P2X7R-Panx1 Complex Impairs Bone Mechanosignaling under High Glucose Levels Associated with Type-1 Diabetes.
P2X7R-Panx1 Complex Impairs Bone Mechanosignaling under High Glucose Levels Associated with Type-1 Diabetes.
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DOI：
10.1371/journal.pone.0155107
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Thi MM
中科院分区：
文献类型：
--
作者：
Seref-Ferlengez Z;Maung S;Schaffler MB;Spray DC;Suadicani SO;Thi MM
1型糖尿病（T1 D）会导致一系列骨骼问题，包括骨密度降低和骨折风险增加。然而，糖尿病骨骼并发症的潜在机制仍不清楚。我们假设T1 D中的高葡萄糖水平改变嘌呤能受体（P2 Rs）和泛连接蛋白1（Panx 1）通道的表达和功能，从而损害ATP信号传导，ATP信号传导对于适当的骨对机械负荷的反应和骨骼完整性的维持是必不可少的。我们首先确定了P2 X7受体-Panx 1在骨细胞机械信号传导中的关键作用，表明这些蛋白质共表达，为流动诱导的ATP释放提供了主要途径。为了在体外模拟骨细胞在健康骨与糖尿病骨中暴露的葡萄糖水平，我们将成骨细胞和骨细胞系在含有5.5或25 mM葡萄糖的培养基中培养10天。通过蛋白质印迹分析、定量对P2 R激动剂和振荡流体剪切应力（± 10 dyne/cm 2）的Ca 2+响应以及测量流动诱导的ATP释放来确定高糖对P2 R和Panx 1通道的表达和功能的影响。使用糖尿病C57 BL/6 J-Ins 2 Akita小鼠来评估高葡萄糖对P2 R和Panx 1的体内影响。蛋白质印迹法表明，改变P2 X7 R，P2 Y2 R和P2 Y 4 R的表达在高糖暴露的骨细胞，并在糖尿病骨组织。此外，高葡萄糖钝化正常的P2 R-和流量诱导的Ca 2+信号和ATP释放的骨细胞。这些发现表明，T1 D损害骨细胞中负荷诱导的ATP信号传导，并影响成骨细胞功能，这对维持骨骼健康至关重要。
Type 1 diabetes (T1D) causes a range of skeletal problems, including reduced bone density and increased risk for bone fractures. However, mechanisms underlying skeletal complications in diabetes are still not well understood. We hypothesize that high glucose levels in T1D alters expression and function of purinergic receptors (P2Rs) and pannexin 1 (Panx1) channels, and thereby impairs ATP signaling that is essential for proper bone response to mechanical loading and maintenance of skeletal integrity. We first established a key role for P2X7 receptor-Panx1 in osteocyte mechanosignaling by showing that these proteins are co-expressed to provide a major pathway for flow-induced ATP release. To simulate in vitro the glucose levels to which bone cells are exposed in healthy vs. diabetic bones, we cultured osteoblast and osteocyte cell lines for 10 days in medium containing 5.5 or 25 mM glucose. High glucose effects on expression and function of P2Rs and Panx1 channels were determined by Western Blot analysis, quantification of Ca2+ responses to P2R agonists and oscillatory fluid shear stress (± 10 dyne/cm2), and measurement of flow-induced ATP release. Diabetic C57BL/6J-Ins2Akita mice were used to evaluate in vivo effects of high glucose on P2R and Panx1. Western blotting indicated altered P2X7R, P2Y2R and P2Y4R expression in high glucose exposed bone cells, and in diabetic bone tissue. Moreover, high glucose blunted normal P2R- and flow-induced Ca2+ signaling and ATP release from osteocytes. These findings indicate that T1D impairs load-induced ATP signaling in osteocytes and affects osteoblast function, which are essential for maintaining bone health.