BACKGROUND The hypoxic environment during bone healing is important in regulating the differentiation of periosteal stem cells(PSCs)into osteoblasts or chondrocytes;however,the underlying mechanisms remain unclear.AIM...BACKGROUND The hypoxic environment during bone healing is important in regulating the differentiation of periosteal stem cells(PSCs)into osteoblasts or chondrocytes;however,the underlying mechanisms remain unclear.AIM To determine the effect of hypoxia on PSCs,and the expression of microRNA-584-5p(miR-584-5p)and RUNX family transcription factor 2(RUNX2)in PSCs was modulated to explore the impact of the miR-584-5p/RUNX2 axis on hypoxiainduced osteogenic differentiation of PSCs.METHODS In this study,we isolated primary mouse PSCs and stimulated them with hypoxia,and the characteristics and functional genes related to PSC osteogenic differentiation were assessed.Constructs expressing miR-584-5p and RUNX2 were established to determine PSC osteogenic differentiation.RESULTS Hypoxic stimulation induced PSC osteogenic differentiation and significantly increased calcified nodules,intracellular calcium ion levels,and alkaline phosphatase(ALP)activity in PSCs.Osteogenic differentiation-related factors such as RUNX2,bone morphogenetic protein 2,hypoxia-inducible factor 1-alpha,and ALP were upregulated;in contrast,miR-584-5p was downregulated in these cells.Furthermore,upregulation of miR-584-5p significantly inhibited RUNX2 expression and hypoxia-induced PSC osteogenic differentiation.RUNX2 was the target gene of miR-584-5p,antagonizing miR-584-5p inhibition in hypoxia-induced PSC osteogenic differentiation.CONCLUSION Our study showed that the interaction of miR-584-5p and RUNX2 could mediate PSC osteogenic differentiation induced by hypoxia.展开更多
Vitamin K2 (VK2, menaquinone) is a drug for osteoporosis. VK2 acts as a cofactor for γ-glutamyl carboxylase, which catalyzes the carboxylation of specific glutamic acid residues (γ-carboxylation) of substrate protei...Vitamin K2 (VK2, menaquinone) is a drug for osteoporosis. VK2 acts as a cofactor for γ-glutamyl carboxylase, which catalyzes the carboxylation of specific glutamic acid residues (γ-carboxylation) of substrate proteins. Here we demonstrate that VK2 also regulate osteoblastgenic marker gene expression. Using VK2-immobilzed nanobeads new target proteins were purified and identified from osteoblastic cell line. They are prohibitin 1 and 2 (PHB1 & 2), respectively. To confirm the PHBs function on VK2-dependent transcription, PHB1 & 2 were knock-down and osteocalcin gene 2 transcriptions were analyzed, indicating that PHBs regulate VK2-dependent transcription. Taken together PHBs are VK2 target proteins for osteoblastgenic transcription.展开更多
Background Fibroblast growth factor 9 （FGF9）, expressed in brain, kidney and developing skeletal tissues, can physiologically inhibit endochondral ossification; but little is known about how FGF9 affects osteoblasts...Background Fibroblast growth factor 9 （FGF9）, expressed in brain, kidney and developing skeletal tissues, can physiologically inhibit endochondral ossification; but little is known about how FGF9 affects osteoblasts and its detailed regulatory mechanism. Here we examined the effect of FGF9 on the activity of the murine Runt-related transcription factor2 （Runx2） gene promoter in preosteoblast MC3T3-E1 and premyoblast C2C12 cells. Methods Plasmids containing the Runx2 promoter region were transfected into MC3T3-E1 and C2C12 cells and stably transfected cell lines were established. The method of luciferase reporter gene activation was used to examine the effects of FGF9 on the promoter activity. Results FGF9 （10 ng/ml） increased Runx2 promoter activity in MC3T3-E1 cells. When MC3T3-E1 cells were treated with FGF9 plus the various inhibitors or activator of the intracellular signaling transducation pathways, including 10 μmol/L U0126 （the inhibitor of mitogen-activated protein kinase kinase）, 10 pmol/L SB203580 （the inhibitor of p38/mitogen activated protein kinase）, or 1 pmol/L C6 ceramide （an activator of mitogen activated protein kinase）, the luciferase expression did not change significantly compared with that of the cells treated with FGF9 only. However, when C2C12 cells were treated with 10 ng/ml FGF9, Runx2. gene promoter activity first decreased and then increased over a period of 1 to 5 days. Among the above inhibitors, only U0126 （10 μmol/L） completely blocked the effects of FGF9 on Runx2 gene promoter activity. Conclusions Our data showed that FGF9 can affect Runx2 gene promoter activity in MC3T3-E1 and C2C12 cells. The action of FGF9 appears to depend partly on the mitogen-activated protein kinase kinase/mitogen-activated protein kinase pathways in C2C12 cells.展开更多
基金Supported by Sailing Program of Naval Medical University,Program of Shanghai Hongkou District Health Commission,No.2202-27Special Funds for Activating Scientific Research of Shanghai Fourth People’s Hospital,No.sykyqd05801.
