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A processed pseudogene codes for a new antigen recognized by a CD8(+) T cell clone on melanoma
A Moreau-Aubry1, S Le Guiner, N Labarrière
1Institut National de la Santé et de la Recherche Médicale (INSERM) U463, 44093 Nantes cedex 01, France.
The Journal of Experimental Medicine
|May 3, 2000
Summary
Scientists identified a melanoma antigen (NA88-A) derived from a pseudogene. This pseudogene, originating from the HPX42B gene, produces a specific peptide recognized by T cells, unlike its parent gene.
Area of Science:
- Immunology
- Genetics
- Oncology
Background:
- The M88.7 T cell clone recognizes a specific antigen on the M88 melanoma cell line, presented by HLA B*1302.
- Understanding the origin of tumor antigens is crucial for developing targeted immunotherapies.
Purpose of the Study:
- To identify and characterize the gene encoding the antigen recognized by the M88.7 T cell clone.
- To elucidate the molecular mechanism by which this melanoma antigen is produced.
Main Methods:
- Library transfection approach to isolate the antigen-encoding cDNA (NA88-A).
- Genomic sequence analysis to compare NA88-A with the parent gene (HPX42B).
- RNA analysis to investigate peptide production from both NA88-A and HPX42B.
Main Results:
- The NA88-A gene is a processed pseudogene derived from the HPX42B homeoprotein gene.
- NA88-A contains mutations (stop codons, deletions, insertions) leading to a truncated peptide (MTQGQHFLQKV).
- This truncated peptide is recognized by M88.7 T cells, whereas the full-length HPX42B mRNA does not produce a recognizable antigen due to a different C-terminal sequence.
Conclusions:
- A pseudogene (NA88-A) has been repurposed to generate a melanoma-specific antigen.
- The study proposes a model for the evolution of a functional antigen from a pseudogene through specific genetic events.
- This finding offers insights into novel mechanisms of tumor antigen generation and potential therapeutic targets.