Employing decomposable partially observable Markov decision processes to control gene regulatory networks.

OBJECTIVE

Formulate the induction and control of gene regulatory networks (GRNs) from gene expression data using Partially Observable Markov Decision Processes (POMDPs).

METHODS AND MATERIAL

Different approaches exist to model GRNs; they are mostly simulated as mathematical models that represent relationships between genes. Actually, it has been realized that biological functions at the cellular level are controlled by genes; thus, by controlling the behavior of genes, it is possible to regulate these biological functions. The GRN control problem has been studied mostly with the aid of probabilistic Boolean networks, and corresponding control policies have been devised. Though turns into a more challenging problem, we argue that partial observability would be a more natural and realistic method for handling the control of GRNs. Partial observability is a fundamental aspect of the problem; it is mostly ignored and substituted by assumption that states of GRN are known precisely, prescribed as full observability. We propose a method for the construction of POMDP model of GRN from only raw gene expression data which is original and novel. Then, we introduce a novel approach to decompose/factor the POMDP model into sub-POMDP's in order to solve it efficiently with the help of divide-and-conquer strategy.

RESULTS

In order to demonstrate the effectiveness of the proposed solution we experimented with two synthetic network and one real network data from the literature. We also conducted two sets of separate experiments used to explore the impact of network connectivity and data order to our approach CONCLUSIONS: The reported test results using both synthetic and real GRNs are promising in demonstrating the applicability, effectiveness and efficiency of the proposed approach. This is due to the fact that partial observability fits well to the problem of noisy acquisition of gene expression data as there are technological limitations to measure precisely exact expression levels of genes.