Predicting Long Term behavior of Genetic Regulatory Networks with Answer Set Programming
Using the declarative Answer Set Programming paradigm we showed how biological networks could be efficiently represented in a way that easily allowed computations on top of it.
SET PROGRAMMING 4 Boolean Networks are defined according to a set of rules that control its dynamics E.g. if an inhibitor is present the gene will not be switched on in the next time step We rely on ASP, a rule based declarative framework, to flexibly describe the model
OF ASP 7 To show the use of ASP for Boolean Networks modeling we pursued the problem of calculating the attractors of the modeled dynamic system An attractor is a set of states in which the dynamics of the network cycles indefinitely These attractor states usually correspond to important biological decisions
of GRNs T helper (Th) cells are a subgroup of lymphocytes important for the immune system Divided into Th1 and Th2 cells each responsible for different diseases Pedicini et al (2010) used gene knockout experiments to tell whether Th1 and Th2 are mutually exclusive
of GRNs 0 5,00 10,00 15,00 20,00 COT GATA3 IKBKB IRAK IRF4 JAK1 JAK3 LCK MAF NFAT NFKB Solving time for the Th Cell Helper network (Pedicini et al (2010)) SAT ASP
of GRNs In addition to SAT, which only implements finding attractors for the synchronous updated network we also considered asynchronously updated networks. An asynchronous updated network considers the fact that genes do not change their state all at the same moment
T ) active ( X, T ) , inhibited ( X, T 1) , protein ( X ) , T > 0 . changed ( X, T ) inhibited ( X, T ) , active ( X, T 1) , protein ( X ) , T > 0 . N = # changed ( X, T ) , N 2 , protein ( X ) , T > 0 . active(g1, T), inhibited(g2, T), active(g3, T). Asynchronous 101 Do not repeat visited states ASP for Long Term Behavior of GRNs 001 000 011 010 111 110 101 100
T ) active ( X, T ) , inhibited ( X, T 1) , protein ( X ) , T > 0 . changed ( X, T ) inhibited ( X, T ) , active ( X, T 1) , protein ( X ) , T > 0 . N = # changed ( X, T ) , N 2 , protein ( X ) , T > 0 . active(g1, T), inhibited(g2, T), active(g3, T). Asynchronous 101 Do not repeat visited states ASP for Long Term Behavior of GRNs 000 011 110
encode GRNs’ behavior and adds flexibility ‣ Attractors can be used as predictors of long term behavior of GRNs ‣ The running time for calculating all attractors becomes proportional to the number of attractors rather than in the size of the network (2n) 26 ASP for Long Term Behavior of GRNs
Martine De Cock ‣ Dubrova, Teslenko (2011) A SAT based algorithm for finding Attractors in Synchronous Boolean Networks ‣ Pedicini, Barrenäs, Clancy, Castiglione, Hovig, Kanduri, Santoni et al (2010) Combining network modeling and gene expression microarray analysis to explore the dynamics of Th1 and Th2 cell regulation 27 ASP for Long Term Behavior of GRNs