ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze.
ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze
description
Transcript of ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze
![Page 1: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/1.jpg)
ESSENTIALS OF GLYCOBIOLOGY
LECTURE 15
The O-GlcNAc Modification
Hud Freeze
![Page 2: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/2.jpg)
“Dynamic Interplay Between O-GlcNAc and O-Phosphate: Roles in Transcription,
Signaling and in Cellular Response to Stress.”
Gerald W. HartJohns Hopkins University
School of Medicine
ADAPTED FROM
![Page 3: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/3.jpg)
O-GlcNAcO-GlcNAc O- Linked N-AcetylglucosamineO- Linked N-Acetylglucosamine
Tyr-Ser-Pro-Thr-Ser-Pro-Ser
O
AcNHHO
OH
O
O
AcNHHO
HO
OH
O
HO
A dynamic post-translational modification
O-GlcNAc Transferase O-GlcNAcase
![Page 4: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/4.jpg)
Key Features of O-GlcNAc :Key Features of O-GlcNAc :NOTNOT elongated to more complex elongated to more complex structures.structures.Localized to the cytoplasm and nucleus.Localized to the cytoplasm and nucleus.Present in all higher eukaryotes studied.Present in all higher eukaryotes studied.As abundant as phosphorylation; As abundant as phosphorylation; UDP-GlcNAc is Nearly as abundant as ATP.UDP-GlcNAc is Nearly as abundant as ATP.O-GlcNAc proteins are also O-GlcNAc proteins are also PhosphoproteinsPhosphoproteinsO-GlcNAc and Phosphorylation are often O-GlcNAc and Phosphorylation are often reciprocal.reciprocal. Highly dynamic modification - a Highly dynamic modification - a regulatory role.regulatory role.
![Page 5: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/5.jpg)
Non-CapsidViral
Proteins
Nuclear PoreProteins
RNA Polymerase II& Transcription Factors
Tumor Suppressors& Oncogenes
Cytoskeletal Proteins
ChromatinProteins
Protein TranslationRegulatory Factors
Cytoplasmic Face ofVesicle Proteins
ParasiteProteins
CytosolicEnzymes
Cytoplasmic Tailsof Membrane Proteins
RNA ProcessingProteins
ProteosomalProteosomalProteinsProteins
![Page 6: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/6.jpg)
pI 4 pI 9 pI 4 pI 9
Unbound sWGA bound--GlcNAc Eluted
-110-
MW
-20-
Silver stain of 80 ug total protein from each fraction(starting material 30 mg nucleocytoplamic lysate from HeLa cells)
Enrichment of O-GlcNAc Modified Proteins using sWGA:
![Page 7: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/7.jpg)
pI: 3 --> 10
2nd Dimension:10% SDS-PAGE
Visualization:Silver Stain
CTD 110.6 MAb Immunopurifies Many Glycoproteins From HeLa Cell Cytoplasmic and
Nuclear Extract:
![Page 8: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/8.jpg)
Nuclear Pore ProteinsNuclear Pore Proteins - - p62, Nup54, 155, 180, 153, 214, 358; p62, Nup54, 155, 180, 153, 214, 358; Chromatin ProteinsChromatin Proteins - Many- Many
Transcription Factors - Transcription Factors - SP1, cfos, cJun, CTF, HNF1, v-ErbA, Pancreas Specific TF, SRF, c-Myc, p53, Estrogen Receptors, ß-catenin, NFKB, ELF-1, PAX-6, Enhancer Factor D, Human C1, Oct1, plakoglobin, YY1, PDX-1, CREB, Rb, p107, RNA Polymerase II.
RNA Binding Proteins - HnRNP-G, Ewing Sarcoma RNA binding Protein, EF4A1, EF1alpha, 40S ribosomal s24, many ribosomal proteins.
Phosphatases/Kinases/Adapters nuclear Tyr phos’ase p65, CKII, IRS-1,2, GSK3ß, PI3-kinase
Cytoskeletal Proteins - cytokeratins 8, 13, 18, Neurofilaments H, M, L, Band 4.1, talin, vinculin, ankyrin, synapsin I, myosin, E-cadherin, cofilin, tau, Maps 2, 4, Dynein, alpha tubulin, AP3, AP180, ß-APP, ß-synuclein, piccolo.
