Exendin-4 promotes proliferation and differentiation of MC3T3-E1 osteoblasts by MAPKs activation

Abstract

Glucagon-like peptide-1 (GLP1) and its receptor agonist have been previously reported to play a positive role in bone metabolism in aged ovariectomized rats and insulinresistant models. However, whether GLP1 has a direct effect on the proliferation and differentiation of osteoblasts or any cellular mechanism for this potential role is unknown. We examined the effects of the GLP1 receptor agonist exendin-4 on the proliferation, differentiation, and mineralization of mouse osteoblastic MC3T3-E1 cells. GLP1 receptor was detected in MC3T3-E1 cells by polymerase chain reaction (PCR) and Western blot assay. Cell proliferation was assessed using MTT assay, revealing that exendin-4 increased cell proliferation at effective concentrations between 10 −10 and 10 −5 M. Quantitative PCR analysis showed that exendin-4 increased the mRNA expression of the differentiation markers alkaline phosphatase (ALP), collagen-1 (COL1), osteocalcin (OC), and runt-related transcription factor 2 (RUNX2) under osteogenic conditions. Alizarin red staining confirmed that 10 −7 M exendin-4 increased osteoblast mineralization by 18.7%. Exendin-4 upregulated the phosphorylation of ERK1/2, p38, and JNK, with the peak effect at 1.5 h in the Western blot analysis. The use of selective MAPK inhibitors, namely PD98059, SB203580, and SP600125, blocked the effects of exendin-4 on kinase activation (ERK1/2, p38, and JNK), as well as cell proliferation and differentiation in MC3T3-E1 cells. These findings demonstrate that exendin-4 promotes both the proliferation and differentiation of preosteoblasts MC3T3-E1 via activation of the MAPK pathway.

The Impact of Glucagon-Like Peptide-1 on Bone Metabolism and Its Possible Mechanisms

“…It has been proposed that GLP-1 could promote c-Fos transcription in osteoblasts in combination with ATP, facilitating the participation of GLP-1 in bone turnover (47). It has been shown that exendin-4 enhanced the proliferation and differentiation of osteoblasts partly mediated by MAPK pathways, including ERK1/2, p38, and JNK pathways (48). It was also proposed that liraglutide regulated MC3T3-E1 cells differentiation mediated by adenosine monophosphate-activated protein kinase/mammalian target of rapamycin signaling (49).…”

Wnt5a/FZD4 Mediates the Mechanical Stretch-Induced Osteogenic Differentiation of Bone Mesenchymal Stem Cells

“…Wnt5a, a noncanonical Wnt ligand, activates signalling through both β-catenin-independent mediators, such as c-Jun N-terminal Kinase (JNK) and the β-catenin-dependent pathway [17]. Feng et al found that activated JNK signalling promotes the osteogenic differentiation of mouse MC3T3-E1 cells [18]. Furthermore, previous studies have demonstrated that mechanical stress also enhanced the expression of Wnt5a/Wnt5b mRNA in stem cells and autonomously promoted osteogenic differentiation.…”

Identification of Gli1‐interacting proteins during simvastatin‐stimulated osteogenic differentiation of bone marrow mesenchymal stem cells

“…Rac1 and Rac2 have critical roles in osteoclasts and skeletal metabolism . Rac1 can be significantly stimulated by exendin‐4 to promote differentiation and mineralization of mouse osteoblastic MC3T3‐E1 cells . Rac was also shown to negatively regulate TGF‐β‐stimulated vascular endothelial growth factor synthesis via inhibition of p38 MAPK in osteoblasts .…”