title: Cleavage by MALT1 induces cytosolic release of A20.
abstract: The MALT1 paracaspase has arginine-directed proteolytic activity. A20 is a dual ubiquitin-editing enzyme involved in termination of NF-κB signaling. Upon T- or B-cell receptor engagement human (h) A20 is cleaved by MALT1 after arginine 439, yielding an N-terminal fragment (hA20p50) and a C-terminal one (hA20p37). The hA20p50 fragment has never been detected directly, thus limiting insight into the functional consequences of MALT1-mediated cleavage of A20. Here, various antibodies were tested, including newly generated hA20p50 and hA20p37 specific antibodies, leading to detection of the hA20p50 fragment produced after MALT1-mediated cleavage of ectopically expressed as well as endogenous A20 proteins. The properties of both A20 fragments, generated upon co-expression with a constitutively active MALT1 protein, were further studied by sub-cellular fractionation and fluorescence microscopy. In contrast to full-length A20 which is particulate and insoluble, we found hA20p50 to be soluble and readily released into the cytosol whereas hA20p37 was partially soluble, thus suggesting loss of compartmentalization as a possible mechanism for MALT1-mediated dampening of A20 function.
authors.affiliation: Novartis Institutes for BioMedical Research, Forum 1, Novartis Campus, CH-4056 Basle, Switzerland.
authors.forename: Claire
authors.initials: C
authors.lastname: Malinverni
authors.forename: Adeline
authors.initials: A
authors.lastname: Unterreiner
authors.forename: Jens
authors.initials: J
authors.lastname: Staal
authors.forename: Annelies
authors.initials: A
authors.lastname: Demeyer
authors.forename: Marion
authors.initials: M
authors.lastname: Galaup
authors.forename: Marcel
authors.initials: M
authors.lastname: Luyten
authors.forename: Rudi
authors.initials: R
authors.lastname: Beyaert
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bornancin
mesh_terms: D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D003600:Cytosol / Q000201:enzymology*; D004268:DNA-Binding Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism; D021381:Protein Transport; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein