The actin-bundling protein, PLS3, is part of the mechanoresponsive machinery that regulates osteoblast mineralization.
The actin-bundling protein, PLS3, is part of the mechanoresponsive machinery that regulates osteoblast mineralization.
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DOI：
10.3389/fcell.2023.1141738
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发表时间：
2023
影响因子：
5.5
通讯作者：
中科院分区：
文献类型：
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PLS3是一种钙敏感的肌动蛋白捆绑蛋白，最近被发现与儿童期骨质疏松症的发生有关。临床数据表明，PLS3突变导致成骨细胞功能缺陷，但其潜在机制尚不清楚。为了研究PLS3在骨矿化中的作用，我们生成了稳定地耗尽PLS3的MC3T3-E1前成骨细胞。对照细胞和PLS3敲低细胞（PLS3 KD）的成骨分化分析表明，PLS3的缺失不会改变胶原基质沉积的成骨细胞矿化的第一阶段，但会严重影响该基质的后续矿化。在这一阶段，成骨细胞严重依赖于机械敏感信号通路来维持矿物质沉积，以响应细胞外基质（ECM）刚度的增加。PLS3明显定位于局灶粘连（FAs），这与机械感觉有着复杂的联系。与此一致，我们观察到PLS3的消耗使成骨细胞对ECM刚度的变化没有反应，并且与对照细胞相比，在软底物（6 kPa）和硬底物（100 kPa）上镀时显示相同的细胞大小，FA长度和FA数量，而对照细胞在100 kPa底物上镀时显示这些参数都增加了。表达野生型PLS3可以挽救PLS3 KD细胞在坚硬底物上有缺陷的细胞扩散，但不能通过表达早发性骨质疏松症患者中发现的具有异常肌动蛋白捆绑活性的三种PLS3突变来挽救。总之，我们的研究结果表明，PLS3的肌动蛋白捆绑是促进成骨细胞矿化的机械敏感机制的一部分，从而开始阐明PLS3如何促进骨质疏松症等骨缺陷的发展。
Plastin-3 (PLS3) is a calcium-sensitive actin-bundling protein that has recently been linked to the development of childhood-onset osteoporosis. Clinical data suggest that PLS3 mutations lead to a defect in osteoblast function, however the underlying mechanism remains elusive. To investigate the role of PLS3 in bone mineralization, we generated MC3T3-E1 preosteoblast cells that are stably depleted of PLS3. Analysis of osteogenic differentiation of control and PLS3 knockdown (PLS3 KD) cells showed that depletion of PLS3 does not alter the first stage of osteoblast mineralization in which a collagen matrix is deposited, but severely affects the subsequent mineralization of that matrix. During this phase, osteoblasts heavily rely on mechanosensitive signaling pathways to sustain mineral deposition in response to increasing stiffness of the extracellular matrix (ECM). PLS3 prominently localizes to focal adhesions (FAs), which are intricately linked to mechanosensation. In line with this, we observed that depletion of PLS3 rendered osteoblasts unresponsive to changes in ECM stiffness and showed the same cell size, FA lengths and number of FAs when plated on soft (6 kPa) versus stiff (100 kPa) substrates in contrast to control cells, which showed an increased in each of these parameters when plated on 100 kPa substrates. Defective cell spreading of PLS3 KD cells on stiff substrates could be rescued by expression of wildtype PLS3, but not by expression of three PLS3 mutations that were identified in patients with early onset osteoporosis and that have aberrant actin-bundling activity. Altogether, our results show that actin-bundling by PLS3 is part of the mechanosensitive mechanism that promotes osteoblast mineralization and thus begins to elucidate how PLS3 contributes to the development of bone defects such as osteoporosis.
影响因子：
2.4
作者：
Zouani OF;Rami L;Lei Y;Durrieu MC
通讯作者：
Durrieu MC