Cellular ATP Synthesis Mediated by Type III Sodium-dependent Phosphate Transporter Pit-1 Is Critical to Chondrogenesis
Cellular ATP Synthesis Mediated by Type III Sodium-dependent Phosphate Transporter Pit-1 Is Critical to Chondrogenesis
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DOI：
10.1074/jbc.m110.148403
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发表时间：
2011-01-28
影响因子：
4.8
通讯作者：
Yoneda, Toshiyuki
中科院分区：
文献类型：
--
作者：
Sugita, Atsushi;Kawai, Shinji;Yoneda, Toshiyuki
X-连锁低磷酸盐血症中的紊乱的软骨内骨化表明P-i参与软骨形成。我们研究了钠依赖性P-1协同转运蛋白（NPT）的作用，这是一个广泛认可的调节细胞P-1稳态，和下游事件在软骨形成使用Hyp小鼠，人类X-连锁低磷酸盐血症的小鼠同源物。Hyp小鼠肥大软骨细胞凋亡和矿化减少。与WT软骨细胞相比，Hyp培养的软骨细胞显示细胞凋亡和矿化减少，而软骨形成的早期事件糖胺聚糖合成没有改变。在Hyp软骨细胞中，III型NPT Pit-1的表达和P-i摄取减少，细胞内ATP水平也降低，同时caspase-9和caspase-3活性降低。竞争性NPT抑制剂膦酰基甲酸和ATP合成抑制剂3-溴丙酮酸干扰软骨内骨化，减少体内细胞凋亡，并抑制WT软骨细胞中的细胞凋亡和矿化，同时减少Pi摄取和ATP合成。Pit-1在Hyp软骨细胞中的过表达逆转了P-i摄取和ATP合成，并恢复了凋亡和矿化。我们的研究结果表明，细胞ATP合成继P-i通过Pit-1摄取在软骨细胞凋亡和矿化中起着重要作用，软骨形成是ATP依赖性的。
Disturbed endochondral ossification in X-linked hypophosphatemia indicates an involvement of P-i in chondrogenesis. We studied the role of the sodium-dependent P-i cotransporters (NPT), which are a widely recognized regulator of cellular P-i homeostasis, and the downstream events in chondrogenesis using Hyp mice, the murine homolog of human X-linked hypophosphatemia. Hyp mice showed reduced apoptosis and mineralization in hypertrophic cartilage. Hyp chondrocytes in culture displayed decreased apoptosis and mineralization compared with WT chondrocytes, whereas glycosaminoglycan synthesis, an early event in chondrogenesis, was not altered. Expression of the type III NPT Pit-1 and P-i uptake were diminished, and intracellular ATP levels were also reduced in parallel with decreased caspase-9 and caspase-3 activity in Hyp chondrocytes. The competitive NPT inhibitor phosphonoformic acid and ATP synthesis inhibitor 3-bromopyruvate disturbed endochondral ossification with reduced apoptosis in vivo and suppressed apoptosis and mineralization in conjunction with reduced P-i uptake and ATP synthesis in WT chondrocytes. Overexpression of Pit-1 in Hyp chondrocytes reversed P-i uptake and ATP synthesis and restored apoptosis and mineralization. Our results suggest that cellular ATP synthesis consequent to P-i uptake via Pit-1 plays an important role in chondrocyte apoptosis and mineralization, and that chondrogenesis is ATP-dependent.