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Identification of genes downregulated in the thymus by cyclosporin-A: preliminary characterization of clone CSA-19
N Fisicaro1, M Katerelos, J Williams
1Department of Clinical Immunology, St Vincent's Hospital, Fitzroy, Victoria, Australia.
Abstract:
Using a novel subtractive hybridization approach, we have identified a set of cDNA clones whose expression is downregulated in the thymus by cyclosporin-A (CsA). A number of regulated genes were identified, but the major focus of this report is the clone termed CsA-19. In the adult mouse, CsA-19 is expressed at high levels in lymphoid organs, particularly in secondary lymphoid organs such as lymph node and spleen. CsA-19 expression was also found to be regulated in the brain and liver during mouse development. The full length sequences of the murine and human CsA-19 cDNAs have been determined. Both are 700 nucleotides in length and encode a predicted product of 217 amino acids. Comparison of the full length cDNA sequences of murine and human CsA-19 reveal that they are greater than 91% conserved. At the predicted amino acid level the homology is even greater, with only two amino acid differences in 217 residues (99% identity). The high degree of homology between murine and human CsA-19 indicates that has there been strong evolutionary pressure to conserve the amino acid sequence of CsA-19, and suggests that CsA-19 may play a critical role both during embryogenesis and in mature lymphoid cells.
Insights
Researchers identified a novel gene, CsA-19, downregulated by cyclosporin-A (CsA) in the thymus. This gene is highly expressed in lymphoid organs and conserved across species, suggesting a critical role in development and immunity.
Area of Science:
- Immunology
- Developmental Biology
- Molecular Biology
Background:
- Cyclosporin-A (CsA) is an immunosuppressant affecting T-cell function.
- Understanding gene regulation in lymphoid organs is crucial for immunology.
Purpose of the Study:
- To identify genes downregulated by CsA in the thymus.
- To characterize the novel CsA-19 gene and its function.
Main Methods:
- Subtractive hybridization to identify differentially expressed genes.
- cDNA sequencing to determine gene structure.
- Comparative sequence analysis to assess homology.
Main Results:
- Identified CsA-19 as a gene downregulated by CsA.
- CsA-19 is highly expressed in adult lymphoid organs (lymph node, spleen).
- CsA-19 expression is regulated during mouse development in brain and liver.
- Murine and human CsA-19 cDNAs are highly conserved (91% nucleotide, 99% amino acid identity).
Conclusions:
- CsA-19 is a conserved gene with potential critical roles in embryogenesis and mature lymphoid cells.
- The high homology suggests strong evolutionary pressure to maintain CsA-19 function.