NEDD4-2 (neural precursor cell expressed, developmentally down-regulated 4-2) negatively regulates TGF-beta (transforming growth factor-beta) signalling by inducing ubiquitin-mediated degradation of Smad2 and TGF-beta type I receptor.
Inhibitory Smad, Smad7, is a potent inhibitor of TGF-beta (transforming growth factor-beta) superfamily signalling. By binding to activated type I receptors, it prevents the activation of R-Smads (receptor-regulated Smads). To identify new components of the Smad pathway, we performed yeast two-hybrid screening using Smad7 as bait, and identified NEDD4-2 (neural precursor cell expressed, developmentally down-regulated 4-2) as a direct binding partner of Smad7. NEDD4-2 is structurally similar to Smurfs (Smad ubiquitin regulatory factors) 1 and 2, which were identified previously as E3 ubiquitin ligases for R-Smads and TGF-beta superfamily receptors. NEDD4-2 functions like Smurfs 1 and 2 in that it associates with TGF-beta type I receptor via Smad7, and induces its ubiquitin-dependent degradation. Moreover, NEDD4-2 bound to TGF-beta-specific R-Smads, Smads 2 and 3, in a ligand-dependent manner, and induced degradation of Smad2, but not Smad3. However, in contrast with Smurf2, NEDD4-2 failed to induce ubiquitination of SnoN (Ski-related novel protein N), although NEDD4-2 bound to SnoN via Smad2 more strongly than Smurf2. We showed further that overexpressed NEDD4-2 prevents transcriptional activity induced by TGF-beta and BMP, whereas silencing of the NEDD4-2 gene by siRNA (small interfering RNA) resulted in enhancement of the responsiveness to TGF-beta superfamily cytokines. These data suggest that NEDD4-2 is a member of the Smurf-like C2-WW-HECT (WW is Trp-Trp and HECT is homologous to the E6-accessory protein) type E3 ubiquitin ligases, which negatively regulate TGF-beta superfamily signalling through similar, but not identical, mechanisms to those used by Smurfs.
Kuratomi
Go
G
Department of Biochemistry, The Cancer Institute of the Japanese Foundation for Cancer Research (JFCR), 1-37-1 Kami-ikebukuro, Toshima-ku, Tokyo 170-8455, Japan.
Komuro
Akiyoshi
A
Goto
Kouichiro
K
Shinozaki
Masahiko
M
Miyazawa
Keiji
K
Miyazono
Kohei
K
Imamura
Takeshi
T
D030201:Activin Receptors, Type I / Q000378:metabolism*; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D051379:Mice; D000075702:Nedd4 Ubiquitin Protein Ligases; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D015398:Signal Transduction; D051899:Smad2 Protein; D051900:Smad3 Protein; D051905:Smad6 Protein; D051906:Smad7 Protein; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C060615:SKIL protein, human; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497802:SMAD6 protein, human; C497806:SMAD7 protein, human; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051905:Smad6 Protein; C497803:Smad6 protein, mouse; D051906:Smad7 Protein; C497807:Smad7 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D025801:Ubiquitin; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618461:Nedd4l protein, mouse; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I