Expression data from porcine hepatic tissue of males and females fed with two feeding levels

Liver plays major roles in vital functions including responses to energy deprivation. It is known that body composition and fuel metabolism differs between genders. However there are many unclear aspects related to metabolic pathways affected by feeding level and gender, which could be addressed by transcriptome analyses. To date, no published study in porcine liver has investigated the effects of both gender and feeding level on global gene expression level.We performed a gene expression analysis, using microarrays, in hepatic samples of pigs of the obese Iberian breed to analyze feeding level and gender effects. Results showed that feeding level leads to small expression differences, while gender leads to larger ones. Biological interpretation of the differentially expressed genes conditional on feeding level showed an overrepresentation of genes implicated in general metabolic processes, responses to stimulus and stress, oxidoreductase activity, calcium ion binding and lipid, organic acid and carbohydrate metabolisms. We validated the expression difference of PHYHD1 by qRT-PCR; however we could not validate the expression differences of other relevant genes. Curiously, validation of PGK1, considered reference gene, confirmed expression differences conditional on feeding level and gender. The annotation of the differentially expressed probes for gender effect allowed to observe sex-chromosome enrichment and dosage compensation phenomena in liver. Biological interpretation showed overrepresentation of genes related with oxidoreductase and transferase activities, lipid, organic acid, carbohydrate and steroid metabolisms and genes related with metabolites generation and energy and electron transport. Aside from 13 consistently across tissue differentially expressed genes between gender, gender hepatic expression dimorphism of key genes involved in lipid, carbohydrate and protein metabolisms and antioxidant capacity were also detected. A deeper qRT-PCR analysis showed a downregulation in entire males of all major genes implicated in hepatic degradation processes of androstenone and skatole. We have identified changes in hepatic gene expression conditional on feeding and gender. Reduction of around 25% in feeding level do not lead to great differences but gender effect leads not only to a larger number of differentially expressed probes, but much larger expression differences. Validation of microarray results is needed mainly for small expression differences.

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