title: Dynamic methylation of Numb by Set8 regulates its binding to p53 and apoptosis.
abstract: Although Numb exhibits its tumor-suppressive function in breast cancer in part by binding to and stabilizing p53, it is unknown how the Numb-p53 interaction is regulated in cells. We found that Numb is methylated in its phosphotyrosine-binding (PTB) domain by the lysine methyltransferase Set8. Moreover, methylation uncouples Numb from p53, resulting in increased p53 ubiquitination and degradation. While Numb promotes apoptosis in a p53-dependent manner, the apoptotic function is abolished when Numb is methylated by Set8 or the Lys methylation sites in Numb are mutated. Conversely, the Numb-p53 interaction and Numb-mediated apoptosis are significantly enhanced by depletion of Set8 from cancer cells or by treating the cells with doxorubicin, a chemotherapeutic drug that causes a reduction in the mRNA and protein levels of Set8. Our work identifies the Set8-Numb-p53 signaling axis as an important regulatory pathway for apoptosis and suggests a therapeutic strategy by targeting Numb methylation.
authors.affiliation: Department of Biochemistry and the Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada.
authors.forename: Gurpreet Kaur
authors.initials: GK
authors.lastname: Dhami
authors.forename: Huadong
authors.initials: H
authors.lastname: Liu
authors.forename: Marek
authors.initials: M
authors.lastname: Galka
authors.forename: Courtney
authors.initials: C
authors.lastname: Voss
authors.forename: Ran
authors.initials: R
authors.lastname: Wei
authors.forename: Kimberly
authors.initials: K
authors.lastname: Muranko
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kaneko
authors.forename: Sean P
authors.initials: SP
authors.lastname: Cregan
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Shawn Shun-Cheng
authors.initials: SS
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D006367:HeLa Cells; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D061986:MCF-7 Cells; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D018613:Microscopy, Confocal; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C113026:NUMB protein, human; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; D011495:Histone-Lysine N-Methyltransferase; C470730:KMT5A protein, human; D008239:Lysine