Domain-specific c-Myc ubiquitylation controls c-Myc transcriptional and apoptotic activity.

Zhang Q, Spears E, Boone DN, Li Z, Gregory MA, Hann SR
Proc Natl Acad Sci U S A. 2013 110 (3): 978-83

PMID: 23277542 · PMCID: PMC3549076 · DOI:10.1073/pnas.1208334110

The oncogenic transcription factor c-Myc causes transformation and tumorigenesis, but it can also induce apoptotic cell death. Although tumor suppressors are necessary for c-Myc to induce apoptosis, the pathways and mechanisms are unclear. To further understand how c-Myc switches from an oncogenic protein to an apoptotic protein, we examined the mechanism of p53-independent c-Myc-induced apoptosis. We show that the tumor suppressor protein ARF mediates this switch by inhibiting ubiquitylation of the c-Myc transcriptional domain (TD). Whereas TD ubiquitylation is critical for c-Myc canonical transcriptional activity and transformation, inhibition of ubiquitylation leads to the induction of the noncanonical c-Myc target gene, Egr1, which is essential for efficient c-Myc-induced p53-independent apoptosis. ARF inhibits the interaction of c-Myc with the E3 ubiquitin ligase Skp2. Overexpression of Skp2, which occurs in many human tumors, inhibits the recruitment of ARF to the Egr1 promoter, leading to inhibition of c-Myc-induced apoptosis. Therapeutic strategies could be developed to activate this intrinsic apoptotic activity of c-Myc to inhibit tumorigenesis.

MeSH Terms (19)

Amino Acid Substitution Animals Apoptosis Binding, Competitive Cells, Cultured Cell Transformation, Neoplastic Cyclin-Dependent Kinase Inhibitor p16 Early Growth Response Protein 1 Gene Knockout Techniques Genes, myc HeLa Cells Humans Mice Mutagenesis, Site-Directed Protein Structure, Tertiary Proto-Oncogene Proteins c-myc S-Phase Kinase-Associated Proteins Transcription, Genetic Ubiquitination

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