title: The p66Shc longevity gene is silenced through epigenetic modifications of an alternative promoter.
abstract: The mammal Shc locus encodes three overlapping isoforms (46, 52, and 66 kDa) that differ in the length of their N-terminal regions. p46/p52Shc and p66Shc have been implicated, respectively, in the cytoplasmic propagation of growth and apoptogenic signals. Levels of p66Shc expression correlate with life span duration in mice. p46Shc and p52Shc are ubiquitously expressed, whereas p66Shc is expressed in a cell lineage-specific fashion. However, the mechanisms underlying the regulation of Shc protein expression are unknown. Here we report the identification of two alternative promoters, driving the transcription of two mRNAs coding for p46/p52Shc and p66Shc. We show that treatment with an inhibitor of histone deacetylases or with a demethylating agent results in induction of p66Shc expression in cells that normally do not express this isoform but leaves the levels of the two other isoforms unchanged. Moreover, analysis of the methylation pattern of the p66Shc promoter in a panel of primary and immortalized human cells showed inverse correlation between p66Shc expression and methylation density of its promoter. These results identify histone deacetylation and cytosine methylation as the mechanisms underlying p66Shc silencing in nonexpressing cells.
authors.affiliation: Department of Experimental Oncology, European Institute of Oncology, Milan 20141, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ventura
authors.forename: Lucilla
authors.initials: L
authors.lastname: Luzi
authors.forename: Sonia
authors.initials: S
authors.lastname: Pacini
authors.forename: Cosima T
authors.initials: CT
authors.lastname: Baldari
authors.forename: Pier Giuseppe
authors.initials: PG
authors.lastname: Pelicci
mesh_terms: D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D019070:Cell Lineage; D003596:Cytosine / Q000378:metabolism; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008156:Luciferases / Q000378:metabolism; D008745:Methylation; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D006657:Histones; D006877:Hydroxamic Acids; D020033:Protein Isoforms; D011506:Proteins; D012333:RNA, Messenger; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; C012589:trichostatin A; D003596:Cytosine; D008156:Luciferases; D012260:Ribonucleases; D006655:Histone Deacetylases