomic profiling

• Single-cell expression analysis, as demonstrated in studies using single-cell Mendelian randomisation

When working with antibodies against C3orf18, researchers should note that the commercially available antibody (PACO42546) was developed using a recombinant fragment of human C3orf18 (amino acids 83-162) as the immunogen, and shows reactivity with human and mouse samples .

What genetic manipulation approaches can be used to study C3orf18 function?

Several genetic manipulation approaches are available for studying C3orf18 function:

CRISPR/Cas9 Knockout:

• C3orf18 CRISPR/Cas9 KO Plasmid consists of a pool of 3 plasmids, each encoding Cas9 nuclease and a target-specific 20 nt guide RNA (gRNA) designed to create a double-strand break (DSB) in a 5' constitutive exon within the C3orf18 gene

• This system enables complete gene knockout for loss-of-function studies

CRISPR Activation (CRISPRa):

• C3orf18 CRISPR Activation Plasmid utilizes a D10A and N863A deactivated Cas9 (dCas9) nuclease fused to a VP64 activation domain, along with sgRNA (MS2) that binds the MS2-P65-HSF1 fusion protein

• This synergistic activation mediator (SAM) transcription activation system provides robust upregulation of endogenous gene expression for gain-of-function studies

RNA Interference (RNAi):

• While not specifically mentioned for C3orf18 in the search results, siRNA or shRNA approaches can be employed for transient or stable knockdown of C3orf18 expression

These genetic manipulation tools allow researchers to investigate the functional consequences of C3orf18 overexpression, knockdown, or knockout in relevant cellular models.

What potential cellular functions has C3orf18 been implicated in?

While C3orf18 remains largely uncharacterized, several phenotypic associations provide clues to its potential functions:

• DNA Repair Mechanisms: C3orf18 has been associated with "decreased homologous recombination repair frequency" and "decreased ionizing radiation sensitivity"

• Signaling Pathways: It has been linked to "upregulation of Wnt pathway"

• Viral Interactions: Shows association with "increased vaccinia virus (VACV) infection"

• Cellular Transport: Demonstrates "mildly decreased CFP-tsO45G cell surface transport"

• Cognitive Function: Has been associated with cognitive function measurement

Additionally, the antibody product description suggests C3orf18 may play roles in "cell growth, differentiation, and apoptosis" , though these functional roles require further experimental validation.

What disease associations have been found for C3orf18?

C3orf18 has been studied in the context of several disease states:

• Stroke: Mentioned in research integrating multi-omics data to identify novel disease genes associated with different types of stroke (ischemic stroke, large artery stroke, cardioembolic stroke, small vessel stroke)

• Cancer: Studied in the context of triple-negative breast cancer cell lines in chromatin accessibility research

• Cognitive and Psychiatric Disorders: Associated with cognitive function and mentioned in research on PTSD and cardiovascular conditions

The original antibody product description suggests that investigating C3orf18 function "is crucial for gaining insights into its role in diseases such as cancer, neurological disorders, and metabolic conditions" , indicating potential broader disease relevance that warrants further investigation.

How does C3orf18 interact with genomic regulatory elements and other cellular pathways?

Research using ATAC-seq (Assay for Transposase-Accessible Chromatin with sequencing) has included C3orf18 in studies of chromatin accessibility in triple-negative breast cancer cell lines , suggesting its potential regulation at the chromatin level.

Single-cell Mendelian randomisation studies have also included C3orf18 in their analyses, which examine cell-type specific regulatory variants . This indicates potential involvement in cell-type specific gene regulatory networks.

The association with "upregulation of Wnt pathway" suggests C3orf18 may interact with or influence this important signaling pathway, which regulates diverse cellular processes including proliferation, migration, and cell fate determination.

What can proteomic and genomic approaches reveal about C3orf18 function?

Advanced proteomic and genomic approaches can provide significant insights into C3orf18 function:

Genomic Approaches:

• Genome-wide association studies (GWAS) have included C3orf18 in analyses of stroke genetics

• Single-cell eQTL (expression quantitative trait loci) analyses can identify cell-type specific regulatory variants affecting C3orf18 expression

• Chromatin accessibility studies using ATAC-seq have included C3orf18 in their analyses

Proteomic Approaches:

• Proteome-wide association studies (PWAS) mentioned in the context of PTSD and cardiovascular research could help identify protein-level associations for C3orf18

• Co-immunoprecipitation followed by mass spectrometry could identify protein interaction partners

Studies have examined plasma and brain proteomes in relation to genetic variants (pQTLs) , which could potentially reveal regulatory mechanisms affecting C3orf18 protein levels across different tissues.

What are best practices for working with recombinant C3orf18 protein?

