Mitogen-Activated Protein Kinase 1

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Mitogen-Activated Protein Kinase 1

• Emerlyn Goh

2
Overview

• Introduction
• Structure
• Function
• Related Molecules
• Specific Aspect
• References

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Introduction

• What is a kinase?
• Phosphorylation
• What are mitogen-activated protein kinases?
• a.k.a MAPKs (microtubule-associated protein
  kinase/mitogen activated protein kinase), ERKs
  (extracellular signal-regulated kinases)
• History
• Signal transduction pathways
• Highly Conserved
• Transmembrane communication
• MAP2K, MAP3K

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MAP Kinase Cascades
Source CALBIOCHEM et al, 2008
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ERK1/2 Signal Transduction Pathway

• ERK1/2 similar (ERK2 focus)
• ERK2 MAPK1
• Mitogen(EGF)?Receptor (RTK)?GTPase(ras)?Protein
  kinase (raf)?MAPK cascade?cellular response
• Often called Ras-Raf-MEK-ERK pathway
• Mechanisms of activation of MAP3K largely unknown
• Thr-575 important

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The MAPK Signal Transduction Pathway(Krysan)
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MAP2K (MEK1) ActivationPDB ID 1s9j (Ohren et
al, 2004)
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Structure of ERK2

• Inactive form Tyr-185 blocks active site
• 2 domains further apart
• Active form Tyr-195, Thr-183
• Dual phosphorylation
• Alignment of p-tyrosine p-threonine, turn
  towards surface arginine-rich binding sites to
  maximize ATP binding
• Local and global conformation changes
• Active site closure

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Unphosphorylated ERK2
Phosphorylated ERK2
PDB ID 1ERK (Zhang et al, 1997) and 2ERK
(Canagarajah et al, 1998)
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Structure Comparison Activated/Inactivated
Residues of ERK2
PDB ID 1ERK (Zhang et al, 1997) and 2ERK
(Canagarajah et al, 1998)
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Functions of ERK2

• Regulates proliferation and differentiation of
  post-mitotic cells
• Development of the mesoderm/placenta in many
  eukaryotes
• Cell growth (ex. transcription factor Elk-1)
• Phosphorylation of P53 in cervical/breast
  carcinoma cells by ERK2 suggests apoptosis
• Cell cycle progression and cancer expression (ex.
  transcription factor c-myc)

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Functions, Explained

• Elk-1 transcription factor involved in the
  expression of c-fos (Gille et al, 1995)
• C-fos accounts for cell differentiation, growth
• P53 Breast carcinoma cells doxorubicin ?
  activation of ERK2 ? phosphorylates P53 on Thr-55
  residue ? suggests apoptosis in some cells and
  drug resistance in cancerous mutants (Pei et al,
  2004)
• C-Myc proto-oncogene regulated by MAPK pathway
• Overexpression? pancreatic/colon cancers
• Cyclin expression and G1-S progression
• Cancer treatment? (Marampon et al, 2006)

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Related Molecule MKP3

• Dual specificity MAPK phosphatases (MKPs/DSPs)
• MKP3 (DUSP6) prototypical ERK2-specific
• Able to form stable complex with ERK2
• KIM peptide binds to N-terminal noncatalytic site
  opposite activation loop of ERK2
• Tightly bound for catalytic activation,
  dephosphorylation of ERK2
• Underexpression ? ERK2 overexpression?pancreatic
  carcinogenesis

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DUSP6 KIM Peptide Complexed with ERK2PDB ID 2fys
(Liu et al, 2006)
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Activation of MKP3

• Activation site is a shallow cleft to accommodate
  Tyr/Thr residues on ERK2
• Inactivated MKP3 Asp-262 found in loop 5.5Å
  away from active site
• Once ERK2 binds Asp-262 loop folds to bring
  aspartate into active site? catalytically active
  stable conformation
• (Theodosiou et al, 2002)

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Unactivated MKP3 (PDB ID 1MKP Stewart et al,
1998)
PDB ID 1MKP (Stewart et al, 1999)
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How is MKP3 Regulated?

• Posttranslational mechanism by ERK2
• Via MEK-ERK pathway MKP3 phosphorylated on
  Ser-159, Ser-197
• Phosphorylation on either serine enhances
  proteasomal degradation of MKP3
• Experiment Double mutations on the serines
  caused 3-fold increase in MKP3 half-life
• This is a positive feedback loop by ERK2 by
  promoting degradation of one of its main
  inhibitors
• (Marchetti et al, 2005)

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Related Molecule Aurora-A Kinase

• AURKA gene
• C-terminal domain centered around Leu-374 and
  Arg-371
• Key roles in cell mitosis
• Potential oncogene, uncertain
• Pancreatic cancer linked to hyperactivation and
  overexpression of Aurora-A by MAPK pathway
• Drug treatment options?
• (Fu et al, 2007)

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Aurora-A Kinase in Complex with Adenosine
(PDB ID 1MUO Cheetham et al, 2002)
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Close-up of Adenosine Binding Sites on Aurora-A
Kinase
(PDB ID 1MUO Cheetham et al, 2002)
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Essential Role of ERK2 in Mesodermal and
Placental Development

• Experiment ERK2-deficient mice embryos ?
  placental development problems
• ERK2-deficient mice? poor fetal vascularization
  in placenta?severe defect in labyrinthine layer
  of placenta?poor development
• As a result fetuses exhibited extreme growth
  retardation, thin heart walls, and death (Hatano
  et al, 2003)
• Experiment ERK2 mutant embryos failed to develop
  mesoderm, defective differentiation (Li et al,
  2003)

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Codon 99 Mutant of ERK2 Wildtype, Heterozygous,
and Homozygous compared-Arrowheadfetal
nucleated erythrocytes-Arrowsmother nucleated
erythrocytes-Heterozygous?hypomorphic
alleleHatano et. al, 2003
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References

• Gille et al, 1995 http//www.ncbi.nlm.nih.gov/pub
  med/8548291
• Pei et al, 2004 http//www.nature.com/onc/journal
  /v23/n20/full/1207426a.htmlbib41
• Waas et al, 2007 http//www.ncbi.nlm.nih.gov/pubm
  ed/17251036?ordinalpos1itoolEntrezSystem2.PEntr
  ez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
• Theodosiou et al, 2002 http//www.pubmedcentral.n
  ih.gov/articlerender.fcgi?artid139386
• Marchetti et al, 2005 http//www.ncbi.nlm.nih.gov
  /pubmed/15632084
• Fu et al, 2007 http//mcr.aacrjournals.org/cgi/co
  ntent/full/5/1/1?cknck
• Hatano et al, 2003 http//www.genestocellsonline.
  org/cgi/reprint/8/11/847.pdf
• Stewart et al, 1998 PDB ID 1MKP Structure of
  MKP3
• Liu et al, 2006 PDB ID 1FYS
• Ohren et al, 2004 PDB ID 1s9j
• Krysan, http//www.hort.wisc.edu/Krysan/)
• Zhang et al, 1997 PDB ID 1ERK
• Canagarajah et al, 1998 PDB ID 2ERK
• Calbiochem et al, 2008 http//www.emdbiosciences.
  com/html/CBC/phosphorylation_inhibitors_mitogen-ac
  tivated_protein_kinase.htm
• Li et al, 2003 http//www.pnas.org/cgi/content/ab
  stract/100/22/12759
• Marampon et al, 2006 http//www.molecular-cancer.
  com/content/5/1/31
• Cheetham et al, 2002 http//www.rcsb.org/pdb/expl
  ore/explore.do?structureId1MUO