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PNNL-13501 - Pacific Northwest National Laboratory

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SOS<br />

p 23<br />

EGFR<br />

Professor Rodland at Oregon Health Science University<br />

to investigate the signaling pathways that connect the<br />

extra-cellular calcium-sensing receptor (CaR) to cell<br />

proliferation. Like skin fibroblast, normal cells of the<br />

ovarian surface layer respond to elevated calcium by<br />

proliferation and return to a quiescent state when the<br />

extra-cellular calcium concentration is reduced.<br />

Nonhomogenous chemical kinetics is required to model<br />

this system because signaling involves the release of<br />

calcium from the endoplasmic reticulum that is not<br />

homogeneously distributed in the cell.<br />

Results and Accomplishments<br />

EGF<br />

p 1<br />

t 2<br />

p 2<br />

We have initiated the development of a Petri network<br />

model of cell signaling. The Petri net model transforms<br />

the molecular signal into a linear algebra representation of<br />

a systems process model. The linear algebra<br />

representation defines the stoichiometric system of<br />

t 1<br />

F<br />

p 3<br />

t 3<br />

EGF: EGFR<br />

t 4<br />

p 4<br />

EGF: EGFR_Internal<br />

t5 t t<br />

7<br />

9<br />

SHC : EGF: EGFR EGF: EGFR : SHC-P<br />

SHC SHC -P<br />

p5<br />

p8 p9 p6<br />

t 6<br />

t 11<br />

SHC : P'ase(1)<br />

p10 t 12<br />

t 8<br />

t 13<br />

t 14<br />

p 7<br />

P'ase(1)<br />

t 10<br />

t 15<br />

p11 P'ase(1) : SHC-P<br />

t 16<br />

t 35<br />

t 36<br />

t 41<br />

SOS : Erk-PP<br />

p 27<br />

SOS : P'ase(2) p29 t 42<br />

p 25<br />

Erk-PP<br />

t 37<br />

t 38<br />

t 17<br />

t 18<br />

t 43<br />

t 44<br />

p 26<br />

H<br />

P'ase(2)<br />

Erk-PP : SOS*<br />

p28<br />

GDP : Ras<br />

t 39<br />

t 40<br />

p 12<br />

t19 t21 GDP : Ras : SHC -P : SOS : GRB2<br />

p13 p16 p17 p14<br />

t 20<br />

t 25<br />

GDP : Ras : RasGAP p18 t 26<br />

p30 P'ase(2) : SOS*<br />

t 23<br />

SHC-P : SOS : GRB2 : GTP : Ras<br />

t22 t24 t 27<br />

t 28<br />

p 15<br />

RasGAP<br />

SHC -P : SOS : GRB2<br />

t 29<br />

p19 RasGAP : GTP : Ras<br />

t 30<br />

H<br />

SOS : GRB2<br />

p20 Figure 2. This is a Petri net of the EGFR pathway, SOS. Linkage to other components in the network shown in Figure 1 are<br />

indicated by arrows labeled F and H.<br />

t 45<br />

t 46<br />

GTP : Ras<br />

SOS* : GRB2<br />

energy-mass balanced chemical equations. The Petri<br />

network model provides us with a representation of the<br />

molecular signal that enables us to mathematically predict<br />

the behavior of a molecular communications pathway<br />

when it is no longer in an equilibrium state. This model<br />

will direct us to the eventual construction of the molecular<br />

information analog of Shannon’s laws of information and<br />

communication theory. We will also have an opportunity<br />

to examine the orders of both physical and computational<br />

complexity associated with reliable molecular<br />

communications within and between cells.<br />

Accomplishments include the following.<br />

1. We have shown that cell-signaling pathways are<br />

represented by sets of chemical kinetic rate-reaction<br />

graphs, where the reacting species themselves are<br />

generated from the products of multiple subreaction<br />

cascades of subspecies. In particular, we examined<br />

several subnetworks of the EGFR signaling network<br />

t31<br />

t 32<br />

GRB2<br />

p21<br />

Computational Science and Engineering 119<br />

t 33<br />

t34<br />

p 22<br />

SOS*<br />

p 24

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