Milk Fat Content and DGAT1 Genotype Determine Lipid Composition of the Milk Fat Globule Membrane

Abstract

During secretion of milk fat globules, triacylglycerol (TAG) droplets are enveloped by a phospholipid (PL) trilayer. Globule size has been found to be related to polar lipid composition and fat content, and milk fat content and fatty acid composition have been associated with the diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism; however, the association between the DGAT1 polymorphism and fat globule size and polar lipid composition has not been studied. The ratio between polar and neutral lipids as well as the composition of the polar lipids in milk has industrial as well as nutritional and health implications. Understanding phenotypic and genotypic factors influencing these parameters could contribute to improving milk lipid composition for dairy products. The focus of the present study was to determine the effect of both fat content and DGAT1 polymorphism on PL/TAG ratio, as a marker for milk fat globule size, and detailed PL composition. Milk samples were selected from 200 cows such that there were equal numbers of samples for the different fat contents as well as per DGAT1 genotype. Samples were analyzed for neutral and polar lipid concentration and composition. PL/TAG ratio was significantly associated with both fat content and DGAT1 genotype. Phosphatidylinositol and phosphatidylserine concentrations were associated with fat content*DGAT1 genotype with a stronger association for the AA than the KK genotype. Sphingomyelin concentration tended to interact with fat content*DGAT1 genotype. Phosphatidylethanolamine (PE) concentration showed a biphasic response to fat content, suggesting that multiple biological processes influence its concentration. These results provide a new direction for controlling polar lipid concentration and composition in milk through selective breeding of cows.

Relationships between milks differentiated on native milk fat globule characteristics and fat, protein and calcium compositions

“…Recently, studies by Argov-Argaman et al (2013 and, Logan et al (2014) and Cohen et al (2015) have suggested that the phospholipid (PL) to triacylglycerol (TAG) ratio in cytoplasm, linked to diacylglycerol acyltransferase 1 activity, influences MFG diameter. In the PL, phosphatidylethanolamine, when located in the membrane, would play a major role in the process of intracellular fusion of CLD and thereby in MFG diameter (Keenan and Huang, 1972;Mesilati-Stahy et al, 2011;Argov-Argaman et al, 2013).…”

“…In the PL, phosphatidylethanolamine, when located in the membrane, would play a major role in the process of intracellular fusion of CLD and thereby in MFG diameter (Keenan and Huang, 1972;Mesilati-Stahy et al, 2011;Argov-Argaman et al, 2013). Thus, when PL : TAG ratio is high, de novo FA content and synthesis are low.…”

Mare's and cow's milk: promote similar metabolic effects and expression of innate markers in Caco-2 cells?

“…A potential contributor to these negative effects in intestinal cells could also be the type and concentration of phospholipids with surfactant activity that are bound to allergens (e.g., α-la). The phenotype and genotype influence of both the phospholipid and fat content in the milk products (Argov-Argaman, Mida, Cohen, Visker, & Hettinga, 2013;Mesilati-Stahy & Argov-Argaman, 2014) could also explain in part the differences in the cytotoxic effects.…”

“…To prevent cow's milk protein allergies (CMPA), researchers have attempted to modify the milk protein structure (Bu, Luo, Chen, Liu, & Zhu, 2013;Chandrapala, Zisu, Kentish, & Ashokkumar, 2012;Wróblewska, Jędrychowski, Hajjós, & Szabó, 2008;Wróblewska et al, 2004). The introduction of vegetal milk or other mammalian milk products has also been considered.…”

Influence of glucogenic dietary supplementation and reproductive state of dairy cows on the composition of lipids in milk

“…Milk polar lipid composition and concentration are closely associated with lactation stage (Bitman and Wood, 1990), genetic predisposition (Argov-Argaman et al, 2013), plasma insulin concentration (Argov-Argaman et al, 2012) and diet (Lopez et al, 2008). In general, milk polar lipid composition and concentration are altered when systemic or local -within the mammary gland -changes in lipid metabolism are induced.…”