Chaperones - HSP27, alpha crystallins, HsC70, HsP70, HsP90 Metabolic Enzymes - eNOS, Enolase, Glyceraldehyde-3-phosphate dehydrogenase,
phosphoglycerate kinase, pyruvate kinase, UDP-glucose synthase, glycogen synthaseOther Regulatory Proteins - Eukaryotic peptide chain initiation factor 2 p67, OGT,
CRMP-2, Ubiquitin carboxy hydrolase (UCH), Glut 1, Annexin 1, Nucleophosmin, proteasome components C2, 5/9 and 9/14 of 26S proteasome regulatory & catalytic subunits, respectively, Q04323 UCH homolog, Sec23, Ran, peptidyl prolylisomerase, Rho GDP-dissociation inhibitor, GABA Receptor interacting protein 1,
Viral Proteins - adenovirus fiber, SV40 Large T Ag;, Baculovirus Teg protein,
Some Identified O-GlcNAc-Modified Proteins:Some Identified O-GlcNAc-Modified Proteins:
![Page 9: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/9.jpg)
Some Clues To O-GlcNAc Functions:
Required for Life at Single Cell Level - (OGT -/+ still emb. lethal.) Regulates Transcriptional Activation or Suppression, Dep. upon Metabolism - SP1,
ERs, Stat5, NFkB, p53, c-Myc; Regulates Degradation. Regulates Protein Synthesis (via p67-EIF2 kinase);(Gupta & Datta) Regulates ß-catenin and E-cadherin trafficking (Andrews et al.) Neurodegenerative Disease - Tau, ß-APP, NFs, O-GlcNAcase maps to late-AD locus;
OGT Maps to Parkinson Dystonia Locus; O-GlcNAc is Reduced in Human AD. YY1 Transcription Factor is Regulated by O-GlcNAc - Prevents binding to Rb. O-GlcNAc on Glycogen Synthase Prevents its Activation by Insulin (Parker; McClain). O-GlcNAc on eNOS prevents activation by Akt (Brownlee) Retinoblastoma (Rb) is O-GlcNAc Modified in G1 & O-GlcNAc-Rb binds E2F. O-GlcNAcylation of 26S Proteosome Inhibits Degradation; 5/19 and 9/14 of Catalytic
Core and Reg. Core subunits, respectively, are modified (Cell 115, 715; BBRC 312,1284) Regulator of Gibberellic Acid Signaling in Plants-OGT=Spy; Secret Agent
Blocks Insulin Signaling and OGT Over-Expression in Muscle or Adipose Causes Diabetes in Mice (McClain & Hanover)
(>~200 Papers Since 1984 Directly Concerned with O-GlcNAc)(>~200 Papers Since 1984 Directly Concerned with O-GlcNAc)
![Page 10: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/10.jpg)
SiteA
SiteB
SiteA
SiteB
SiteA
SiteB
SiteA
SiteB
OO
OH
HOHO
HNAc
SiteA
SiteB
OPO3-
OPO3-
OO
OH
HOHO
HNAc
OO
OH
HOHO
HNAc
1
2
3
4
5
6
7
Complex Interplay Between O-Phosphate & O-GlcNAc:Complex Interplay Between O-Phosphate & O-GlcNAc:
![Page 11: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/11.jpg)
QuickTime™ and aGIF decompressor
are needed to see this picture.
OPTIONS FOR O-GlcNAc MODIFICATION
![Page 12: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/12.jpg)
O-GlcNAc Transferase Summary:
OGT has been highly conserved throughout evolution.
OGT is a unique glycosyltransferase. Localized near centromere on X-chromosome. 1 Normal Allele is Required for ES Cell Viability
(Marth et al.)
![Page 13: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/13.jpg)
OGT structure
catalytic
TPR domains - (tetratricopeptide repeats)
Generates O-GlcNAc linkage on peptides
-Single gene encoding103 kDa peptidemigrates at 110 kDa
Inexact peptide sequence motif for glycosylationAssociates with self and other proteins in complex
Expressed in all mammalian tissues studiedLocated in nucleus and cytoplasm
Modified by O-GlcNAc and tyrosine-phosphate
![Page 14: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/14.jpg)
O-GlcNAc O-GlcNAc
TPRDomain
CatalyticDomain
TPR InteractingEffector Proteins
OGT mRNAOGT Splice
Variants
ProteolyticProcessing OGT Variant
O-GlcNAc O-GlcNAc O-GlcNAcO-GlcNAcO-GlcNAc
O-GlcNAc Modified Proteins
OGT
Multimerization
[UDP-GlcNAc][UDP]
SubstrateSelectivity
Post-translationalModifications
TranscriptionalRegulation
RNA Processing
![Page 15: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/15.jpg)
Identified OGT-TPR Binding Proteins:
Co-Repressor mSin3A binds OGT and Suppresses SP1 Driven Transcription (Kudlow)
GRIF-1 - Targets to GABA Receptor (Anne Stephenson) and Regulates its signaling; OGT binding protein (Sai Iyer).
