Negative regulation of αS1-casein (CSN1S1) improves β-casein content and reduces allergy potential in goat milk

Abstract

Compared with other milk proteins, α S1 -casein (encoded by CSN1S1) is associated with higher rates of allergies in humans. Although some studies have revealed that CSN1S1 affects a variety of cellular physiological processes such as immune response and proliferation in various cells, whether CSN1S1 regulates other milk proteins in ruminants is not known. In this study, we observed a negative Pearson correlation between the contents of α S1 -casein and β-casein in goat milk. Thus, we used isolated primary goat mammary epithelial cells along with adenoviral infection or small interference RNA to alter abundance of CSN1S1 and examine its role in milk protein synthesis regulation. Overexpressing CSN1S1 through adenoviral transfection decreased β-casein mRNA (CSN2) and protein abundance, whereas interference of CSN1S1 resulted in a significant increase in β-casein abundance. CSN1S1 reduced phosphorylation level of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 5a (STAT5a). The transcription factor STAT5a activates CSN2 transcription by binding with its promoter region and then promotes β-casein synthesis. Furthermore, CSN1S1 inhibited CSN2 promoter activity and β-casein synthesis by modulating the JAK2/STAT5a signaling pathway. No changes in abundance were detected for α S2 -casein (CSN1S2), κ-casein (CSN3) and major whey proteins (LALBA, BLG). Overall, our results underscored a mechanism whereby CSN1S1 inhibits β-casein synthesis via inhibition of STAT5a. The data suggested that knocking down CSN1S1 not only reduced the content of α S1 -casein, but also increased the abundance of major milk proteins including β-casein. Thus, the present study provides a theoretical basis for manipulating α S1 -casein mRNA to improve quality of ruminant milk for human consumption.

Mutation of Signal Transducer and Activator of Transcription 5 (STAT5) Binding Sites Decreases Milk Allergen αS1-Casein Content in Goat Mammary Epithelial Cells

“…In both mouse cell lines and immortalized GMEC, STAT5a binds to CSN2 promoter and promotes the transcription of β-casein [48]. In primary GMEC, STAT5a binds to the CSN2 promoter region, and STAT5 activity inhibition markedly reduced CSN2 promoter activity and β-casein synthesis [20]. Consistent with the previous studies, in the present study, the inhibition of STAT5 activity significantly reduced phosphorylated STAT5a in the nucleus, which functions as a transcription factor, and downregulated CSN1S1 mRNA level and α S1 -casein synthesis.…”

“…The GMEC were approximately 80% confluence before applying treatments. For luciferase assays, cells were cultured in 48-well plates at a density of 5 × 10 4 cells per well and transfected with the CSN1S1 promoter vectors by X-treme GENE HP DNA Transfection Regent (06366236001, Roche, Mannheim, Germany) for 48 h. Similarly, cells were incubated with pcDNA3.1-STAT5a expression vector [20] or STAT5 inhibitor STAT5-IN-1 (CAS 285986-31-4, MedChemExpress, Monmouth Junction, NJ, USA; 200 µM, dissolved in DMSO) followed by CSN1S1 promoter plasmids transfection, respectively. The pRL-TK vector (renilla luciferase) was the internal control of pGL3-Basic vector (the mass ratio was 1:50).…”

Electrospinning Proteins for Wound Healing Purposes: Opportunities and Challenges

“…Approximately 55% of casein consists of polar amino acid groups, which allow the formation of hydrogen bonds. This property facilitates the formation of films, but also leads to casein's poor electrospinnability, which is further compromised due to the low viscoelasticity of it in solution [99][100][101][102]. Therefore, electrospinning fibers from casein is only possible upon addition of synthetic polymers such as PEO [99] and PVA [103].…”

Recent Insights Into Processing Approaches and Potential Health Benefits of Goat Milk and Its Products: A Review

“…The previously published reviews, generally have focused on providing information on the nutritional content, processing technologies and health benefits of goat milk and its product ( 3 , 10 , 16 , 18 , 33 , 48 , 94 , 105 ). This review provides the detailed comparison of the goat's feeding system in terms of pasture and indoor-based feeding, which conclusively suggested that pasture-based feeding enhances the fatty acid content of goat milk, resulting thus, in higher economic value and consumer benefit ( 24 ).…”

“…Goat milk is a great dietary source. It provides ample benefits for the health maintenance, physiological process, and in the nutrition of younger and the elderly population, and some studies have reported that it may be consumed by most of the population susceptible to cow milk allergy ( 16 ). Due to its non-allergic nature, digestibility, and contribution to the reduction of poverty and hunger at the community level in local producers and the ultimate consumer, the positioning of goat milk, should be on a global level ( 10 ).…”