M ODELLING OF B IOCHEMICAL N ETWORKS WITH T IME P ETRI N ETS Monika - - PowerPoint PPT Presentation

HU BERLIN, APRIL 2005

MODELLING OF BIOCHEMICAL NETWORKS

WITH TIME PETRI NETS

Monika Heiner Brandenburg University of Technology Cottbus, Department of CS

MODEL- BASED SYSTEM ANALYSIS

Petrinetz model Problem system

system properties model properties

MODEL- BASED SYSTEM ANALYSIS

Petrinetz model Problem system

system properties model properties

technical system requirement specification verification

CONSTRUCTION

MODEL- BASED SYSTEM ANALYSIS

Petrinetz model Problem system

system properties model properties

biological system known unknown properties properties validation behaviour prediction

UNDERSTANDING

WHAT KIND OF MODEL

SHOULD BE USED ?

NETWORK REPRESENTATIONS, EX1

APOPTOSIS

FasL TNFα TNFβ

CD40L

NGF FAP-1 Daxx FADD

TRF2 TRF1 TRF3 TRF6 RIP NF-kB I-kB

RAIDD CASP8

Cytc CSP10

CASP4 CASP1 CASP6

DFF45 DFF40

CASP3 CASP7 CASP2 CASP9

Apaf-1 Bcl-xL Bcl-2a Hrk Bad Bax Mtd Mcl-1 A-1 Bcl-w DNA fragmentation Fas

TNFR1

CD40 TNFR2 GR

trkA Nucleus Mitochondria rupture Caspase cascade

Glucocortocoid

KEGG

NETWORK REPRESENTATIONS, EX1

APOPTOSIS

FasL TNFα TNFβ

CD40L

NGF FAP-1 Daxx FADD

TRF2 TRF1 TRF3 TRF6 RIP NF-kB I-kB

RAIDD CASP8

Cytc CSP10

CASP4 CASP1 CASP6

DFF45 DFF40

CASP3 CASP7 CASP2 CASP9

Apaf-1 Bcl-xL Bcl-2a Hrk Bad Bax Mtd Mcl-1 A-1 Bcl-w DNA fragmentation Fas

TNFR1

CD40 TNFR2 GR

trkA Nucleus Mitochondria rupture Caspase cascade

Glucocortocoid

• > INHIBITOR

ARCS KEGG

NETWORK REPRESENTATIONS, EX1

APOPTOSIS

FasL TNFα TNFβ

CD40L

NGF FAP-1 Daxx FADD

TRF2 TRF1 TRF3 TRF6 RIP NF-kB I-kB

RAIDD CASP8

Cytc CSP10

CASP4 CASP1 CASP6

DFF45 DFF40

CASP3 CASP7 CASP2 CASP9

Apaf-1 Bcl-xL Bcl-2a Hrk Bad Bax Mtd Mcl-1 A-1 Bcl-w DNA fragmentation Fas

TNFR1

CD40 TNFR2 GR

trkA Nucleus Mitochondria rupture Caspase cascade

Glucocortocoid

• > INHIBITOR

ARCS

• > ERROR

KEGG

NETWORK REPRESENTATIONS, EX1

APOPTOSIS

FasL TNFα TNFβ

CD40L

NGF FAP-1 Daxx FADD

TRF2 TRF1 TRF3 TRF6 RIP NF-kB I-kB

RAIDD CASP8

Cytc CSP10

CASP4 CASP1 CASP6

DFF45 DFF40

CASP3 CASP7 CASP2 CASP9

Apaf-1 Bcl-xL Bcl-2a Hrk Bad Bax Mtd Mcl-1 A-1 Bcl-w DNA fragmentation Fas

TNFR1

CD40 TNFR2 GR

trkA Nucleus Mitochondria rupture Caspase cascade

Glucocortocoid

• > INHIBITOR

ARCS

• > ERROR
• > INTERPRETATION ?

NETWORK REPRESENTATIONS, EX2

Ru5P 4 5 Xu5P R5P 6 S7P GAP 7 E4P F6P 8 GAP 15 NAD+ + Pi G6P F6P 10 ATP ADP FBP 11 12 DHAP 13 14 ATP ADP 9 Gluc 1,3-BPG ATP ADP 16 ATP ADP 19 NAD+ NADH 20 3PG 17 2PG PEP 18 Pyr Lac 2 NADP+ 2 NADPH 4 GSH 2 3 1 2 GSSG NADH

NETWORK REPRESENTATIONS, EX2

Ru5P 4 5 Xu5P R5P 6 S7P GAP 7 E4P F6P 8 GAP 15 NAD+ + Pi G6P F6P 10 ATP ADP FBP 11 12 DHAP 13 14 ATP ADP 9 Gluc 1,3-BPG ATP ADP 16 ATP ADP 19 NAD+ NADH 20 3PG 17 2PG PEP 18 Pyr Lac 2 NADP+ 2 NADPH 4 GSH 2 3 1 2 GSSG NADH

?? ??

