ELF5 modulates casein synthesis in goat mammary epithelial cells via JAK2/STAT5 signaling pathway.

Abstract

Objective: Goat milk is enriched in caseins which are beneficial to human health. Understanding the regulatory mechanism of casein synthesis in goats contribute to improving milk quality. Epithelial-specific E74-like factor 5 (ELF5) is involved in milk protein synthesis, whereas the molecular mechanism by which ELF5 regulates casein synthesis remains unclear. This study aims to investigate the regulatory roles of ELF5 on casein synthesis in goat mammary epithelial cells (GMECs).

Methods: Primary GMECs were isolated from goats and identified by immunofluorescence and oil red O staining. Goat ELF5 gene overexpression vector and small interference RNA were transfected into GMECs, respectively. Cell viability was carried out by cell counting kit-8 assay, and cell apoptosis was detected by flow cytometry. Genes involved in cell proliferation, apoptosis, and casein synthesis were examined by quantitative real-time polymerase chain reaction and Western blot. After co-treatment of Janus kinase 2 (JAK2) or signal transducer and activator of transcription 5 (STAT5) inhibitor, casein genes were examined by Western blot. Then, the interaction between ELF5 and STAT5 was verified by co-immunoprecipitation assay.

Results: ELF5 enhances cell viability and the expression of proliferation-related genes, and inhibits cell apoptosis and the expression of apoptosis-related genes. Then, ELF5 upregulates the expression of αS1-, αS2-, β- and κ-casein, as well as the activity of JAK2/STAT5 signaling pathway. JAK2 and STAT5 activity inhibition assay reveals that ELF5 regulates casein synthesis via JAK2/STAT5 signaling pathway.

Conclusion: ELF5 upregulates casein synthesis by activating JAK2/STAT5 signaling pathway, which provides the strategy for manipulating ELF5 to increase casein content and improve goat milk protein quality.