Collagen production ability of milk basic protein is dependent on stimulatory effect of transforming growth factor-β1 and β2

Abstract

Milk basic protein (MBP), a mixture of positively charged whey proteins extracted from cows' milk, regulates bone-turnover and stimulates collagen production in osteoblasts. Whey contains growth factors, including transforming growth factor (TGF)-β1, which enhances collagen production in fibroblasts and osteoblasts. However, the extent to which bovine TGF-β1 and TGF-β2 in MBP contribute to collagen production in human mesenchymal cells has not been clarified. The separated MBP fractions increased the concentration of procollagen C-terminal peptide in human dermal fibroblasts in correlation to the bovine TGF-β1 and TGF-β2 concentrations. A similar trend was observed with respect to bovine TGF-β2 and human osteoblasts. These stimulatory effects were inhibited by ALK5 inhibitor II as a TGF-β receptor I signal inhibitor. Accordingly, bovine TGF-β1 and TGF-β2 in MBP could induce collagen production in human mesenchymal lineages, such as fibroblasts and osteoblasts. These results may extend the use of MBP as a functional food ingredient.