NETWORK REPRESENTATIONS, EX2

Ru5P 4 5 Xu5P R5P 6 S7P GAP 7 E4P F6P 8 GAP 15 NAD+ + Pi G6P F6P 10 ATP ADP FBP 11 12 DHAP 13 14 ATP ADP 9 Gluc 1,3-BPG ATP ADP 16 ATP ADP 19 NAD+ NADH 20 3PG 17 2PG PEP 18 Pyr Lac 2 NADP+ 2 NADPH 4 GSH 2 3 1 2 GSSG NADH

• > INTERPRETATION ?

NETWORK REPRESENTATIONS, EX3

NETWORK REPRESENTATIONS, EX3 + EX4

NETWORK REPRESENTATIONS, EX3 + EX4

• > INHIBITOR

ARCS

NETWORK REPRESENTATIONS, EX3 + EX4

• > FORMAL SEMANTICS ?

NETWORK REPRESENTATIONS, EX5

NETWORK REPRESENTATIONS, EX5

• > READABILITY ?

BIONETWORKS, SOME PROBLEMS

❑ various, mostly ambiguous representations

• > PROBLEM 1
• > verbose descriptions
• > diverse graphical representations
• > contradictory and / or fuzzy statements

❑ knowledge

• > PROBLEM 2
• > uncertain
• > growing, changing
• > distributed over independent data bases, papers, journals, . . .

❑ network structures

• > PROBLEM 3
• > tend to grow fast
• > dense, apparently unstructured
• > hard to read
• - >> models are full of ASSUMPTIONS

<< - -

FRAMEWORK

bionetworks knowledge quantitative modelling quantitative models analysis /simulation understanding model validation quantitative behaviour prediction

ODEs

FRAMEWORK

quantitative parameters bionetworks knowledge qualitative modelling qualitative models quantitative modelling quantitative models animation / analysis analysis /simulation understanding model validation qualitative behaviour prediction understanding model validation quantitative behaviour prediction (invariants) model checking Petri net theory

ODEs

FRAMEWORK

bionetworks knowledge qualitative modelling qualitative models quantitative modelling quantitative models quantitative parameters animation / analysis analysis /simulation understanding model validation qualitative behaviour prediction understanding model validation quantitative behaviour prediction (invariants) model checking Petri net theory

ODEs

FRAMEWORK

bionetworks knowledge qualitative modelling qualitative models quantitative modelling quantitative models quantitative parameters animation / analysis animation / analysis /simulation understanding model validation qualitative behaviour prediction understanding model validation quantitative behaviour prediction (invariants) model checking Petri net theory

ODEs

L P S L I R G

PETRI NETS -

AN INFORMAL CRASH COURSE

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

O2 H+ NADH H2O NAD+

hyperarcs

2 2 2 2

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

❑ local conditions

• > Petri net places
• > chemical compounds

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2 pre-conditions post-conditions

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

❑ local conditions

• > Petri net places
• > chemical compounds

❑ multiplicities

• > Petri net arc weights
• > stoichiometric relations

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

❑ local conditions

• > Petri net places
• > chemical compounds

❑ multiplicities

• > Petri net arc weights
• > stoichiometric relations

❑ condition’s state

• > token(s) in its place
• > available amount (e.g. mol)

❑ system state

• > marking
• > compounds distribution

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

PETRI NETS, BASICS - THE STRUCTURE

❑ atomic actions

• > Petri net transitions
• > chemical reactions

❑ local conditions

• > Petri net places
• > chemical compounds

❑ multiplicities

• > Petri net arc weights
• > stoichiometric relations

❑ condition’s state

• > token(s) in its place
• > available amount (e.g. mol)

❑ system state

• > marking
• > compounds distribution

❑ PN = (P, T, F, m0), F: (P x T) U (T x P) -> N0, m0: P -> N0 input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

PETRI NETS, BASICS - THE BEHAVIOUR

❑ atomic actions

• > Petri net transitions
• > chemical reactions

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

PETRI NETS, BASICS - THE BEHAVIOUR

❑ atomic actions

• > Petri net transitions
• > chemical reactions

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

2 2 2 2 r1 O2 H+ NADH H2O NAD+

FIRING

PETRI NETS, BASICS - THE BEHAVIOUR

❑ atomic actions

• > Petri net transitions
• > chemical reactions

input compounds

• utput

compounds

2 2 2 2 r1 O2 H+ NADH H2O NAD+

2 NAD+ + 2 H2O -> 2 NADH + 2 H+ + O2

2 2 2 2 r1 O2 H+ NADH H2O NAD+

FIRING TOKEN GAME DYNAMIC BEHAVIOUR

(substance flow)

