Meta-Biol

• Pathways

Ubiquitin C-terminal hydrolase UCHL5 (UCH37) deubiquitinates TGFBR1, stabilizing TGF-beta receptor complex and prolonging TGF-beta receptor signaling. Deubiqutination of SMAD7 by UCHL5 has not been examined in this context (Wicks et al. 2005). Ubiquitin peptidase USP15 also deubiquitinates and stabilizes TGFBR1, leading to enhanced signaling by TGF-beta receptor complex. USP15 does not affect the ubiquitination status of SMAD7. Amplification of USP15 has recently been reported in glioblastoma, breast and ovarian cancer. In advanced glioblastoma, TGF-beta receptor signaling acts as an oncogenic factor, and USP15-mediated upregulation of TGF-beta receptor signaling may be a key factor in glioblastoma pathogenesis (Eichhorn et al. 2012). The role of UCHL5 was inferred from experiments using recombinant mouse Uchl5 and Smad7 with recombinant human TGF-beta receptors. The role of USP15 was established by experiments using human proteins.