Phosphorylation regulates human OCT4.
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- CitationCopy to clipboard
Brumbaugh J, Hou Z, Russell JD, Howden SE, Yu P, Ledvina AR, Coon JJ, Thomson JA
Phosphorylation regulates human OCT4.
Proc Natl Acad Sci U S A. 2012 May 8;109(19):7162-8. doi: 10.1073/pnas.1203874109. Epub 2012 Apr 2.
- PubMed ID
- 22474382 [ View in PubMed]
- Abstract
The transcription factor OCT4 is fundamental to maintaining pluripotency and self-renewal. To better understand protein-level regulation of OCT4, we applied liquid chromatography-MS to identify 14 localized sites of phosphorylation, 11 of which were previously unknown. Functional analysis of two sites, T234 and S235, suggested that phosphorylation within the homeobox region of OCT4 negatively regulates its activity by interrupting sequence-specific DNA binding. Mutating T234 and S235 to mimic constitutive phosphorylation at these sites reduces transcriptional activation from an OCT4-responsive reporter and decreases reprogramming efficiency. We also cataloged 144 unique phosphopeptides on known OCT4 interacting partners, including SOX2 and SALL4, that copurified during immunoprecipitation. These proteins were enriched for phosphorylation at motifs associated with ERK signaling. Likewise, OCT4 harbored several putative ERK phosphorylation sites. Kinase assays confirmed that ERK2 phosphorylated these sites in vitro, providing a direct link between ERK signaling and the transcriptional machinery that governs pluripotency.