Anabolic effects and mechanisms of lactoferrin in osteoblasts
Objectives: Lactoferrin (LF), an iron-binding protein, is present at a high concentration in exocrine secretions of mammals, including milk, saliva and others. Milk proteins play important roles in growth of bony tissue especially before starting food feeding. Because Lactoferrin is the second most abundant protein in milk, its roles in osteogenesis can be implied. We previously reported that bovine LF (bLF) attenuates LPS-induced bone resorption through a reduction of RANKL and TNF-a production in osteoblasts and that bLF inhibits LPS and IL-1b induced osteoclastogenesis through a novel mechanism. However, the essential effects of LF on the anabolic bone cell function and the detailed mechanisms are not well demonstrated. The purpose of the present study is to clarify the effects and the mechanisms of bLF on the osteoblast function.
Methods: We used osteoblast-like cell line MC3T3-E1 for the studies. Gene and protein expressions were analyzed by RT-PCR and Western blotting, respectively. Mineralized nodule formation was evaluated by alizarin-red staining.
Results: bLF up-regulated the proliferation of MC3T3-E1. bLF enhanced the mineralized nodule formation in a dose dependent manner. The expression of BSP, but not ALP and OPN, mRNA was significantly up-regulated by bLF treatment. Western blotting revealed that bLF induced the phosphorylation of p38 and JNK. Furthermore, inhibition of JNK function and knockdown of LRP1, a member of the low-density lipoprotein (LDL)-receptor, eliminated up-regulation of BSP mRNA expression.
Conclusions: bLF promotes proliferation and mineralization of osteoblasts. The anabolic effects of bLF on osteoblasts are mediated through LRP1/JNK pathway. Our results demonstrate that bLF has anabolic effects, affecting osteoblasts proliferation and function. It is suggested that bLF can be a potent therapeutic agents for bone regeneration therapy in the future.
Division: Japanese Division Meeting
Meeting:2012 Japanese Division Meeting (Niigata, Japan) Location: Niigata, Japan
Year: 2012 Final Presentation ID: Abstract Category|Abstract Category(s):Scientific Program
Authors
Inubushi, Toshihiro
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)
Kosai, Azuma
( Hiroshima University, Hiroshima, N/A, Japan
)
Yanagisawa, Syunryo
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)
Nishiyama, Kyoko
( Hiroshima University, Hiroshima, N/A, Japan
)
Furusho, Hisako
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)
Ao, Min
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)
Ishikado, Atsushi
( Sunstar, Inc, Takatsuki, N/A, Japan
)
Miyauchi, Mutsumi
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)
Takata, Takashi
( Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, N/A, Japan
)