title: Quercetin promotes the osteogenic differentiation of rat mesenchymal stem cells via mitogen-activated protein kinase signaling.
abstract: The aim of the present study was to investigate the effects of quercetin on the mitogen-activated protein kinase (MAPK) signaling pathway in the osteogenic differentiation of rat mesenchymal stem cells (MSCs). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and an alkaline phosphatase (ALP) assay were used to determine the effects of quercetin (concentrations of 0.1, 1 and 10 µmol/l) on the proliferation and differentiation of MSCs and the expression of ALP, respectively. In addition, through the introduction of inhibitors of p38 MAPK, extracellular signal-regulated kinase (ERK)1/2 and c-Jun NH2-terminal kinase (JNK), the effects of quercetin on the proteins, ALP, collagen type I (COL I) and bone γ-carboxyglutamate protein (BGP), which are indicators of osteogenic differentiation, were investigated. Immunoblotting was performed to determine the phosphorylation levels of p38 MAPK, ERK1/2 and JNK, while fluorescent quantitative polymerase chain reaction was used to determine the mRNA expression levels of transforming growth factor (TGF)-β1, bone morphogenetic protein (BMP)-2 and core binding factor (CBF)α1. At all the concentrations tested, the concentrations of 10, 1 and 0.1 µmol/l quercetin were shown to promote the differentiation of MSCs and the expression of ALP, in which the concentration of 10 µmol/l was optimal. When compared with the control group, the phosphorylation levels of p38 MAPK, ERK1/2 and JNK, the protein expression levels of ALP, COL I and BGP, and the mNRA expression levels of TGF-β1, BMP-2 and Cbfα1 were increased in the quercetin-treated group. However, with the introduction of inhibitors, the levels of phosphorylated p38 MAPK, ERK1/2 and JNK, and the protein expression levels of ALP, COL I and BGP decreased. Furthermore, the mRNA expression levels of TGF-β1, BMP-2 and CBFα1 decreased in the quercetin + SP600125 (inhibitor of JNK) and quercetin + PD98059 (inhibitor of ERK1/2) groups. Therefore, quercetin was demonstrated to promote the osteogenic differentiation of MSCs by activating the MAPK signaling pathway. The ERK1/2 and JNK signaling pathways regulate the expression of TGF-β1, BMP-2 and CBFα1. Thus, activation of the ERK1/2 and JNK signaling pathways may play a leading role in the quercetin-promoted osteogenic proliferation and differentiation of MSCs.
authors.affiliation: Department of Traditional Chinese Medicine, College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Traditional Chinese Medicine, College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Jiefang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Traditional Chinese Medicine, College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Traditional Chinese Medicine, College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Shuiwang
authors.initials: S
authors.lastname: Feng
authors.affiliation: Department of Traditional Chinese Medicine, First Affiliated Hospital of Jinan University, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Panpan
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Traditional Chinese Medicine, First Affiliated Hospital of Jinan University, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Traditional Chinese Medicine, College of Pharmacy, Jinan University, Guangzhou, Guangdong 510632, P.R. China.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Zhang
keywords: bone-marrow mesenchymal stem cells; mitogen-activated protein kinase; mitogen-activated protein kinase signaling pathway; osteogenic differentiation