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HTLV-1 proviruses encoding non-functional TAX in adult T-cell leukemia
S Okazaki1, R Moriuchi, N Yosizuka
1Department of Pediatrics, Nagasaki University School of Medicine, Japan.
Virus Genes
|November 29, 2001
Summary
Human T-cell leukemia virus type 1 (HTLV-1) TAX protein may initiate Adult T-cell leukemia (ATL) by causing genome instability, but it is not essential for maintaining ATL cells. This study investigated TAX's role in ATL development.
Area of Science:
- Oncology
- Virology
- Molecular Biology
Background:
- Adult T-cell leukemia (ATL) is linked to human T-cell leukemia virus type 1 (HTLV-1) infection.
- The HTLV-1 transactivator protein, TAX, is suspected in T-cell immortalization, but its role in malignant transformation in vivo is not fully understood.
Purpose of the Study:
- To investigate the role of the HTLV-1 TAX protein in the monoclonal proliferation of ATL cells.
- To analyze the function of TAX DNA clones from ATL patients.
Main Methods:
- Sequencing of tax DNA clones from 6 ATL patients.
- Analysis of the biological function of the encoded TAX proteins.
- Assessment of microsatellite instability in key genes.
Main Results:
- Non-functional TAX proteins (due to nonsense or frame-shift mutations) were found in 2 patients, indicating TAX is not essential for ATL cell maintenance.
- Functional TAX DNA clones showed fewer nucleotide substitutions than non-functional ones, suggesting TAX contributes to genome instability.
- Microsatellite instability was observed in the E2F4 gene in one patient.
Conclusions:
- TAX is likely a prerequisite for HTLV-1-induced malignant transformation of T-cells.
- TAX is not essential for the ongoing maintenance of ATL cells in vivo.
- TAX may contribute to ATL pathogenesis through genome instability.