Linking our understanding of mammary gland metabolism to amino acid nutrition

Abstract

Amino acids (AA) are not only building blocks of protein but are also key regulators of metabolic pathways in animals. Understanding the fate of AA is crucial to optimize utilization of AA for milk protein synthesis and, therefore, to reduce inefficiencies of nutrient utilization during lactation. By understanding the functional role of AA metabolism in mammary tissue, we can uncover pathways and molecular targets to improve AA utilization by mothers and neonates during the lactation period. The major objective of this article is to highlight recent advances in mammary AA transport, metabolism and utilization. Such knowledge will aid in refining dietary requirements of AA for lactating mammals, including women, sows and cows.

Phosphorylation of AKT serine/threonine kinase and abundance of milk protein synthesis gene networks in mammary tissue in response to supply of methionine in periparturient Holstein cows

“…For example, SLC27A1 transports cationic L-AA (His, Arg, and Lys; Closs et al, 2006). The SLC38A1 and SLC38A2 transport neutral-AA such as Ala, Ser, Gly, Pro, Cys, and Gln (Mackenzie and Erickson, 2004;Manjarin et al, 2014). The abundance of SLC7A1, SLC38A1, and SLC38A2 along with CSN1S1 was upregulated in response to enhanced Met supply (P ≤ 0.03; Table 4).…”

Proteolytic Systems in Milk: Perspectives on the Evolutionary Function within the Mammary Gland and the Infant

“…Free amino acids in blood enter into mammary cells by amino acid transport systems with respective transporters for different groups of amino acids (90, 94). After the uptake of amino acids from blood, the basic process for protein synthesis in the mammary gland is similar to that in other tissues.…”

Milk protein synthesis is regulated by T1R1/T1R3, a G protein-coupled taste receptor, through the mTOR pathway in the mouse mammary gland

“…A recent study reported that exogenous growth hormone can increase milk protein synthesis . Additionally, numerous studies in mice and cows have demonstrated that amino acids (AA), such as Leu, Ile, Met, and Thr, act as signaling molecules to regulate milk synthesis and lactation . The mammalian target of rapamycin (mTOR) pathway participates in milk protein synthesis.…”