101. Stability and subcellular localization of API2-MALT1 chimeric protein involved in t(11;18) (q21;q21) MALT lymphoma.
- Author
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Izumiyama K, Nakagawa M, Yonezumi M, Kasugai Y, Suzuki R, Suzuki H, Tsuzuki S, Hosokawa Y, Asaka M, and Seto M
- Subjects
- Animals, Apoptosis genetics, Apoptosis physiology, Blotting, Western, Caspases, Fluorescent Antibody Technique, Humans, Inhibitor of Apoptosis Proteins, Lymphoma, B-Cell, Marginal Zone metabolism, Microscopy, Fluorescence, Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein, Neoplasm Proteins genetics, Neoplasm Proteins metabolism, Oncogene Proteins, Fusion metabolism, Proteins genetics, Proteins metabolism, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Chromosomes, Human, Pair 11, Chromosomes, Human, Pair 18, Genomic Instability, Lymphoma, B-Cell, Marginal Zone genetics, Oncogene Proteins, Fusion genetics, Translocation, Genetic
- Abstract
t(11; 18) (q21; q21) is a chromosomal aberration specific to low-grade mucosa-associated lymphoid tissue (MALT) lymphoma, and generates the chimeric product apoptosis inhibitor 2 (API2)-MALT1, which has been suggested to play an important role in MALT lymphomagenesis. However, little is known about the characteristics of API2, MALT1, and API2-MALT1 proteins. We therefore investigated the subcellular localization and stability of these products. API2 was localized in the nucleus and the cytoplasm, and MALT1 and API2-MALT1 in the cytoplasm only. Western blot analysis showed that the products of API2 and MALT1 were unstable, while the API2-MALT1 product was stable. The API2 deletion mutants at the end of the C-terminal and the MALT1 deletion mutants at the end of the N-terminal were stable compared with the full-length products. These results indicate that the domains responsible for protein instability are located in the end of the C-terminal of API2 and in that of the N-terminal of MALT1, and also that API2-MALT1 became stable because it lacks these domains. It has been suggested that NF-kappaB activation plays an important role in the tumorigenesis of MALT lymphoma. Our findings further suggest that the stabilized expression of API2-MALT1 products may continuously stimulate the NF-kappaB activating pathway, thus leading to MALT lymphomagenesis.
- Published
- 2003
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