Milton (Drosophila GRIF-1 analog) required for kinesin-mediated axonal transport of mitochondria to Synapses (Neuron 36, 1063 (Schwarz).
OIP106 - GRIF-1-Like Protein Targets OGT to RNA polymerase II - binds via TPRs.
Many more yet to be identified - pulled out by yeast 2H.
(Proteins That Target OGT and Control Specificity)(Proteins That Target OGT and Control Specificity)
![Page 16: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/16.jpg)
Effect of [UDP-GlcNAc] On OGT Activity In the Presence of Alkaline Phosphatase
0
200
400
600
800
1000
1200
1400
0 10 20 30 40 50
y = 0.6802 + 27.714x R= 0.99833
pmol
inco
rpor
ated
[UDP-GlcNAc] mM
50 mM!!50 mM!!
PhysiologicalPhysiologicalRangeRange
![Page 17: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/17.jpg)
O-GlcNAc’ase Structure
OGA
Expressed in all human tissues studied
OGA peptide cleaves GlcNAc from glycopeptides
Single gene encodes 916 amino acid polypeptide of 103 kDa migrates at 130 kDa
Predominantly expressed in the cytoplasm
Highly conserved in mammals and found in C. Elegans
Located on Chromosome 10 in humans
![Page 18: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/18.jpg)
Functional aspects of O-
GlcNAcase Maps exactly to 10q23.1 - late onset
Alzheimer’s Disease Locus. Ogase has Histone Acetyltransferases
activity.Inhibition BLOCKS insulin signaling.
53 nM Ki inhibitor of53 nM Ki inhibitor ofO-GlcNAcase.O-GlcNAcase.
![Page 19: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/19.jpg)
Identification of O-GlcNAc Modified
Proteins by Mass Spectrometry
Generally Generally Not Not Affect Gel Affect Gel Electrophoresis Electrophoresis Not Easily Labeled - No Not Easily Labeled - No 3232P!P!Very LabileVery Labile - both Chemically - both Chemically and Enzymatically- Falls Off in and Enzymatically- Falls Off in MS.MS.StoichiometryStoichiometry Similar to O- Similar to O-Phosphate.Phosphate.
Why Did O-GlcNAc Remain Undetected?Why Did O-GlcNAc Remain Undetected?
![Page 20: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/20.jpg)
Fragmentation of GlcNAc-CTD by CID-MS/MS Parent ion 535 ([M+2H+] + 1 GlcNAc)
200 300 400 500 600 700 800 900 1000 1100 1200
m/z
05
101520253035404550556065707580859095
100
Rel
ativ
e A
bund
ance
866.3
410.3 819.2203.8616.2
433.8250.9476.8
NL 7.62e6Y--S--P--T--S--P--S--K
b ions - 164 251 348 449 536 633 720 848
866 703 616 519 418 331 234 147 - y ions
O-GlcNAc (204)
848.4
GlcNAc
b2
y6
b8
y8
Poor FragmentationPoor Fragmentation
No Site Information.No Site Information.PeptidePeptide
sugarsugar
![Page 21: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/21.jpg)
Alkaline inducedElimination
CNH
C
O
CH2
(Serine-O-GlcNAc)(dehydroalanine)
CNH
C
O
CH2
OGlcNAc
H
Strategy for O-GlcNAc/O-Phosphate site mapping
0
100
0
100
0
100
1314.3
PSVPVSerGSAPGR
O-GlcNAc
PSVPVSerGSAPGR
DTT
PSVPVSerGSAPGR
BAP
1247.4
1421.7
m/z1100 1650
m/z1100 1650
m/z1100 1650
MALDI-TOF
Replacement of O-GlcNAc with DTTUsing -elimination/michael addition
CNH
C
O
CH2H
DTT (or BAP)
Michael Addition
HSCH2CHOHCHOHCH2SH (DTT)
1. Provides tag forAffinity enrichment
2. Tag is stable in massspectrometer
Relative intensity
Relative intensity
Relative intensity
![Page 22: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/22.jpg)
BEMAD Useful for Simultaneous Mapping of O-GlcNAc and O-Phosphate:
O-GlcNAc much more sensitive to ß-Elimination. Treatment with Phosphatase & O-GlcNAcase. Density-Labeled DTT is Cheap & Available. Same Approach work for ‘classical’ O-glycans.
