The development of the mammary gland encompasses four key periods. They are controlled by a set of gene products, either expressed at the period or acting in it, although they have already been expressed before. Conducting text-mining analysis, we collected 406 genes involved in the four periods of breast development: (i) embryonic development, (ii) puberty, (iii) pregnancy and lactation and (iv) regression after lactation. Comparative profiles of gene expression are available from several sources, and one of them is the Genotype-Tissue Expression (GTEx) project which comprises RNAseq data from 53 tissues. Here we analyzed the expression of the set of text-mined mammary gland genes with a novel criterion which indicates if they are highly differentially expressed as outliers in the different tissues contained in the GTEx dataset. This approach aims to reveal in which tissues they are either “overactive” or “tissue-specific” and concomitantly being implicated in breast development. Data showed that, in most of the cases, genes of the mammary gland development, which are GOAT (Gene OverActive or Tissue-specific) in a subset of tissues, are not GOAT in breast. Thus, development of different tissues might require GOATs that will likewise act as controllers of breast development without being highly differentially expressed to play their role. Our analyses contribute to the understanding of the scenario of developmental control by gene expression, while providing a simple way to point out highly differentially expressed genes in different tissues.
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