BIONETWORKS, INTRO

r1 A B

r1: A -> B

BIONETWORKS, INTRO

r3 r2 r1 E D C A B

r1: A -> B r2: B -> C + D r3: B -> D + E

• > alternative reactions

BIONETWORKS, INTRO

r3 r4 r7 r6 r2 r1 a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r6: C + b -> G + c r7: D + b -> H + c

• > concurrent reactions

BIONETWORKS, INTRO

r8 r5 r5_rev r8_rev r3 r4 r7 r6 r2 r1 a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r5: E + H <-> F r6: C + b -> G + c r7: D + b -> H + c r8: H <-> G

• > reversible reactions

BIONETWORKS, INTRO

r5 r8 r3 r4 r7 r6 r2 r1 a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r5: E + H <-> F r6: C + b -> G + c r7: D + b -> H + c r8: H <-> G

• > reversible reactions
• hierarchical nodes

BIONETWORKS, INTRO

2 28 29 29 r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a K b c c b d a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r5: E + H <-> F r6: C + b -> G + c r7: D + b -> H + c r8: H <-> G r9: G + b -> K + c + d r10: H + 28a + 29c -> 29b r11: d -> 2a

BIONETWORKS, INTRO

2 28 29 29 r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a K b c c b d a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r5: E + H <-> F r6: C + b -> G + c r7: D + b -> H + c r8: H <-> G r9: G + b -> K + c + d r10: H + 28a + 29c -> 29b r11: d -> 2a

BIONETWORKS, INTRO

2 28 29 29 r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a K b c c b d a F c b c b H G E D C A B

r1: A -> B r2: B -> C + D r4: F -> B + a r3: B -> D + E r5: E + H <-> F r6: C + b -> G + c r7: D + b -> H + c r8: H <-> G r9: G + b -> K + c + d r10: H + 28a + 29c -> 29b r11: d -> 2a input compound

• utput compound

stoichiometric relations fusion nodes - auxiliary compounds

TYPICAL BASIC STRUCTURES

❑ metabolic networks

• > substance flows

❑ signal transduction networks

• > signal flows

r3 r2 r1 e3 e2 e1 r3 r2 r1

BIONETWORKS, SUMMARY

❑ networks of (abstract) chemical reactions ❑ biochemically interpreted Petri net

• > partial order sequences of chemical reactions (= elementary actions)

transforming input into output compounds / signals [ respecting the given stoichiometric relations, if any ]

• > set of all pathways

from the input to the output compounds / signals [ respecting the stoichiometric relations, if any ] ❑ pathway

• > self-contained partial order sequence of elementary (re-) actions

❑ typical (structural) properties

INA ORD HOM NBM PUR CSV SCF CON SC Ft0 tF0 Fp0 pF0 MG SM FC EFC ES N N N Y N N Y N N N Y Y N N N N N DTP CPI CTI B SB REV DSt BSt DTr DCF L LV L&S N N N Y Y ? ? ? ? ? N ? N

BIONETWORKS, SUMMARY

❑ networks of (abstract) chemical reactions ❑ biochemically interpreted Petri net

• > partial order sequences of chemical reactions (= elementary actions)

transforming input into output compounds / signals [ respecting the given stoichiometric relations, if any ]

• > set of all pathways

from the input to the output compounds / signals [ respecting the stoichiometric relations, if any ] ❑ pathway

• > self-contained partial order sequence of elementary (re-) actions

❑ typical (structural) properties

INA ORD HOM NBM PUR CSV SCF CON SC Ft0 tF0 Fp0 pF0 MG SM FC EFC ES N N N Y N N Y N N N Y Y N N N N N DTP CPI CTI B SB REV DSt BSt DTr DCF L LV L&S N N N Y Y ? ? ? ? ? N ? N

BIONETWORKS NEED ENVIRONMENT BEHAVIOUR

❑ to animate the model

• > infinite substance flow
• > deeper insights

❑ to validate the model

• > consistency criteria

❑ steady flow

• > input substances
• > output substances

❑ auxiliary substances

• > as much as necessary

❑ minimal assumptions

2 28 29 29 r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a K b c c b d a F c b c b H G E D C A B

BIONETWORK WITH ENVIRONMENT BEHAVIOUR

❑ input substances

• > generating pre-transitions

❑

• utput substances
• > consuming post-transitions

❑ auxiliary substances

• > both

❑ no boundary places, but boundary transitions ❑ transitions without pre-places

• > live
• > all post-places are unbounded
• > all places simultaneously

unbounded (?)

