Outlier detection at the transcriptome-proteome interface

Gunawardana, Y., Fujiwara, S., Takeda, A., Woelk, C.H. and Niranjan, Mahesan (2015) Outlier detection at the transcriptome-proteome interface Bioinformatics (doi:10.1093/bioinformatics/btv182). (PMID:25819671).


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In high-throughput experimental biology, it is widely acknowledged that while expression levels measured at the levels of transcriptome and the corresponding proteome do not, in general, correlate well, messenger RNA levels are used as convenient proxies for protein levels. Our interest is in developing data-driven computational models that can bridge the gap between these two levels of measurement at which different mechanisms of regulation may act on different molecular species causing any observed lack of correlations. To this end, we build data-driven predictors of protein levels using mRNA levels and known proxies of translation efficiencies as covariates. Previous work showed that in such a setting, outliers with respect to the model are reliable candidates for post-translational regulation.

Here, we present and compare two novel formulations of deriving a protein concentration predictor from which outliers may be extracted in a systematic manner. The first approach, outlier rejecting regression, allows explicit specification of a certain fraction of the data as outliers. In a regression setting, this is a non-convex optimization problem which we solve by deriving a difference of convex functions algorithm (DCA). With post-translationally regulated proteins, one expects their concentrations to be affected primarily by disruption of protein stability. Our second algorithm exploits this observation by minimizing an asymmetric loss using quantile regression and extracts outlier proteins whose measured concentrations are lower than what a genome-wide regression would predict. We validate the two approaches on a dataset of yeast transcriptome and proteome. Functional annotation check on detected outliers demonstrate that the methods are able to identify post-translationally regulated genes with high statistical confidence.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1093/bioinformatics/btv182
ISSNs: 1367-4803 (print)
Subjects: Q Science > QH Natural history > QH426 Genetics
Organisations: Clinical & Experimental Sciences
ePrint ID: 379219
Date :
Date Event
24 March 2015Accepted/In Press
29 March 2015e-pub ahead of print
Date Deposited: 18 Jul 2015 14:41
Last Modified: 17 Apr 2017 05:41
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/379219

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