Phosphorylation Mapping studies Must Account for Abundance of O-GlcNAc.
![Page 23: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/23.jpg)
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Make GlcNAc derivative with a N3-reactive azide instead of AcUDP-GlcN -->-->Protein with O-GlcN
Probe with FLAG or biotin
Detect Probe
Another way to recognize O-GlcNAc proteins
Vocadlo DJ, Hang HC, Kim EJ, Hanover JA, Bertozzi CR.Proc Natl Acad Sci U S A. 2003 Aug 5;100(16):9116-21
![Page 24: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/24.jpg)
OH
O
AcNHHO
HOO
-Leu-Leu-Pro-Thr58-Pro-Pro-Leu-
-Leu-Leu-Pro-Thr58-Pro-Pro-Leu-OO
O O
Reciprocal Reciprocal O-GlcNAcylation & Phosphorylation of O-GlcNAcylation & Phosphorylation of c-Mycc-Myc::
-P-O-P-O----OO
Thr58 is Mutation Hot Spot Thr58 is Mutation Hot Spot In Human Lymphomas.In Human Lymphomas.
![Page 25: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/25.jpg)
Mutations of c-Myc in LymphomasMajor O-GlcNAc Site.Major O-GlcNAc Site.
Transactivation DomainTransactivation Domain
GSK3GSK3
ErkErk
Site-Specific mAB - Thr58-O-GlcNAc:1. Prevention of Phosphorylation at Ser 62 Elevates O-GlcNAc at Thr 58.2. Stim. Of Growth Reduces O-GlcNAc at T58; Increases Phos. & vice versa.3. Inhibition of GSK3ß increases O-GlcNAc at T58.4. Regulates c-Myc association with Tumor Suppressor Rb p107.
![Page 26: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/26.jpg)
Heat ShockUV
Osmotic StressFree Radicals
Reductive Stress
Heat Shock ProteinsGlutathione
SODCatalase
X X
O-GlcNAc O-GlcNAc
The rapid increase in O-GlcNAc and the effect of increased HSP70 in the presence of increased O-GlcNAc suggests that O-
GlcNAc forms an integral component of the cell’s stress signaling pathways.Natasha ZacharaNatasha Zachara
![Page 27: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/27.jpg)
The Addition of O-GlcNAc to Proteins in Response to Stress is Dynamic
Cos-7 cells were treated with heat shock (45oC, 1h) and allowed to recover at 37oC.
177
114
80
64
50
37
WB: O-GlcNAc
WB: HSC/HSP70
1 3 6 48 48 hTime post-heat shockCont Cont
9 241
O-GlcNAc Precedes HSP70 O-GlcNAc Precedes HSP70
![Page 28: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/28.jpg)
O-GlcNAc is A Sensor of Cellular Stress:
O-GlcNAc and OGT are rapidly elevated in response to many forms of cellular stressThis is dose dependent; does not require mRNA or Protein
Synthesis Increased levels of O-GlcNAc results in increased
thermotolerance In part a result of more rapid increased HSP70
production/stabilization.HSP70 as an O-GlcNAc lectin - 2 French Groups.Decreased protein aggregation?
Decreased O-GlcNAc Results in decreased thermotolerance
![Page 29: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/29.jpg)
UDP-GlcNAc as a Metabolic Sensor:
UDUDPP--GlcGlcNNAcAc
Glucose Glucose MetabolismMetabolism
NitrogenNitrogenMetabolismMetabolism
Fatty AcidFatty AcidMetabolismMetabolism
Nucleotide Nucleotide MetabolismMetabolism
OverallOverallEnergy Energy
![Page 30: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/30.jpg)
REVIEW OF METABOLIC PATHWAYS
![Page 31: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/31.jpg)
Elevation of O-GlcNAc Blocks Insulin Signaling:Elevation of O-GlcNAc Blocks Insulin Signaling:• Huge Literature - Diabetes Requires Glc to GlcNAc.Huge Literature - Diabetes Requires Glc to GlcNAc.• GlcN 10X more potent than Glc in inducing Insulin-Resistance.GlcN 10X more potent than Glc in inducing Insulin-Resistance.• O-GlcNAc is Elevated in Muscle and Adipose in Diabetic Animals.O-GlcNAc is Elevated in Muscle and Adipose in Diabetic Animals.