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B

UNBOUNDEDNESS -

WHAT NEXT ?

BIONETWORKS, STEADY STATE BEHAVIOUR

❑ steady state behaviour

• > all possible flows preserving a given compounds distribution
• > elementary modes [Schuster 1993] = minimal T-invariants

❑ consistency criteria

• > pathways analysis
• > CTI
• > no minimal T-invariant without biological interpretation
• > no known biological behaviour without corresponding T-invariant

❑ typical properties

INA ORD HOM NBM PUR CSV SCF CON SC Ft0 tF0 Fp0 pF0 MG SM FC EFC ES N N N Y N N Y N Y Y N N N N N N N DTP CPI CTI B SB REV DSt BSt DTr DCF L LV L&S ? N Y N N ? N ? n n y y N

how to prove ?

T-INVARIANTS -

AN INFORMAL CRASH COURSE

INCIDENCE MATRIX C

❑ a representation of the net structure => stoichiometric matrix ❑ matrix entry cij: token change in place pi by firing of transition tj ❑ matrix column ∆tj: vector describing the change of the whole marking by firing of tj ❑ side-conditions are neglected

P T t1 tj tm p1 pi pn

cij

cij = (pi, tj) = F(tj,pi) - F(pi, tj) = ∆ tj(pi)

. . . . . . . . .

C =

∆tj ∆tj = ∆ tj(*)

enzyme MB2 MB1 enzyme-catalysed reaction x x

cij = 0 j i

T-INVARIANTS, BASICS

❑ Lautenbach, 1973 ❑ T-invariants

• > multisets of transitions
• > integer solutions x of
• > Parikh vector

❑ minimal T-invariants

• > there is no T-invariant with a smaller support
• > sets of transitions
• > gcD of all entries is 1

❑ any T-invariant is a non-negative linear combination of minimal ones

• > multiplication with a positive integer
• > addition
• > Division by gcD

❑ Covered by T-Invariants (CTI)

• > each transition belongs to a T-invariant
• > BND & LIVE => CTI (necessary condition)

Cx 0 x 0 x ≥ , ≠ , = kx aixi i

∑

=

T-INVARIANTS, INTERPRETATION

❑ T-invariants = (multi-) sets of transitions

• > zero effect on marking
• > reproducing a marking / system state
• > steady state substance flows / reaction rates
• > elementary modes [Schuster 1993]

❑ realizable T-invariants correspond to cycles in the RG

• > RG: concurrent transitions -> all transitions’ interleaving sequences
• > if there are concurrent transitions in a realizable T-invariant,

then there is a RG cycle for each interleaving sequence

• > analogously for conflicts

❑ a T-invariant defines a subnet

• > partial order structure
• > the T-invariant’s transitions (the support),

+ all their pre- and post-places + the arcs in between

• > pre-sets of support = post-sets of support

T-INVARIANTS IN BIONETWORKS trivial min. T-invariants (5)

❑ boundary transitions of auxiliary compounds

• > (g_a, r_a), (g_b, r_b),

(g_c, r_c) ❑ reversible reactions

• > (r5, r5_rev), (r8, r8_rev)

non-trivial min. T-invariants (7)

❑ covering boundary transitions of input / output compounds

• > i/o-T-invariants

❑ inner cycles

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B

• > CTI

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

BIOETWORK, I/O-T-INVARIANT

❑ i/o-T-invariant, example 12 | 0.r1 : 1 | 1.r2 : 1, | 3.r8_rev : 1, | 4.r6 : 1, | 5.r7 : 1, | 9.r9 : 2, | 12.r11 : 2, | 13.g_A : 1, | 14.r_K : 2, | 15.g_b : 4, | 18.r_c : 4, | 20.r_a : 4 ❑ sum equation A + 4b -> 2K +4a + 4c

2 28 29 29 r_a g_a r_c g_c r_b g_b r_K g_A r11 r5 r8 r3 r10 r9 r4 r7 r6 r2 r1 a b c a K b c c b d a F c b c b H G E D C A B 2x 2x 2x 4x 4x 4x

T-INVARIANTS, TWO INTERPRETATIONS

❑ Parikh vector

• > state-reproducing transition sequence (partial order)
• f transitions occuring one after the other
• > relative transition firing rates
• f transitions occuring permanently & concurrently

