Tissue-specific mRNA expression patterns reveal a coordinated metabolic response associated with genetic selection for milk production in cows

Abstract

The molecular mechanisms regulating the physiological adaptation of tissues important for nutrient partitioning and metabolism in lactating cows are still not completely understood. The aim of our study was to identify tissue-specific regulatory mechanisms necessary to accommodate metabolic changes associated with different genetic potential for milk performance. For this purpose, we analyzed mRNA expression of genes involved in energy metabolism of segregating F(2) beef type cows with a combined genetic dairy and beef background (Charolais × German Holstein cross, CH×GH) in contrast to purebred German Holstein (GH) dairy cows. Three groups of cows differing in milk performance were examined using quantitative real-time PCR in liver, mammary gland, and skeletal muscle. Our results describe substantial tissue-specific differences in mRNA transcription profiles between cow groups in relation to their genetic potential for milk performance and highlight genes exhibiting specific, partially yet-unknown functions in dairy and beef type cows, e.g., upregulation of PCK2 transcripts in the mammary gland and FBP2 transcripts in skeletal muscle of dairy cows. Noticeably, PCCA and PPARGC1A mRNA abundance varied significantly across experimental groups in all three tissues, pointing to potential key gene functions in the metabolic adaptation relative to divergent milk production performance. Correlations of mRNA expression levels to milk performance traits indicate that gene transcriptional processes may play a regulatory role in liver, mammary gland, and skeletal muscle to enable cows with different genetic potential for milk performance to cope with metabolic lactation-associated challenges.

Proceedings of the 10th International Symposium on the Nutrition of Herbivores

“…It may result from modifications of mammary epithelium permeability, may be linked to the secretion of metabolites related to oxidative pathways in milk during early lactation (communication Pires et al, this symposium), and may constitute molecular signatures of physiological negative energy balance typical of this period. In agreement with these hypotheses, the abundance of PCK2 mRNA (a neoglugogenic gene expressed in liver) was increased in the mammary tissue of high genetic merit dairy cows (Weikard et al, 2012), and may contribute to glyceroneogenesis during fasting or compromised feed intake, as already proposed for lipogenic tissues. Introduction Improving the survival of young sheep between birth and 12 months of age is a priority for the sheep industry in Australia (Young et al 2014).…”

Tissues, Metabolic Pathways and Genes of Key Importance in Lactating Dairy Cattle

“…These adaptations include metabolism adjustments in liver and peripheral tissues (including adipose tissue, mammary gland, skeletal muscle tissues and kidney), and mobilization of body reserves and increased lipid metabolism [163]. The increase in lipid metabolism results in an increase in concentrations of key metabolites NEFA and BHBA in plasma (Fig.…”

“…A gene-based mapping and pathway analysis indicated that three pathways (steroid hormone biosynthesis, ether lipid metabolism and glycerophospholipid metabolism) jointly affect the concentrations of NEFA, BHBA and glucose in cows during the transition period [53]. The key genes that are involved in regulating energy metabolism in multiple tissues include PPRA, PCK1, PCK, ACACA, FASN, FBP2, FABP3, PPARGC1A, ACSL1, PPARGC1A, AGPAT6, PCCA, LPIN1, ACO, CPT-I, CPT-II and ACSL [4,15,27,94,131,163]. These genes are involved in fatty acid uptake (mainly in the liver and mammary gland), mitochondrial and peroxisomal fatty acid oxidation, ketone body metabolism (ketogenesis) and cholesterol metabolism (in liver) early in lactation in dairy cattle [135] and are discussed in the following tissue-specific sections in more detail.…”

“…Gene expression studies are revealing the extent to which different genes are involved in different tissues [4,135,163,167]. For example, genes that are involved in carbohydrate metabolism, such as those encoding gluconeogenesis and propionate metabolism enzymes (including PCK1), were expressed more in liver than mammary tissues [4,167].…”

Liver functional genomics in beef cows on grazing systems: novel genes and pathways revealed

“…In is well known that dairy and beef cows have been selected for different purposes and consequently, they have developed different metabolic adaptation strategies (47,51). However, to our knowledge, no studies have evaluated hepatic metabolism adaptation during gestation and early lactation in beef cows in different nutritional environments.…”