![Page 32: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/32.jpg)
[UDP-GlcNAc]
HSP
OGT
x-Ser/thr-x-x x-Ser/thr-x-xO-GlcNAc
O-GlcNAcase
glucoseGlut4vesicle
PDK1
AKT1/2
Thr 308-P
PKC
GSK3
P-Y IRS1/2
Insulinreceptor
P-Y
p85
p110
PI 3-kinase
Glycogen synthesis
Ser 9-P
PUGNAc
!Insulin resistance
Elevation of O-GlcNAc Blocks Insulin Elevation of O-GlcNAc Blocks Insulin Signaling:Signaling:
• Huge Literature - Diabetes Requires Glc to GlcNAc.Huge Literature - Diabetes Requires Glc to GlcNAc.• GlcN 10X more potent than Glc in inducing Insulin-Resistance.GlcN 10X more potent than Glc in inducing Insulin-Resistance.• O-GlcNAc is Elevated in Muscle and Adipose in Diabetic O-GlcNAc is Elevated in Muscle and Adipose in Diabetic Animals.Animals.
****
**??
Does Specific Elevation of Does Specific Elevation of O-GlcNAc Cause InsulinO-GlcNAc Cause InsulinResistance? Resistance? Yes!Yes!
**
**
![Page 33: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/33.jpg)
Glucosamine (mM) 0 0 5 5chronic insulin (nM) 0 1 1 0
Deo
x ygl
ucos
e u p
tak e
(in
sulin
de p
end e
nt 14
[C] D
PM)
20000
10000
0
51%
WB: anti-O-GlcNAc
Insulin Resistance induced through the HBP correlates with increased O-GlcNAc in 3T3-L1 Adipocytes
Requires Both GlcN & InsulinRequires Both GlcN & Insulinfor Insulin-Resistancefor Insulin-Resistance& for Elevated O-GlcNAc.& for Elevated O-GlcNAc.
![Page 34: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/34.jpg)
(A)
Insulin concentration (nM)
23%
39%
Acute insulin (nM) 0 0 1 1 10 10PUGNAc - + - + - +
WB:anti-O-GlcNAc110.6 antibody
PUGNAc - + - + - + - + - + Acute Insulin (nM) 0.1 0.33 1 3.3 10
Deo
xygl
ucos
e u p
tak e
(in
sulin
de p
end e
nt 14
[C] D
PM)
(B)
PUGNAc Elevates O-GlcNAc and Induces
Insulin Resistance in 3T3-L1 adipocytes:
53 nM Ki inhibitor of53 nM Ki inhibitor ofO-GlcNAcase.O-GlcNAcase.
![Page 35: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/35.jpg)
Insulin Signaling Pathway for Glut4 Translocation to Plasma Membrane - Where is O-GlcNAc
Blocking?
IRS
PI3K
PDK1
AKT
GSK3
PKC
Glut4
???
IR
-O-GlcNAc-O-GlcNAc
Many O-GlcNAcMany O-GlcNAcIncluding Including Munc18Munc18
Glycogen SynthaseGlycogen Synthase-->-->
-O-GlcNAc-O-GlcNAc
-O-GlcNAc
-O-GlcNAc
![Page 36: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/36.jpg)
PUGNAc does PUGNAc does notnot effect the protein levels or insulin stimulated effect the protein levels or insulin stimulated tyrosine phosphorylation of the insulin receptor or IRS-2.tyrosine phosphorylation of the insulin receptor or IRS-2.
PUGNAC PUGNAC BlocksBlocks Insulin-Stimulated Insulin-Stimulated Phosphorylation of Phosphorylation of Threonine 308Threonine 308 on AKT/PkB*: on AKT/PkB*:
AKT Activation is Blocked!AKT Activation is Blocked!
PUGNAc PUGNAc BlocksBlocks Insulin-Stimulated Phosphorylation of GSK3ß at Insulin-Stimulated Phosphorylation of GSK3ß at Ser9Ser9, , But But NotNot Thr202/204 MAPK or Ser473 on Akt/PKB: Thr202/204 MAPK or Ser473 on Akt/PKB:
GSK3ß Activation is Blocked!GSK3ß Activation is Blocked!
