title: Methylation by Set9 modulates FoxO3 stability and transcriptional activity.
abstract: The FoxO family of transcription factors plays an important role in longevity and tumor suppression by regulating the expression of a wide range of target genes. FoxO3 has recently been found to be associated with extreme longevity in humans and to regulate the homeostasis of adult stem cell pools in mammals, which may contribute to longevity. The activity of FoxO3 is controlled by a variety of post-translational modifications that have been proposed to form a 'code' affecting FoxO3 subcellular localization, DNA binding ability, protein-protein interactions and protein stability. Lysine methylation is a crucial post-translational modification on histones that regulates chromatin accessibility and is a key part of the 'histone code'. However, whether lysine methylation plays a role in modulating FoxO3 activity has never been examined. Here we show that the methyltransferase Set9 directly methylates FoxO3 in vitro and in cells. Using a combination of tandem mass spectrometry and methyl-specific antibodies, we find that Set9 methylates FoxO3 at a single residue, lysine 271, a site previously known to be deacetylated by Sirt1. Methylation of FoxO3 by Set9 decreases FoxO3 protein stability, while moderately increasing FoxO3 transcriptional activity. The modulation of FoxO3 stability and activity by methylation may be critical for fine-tuning cellular responses to stress stimuli, which may in turn affect FoxO3's ability to promote tumor suppression and longevity.
authors: Cancer Biology Program, Stanford University, CA 94305, USA.
authors: Daniel R
authors: DR
authors: Calnan
authors: Ashley E
authors: AE
authors: Webb
authors: Jamie L
authors: JL
authors: White
authors: Timothy R
authors: TR
authors: Stowe
authors: Tapasree
authors: T
authors: Goswami
authors: Xiaobing
authors: X
authors: Shi
authors: Alexsandra
authors: A
authors: Espejo
authors: Mark T
authors: MT
authors: Bedford
authors: Or
authors: O
authors: Gozani
authors: Steven P
authors: SP
authors: Gygi
authors: Anne
authors: A
authors: Brunet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002843:Chromatin; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D011495:Histone-Lysine N-Methyltransferase; C540312:SETD7 protein, human