Phosphatidylethanolamine dynamics are required for osteoclast fusion.
Phosphatidylethanolamine dynamics are required for osteoclast fusion.
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DOI：
10.1038/srep46715
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发表时间：
2017-04-24
影响因子：
4.6
通讯作者：
Murakami M
中科院分区：
文献类型：
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作者：
Irie A;Yamamoto K;Miki Y;Murakami M
破骨细胞负责骨吸收，是由单核前破骨细胞细胞间融合形成的多核细胞。虽然破骨细胞融合是破骨细胞发生的关键步骤，但对其机制知之甚少。为了阐明其潜在的过程，我们在体外研究了破骨细胞形成过程中膜磷脂的动态变化。我们发现细胞内磷脂，特别是磷脂酰乙醇胺（PE）的含量在破骨细胞分化过程中增加。此外，在破骨细胞形成过程中，PE在质膜双分子层的外小叶中大量增加，并集中在参与细胞-细胞融合的丝状足中。固定细胞表面PE阻断破骨细胞融合，揭示了PE丰度和分布的重要性。为了确定这些PE动力学的分子，我们通过定量PCR和shrna介导的敲低筛选了一系列与脂质相关的基因。其中，一种PE生物合成酶酰基辅酶a：溶血磷脂酰乙醇胺酰基转移酶2 （LPEAT2）和两种atp结合盒（ABC）转运蛋白ABCB4和ABCG1在破骨细胞形成过程中显著增加，它们在破骨前细胞中的下调导致细胞表面PE暴露减少，随后破骨细胞融合。这些发现表明，PE动力学在破骨细胞融合中起重要作用，其中LPEAT2、ABCB4和ABCG1是PE生物合成和再分配的关键参与者。
Osteoclasts, responsible for bone resorption, are multinucleated cells formed by cell-cell fusion of mononuclear pre-osteoclasts. Although osteoclast fusion is a pivotal step for osteoclastogenesis, little is known about the mechanism involved. To clarify the underlying process, we investigated dynamics of membrane phospholipids during osteoclastogenesis in vitro. We found that the cellular content of phospholipids, phosphatidylethanolamine (PE) in particular, was increased during osteoclast differentiation. Furthermore, PE was greatly increased in the outer leaflet of the plasma membrane bilayer during osteoclastogenesis, being concentrated in filopodia involved in cell-cell fusion. Immobilisation of the cell surface PE blocked osteoclast fusion, revealing the importance of PE abundance and distribution. To identify the molecules responsible for these PE dynamics, we screened a wide array of lipid-related genes by quantitative PCR and shRNA-mediated knockdown. Among them, a PE-biosynthetic enzyme, acyl-CoA:lysophosphatidylethanolamine acyltransferase 2 (LPEAT2), and two ATP-binding cassette (ABC) transporters, ABCB4 and ABCG1, were markedly increased during osteoclastogenesis, and their knockdown in pre-osteoclasts led to reduction in PE exposure on the cell surface and subsequent osteoclast fusion. These findings demonstrate that the PE dynamics play an essential role in osteoclast fusion, in which LPEAT2, ABCB4 and ABCG1 are key players for PE biosynthesis and redistribution.