Degradation of Stop Codon Read-through Mutant Proteins via the Ubiquitin-Proteasome System Causes Hereditary Disorders

• Published in: The Journal of biological chemistry 2015-11, Vol.290 (47), p.28428-28437
• Main Authors: Shibata, Norihito, Ohoka, Nobumichi, Sugaki, Yusuke, Onodera, Chiaki, Inoue, Mizuho, Sakuraba, Yoshiyuki, Takakura, Daisuke, Hashii, Noritaka, Kawasaki, Nana, Gondo, Yoichi, Naito, Mikihiko
• Format: Article
• Language: English
• Subjects: Animals; apoptosis; CASP8 and FADD-Like Apoptosis Regulating Protein - genetics; CASP8 and FADD-Like Apoptosis Regulating Protein - metabolism; cFLIP-L; Codon, Terminator; Genetic Diseases, Inborn - genetics; Homozygote; HSD3B2; Mice; Mice, Mutant Strains; Molecular Bases of Disease; mutagenesis; Mutation; PNPO; proteasome; Proteasome Endopeptidase Complex - metabolism; Protein Binding; read-through mutation; Ribonucleoproteins - metabolism; TRIM21; ubiquitin; Ubiquitin - metabolism; ubiquitylation (ubiquitination)
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.670901

During translation, stop codon read-through occasionally happens when the stop codon is misread, skipped, or mutated, resulting in the production of aberrant proteins with C-terminal extension. These extended proteins are potentially deleterious, but their regulation is poorly understood. Here we show in vitro and in vivo evidence that mouse cFLIP-L with a 46-amino acid extension encoded by a read-through mutant gene is rapidly degraded by the ubiquitin-proteasome system, causing hepatocyte apoptosis during embryogenesis. The extended peptide interacts with an E3 ubiquitin ligase, TRIM21, to induce ubiquitylation of the mutant protein. In humans, 20 read-through mutations are related to hereditary disorders, and extended peptides found in human PNPO and HSD3B2 similarly destabilize these proteins, involving TRIM21 for PNPO degradation. Our findings indicate that degradation of aberrant proteins with C-terminal extension encoded by read-through mutant genes is a mechanism for loss of function resulting in hereditary disorders. Background: 20 read-through mutations that produce C-terminally extended proteins are related to human hereditary disorders. Results: The C-terminal extended proteins of mouse cFLIP-L (cellular FLICE-like apoptosisinhibitory protein) and human PNPO (pyridoxamine 5-phosphate oxidase) and HSD3B2 (3-hydroxysteroid dehydrogenase type II) are ubiquitylated and degraded, involving an E3 ligase, TRIM21, for cFLIP-L and PNPO degradation. Conclusion: Read-through mutant cFLIP-L, PNPO, and HSD3B2 are degraded by the ubiquitin-proteasome system. Significance: Degradation of read-through mutant proteins may cause hereditary disorders.