title: Ankyrin repeat and SOCS box 3 (ASB3) mediates ubiquitination and degradation of tumor necrosis factor receptor II.
abstract: Ankyrin repeat and SOCS box (ASB) family members have a C-terminal SOCS box and an N-terminal ankyrin-related sequence of variable repeats belonging to the SOCS superfamily. While SH2-domain-bearing SOCS proteins are mainly involved in the negative feedback regulation of the protein tyrosine kinase-STAT pathway in response to a variety of cytokines, the roles of ASB family members remain largely unknown. To investigate ASB functions, we screened for ASB3-interacting factors by using antibody array technology and identified tumor necrosis factor receptor II (TNF-R2) as an ASB3 binding target. ASB3 expression and activities are required for (i) TNF-R2 ubiquitination both in vivo and in vitro, (ii) TNF-R2 proteolysis via the proteasome pathway, and (iii) the inhibition of TNF-R2-mediated Jun N-terminal protein kinase (JNK) activation. While the ankyrin repeats of ASB3 interact with the C-terminal 37 amino acids of TNF-R2, the SOCS box of ASB3 is responsible for recruiting the E3 ubiquitin ligase adaptors Elongins-B/C, leading to TNF-R2 ubiquitination on multiple lysine residues within its C-terminal region. Downregulation of ASB3 expression by a small interfering RNA inhibited TNF-R2 degradation and potentiated TNF-R2-mediated cytotoxicity. The data presented here implicate ASB3 as a negative regulator of TNF-R2-mediated cellular responses to TNF-alpha by direct targeting of TNF-R2 for ubiquitination and proteasome-mediated degradation.
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Brown University School of Medicine and Rhode Island Hospital, Providence, RI 02903, USA.
authors.forename: Alicia S
authors.initials: AS
authors.lastname: Chung
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Guan
authors.forename: Zheng-Long
authors.initials: ZL
authors.lastname: Yuan
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Albina
authors.forename: Y Eugene
authors.initials: YE
authors.lastname: Chin
mesh_terms: D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D017209:Apoptosis; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015536:Down-Regulation; D000075065:Elongin; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000502:physiology*; D034622:RNA Interference; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000378:metabolism*; D050826:Suppressor of Cytokine Signaling Proteins; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000819:agonists / Q000502:physiology; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: C502210:ASB3 protein, human; D002352:Carrier Proteins; D000075065:Elongin; D047889:Receptors, Tumor Necrosis Factor, Type II; D050826:Suppressor of Cytokine Signaling Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D014452:Ubiquitins; D048031:JNK Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; D008239:Lysine