When working with recombinant C3orf18 protein, researchers should consider:

Protein Expression Systems:

• E. coli has been used successfully for expressing full-length C3orf18 (amino acids 1-162) with a His-tag

• HEK293 cells have been used to produce C3orf18 cell lysates

Storage and Handling:

• While specific conditions for C3orf18 aren't detailed in the search results, standard practices for recombinant proteins would apply

• Based on similar recombinant proteins, recommendations may include:

  • Using a manual defrost freezer and avoiding repeated freeze-thaw cycles

  • Reconstituting lyophilized protein in appropriate buffers (typically sterile PBS with or without carrier protein)

  • Aliquoting the reconstituted protein to minimize freeze-thaw cycles

Quality Control:

• Verification of protein integrity by SDS-PAGE

• Confirmation of protein identity by Western blotting with validated antibodies

• Assessment of functional activity if assays are available

What experimental challenges might researchers encounter when studying C3orf18?

Researchers working with uncharacterized proteins like C3orf18 may face several challenges:

Limited Functional Information:

• As an uncharacterized protein, there are few established functional assays specific to C3orf18

• Researchers may need to design exploratory experiments based on predicted functions or phenotypic associations

Antibody Specificity:

• Ensuring antibody specificity is critical, especially for uncharacterized proteins

• Validation using knockout controls (e.g., from CRISPR/Cas9 KO cells) is recommended

Expression Level Detection:

• If endogenous expression levels are low, detection may be challenging

• CRISPR activation systems may help increase expression for functional studies

Membrane Protein Challenges:

• As C3orf18 is predicted to be a membrane protein , researchers may encounter typical challenges of membrane protein work including solubility issues, proper folding, and maintaining native conformation

How can researchers validate the functional effects of C3orf18 manipulation in experimental systems?

To validate functional effects of C3orf18 manipulation, researchers should consider multiple complementary approaches:

Genetic Manipulation Validation:

• Confirm knockout efficiency using PCR, Western blot, or sequencing after CRISPR/Cas9 targeting

• Verify upregulation after CRISPR activation using qPCR or Western blot

• Include appropriate controls (e.g., non-targeting gRNA controls)

Phenotypic Assays:

• Based on reported associations, researchers might examine:

  • DNA damage repair efficiency (homologous recombination assays)

  • Response to ionizing radiation

  • Wnt pathway activity (using reporter assays)

  • Susceptibility to vaccinia virus infection

  • Cell surface transport assays

  • Cognitive function in appropriate model systems

Rescue Experiments:

• Reintroduce wild-type C3orf18 into knockout models to confirm phenotype specificity

• Perform domain-specific mutations to identify functional regions

Cross-validation:

• Use multiple independent methods to manipulate C3orf18 (e.g., CRISPR KO, RNAi, small molecule inhibitors if available)

• Test effects in multiple relevant cell types or model systems

What are emerging research areas involving C3orf18?

Several emerging research areas involving C3orf18 can be identified from the literature:

Multi-omics Integration:

• Integration of genomic, transcriptomic, and proteomic data to understand C3orf18 function in complex diseases like stroke

• Single-cell approaches to identify cell-type specific roles

Chromatin Regulation:

• Studies of chromatin accessibility in triple-negative breast cancer include analyses related to C3orf18

Neuropsychiatric and Cardiovascular Comorbidity:

• Research on shared genetic mechanisms between PTSD and cardiovascular conditions has examined C3orf18

Functional Genomics:

• CRISPR-based functional screening approaches are being applied to understand uncharacterized genes like C3orf18

What technologies and methodologies are advancing C3orf18 research?

Advanced technologies driving C3orf18 research include:

CRISPR Technologies:

• Both knockout and activation systems specific to C3orf18 are available for functional studies

Single-cell Technologies:

• Single-cell approaches enable cell-type specific analyses of gene expression and regulation

Epigenetic Profiling:

• ATAC-seq for chromatin accessibility

• Potentially H3K27ac ChIP-seq, H3K4me3 ChIP-seq and proximity ligation-assisted ChIP-seq (PLAC-seq) mentioned in methodology sections

Multi-omics Integration:

• Combining GWAS with eQTL, methylation QTL, and proteomics data to understand gene function

Large Biobank Resources:

• Studies utilizing resources like the UK Biobank and All of Us Research Program for genetic and phenotypic data

How might understanding C3orf18 function contribute to therapeutic development?

While therapeutic applications remain speculative given the uncharacterized nature of C3orf18, several potential contributions can be considered:

Target Identification:

• If C3orf18's role in disease processes is validated, it could become a novel therapeutic target

• Its predicted membrane localization makes it potentially accessible to antibody-based therapies

Biomarker Development:

• Association with multiple disease states including stroke and potential links to cancer suggest possible biomarker applications

Pathway Insights:

• Understanding C3orf18's role in the Wnt pathway could contribute to therapeutic approaches targeting this pathway in cancer and other diseases

Precision Medicine:

• Genetic variation affecting C3orf18 expression or function could potentially inform personalized treatment approaches

• Integration with multi-omics data could help identify patient subgroups for targeted therapies

The continued characterization of C3orf18 function through advanced research methodologies will be essential for revealing its potential therapeutic relevance.