Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, 76100, Israel.
School of Cellular & Molecular Medicine, University of Bristol, Bristol, BS8 1TD, United Kingdom.
Exp Cell Res. 2023 Oct 1;431(1):113758. doi: 10.1016/j.yexcr.2023.113758. Epub 2023 Aug 22.
The cytokine RANKL (Receptor Activator of NFκB Ligand) is the key driver of differentiation of monocytes/macrophages to form multi-nucleated, bone-resorbing osteoclasts, a process that is accompanied by significant changes in gene expression. We show that exposure to RANKL rapidly down-regulates expression of Brain Acid Soluble Protein 1 (BASP1) in cultured primary mouse bone marrow macrophages (BMMs), and that this reduced expression is causally linked to the osteoclastogenic process in vitro. Knocking down BASP1 expression in BMMs or eliminating its expression in these cells or in RAW 264.7 cells enhanced RANKL-induced osteoclastogenesis, promoted cell-cell fusion, and generated cultures containing larger osteoclasts with increased mineral degrading abilities relative to controls. Expression of exogenous BASP1 in BMMs undergoing osteoclastogenic differentiation produced the opposite effects. Upon exposure to RANKL, primary mouse BMMs in which BASP1 had been knocked down exhibited increased expression of the key osteoclastogenic transcription factor Nfatc1and of its downstream target genes Dc-stamp, Ctsk, Itgb3, and Mmp9 relative to controls. The knock-down cells also exhibited increased sensitivity to the pro-osteoclastogenic effects of RANKL. We conclude that BASP1 is a negative regulator of RANKL-induced osteoclastogenesis, which down-regulates the pro-osteoclastogenic gene expression pattern induced by this cytokine. Decreased expression of BASP1 upon exposure of BMMs to RANKL removes a negative regulator of osteoclastogenesis and promotes this process.
细胞因子 RANKL（核因子 κB 配体受体激活剂）是单核细胞/巨噬细胞分化为形成多核、骨吸收破骨细胞的关键驱动因素，这一过程伴随着基因表达的显著变化。我们表明，暴露于 RANKL 可迅速下调培养的原代小鼠骨髓巨噬细胞（BMM）中 Brain Acid Soluble Protein 1（BASP1）的表达，并且这种表达减少与体外破骨细胞生成过程有关。在 BMM 中敲低 BASP1 表达或消除其在这些细胞或 RAW 264.7 细胞中的表达增强了 RANKL 诱导的破骨细胞生成，促进了细胞融合，并产生了含有更大破骨细胞的培养物，与对照相比，其具有增加的矿物质降解能力。在经历破骨细胞生成分化的 BMM 中表达外源性 BASP1 产生了相反的效果。暴露于 RANKL 后，与对照相比，BASP1 被敲低的原代小鼠 BMM 中关键破骨细胞生成转录因子 Nfatc1 的表达及其下游靶基因 Dc-stamp、Ctsk、Itgb3 和 Mmp9 的表达增加。敲低细胞对 RANKL 的促破骨细胞生成作用也表现出更高的敏感性。我们得出结论，BASP1 是 RANKL 诱导的破骨细胞生成的负调节剂，它下调了该细胞因子诱导的促破骨细胞生成基因表达模式。BMM 暴露于 RANKL 时 BASP1 的表达减少去除了破骨细胞生成的负调节剂，并促进了这一过程。
