Browsing by Subject "protein methylation"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A Role for Widely Interspaced Zinc Finger (WIZ) in Retention of the G9a Methyltransferase on Chromatin*.
    (ASBMB, 2015-10-23) Simon, Jeremy M.; Parker, Joel S.; Liu, Feng; Rothbart, Scott B.; Ait-Si-Ali, Slimane; Strahl, Brian D.; Jin, Jian; Davis, Ian J.; Mosley, Amber L.; Pattenden, Samantha G.; Department of Biochemistry and Molecular Biology, IU School of Medicine
    Background: G9a-GLP lysine methyltransferases mono- and di-methylate histone H3 lysine 9 (H3K9me2).Results: Widely interspaced zinc finger (WIZ) regulates H3K9me2 levels through a mechanism that involves retention of G9a on chromatin.Conclusion: The G9a-GLP-WIZ complex has unique functions when bound to chromatin that are independent of the H3K9me2 mark.Significance: Combining pharmacologic and genetic manipulations is essential to any translational hypotheses related to G9a function.
  • Thumbnail Image
    Item
    Transcriptional Activity of the Islet β Cell Factor Pdx1 is Augmented by Lysine Methylation Catalyzed by the Methyltransferase Set7/9
    (2015-04) Maganti, Aarthi V.; Maier, Bernhard; Tersey, Sarah A.; Sampley, Megan L.; Mosley, Amber L.; Özcan, Sabire; Pachaiyappan, Boobalan; Woster, Patrick M.; Hunter, Chad S.; Stein, Roland; Mirmira, Raghavendra G.; Department of Cellular & Integrative Physiology, IU School of Medicine
    The transcription factor Pdx1 is crucial to islet β cell function and regulates target genes in part through interaction with coregulatory factors. Set7/9 is a Lys methyltransferase that interacts with Pdx1. Here we tested the hypothesis that Lys methylation of Pdx1 by Set7/9 augments Pdx1 transcriptional activity. Using mass spectrometry and mutational analysis of purified proteins, we found that Set7/9 methylates the N-terminal residues Lys-123 and Lys-131 of Pdx1. Methylation of these residues occurred only in the context of intact, full-length Pdx1, suggesting a specific requirement of secondary and/or tertiary structural elements for catalysis by Set7/9. Immunoprecipitation assays and mass spectrometric analysis using β cells verified Lys methylation of endogenous Pdx1. Cell-based luciferase reporter assays using wild-type and mutant transgenes revealed a requirement of Pdx1 residue Lys-131, but not Lys-123, for transcriptional augmentation by Set7/9. Lys-131 was not required for high-affinity interactions with DNA in vitro, suggesting that its methylation likely enhances post-DNA binding events. To define the role of Set7/9 in β cell function, we generated mutant mice in which the gene encoding Set7/9 was conditionally deleted in β cells (SetΔβ). SetΔβ mice exhibited glucose intolerance similar to Pdx1-deficient mice, and their isolated islets showed impaired glucose-stimulated insulin secretion with reductions in expression of Pdx1 target genes. Our results suggest a previously unappreciated role for Set7/9-mediated methylation in the maintenance of Pdx1 activity and β cell function.