Historical Background of O- GlcNAc
O-GlcNAc was first shown to be a major form of intracellular glycosylation in murine lymphocytes in 1984
O-Linked β-N-acetylglucosamine (O-GlcNAc) is a dynamic protein modification abundant within the nucleus and cytoplasm
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Essentials of Glycobiology Second Edition
Chapter 18, Figure 1
O-GlcNAcylated proteins occur in many different cellular compartments
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Essentials of Glycobiology Second Edition
Diverse Functions of O-GlcNAc Modification
transcription
signaling
protein–protein interactions
(2002) 6:851
Results
• 1.H1 histone ,as well as core histones ,may be mannosylated and N-acetylglucosaminylated • 2. Glycosylation of H1 histone and core histones may be conserved in mammalian cells.
O-GlcNAc is part of the histone code
Kun Ming institute of botany, CAS Yang Yan Long
Content
• 1. Historical Background of O- GlcNAc
• 2. The O-GlcNAcylation of histones • 3. Role of histone O-GlcNAyclation • 4. Discussion
• 3. Direct analysis of carbohydrates in histones to confirm that they are glycosylated
The O-GlcNAcylation of histones
The O-GlcNAcylation of histones
Chapter 18, Figure 2
O-GlcNAcylation exhibits a complex dynamic interplay with O-phosphorylation
Multiple States of O-GlcNAc Modification
O-GlcNAc transferase (OGT) is regulated by multiple complex mechanisms
Essentials of Glycobiology Second Edition
Chapter 18, Figure 6
UDP-GlcNAc is the donor for O-GlcNAc transferase (OGT) and an ideal sensor of the metabolic status of the cell
1. we demonstrate by multiple specific immunological and enzymatic approaches that histones are OGlcNAcylated in vivo.
2. Histones also are substrates for OGT in vitro 3. We identify O-GlcNAc sites on histones H2A, H2B, and H4 using mass spectrometry
• 2. In nucleo OGT assays also demonstrate that OGT activity toward histones decreases during mitosis
Changes in O-GlcNAc levels on histones increased during the recovery after heat shock 2. After recovery for 1 h, MNase digestion revealed that the chromatin had condensed even further, correlating with increased histone O-GlcNAcylation.
map O-GlcNAc sites on histones
• • • H2A: Thr101
H2B： Ser36 H 4： Ser47
Changes in histone O-GlcNAcylation in vivo
• 1. O-GlcNAc levels on histones decreased during mitosis and subsequently returned to basal levels in G1
• 1.Further studies should focus on the incorporation of radioactive monosaccharides into histone
• 2. Cell cycle related alteration of glycosylation in nuclear proteins to address the functions of glycosylation in the nuclear proteins