糖尿病,其特征是血糖浓度增加,伴随着低骨转换,骨折风险增加,和胚胎骨骼畸形的形成。然而,很少有研究阐明导致这些成骨缺损的信号通路的潜在改变。我们在此假设高糖环境中的骨形成缺陷是由β-连环蛋白(CTNNB1)活性改变引起的,成骨分化的关键贡献者,其失调也与糖尿病的发展有关。
为了检验这一假设,我们使用了先前建立的胚胎干细胞(ESC)分化模型,该模型模拟了发育中胚胎的糖尿病环境.我们在含有高(糖尿病)或低(生理)水平的D-葡萄糖的成骨诱导培养基中分化了鼠ESC,并进行了时程分析以研究高葡萄糖对早期和晚期骨细胞分化的影响。
成骨分化的终点测量以葡萄糖依赖性方式降低,并且前体特异性标志物的表达在多个时间点改变。此外,在前体形成阶段,淋巴增强因子(LEF)/T细胞因子(TCF)转录因子的转录活性显着升高,而与叉头盒O3a(FOXO3a)复合的CTNNB1水平下降。AKT的调制,LEF/TCF和FOXO3a的已知上游调节器,以及CTNNB1挽救了在高糖条件下观察到的成骨输出的一些减少。
在我们的体外模型中,我们发现LEF/TCF和FOXO3a信号通路明显参与成骨分化的调节,这可能是糖尿病母亲新生儿骨骼缺陷的原因。
Diabetes, which is characterized by an increase in blood glucose concentration, is accompanied by low bone turnover, increased fracture risk, and the formation of embryonic skeletal malformations. Yet, there are few studies elucidating the underlying alterations in signaling pathways leading to these osteogenic defects. We hypothesized here that bone formation deficiencies in a high glucose environment result from altered activity of beta-catenin (CTNNB1), a key contributor to osteogenic differentiation, dysregulation of which has also been implicated in the development of diabetes.
To test this hypothesis, we used a previously established embryonic stem cell (ESC) model of differentiation that mimics the diabetic environment of the developing embryo. We differentiated murine ESCs within osteogenic-inducing media containing either high (diabetic) or low (physiological) levels of D-glucose and performed time course analyses to study the influence of high glucose on early and late bone cell differentiation.
Endpoint measures for osteogenic differentiation were reduced in a glucose-dependent manner and expression of precursor-specific markers altered at multiple time points. Furthermore, transcriptional activity of the lymphoid enhancer factor (LEF)/T cell factor (
TCF) transcription factors during precursor formation stages was significantly elevated while levels of CTNNB1 complexed with Forkhead box O 3a (FOXO3a) declined. Modulation of AKT, a known upstream regulator of both LEF/
TCF and FOXO3a, as well as CTNNB1 rescued some of the reductions in osteogenic output seen in the high glucose condition.
Within our in vitro model, we found a clear involvement of LEF/
TCF and FOXO3a signaling pathways in the regulation of osteogenic differentiation, which may account for the skeletal deficiencies found in newborns of diabetic mothers.