❑ relative transition firing rates

• > may be implemented by transition firing times
• constant
• interval

❑ quantitative model

• > qualitative model + firing times reflecting the firing rates
• > time-dependent model

❑ claim

• > transformation preserves all possible behaviour (= minimal T-invariants)

TRANSFORMATION, EX1

3 2 prod_B cons_D cons_C r1 prod_A B D C A

• > properties as time-less net

TRANSFORMATION, EX1

3 2 prod_B cons_D cons_C r1 prod_A B D C A

• > properties as time-less net

T-INVARIANT

1 2 1 3 1

TRANSFORMATION, EX1

3 2 prod_B <3> cons_D <2> cons_C <6> r1 <6> prod_A <6> B D C A

• > properties as time net

T-INVARIANT

1 2 1 3 1

TRANSFORMATION, EX2

• > properties as time-less net

2 3 cons_C cons_B r2 r1 prod_A C B A

TRANSFORMATION, EX2

• > properties as time-less net

2 3 cons_C cons_B r2 r1 prod_A C B A

1 1 2

T-INVARIANT 1 T-INVARIANT 2

1 1 3

TRANSFORMATION, EX2

• > properties as time net

2 3 cons_C <2> cons_B <3> r2 <6> r1 <6> prod_A <3> C B A

1 1 2

T-INVARIANT 1 T-INVARIANT 2

1 1 3

RG(EX2), PART 1

❑ transient state

RG(EX2), PART 2

❑ steady state

RG(EX2), TERMINAL SCC

❑ contains all transitions

• > always running
• > start / end

at different time points ❑ contains all minimal T-invariants ❑ timing diagram ❑ relative transition firing rates prod_A : 1 + 1 r1 : 1 r2 : 1 cons_B : 2 cons_C : 3

s6 s7 s8 s9 s6 prod_A r1 r2 cons_B cons_C 6 time units

EX1+ EX2, SUMMARY

❑ CTI, but not CPI ❑ transient state

• >

initial behaviour to reach steady state

• >

not REV

• >

generally, not DCF ❑ steady state behaviour

• >

terminal scc

• >

here, BND

• >

here, DCF

PN D/I NET

time not BND REV LIVE BND not REV LIVE

BUT, WHAT DO WE DO

❑ if the timed model is bounded,

but the reachability graph does not fit into memory ?

❑ if the timed model is (still) unbounded ?

QUANTITATIVE ANALYSIS, QUESTIONS

interval time Petri net I: T Q0

Q0

holds , where → × t T ∈ at bt ≤ I t ( ) at bt , ( ) = initial marking / state finite transition word w w T∗ ∈

w is time-dependent realizable / not realizable

min/max time length of w which time windows guarantee realizability

LOUCHKA

QUANTITATIVE ANALYSIS, QUESTIONS

min / max x1 + ... + xn + ...+ ... + ...+ )) b1 a11x1 ≤ a1nxn c1 ≤ bm am1x1 ≤ amnxn cm ≤ aij 0 1 , { } bi N ci N ∈ , ∈ , ∈ i s k 1 i n ≤ ≤ 1 s k m ∧ ≤ ≤ ≤ ∧ ( ∀ ∀ ∀ ais aik 1 = = j( ∀ → s j k ≤ ≤ aij 1 = → (LP) interval time Petri net I: T Q0

Q0

holds , where → × t T ∈ at bt ≤ I t ( ) at bt , ( ) = initial marking / state finite transition word w w T∗ ∈

w is time-dependent realizable / not realizable

min/max time length of w which time windows guarantee realizability

COOPERATIONS / CASE STUDIES

❑ Ina Koch, TFH, Bioinformatics

• > E. coli pathway
• > G1/S - phase in mammalian cells
• > yeast pheromone pathway

❑ Katrin Hafez, HUB

• > lipoprotein metabolism (liver)

❑ Björn Junker, MPI Golm/IPK Gatersleben

• > potato tuber

❑ David Gilbert, Univ. Glasgow, Bioinformatics Research Center

• > signal transduction networks (ERK/RKIP)

❑ Dennis Thieffry, Univ. Marseille, Institute of Developmental Biology

• > gene regulatory networks

SUMMARY

❑ representation of bionetworks by Petri nets

• > partial order representation
• > formal semantics
• > various sound analysis techniques
• > unifying view

❑ purposes

• > animation
• > to experience the model
• > model validation against consistency criteria
• > to increase confidence
• > qualitative / quantitative behaviour prediction
• > new insights

❑ two-step model development

• > qualitative model
• > discrete Petri nets
• > quantitative model
• > timed Petri nets, continuous Petri nets

❑ many challenging questions for analysis techniques

• > qualitative as well as quantitative ones

THANKS !