cell cycle

1
The LINKS and CONTROLS between the
INITIATION of the CELL CYCLE the INITIATION of
APOPTOSIS Baltazar D. Aguda Dept Genetics
Genomics Boston Univ School of Medicine Dept
Biomedical Engineering Boston University bdaguda
_at_bu.edu http//www.bu.edu/genome
Mathematical Biosciences Institute (Ohio State
Univ), 2 October 2003
2
Partitioning network into modules signaling,
cell cycle, apoptosis
Control nodes
Module for initiation of S-phase CDK2 activation
Module for initiation of apoptosis Caspase
activation
Module-module interactions computer simulations
Experimental Controlling onset of apoptosis in a
CML cell line
3
CLASSIFICATION OF SIGNALING PATHWAYS
signal
signal
signal
signal
die
cycle
die
cycle
die
cycle
die
cycle
I
II
III
IV
4
Mammalian Cell Cycle
5
INITIATION OF S PHASE
GFs
Cyclin-D/cdk4
Cyclin-A/cdk2
TK, DHFR
p16, p27
pRb
pRB
Cdc6
Cdc45
E2F
ORC
DP
MCMs
GFs
Cdc7/Dbf4
Cdk2/Cyclin-E
Cdk2/Cyclin-E
Cdc25A
p27
Myc
Max
GFs
6
How to handle qualitative information? (an
aside)
.
X F(X)
.
mij ? 0 Xj activates
Xi ( Xj Xi )
mij ? 0 Xj inhibits Xi
( Xj Xi )
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Measurement of mijs
X1
?X1/ ?X2 m12 ? 0
X2
X2
X1
X2
X1
t2
t3
t2
t3
t1
t1
time
X1
?X1/ ?X2 m12 ? 0
X2
X2
X1
X2
X1
t2
t3
t2
t3
t1
t1
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Cycles and Linear Stability Analysis
P(l) det(lI-M) ln a1ln-1
a2 ln-2 an-1l an 0 where a1
?i -C1(i) a2 ?i,j -C1(i)-C1(j)
?jk -C2(jk) a3 ?i,j,k -C1(i)-C1(j)-C1(
k) ?i,jk -C1(i)-C2(jk) ?ijk -C3(ijk)
... where C1(i) mii (1-cycles)
C2(jk) mjkmkj (2-cycles) C3(ijk)
mijmjkmki (3-cycles) ...
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Reaction mechanism
0
k2
1
2
3
X
Y
dX/dt k1 k2X dY/dt k2X k3Y
M
k2
k3
m11
m22
X
Y
m21
qNET graph
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initiation of S phase
Cyclin-D/cdk4
Cyclin-A/cdk2
TK, DHFR
pRb
pRB
Cdc6
E2F
ORC
DP
MCMs
pre-RC
Cdc7
Cdk2/Cyclin-E
Cdk2/Cyclin-E
Cdc25A
p27
Myc
Max
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A SHARP SWITCH
p27/CycE/CDK2
.
.
.
iCycE/CDK2
p27
aCycE/CDK2
.
.
.
.
aCdc25A
iCdc25A
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Transcritical Bifurcation in Positively Coupled
Cycles
Y2ss
s
u
s
0
E2
Y2ss
0
E1
ss
Y1
ss
ss
Y2
mass-action kinetics in graphs shown similar for
Michaelis-Menten kinetics
0
E1
Ei Xi Yi
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Simulation of CDK2 activation
1 sustained 2 t_off 80 3 t_off 50 4
t_off 30 5 t_off 29 6 t_off 28
time
GFs
Cyclin D/CDK4
BD Aguda Y Tang (1999) Cell Prolif. 32 321.
14
Ekholm SV, Zickert P, Reed SI,
Zetterberg A. (2001) Mol Cell Biol 21 3256-3265.
Fig 7 of reference above
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16
Links between Myc, E2F and S-phase initiation
Myc
E2F
Rb
cycD/cdk4
p27
Cdc25A
cycE/cdk2
S phase
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INITIATION OF APOPTOSIS
Pathways of Caspase activation (from Zheng
Flavell, 2000)
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Links between Myc, E2F and apoptosis
initiation
Myc
E2F
p53
Mdm2
ARF
Bax
Bcl-2
Bad
DISC
Apoptosome
Exec. Caspases
Apoptosis
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signal
details of Case I
die
cycle
Myc
E2F
Rb
cycD/cdk4
p53
Mdm2
ARF
Bax
Bcl-2
Bad
p27
Cdc25A
cycE/cdk2
DISC
S phase
Apoptosome
Exec. Caspases
Apoptosis
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dividing dying at the same time
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modeling Case I
A
B
vs
vms
signal
signal
b
v1
S1
S2
b
vm1
v2
vm2
G2
a
c
v4
v3
die
A1
A2
C1
C2
cycle
vm4
vm3
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Negative feedback b
Meloche S (1995). J Cellular Physiology 163 577.
multiple activation of Ras pathway Lee KY et
al. (1999) Mol Cell Biol 19 7724. Rb to Ras
Feedforward c
Konishi Y et al. (2002). Mol Cell 9 1005. cdc2
to BAD Mendelsohn AR et al. (2002) PNAS 996871.
cyclin D3 to caspase2
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quiescence to cell cycle to apoptosis
25
Coupling between Cases I and II
Signal II
Signal I
Transcrip. factors (e.g. Myc, E2F-1)
Signaling proteins (e.g. Akt )
Cell cycle
Apoptosis
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Akt suppresses apoptosis and enhances
proliferation.
Akt
Myc
E2F
Rb
cycD/cdk4
p53
Mdm2
ARF
Bax
Bcl-2
Bad
p27
Cdc25A
cycE/cdk2
p21
DISC
S phase
Apoptosome
Exec. Caspases
Apoptosis
28
CHRONIC MYELOID LEUKEMIA (CML)
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BCR-ABL
Ras/MAPK
STATs
PI3K/Akt
Sonoyama et al. (2002) Functional cooperation
among Ras, STAT5, and Phosphatidylinositol
3-Kinase is required for full oncogenic
activities of BCR/ABL in K562 cells, J. Biol.
Chem. 277 8076.
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31
Inhibition of Akt in K562 cells
A
B
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Caspase-3,-7 activation
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Akt inhibitor - treated K562 cells
12 h
control
12 h
36 h
36 h
gt 36 h
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Dramatic changes in the cell cycle profile of Akt
inhibitor-treated K562 cells, after 25h
incubation. Treatment of the K562 cells with the
Akt inhibitor for about 25h (unshaded solid line
histogram), induced an even more dramatic shift
in the first peak to a lower channel in the FACS
histogram (compare with 18h incubation shown in
Fig. 3a). The insets (A, B and C) are ModFit
analysis of the raw FACS histograms for more
quantitative modeling of cells at various cell
cycle phases (insets A B) as well as the
proportion of cell debris, aggregates and
subG1/G0 phase (inset C). There was a dramatic
decrease in the percentage of cells in diploid
state (compare Control and Akt inhibitor in inset
A), complicating the interpretation of the
histograms these are discussed further in the
Results and Discussion.
35
http//www.bu.edu/genome bdaguda_at_bu.edu
Lab Members
Baltazar D. Aguda Yang Su Mary
Wong Cornelio Caday Yuan Cheng
Collaborators
Joyce Wong cell cycle/apoptosis in
EC/SMC Landon Moore chromosomal instability in
C. elegans
Whitaker Foundation Grant