Expression Changes In The Related Factors Of Wnt Signaling Pathway During The Differentiation Of Rat BMSCs Into Osteoblasts In Hyperlipidemia Environment

Backgrounds’.The morbidity of Osteoporosis and hyperlipidemia increasing day by day, many studies show that there is a close relationship between them, but the specific pathogenesis is still unclear.Wnt signal pathway has become a hot study on bone metabolism in recent years.Objective:To study the expression changes in the Wnt signaling pathway related factors in hyperlipidemia environment during the differentiation of rat bone marrow mesenchymal stem cells (BMSCs) into osteoblasts.Methods:The third generation BMSCs were used to induce osteoblast.The experiment was divided into two groups:high fat group and control group,and each group has three samples. After 5 days 、7 days、14 days, Alkaline phosphatase (ALP) activity measurement was conducted to examine the early osteoblast differentiation. At 28 days, Alizarin red staining was applied for observing extra cellular matrix mineralization.At 14 days, Oil Red-O was stained to examine the adipogenic differentiation.RT-PCR was used to evaluate the expression level of LRP5、Wnt3a、 sFRP1、β-catenin and PPAR-γ mRNA at 7 days、14 days and 21 days. At the same time, Westen bolt detection the β-catenin protein expression. Statistically analyses were conducted through SPSS 17.0 software.Results:Alkaline phosphatase (ALP) activity showed with the extended response time activity increased, and the high fat group activity were lower than the control group at 7 days、21 days. Alizarin red staining showed that calcium nodules in the control group was more than the high fat group. Oil Red-O staining show that fat cells is higher in the high fat group.RT-PCR results showed that in 7 days, the expression of sFRP1 and PPAR-y in the high fat group higher than in control group, the difference was significant (p<0.01), at the 14 day,Wnt3a, β-catenin expression in control group was higher than that in the high fat group(p<0.05), the expression level of sFRP1 and PPAR-y were significantly higher in the high fat group, the difference was significant (p<0.01), at 21 day, when LRP-5, β-catenin expression in the control group was higher than the high lipid group, the difference was significant (p<0.01). Western blot showed, β-catenin protein expression in high fat group was lower than the control group(p<0.05), was consistent with RT-PCR.Conclusion:1. Under the hyperlipidemia environment, the osteoblast differentiation reduce.2. At different time,The expression of Wnt signaling pathway factors are differentin the early time of the osteogenic differentiation sFRPl plays a role, in the medium, Wnt3a is Important, and in the end ｛-catenin,LRP5 changes Significant, the specific reasons need to further explore.3. Wnt signaling pathway is involved in the differentiation process of BMSCs into osteoblast, the related factors Contact closely, in hyperlipidemia environment, Wnt3a, LRP5, β-catenin are inhibited, SFRPl and PPAR-y are activated, this may be one of the reasons leading to osteoporosis.