The Effect and Mechanism of DNAJA1‐Mediated Met/Leu Promoting the Proliferation of Bovine Mammary Epithelial Cells

Milk is a natural product synthesized and secreted by Bovine mammary epithelial cells (BMECs), providing the nutrients needed for the growth and development of calves. At the same time, it is also one of the common beverages in our daily life. The research on the expansion mechanisms of BMECs is of great significance for increasing dairy yield. DNAJA1 pertains to the HSP40 family (alternatively called DNAJ proteins). As an essential mammalian molecular chaperone, this protein features a structurally distinctive J‐domain region enabling functional coordination with HSP70 (HSPA). However, the expression mechanism and biological function of DNAJA1 in BMECs remain unclear. This investigation demonstrates DNAJA1's critical involvement in methionine (Met) and leucine (Leu)‐modulated BMEC proliferation. Experimental findings reveal that both Met and Leu stimulate BMEC proliferation, with DNAJA1 similarly exerting a positive regulatory influence on cellular multiplication. Within BMECs, Met and Leu augment proliferation by activating the PI3K‐AKT‐DNAJA1 signaling axis. Concurrently, an interaction between DNAJA1 and TAK1 potentially contributes further to regulating this proliferative process.