Lactoferrin inhibits apoptosis through insulin-like growth factor I in primary rat osteoblasts
Abstract
Jian-ming HOU1, 2, #, *, En-yu CHEN#, 2, Shi-chao WEI1, 2, #, Fan LIN1, 2, #, Qing-ming LIN1, 2, Xu-hua LAN1, 2, Ying XUE1, 2, Man WU2
1Fujian Provincial Hospital, Fuzhou 350001, China; 2Provincial Clinical Medical College of Fujian Medical University, Fuzhou 350004, China
Aim: Excessive apoptosis of osteoblasts is the major cause of low bone mass, and bovine lactoferrin (bLF), an iron-binding glycoprotein, might protect osteoblastic cells from apoptosis induced by serum withdrawal. The aim of this study was to elucidate the mechanisms underlying the anti-apoptotic action of bLF in rat osteoblasts in vitro.
Methods: Primary rat osteoblasts were incubated in the presence of varying concentrations of bLF for 24 h. The expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) was measured uisng RT-PCR and Western blotting. Cell apoptosis was examined with flow cytometry. siRNAs targeting IGF-I was used in this study.
Results: Treatment of bLF (0.1–1000 μg/mL) dose-dependently increased the expression of IGF-I and IGF-IR in the osteoblasts. Treatment with bLF (10, 100 μg/mL) markedly inhibited the osteoblast apoptosis (with the rate of total apoptosis of 70% at 10 μg/mL), but the high concentration of bLF (1000 μg/mL) significantly promoted the osteoblast apoptosis. Knockdown of the IGF-I gene in osteoblasts with siRNA markedly increased the osteoblast apoptosis.
Conclusion: Lactoferrin (10 and 100 μg/mL) effectively inhibits apoptosis of primary rat osteoblasts by upregulating IGF-I expression.
Keywords: lactoferrin; osteoblast; IGF-I; apoptosis; RNA interference; bone remodeling; osteoporosis
This study was supported by the National Natural Science Foundation of China (No 81270968).
# These authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail hjm996@126.com
Received 2013-08-01 Accepted 2013-11-05
Keywords:
1Fujian Provincial Hospital, Fuzhou 350001, China; 2Provincial Clinical Medical College of Fujian Medical University, Fuzhou 350004, China
Aim: Excessive apoptosis of osteoblasts is the major cause of low bone mass, and bovine lactoferrin (bLF), an iron-binding glycoprotein, might protect osteoblastic cells from apoptosis induced by serum withdrawal. The aim of this study was to elucidate the mechanisms underlying the anti-apoptotic action of bLF in rat osteoblasts in vitro.
Methods: Primary rat osteoblasts were incubated in the presence of varying concentrations of bLF for 24 h. The expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) was measured uisng RT-PCR and Western blotting. Cell apoptosis was examined with flow cytometry. siRNAs targeting IGF-I was used in this study.
Results: Treatment of bLF (0.1–1000 μg/mL) dose-dependently increased the expression of IGF-I and IGF-IR in the osteoblasts. Treatment with bLF (10, 100 μg/mL) markedly inhibited the osteoblast apoptosis (with the rate of total apoptosis of 70% at 10 μg/mL), but the high concentration of bLF (1000 μg/mL) significantly promoted the osteoblast apoptosis. Knockdown of the IGF-I gene in osteoblasts with siRNA markedly increased the osteoblast apoptosis.
Conclusion: Lactoferrin (10 and 100 μg/mL) effectively inhibits apoptosis of primary rat osteoblasts by upregulating IGF-I expression.
Keywords: lactoferrin; osteoblast; IGF-I; apoptosis; RNA interference; bone remodeling; osteoporosis
This study was supported by the National Natural Science Foundation of China (No 81270968).
# These authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail hjm996@126.com
Received 2013-08-01 Accepted 2013-11-05