Journal
TISSUE ENGINEERING AND REGENERATIVE MEDICINE
Volume 19, Issue 1, Pages 189-202Publisher
KOREAN TISSUE ENGINEERING REGENERATIVE MEDICINE SOC
DOI: 10.1007/s13770-021-00408-2
Keywords
Neuropeptide; Spexin; Bone regeneration; MEK; ERK pathway
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Funding
- National Research Foundation of Korea (NRF) - Korean Government (MSIT) [NRF-2020R1A2C1007476, NRF-2017R1A5A2015391]
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The study demonstrated that SPX promoted osteogenic differentiation in vitro and increased in vivo bone regeneration through the MEK/ERK pathway.
BACKGROUND: The neural regulation of bone regeneration has emerged recently. Spexin (SPX) is a novel neuropeptide and regulates multiple biological functions. However, the effects of SPX on osteogenic differentiation need to be further investigated. Therefore, the aim of this study is to investigate the effects of SPX on osteogenic differentiation, possible underlying mechanisms, and bone regeneration. METHODS: In this study, MC3T3-E1 cells were treated with various concentrations of SPX. Cell proliferation, osteogenic differentiation marker expressions, alkaline phosphatase (ALP) activity, and mineralization were evaluated using the CCK-8 assay, reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), ALP staining, and alizarin red S staining, respectively. To determine the underlying molecular mechanism of SPX, the phosphorylation levels of signaling molecules were examined via western blot analysis. Moreover, in vivo bone regeneration by SPX (0.5 and 1 mu g/mu l) was evaluated in a calvarial defect model. New bone formation was analyzed using micro-computed tomography (micro-CT) and histology. RESULTS: The results indicated that cell proliferation was not affected by SPX. However, SPX significantly increased ALP activity, mineralization, and the expression of genes for osteogenic differentiation markers, including runt-related transcription factor 2 (Runx2), Alp, collagen alpha-1(I) chain (Col1a1), osteocalcin (Oc), and bone sialoprotein (Bsp). In contrast, SPX downregulated the expression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (Enpp1). Moreover, SPX upregulated phosphorylated mitogen-activated protein kinase kinase (MEK1/2) and extracellular signal-regulated kinase (ERK1/2). In vivo studies, micro-CT and histologic analysis revealed that SPX markedly increased a new bone formation. CONCLUSION: Overall, these results demonstrated that SPX stimulated osteogenic differentiation in vitro and increased in vivo bone regeneration via the MEK/ERK pathway.
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