Identification of a tumor-associated mutant form of the NF-κB RelA gene with reduced DNA-binding and transactivating activities

• Published in: Oncogene Vol. 14; no. 7; pp. 791 - 799
• Main Authors: TRECCA, D, GUERRINI, L, FRACCHIOLLA, N. S, POMATI, M, BALDINI, L, MAIOLO, A. T, NERI, A
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 20-02-1997; Nature Publishing Group
• Subjects: Amino acid substitution; Binding sites; Biological and medical sciences; Blood cells; Bone marrow; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Deoxyribonucleic acid; DNA; Fundamental and applied biological sciences. Psychology; Fusion protein; Molecular and cellular biology; Multiple myeloma; Mutation; NF-κB protein; Nucleotide sequence; Peripheral blood; Point mutation; Proteins; RelA gene; RelA protein; Transfection; Tumors; Human; Transcription; DNA binding protein; Molecular interaction; Malignant hemopathy; Non Hodgkin lymphoma; Gene expression; Cell transformation; Lymphoma; Lymphocytic lymphoma; Gene; Lymphoproliferative syndrome; Mutation; Transcription factor NFκB
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1200895

Alterations of NF-κB family members have been found to be associated with various forms of lymphoid malignancies. In order to determine whether alterations of the RelA gene are involved in lymphomagenesis, we analysed a large and representative panel (200 cases) of such tumors. Southern blot analysis did not reveal any rearrangements or locus amplification, suggesting that structural alterations of the RelA gene may represent rare events in lymphoid neoplasia. By means of PCR-SSCP analysis, we were able to identify a single point mutation leading to amino acid substitution (codon 494, Glu-Asp) in the transactivating (TA) domain in one case of multiple myeloma. The mutated allele was expressed in the pathological bone marrow sample but not in the peripheral blood cells of the patient. We demonstrate that the RelA protein carrying this specific mutation (called RelA494D) has less transactivating ability than the normal RelA protein. Interestingly, the mutated protein has a lower affinity for κB binding sites both as a homodimer or in association with the NFKB1/p50 subunit. Transfection experiments using a Gal4-RelA494D fusion protein indicated that the mutation does not alter the intrinsic transactivating ability of the TA domain of RelA. Furthermore, in vitro translated RelA494D is able to dimerize efficiently with other NF-κB members, such as p50, cREL and IκBα. Our data therefore suggest that this mutation may alter the specific structural conformation needed for the DNA interaction of RelA, and provide insights into the amino acid sequences involved in mediating the biological activities of RelA.