title: Necdin promotes ubiquitin-dependent degradation of PIAS1 SUMO E3 ligase.
abstract: Necdin, a pleiotropic protein that promotes differentiation and survival of mammalian neurons, is a member of MAGE (melanoma antigen) family proteins that share a highly conserved MAGE homology domain. Several MAGE proteins interact with ubiquitin E3 ligases and modulate their activities. However, it remains unknown whether MAGE family proteins interact with SUMO (small ubiquitin-like modifier) E3 ligases such as PIAS (protein inhibitor of activated STAT) family, Nsmce2/Mms21 and Cbx4/Pc2. In the present study, we examined whether necdin interacts with these SUMO E3 ligases. Co-immunoprecipitation analysis revealed that necdin, MAGED1, MAGEF1 and MAGEL2 bound to PIAS1 but not to Nsmce2 or Cbx4. These SUMO E3 ligases bound to MAGEA1 but failed to interact with necdin-like 2/MAGEG1. Necdin bound to PIAS1 central domains that are highly conserved among PIAS family proteins and suppressed PIAS1-dependent sumoylation of the substrates STAT1 and PML (promyelocytic leukemia protein). Remarkably, necdin promoted degradation of PIAS1 via the ubiquitin-proteasome pathway. In transfected HEK293A cells, amino- and carboxyl-terminally truncated mutants of PIAS1 bound to necdin but failed to undergo necdin-dependent ubiquitination. Both PIAS1 and necdin were associated with the nuclear matrix, where the PIAS1 terminal deletion mutants failed to localize, implying that the nuclear matrix is indispensable for necdin-dependent ubiquitination of PIAS1. Our data suggest that necdin suppresses PIAS1 both by inhibiting SUMO E3 ligase activity and by promoting ubiquitin-dependent degradation.
authors.affiliation: Laboratory of Regulation of Neuronal Development, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Gur
authors.affiliation: Laboratory of Regulation of Neuronal Development, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Kazushiro
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Laboratory of Regulation of Neuronal Development, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Laboratory of Regulation of Neuronal Development, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshikawa
mesh_terms: D000818:Animals; D002460:Cell Line; D006801:Humans; D058950:Melanoma-Specific Antigens / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D050828:Protein Inhibitors of Activated STAT / Q000737:chemistry / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D059748:Proteolysis; D013379:Substrate Specificity; D058207:Sumoylation; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D058950:Melanoma-Specific Antigens; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D050828:Protein Inhibitors of Activated STAT; D025801:Ubiquitin; C069766:necdin; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex