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1 IRIT - Institut de recherche en informatique de Toulouse 2 Institute for Genome Sciences and Policy - IGPS Durham, USA 3 Center for Computational Biology and Bioinformatics - CCMB Ann Arbor, USA

Abstract : Background: This paper introduces a new constrained model and the corresponding algorithm, called unsupervised Bayesian linear unmixing uBLU, to identify biological signatures from high dimensional assays like gene expression microarrays. The basis for uBLU is a Bayesian model for the data samples which are represented as an additive mixture of random positive gene signatures, called factors, with random positive mixing coefficients, called factor scores, that specify the relative contribution of each signature to a specific sample. The particularity of the proposed method is that uBLU constrains the factor loadings to be non-negative and the factor scores to be probability distributions over the factors. Furthermore, it also provides estimates of the number of factors. A Gibbs sampling strategy is adopted here to generate random samples according to the posterior distribution of the factors, factor scores, and number of factors. These samples are then used to estimate all the unknown parameters. Results: Firstly, the proposed uBLU method is applied to several simulated datasets with known ground truth and compared with previous factor decomposition methods, such as principal component analysis PCA, non negative matrix factorization NMF, Bayesian factor regression modeling BFRM, and the gradient-based algorithm for general matrix factorization GB-GMF. Secondly, we illustrate the application of uBLU on a real time-evolving gene expression dataset from a recent viral challenge study in which individuals have been inoculated with influenza A-H3N2-Wisconsin. We show that the uBLU method significantly outperforms the other methods on the simulated and real data sets considered here. Conclusions: The results obtained on synthetic and real data illustrate the accuracy of the proposed uBLU method when compared to other factor decomposition methods from the literature PCA, NMF, BFRM, and GB-GMF. The uBLU method identifies an inflammatory component closely associated with clinical symptom scores collected during the study. Using a constrained model allows recovery of all the inflammatory genes in a single factor.

Keywords : Gene analysis Linear mixing model Bayesian analysis Hyperspectral imaging





Author: Cécile Bazot - Nicolas Dobigeon - Jean-Yves Tourneret - Aimee K. Zaas - Geoffrey S. Ginsburg - Alfred O. Hero -

Source: https://hal.archives-ouvertes.fr/



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