Zhuet al.,Science 375 , eabg9765 (2022) 21 January 2022 5 of 11
B External inducers switch cells between states
A Modulating TF stability destabilizes specific states and allows irreversible transitions
0 12
TF A
0
12
TF B
0 25
TF A
0
25
TF B
0 25
TF A
0
25
TF B
Modeling
High TMP Low TMP High TMP
Nullclines
Stable fixed point
Unstable fixed point
Separatrix
Attractor basins
Simulated cells
= 0.8, = 20
Experiment
= 0.4, = 10 = 0.8, = 20
A-only
B-only A + B
OFF
0
20
40
60
80
100
% of cells
High TMP Low TMP High TMP
Initial state Day 0 Day 9 Day 18 Day 27 Day 36 Day 45
A + B
Day 0 Day 3 Day 6 Day 9 Day 18
Type II tristability regime
High TMP
- Dox + Dox - Dox
- 4-OHT + 4-OHT - 4-OHT
High TMP Low TMP High TMP
A-only
High TMP
- 4-OHT + 4-OHT - 4-OHT
B-only
A + B
Initial state
High TMP
- Dox + Dox - Dox
Low TMP High TMP
A + B
Bistability regime
Low TMP
- Dox + Dox - Dox
Low TMP
- 4-OHT + 4-OHT - 4-OHT
A-only
B-only
Initial state Day 0 Day 3 Day 6 Day 9 Day 18
B
Dox
A
4-OHT
Fig. 4. MultiFate-2 supports modulation of state stability and allows
state switching.(A) Escape from the destabilized A+B state was irreversible,
as shown by both modeling and experiments that used MultiFate-2.1 cells.
Top: The model used here is symmetric and nondimensionalized, with rescaled
dimerization dissociation constantKd= 1 and Hill coefficientn= 1.5 (Box 1).
Thexandyaxes are total dimensionless concentrations of TF A and TF B,
respectively. Simulated cells on phase portraits were calculated using the Gillespie
algorithm ( 25 , 54 ). Note that in the nondimensionalized model, changing protein
stability is equivalent to multiplyingaandbwith the same factor (Box 1).
Bottom: Throughout the experiment, we added 100 nM AP1903. Exact concen-
trations of TMP are shown in fig. S9. (B) MultiFate-2.3 cells can be switched
between states by transient 4-OHT (25 nM) or Dox (500 ng/ml) treatment. In
all conditions, we added 100 nM AP1903. Exact concentrations of TMP are
shown in fig. S16. In all panels, initial A-only, B-only, and A+B cells
were sorted from a population of cells in different states. Each square repre-
sents the mean fractions of three biological replicates.
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