RESUMO
Poncirin, a flavonoid isolated from the fruit of Poncirus trifoliata, possesses anti-bacterial and anti-inflammatory activities. However, the action of poncirin in bone biology is unclear. In this study, the in vivo and in vitro effects of poncirin in a glucocorticoid-induced osteoporosis (GIO) mouse model were investigated. Seven-month-old male mice were assigned to the following five groups: (1) sham-implantation (sham), (2) prednisolone 2.1 mg/kg/day (GC), (3) GC treated with 10 mg/kg/day of genistein, (4) GC treated with 3 mg/kg/day of poncirin, (5) and GC treated with 10 mg/kg/day of strontium (GC + SrCl(2)). After 8 weeks, bone loss was measured by microcomputed tomography. Osteocalcin (OC) and C-terminal telopeptides of type I collagen (CTX) were evaluated in sera. Runx2 protein, OC and osteoprotegerin (OPG) mRNA expression, alkaline phosphatase (ALP) activity, and mineral nodule assay were performed in C3H10T1/2 or primary bone marrow stromal cells. Poncirin significantly increased the bone mineral density and improved the microarchitecture. Poncirin increased serum OC, Runx2 protein production, expression of OC and OPG mRNA, ALP activity, and mineral nodule formation; and decreased serum CTX. These effects were more prominent in the poncirin group compared to the other positive control groups (genistein and strontium). The poncirin-mediated restoration of biochemical bone markers, increased bone mineral density, and improved trabecular microarchitecture likely reflect increased bone formation and decreased bone resorption in GIO mice.
Assuntos
Reabsorção Óssea/prevenção & controle , Flavonoides/farmacologia , Osteoporose/prevenção & controle , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Animais , Biomarcadores/sangue , Biomarcadores/metabolismo , Densidade Óssea/efeitos dos fármacos , Densidade Óssea/fisiologia , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Reabsorção Óssea/genética , Reabsorção Óssea/metabolismo , Reabsorção Óssea/patologia , Células Cultivadas , Colágeno Tipo I/sangue , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/sangue , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Glucocorticoides/efeitos adversos , Vértebras Lombares/efeitos dos fármacos , Vértebras Lombares/metabolismo , Vértebras Lombares/patologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Osteocalcina/sangue , Osteocalcina/genética , Osteocalcina/metabolismo , Osteoporose/genética , Osteoporose/metabolismo , Osteoporose/patologia , Osteoprotegerina/genética , Osteoprotegerina/metabolismo , RNA Mensageiro/genética , Células Estromais/efeitos dos fármacos , Células Estromais/metabolismo , Células Estromais/patologiaRESUMO
Poncirin, flavanone glycoside, isolated from the fruit of Poncirus trifoliata, has anti-bacterial and anti-inflammatory activities. In this study, the effects of poncirin on the differentiation of mesenchymal stem cells were investigated. The C3H10T1/2 mesenchymal stem cells and primary bone marrow mesenchymal stem cells were studied. In the C3H10T1/2 cells, poncirin prevented adipocyte differentiation, as demonstrated by inhibition of cytoplasm lipid droplet accumulation and peroxisome proliferator-activating receptor-γ (PPAR-γ) and CCAAT-enhancer-binding protein-ß (C/EBP-ß) mRNA expression. By contrast, poncirin enhanced the expression of the key osteogenic transcription factors, runt-related transcription factor 2 (Runx2) and transcriptional coactivator with PDZ-binding motif (TAZ). Poncirin also enhanced expression of the osteogenic marker genes including alkaline phosphatase (ALP) and osteocalcin (OC). Poncirin increased mineral nodule formation in primary bone marrow mesenchymal stem cells. These results suggest that poncirin prevents adipogenesis and enhances osteoblast differentiation in mesenchymal stem cells.
Assuntos
Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Flavonoides/farmacologia , Células-Tronco Mesenquimais/citologia , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Adipogenia/efeitos dos fármacos , Animais , Biomarcadores/metabolismo , Células da Medula Óssea/citologia , Linhagem Celular , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Fêmur/efeitos dos fármacos , Fêmur/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Camundongos , Minerais/metabolismo , Tíbia/efeitos dos fármacos , Tíbia/metabolismo , Transcrição Gênica/efeitos dos fármacosRESUMO
Glycogen synthase kinase-3beta (GSK3beta) controls the survival of osteoblasts during bone development through Wnt canonical signaling. GSK3beta is a key factor for osteoblastogenesis, but relatively less is known regarding its role in osteoblast apoptosis. Genotoxic stress induced by etoposide promoted apoptotic signaling by GSK3beta activation in C3H10T1/2 cells, a mouse mesenchymal cell line. Etoposide led to the time-dependent activation of GSK3beta and caspase-3, which resulted in PARP cleavage. LiCl (a specific inhibitor) and siRNA (gene knock-down) of GSK3beta prevented the effects of etoposide on apoptosis. Staurosporine also induced apoptosis in C3H10T1/2 cells, but LiCl could not rescue. Bcl-2 was decreased in the cells by exposure to etoposide. LiCl completely recovered Bcl-2 expression as shown by both the mRNA and the protein expression levels. In conclusion, etoposide-induced apoptosis in C3H10T1/2 cells is mediated by GSK3beta, which leads to caspase-3 activation via decrease in Bcl-2 expression.