![Page 37: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/37.jpg)
[UDP-GlcNAc]
HSP
OGT
x-Ser/thr-x-x x-Ser/thr-x-xO-GlcNAc
O-GlcNAcase
glucoseGlut4vesicle
PDK1
AKT1/2
Thr 308-P
PKC
GSK3
P-Y IRS1/2
Insulinreceptor
P-Y
p85
p110
PI 3-kinase
Glycogen synthesis
Ser 9-P
PUGNAc
!Insulin resistance
Elevation of O-GlcNAc Blocks Insulin Signaling:Elevation of O-GlcNAc Blocks Insulin Signaling:•Blocks AKT phos. at T308 and S9 on GSK3ßBlocks AKT phos. at T308 and S9 on GSK3ß
•Inhib. OGase greatly increases OG on ß-catenin Inhib. OGase greatly increases OG on ß-catenin and IRS1.and IRS1.
Transgenic Mice with OverexpressedTransgenic Mice with OverexpressedOGT in Muscle or Adipose - OGT in Muscle or Adipose - BecomeBecome
Diabetic.Diabetic. (McClain & Hanover) (McClain & Hanover)
****
**??
**
??
![Page 38: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/38.jpg)
Insulin (nM) 0 1 100
IP: OGTWB: OGT
IP: OGTWB:PY
OGT
OGT
Fig. Insulin stimulated tyrosine phosphorylation of O-GlcNAc transferase (OGT). 3T3L1 adipocytes starved of growth factorsFor 16 hours were stimulated 10 minutes with insulin at suboptimal (1 nM) or optimal (100 nM) concentrations, and OGT Immunoprecipitates were western blotted for either OGT levels or phosphotyrosine.
Note: activity of these immunoprecipWas tested with no differences against CKII peptide. Post-translational modification may effectlocalization, substrate specificity, binding Partners, ect. (SH2 domain containing protein?)Phospho-tyrosine response would place OGT in Signaling pathway downstream of insulin Receptor. time point coincides with start of glucose Uptake assay.
Insulin Stimulates (10 Insulin Stimulates (10 min)Tyr-min)Tyr-PP
Of O-GlcNAc Transferase:Of O-GlcNAc Transferase:
OGT is Directly in the IR Signaling Pathway.OGT is Directly in the IR Signaling Pathway.
![Page 39: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/39.jpg)
Fig. Insulin stimulates dynamic O-GlcNAcylation in 3T3L1 adipocytes. 3T3L1 adipocytes starved of growth factors for 16 hours Were stimulated with 100 nm insulin for 10 minutes, and whole cell lysates were separated by 2D gel electrophoresis and western blotted With an anti-O-GlcNAc specific antibody.
Spot # response to insulin1 decreased O-GlcNAc2 decreased O-GlcNAc3 likely phosphorylation shift4 decreased O-GlcNAc5 likely phosphorylation shift6 decreased O-GlcNAc7 decreased O-GlcNAc
1
1
2
2
3
3
4
4 5
5
6
6
7
7
pI 4.5pI 5
unstimulated
Insulin stimulated(100 nM for 10 min.)
Proteomics Approach to O-GlcNAc & Insulin SignalingProteomics Approach to O-GlcNAc & Insulin Signaling::Insulin Insulin Rapidly DecreasesRapidly DecreasesO-GlcNAc on Many Proteins:O-GlcNAc on Many Proteins:
Insulin Causes Major Insulin Causes Major Changes in O-GlcNAc Changes in O-GlcNAc in in 10 min.10 min.
(Small Portion of (Small Portion of Gel Shown)Gel Shown)
![Page 40: ESSENTIALS OF GLYCOBIOLOGY LECTURE 15 The O-GlcNAc Modification Hud Freeze](https://reader031.fdocuments.in/reader031/viewer/2022020919/56816039550346895dcf5b35/html5/thumbnails/40.jpg)
Conclusions:• O-GlcNAc is a Major Regulatory PTM in all multicellular
eukaryotes - Plants & Animals.• O-GlcNAc Accounts for Many of the Biological Affects
Attributed Hexosamine Biosynthetic Pathway - Diabetes & Glucose Toxicity.
• O-GlcNAc is Required for Life at the Single Cell Level.• O-GlcNAc is as abundant as Phosphorylation and
Often Competes with it.• O-GlcNAc - “Metabolic Sensor” to Modulate Signaling
& Transcription in Response to Cellular Status.• Many Toxic Effects of Hyperglycemia Likely Result
From Dysregulation of the Balance Between O-GlcNAc and Phosphorylation.