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Adhesion? Sticking & Signalling. E. Yvonne Jones Erice 2006. T cell – target cell interactions, a particular form of cell-cell communication with specificity contributed by pMHC – TCR binding. Result: T cell receptor (TCR) signalling and formation of an ‘Immunological Synapse’. - PowerPoint PPT Presentation
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Adhesion?
Sticking &Signalling
E. Yvonne JonesErice 2006
T cell – target cell interactions, a particular form of cell-cell communication withspecificity contributed by pMHC – TCR binding.
Result: T cell receptor (TCR) signalling and formation of an ‘ImmunologicalSynapse’.
Immunodominant HLA-A2 tumour epitope NY-ESO-1157-165: SLLMWITQC
SLLMWITQV stimulates faster polarisation of lytic granules to the immunological synapse
Chen & Stewart-Jones et al (2005) J. Exp. Med. 201 1243-1255
But, all pMHCs are not equal…
Structure of the immunodominant V17-V10s2 T cell receptor with HLA A2/influenza matrix epitope
…..as used by >one billion humans!
and all TCRs are not equal…
Stewart-Jones et al (2003) Nature Immunol. 4 657-663
Vβ17 Flu Matrix T Cells- The Most Abundant T cell Clonotype on the Planet
• An estimated 3 billion people have HLA-A2• All have had Influenza• Flu matrix responses dominate the immune
reaction to infection• Vβ17 clonotype constitutes > 80% of that
response• 0.5 kg of this receptor circulating in the world• Stacking the receptors end-to-end would stretch
more than halfway to Neptune (2.6 billion km)
Guillaume Stewart-Jones, Jeffrey Ishizuka & John Bell, unpublished calculation
Why is a V17-V10s2 TCRso good at recognising HLA A2/influenza matrix epitope?
Kuby, 4th edition
T cell receptors
(TCRs)
Gene segment
s
Combinations
Vα 50
Jα 502.5 x 103 alpha chains
Vβ 20
Jβ 13
Dβ 2520 beta chains
Any alpha with any beta chain
1.3 x 106The potential TCR repertoire is further increased by the addition of N region nucleotides. The recombination process is not precise. • the exact points of splicing between V, D and J regions can vary over several nucleotides • extra nucleotides, called N regions, can also be inserted at these joints.
The number of TCRs that we make is ~2.5 x 107
Flu matrixpeptide presentedby HLA-A2 providesfew sidechainsfor TCR recognition
The challenge
TCR positioned to insert CRD3 between peptideand alpha 2 helix
The answer
Why is a V17-V10s2 TCRso good at recognising HLA A2/influenza matrix epitope?
Its because of a distinctive CDR3 motifand combination of residues unique to V17-V10s2 CDR1 and CDR2 loopsthat allow the CDR3 to be positioned optimally to sample a unique feature of the pMHC surface
Stewart-Jones et al (2003) Nature Immunol. 4, 657-663
sTCR mutants made and testedMutation (Vβ) Construct Produced? Expressed? Refolded and Purified? Measurable Binding to pMHC? Kinetic Data collected? Thermodynamic Data Collected?Wildtype Y Y Y Y Y YD32A Y Y Y Y Y ND32S Y Y Y N N NQ52A Y Y Y N N NQ52E Y Y Y N N NI53A Y Y Y N N NI53G Y Y Y N N NI53N Y Y Y N N NI53V Y Y Y Y Y YI53L Y Y Y Y Y NN55A Y Y Y Y Y YN55D Y Y Y Y Y YD56A Y Y Y Y Y YQ58A Y Y Y Y Y YQ58E Y Y Y Y Y YS99A Y Y Y Y Y YR98A Y Y Y N N NR98H Y Y Y N N NY101A Y Y Y Y Y YY101F Y Y Y Y Y Y
Mutation (Vα)S31A Y Y Y Y Y YS31T Y Y Y N N NS32A Y Y Y Y Y YS32R Y Y Y Y Y NQ34A Y Y Y Y Y YV51A Y N N N N NA93S Y Y Y Y Y NS95R/Q96E Y Y Y Y Y Y
Jeffrey Ishizuka & Guillaume Stewart-Jones
Vβ17 CDR2 Offers a Unique Sequence and Energetic Landscape
So we are still on target with our hypothesis for why a V17-V10s2 TCR is so good at recognising HLA A2/influenza matrix epitope.
But why is this TCR-pMHC immunodominant over all other TCR-pMHC interactions involving influenza virus epitopes presented by theMHC class I molecule HLA A2?
T cell – target cell interactions, a particular form of cell-cell communication withspecificity contributed by pMHC – TCR binding.
Result: T cell receptor (TCR) signalling and formation of an ‘ImmunologicalSynapse’.
SS
SS
SS
SS
SS
SS
CD
45
CR
YP
RP
TP
LA
RR
PT
P
1 2D
PT
P6 9
D
RP
TP
RP
TP
RP
TP
DP
TP
10D
CR
YP
2
DP
TP
99A
RP
TP
RP
TP
RP
TP
PT
P-
S
RP
TP
Ph
osp
hac
an
PT
P-I
A2
Type I IIA IIB III IV V VI VII
PT
P-B
R7/
SL
SS
SS
SS
SS
SS
SS
DL
AR
catalyticPTP domain
FN-III-likedomain
Ig-like domain
MAM domain
Highlyglycosilateddomain
carbonic anhydrase-related domain
Cys-rich domain
related to cadherinintracellular region
protease cleavage site
SS
Receptor protein tyrosine phosphatases: classification
A
B
C
D
RPTP expression on axonal growth cones (A and B, Ledig et al., 1999) and at the endothelial cell junctions (C and D, Bianchi et al., 1999).
RPTP is a cell-adhesion molecule involved in neural development (axon growth) and angiogenesis.
SS
RPTP
Crystal structure of the MAM-Ig unit Aricescu & Hon (2006) EMBO J. 25 701-712
RPTP
SS
N
C
for dimersneedMIg-FNIII
RPTP
SS
N
C
SS
MAM-Ig
RPTP
SS
N
C
and for adhesionneedMIg-2xFNIII
so…
*
structure
function?
NO
MIg structure plus biophysical and functional data generatedseveral possible models for RPTP adhesive interactions
****
monomer pH-dependent dimer (trans)
trans/trans zipper trans/cis zipper
Zipper model, consistent with the extended planarity of the plasma membrane observed at intercellular contact sites and with the multiple interactions observed between RPTP ectodomains
I recommend you go and see Radu Aricescu’s poster in the Thursday afternoon session
(also Christian Siebold’s poster on cell guidance signalling…)
Christian Siebold
Radu Aricescu
Weixian Lu
(Jeffrey Ishizuka) &Guillaume Stewart-Jones
In collaboration with: John Bell, Vincenzo Cerundolo,Andrew McMichael & Anton van der Merwe
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