Nephronectin promotes osteoblast differentiation via the epidermal growth factor-like repeats

• Published in: FEBS letters Vol. 584; no. 1; pp. 233 - 238
• Main Authors: Kahai, Shireen, Lee, Shao-Chen, Seth, Arun, Yang, Burton B.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 04.01.2010
• Subjects: alkaline phosphatase; ALP; alpha-minimum essential medium; Animals; Cell Differentiation; Cell Line; ECM; Epidermal Growth Factor - genetics; Epidermal Growth Factor - physiology; ERK; extracellular matrix; Extracellular Matrix Proteins - genetics; Extracellular Matrix Proteins - physiology; Extracellular Signal-Regulated MAP Kinases - metabolism; FBS; fetal bovine serum; Gene expression; Matrix; Mice; Nephronectin; Npnt; Osteoblasts - cytology; Osteoblasts - physiology; Osteogenesis; PAGE; Phosphorylation; polyacrylamide gel electrophoresis; Repetitive Sequences, Amino Acid - genetics; Repetitive Sequences, Amino Acid - physiology; α-MEM; α-MEM; Matrix; ALP; FBS; PAGE; Gene expression; Npnt; ECM; Nephronectin; ERK
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2009.11.077

We found that nephronectin was significantly down-regulated by TGF-β1. To determine the function of nephronectin in osteogenesis, we generated various constructs to produce stable MC3T3-E1 cell lines, expressing and secreting nephronectin protein, including full-length (Npnt), lacking EGF-like repeats (Np-MAM), and lacking RGD and MAM domains (Np-EGF). We demonstrated that nephronectin promotes differentiation during osteoblast differentiation and the EGF-like repeats were essential. Lack of these repeats resulted in inhibiting the change in morphology. Over-expression of nephronectin results in earlier formation of bone nodules than the vector control. ERK activation is essential for nephronectin-induced osteoblast differentiation.