title: Constitutive NF-kappaB activation by the t(11;18)(q21;q21) product in MALT lymphoma is linked to deregulated ubiquitin ligase activity.
abstract: Mucosa-associated lymphoid tissue (MALT) lymphoma is a common type of lymphoma in extranodal sites. The most frequent chromosome translocation associated with MALT lymphoma is t(11;18)(q21;q21), which generates a chimeric protein of c-IAP2 and MALT1/paracaspase. The c-IAP2/MALT1 fusion protein activates the NF-kappaB pathway, which is considered critical to malignant B cell transformation and lymphoma progression. The mechanism by which this fusion protein activates NF-kappaB, however, remains unclear. Here we show that self-oligomerization of the c-IAP2/MALT1 protein causes deregulated ubiquitin ligase activity of MALT1/paracaspase. The chimeric protein targets NEMO for polyubiquitination and thereby activates NF-kappaB. Consistent with this finding, NEMO ubiquitination is increased in t(11;18)(q21;q21)-positive MALT lymphoma samples. Thus, t(11;18)(q21;q21) deregulates MALT1/paracaspase ubiquitin ligase activity, causing constitutive NF-kappaB activation and promoting tumorigenesis.
authors.affiliation: Molecular Oncology, Genentech, 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Honglin
authors.initials: H
authors.lastname: Zhou
authors.forename: Ming-Qing
authors.initials: MQ
authors.lastname: Du
authors.forename: Vishva M
authors.initials: VM
authors.lastname: Dixit
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases; D002460:Cell Line; D006801:Humans; D051550:I-kappa B Kinase; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics / Q000378:metabolism*; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D011506:Proteins / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014178:Translocation, Genetic; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; C491731:IKBKG protein, human; D016328:NF-kappa B; D009363:Neoplasm Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D051550:I-kappa B Kinase; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein