Novel Interacting Partners of MGP-40, a Chitinase-Like Protein in Buffalo Mammary Epithelial Cells.

Mammary Gland Protein-40 (MGP-40), also known as chitinase-3-like protein 1 (CHI3L1), is involved in critical biological processes such as inflammation, tissue remodeling, and cell proliferation, especially during the involution phase of the mammary gland. This study aimed to explore the molecular mechanisms of MGP-40 by identifying its novel interacting partners in buffalo mammary epithelial cells (BuMECs). Stable overexpression of MGP-40 in BuMECs was achieved through transfection with the pCIneo-MGP-40 vector, followed by G418 selection and confirmation by Western blot analysis. To identify interacting proteins, Co-immunoprecipitation (Co-IP) of BuMEC lysate using an anti-YKL-40 antibody was performed, and the eluted proteins were analyzed using SDS-PAGE and mass spectrometry (MALDI-TOF/TOF). The analysis revealed several interacting proteins, including synaptotagmin-like 3, Ras-related Rab19, RIB34A-like protein with coiled coils, and ATP synthase subunit g. These interacting partners suggest that MGP-40 is involved in crucial cellular processes like vesicle trafficking, cytoskeletal organization, and energy metabolism, extending its known functions in inflammation and tissue remodeling. Notably, the interactions with synaptotagmin-like 3 and Rab proteins emphasize MGP-40's potential role in vesicular transport, essential for milk production in mammary epithelial cells, while the association with ATP synthase subunit g links MGP-40 to energy regulation during lactation. These findings provide preliminary insights into the potential roles of MGP-40 in mammary gland physiology, particularly in cellular processes such as vesicle trafficking and energy metabolism. Further studies, including in vivo validation, are essential to confirm these interactions and clarify their relevance to mammary gland function and pathology.