title: Antiapoptotic function of apoptosis inhibitor 2-MALT1 fusion protein involved in t(11;18)(q21;q21) mucosa-associated lymphoid tissue lymphoma.
abstract: t(11;18)(q21;q21) is a characteristic chromosomal translocation in mucosa-associated lymphoid tissue (MALT) type lymphoma, and this translocation results in fusion transcript of apoptosis inhibitor 2 (API2), also known as c-IAP2, and MALT translocation gene 1 (MALT1). Although the API2-MALT1 fusion protein has been shown to enforce activation of nuclear factor kappaB signaling, its precise role in the apoptotic signaling pathway remains to be established. To identify proteins that bind the API2-MALT1 protein, we used coimmunoprecipitation and SDS-PAGE, followed by liquid chromatography-electrospray ionization tandem mass spectrometry. As a result, three important regulators of apoptosis, Smac, HtrA2, and TRAF2, and three other proteins were identified as potential API2-MALT1-binding proteins. Immunoprecipitation analyses verified that API2-MALT1 indeed binds to both exogeneous and endogeneous Smac proteins. It is especially noteworthy that stably transfected API2-MALT1 significantly suppressed both UV- and etoposide-induced apoptosis in HeLa cells, thus demonstrating for the first time that API2-MALT1 indeed possesses antiapoptotic function. Furthermore, API2-MALT1 significantly suppressed Smac-promoted apoptosis in UV-irradiated HeLa cells. Thus, our results provide direct experimental evidence that API2-MALT1 can confer resistance to apoptosis, at least in part, by neutralizing apoptosis promoted by Smac.
authors.affiliation: Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan. yhosokaw@aichi-cc.jp
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hosokawa
authors.forename: Hiroko
authors.initials: H
authors.lastname: Suzuki
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Takahashi
authors.forename: Masao
authors.initials: M
authors.lastname: Seto
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000378:metabolism; D002880:Chromosomes, Human, Pair 11; D002887:Chromosomes, Human, Pair 18; D004591:Electrophoresis, Polyacrylamide Gel; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D011233:Precipitin Tests; D011485:Protein Binding; D021241:Spectrometry, Mass, Electrospray Ionization; D014178:Translocation, Genetic; D014466:Ultraviolet Rays
chemical_list: C415943:API2-MALT1 fusion protein, human; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C412403:DIABLO protein, human; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D015514:Oncogene Proteins, Fusion; D005047:Etoposide