文摘BACKGROUND The hypoxic environment during bone healing is important in regulating the differentiation of periosteal stem cells(PSCs)into osteoblasts or chondrocytes;however,the underlying mechanisms remain unclear.AIM To determine the effect of hypoxia on PSCs,and the expression of microRNA-584-5p(miR-584-5p)and RUNX family transcription factor 2(RUNX2)in PSCs was modulated to explore the impact of the miR-584-5p/RUNX2 axis on hypoxiainduced osteogenic differentiation of PSCs.METHODS In this study,we isolated primary mouse PSCs and stimulated them with hypoxia,and the characteristics and functional genes related to PSC osteogenic differentiation were assessed.Constructs expressing miR-584-5p and RUNX2 were established to determine PSC osteogenic differentiation.RESULTS Hypoxic stimulation induced PSC osteogenic differentiation and significantly increased calcified nodules,intracellular calcium ion levels,and alkaline phosphatase(ALP)activity in PSCs.Osteogenic differentiation-related factors such as RUNX2,bone morphogenetic protein 2,hypoxia-inducible factor 1-alpha,and ALP were upregulated;in contrast,miR-584-5p was downregulated in these cells.Furthermore,upregulation of miR-584-5p significantly inhibited RUNX2 expression and hypoxia-induced PSC osteogenic differentiation.RUNX2 was the target gene of miR-584-5p,antagonizing miR-584-5p inhibition in hypoxia-induced PSC osteogenic differentiation.CONCLUSION Our study showed that the interaction of miR-584-5p and RUNX2 could mediate PSC osteogenic differentiation induced by hypoxia.
文摘Vitamin K2 (VK2, menaquinone) is a drug for osteoporosis. VK2 acts as a cofactor for γ-glutamyl carboxylase, which catalyzes the carboxylation of specific glutamic acid residues (γ-carboxylation) of substrate proteins. Here we demonstrate that VK2 also regulate osteoblastgenic marker gene expression. Using VK2-immobilzed nanobeads new target proteins were purified and identified from osteoblastic cell line. They are prohibitin 1 and 2 (PHB1 & 2), respectively. To confirm the PHBs function on VK2-dependent transcription, PHB1 & 2 were knock-down and osteocalcin gene 2 transcriptions were analyzed, indicating that PHBs regulate VK2-dependent transcription. Taken together PHBs are VK2 target proteins for osteoblastgenic transcription.
文摘Background Fibroblast growth factor 9 （FGF9）, expressed in brain, kidney and developing skeletal tissues, can physiologically inhibit endochondral ossification; but little is known about how FGF9 affects osteoblasts and its detailed regulatory mechanism. Here we examined the effect of FGF9 on the activity of the murine Runt-related transcription factor2 （Runx2） gene promoter in preosteoblast MC3T3-E1 and premyoblast C2C12 cells. Methods Plasmids containing the Runx2 promoter region were transfected into MC3T3-E1 and C2C12 cells and stably transfected cell lines were established. The method of luciferase reporter gene activation was used to examine the effects of FGF9 on the promoter activity. Results FGF9 （10 ng/ml） increased Runx2 promoter activity in MC3T3-E1 cells. When MC3T3-E1 cells were treated with FGF9 plus the various inhibitors or activator of the intracellular signaling transducation pathways, including 10 μmol/L U0126 （the inhibitor of mitogen-activated protein kinase kinase）, 10 pmol/L SB203580 （the inhibitor of p38/mitogen activated protein kinase）, or 1 pmol/L C6 ceramide （an activator of mitogen activated protein kinase）, the luciferase expression did not change significantly compared with that of the cells treated with FGF9 only. However, when C2C12 cells were treated with 10 ng/ml FGF9, Runx2. gene promoter activity first decreased and then increased over a period of 1 to 5 days. Among the above inhibitors, only U0126 （10 μmol/L） completely blocked the effects of FGF9 on Runx2 gene promoter activity. Conclusions Our data showed that FGF9 can affect Runx2 gene promoter activity in MC3T3-E1 and C2C12 cells. The action of FGF9 appears to depend partly on the mitogen-activated protein kinase kinase/mitogen-activated protein kinase pathways in C2C12 cells.
