The role of plastin-3 in skeletal remodeling

骨骼是一个高度复杂的组织，在成骨细胞和骨吸收破骨细胞的协调活动的调节下，不断地进行重塑。骨吸收的相对增加是骨质疏松症的原因，骨质疏松症是老年人中最常见的疾病之一。我们之前已经确认了两名携带PLS3基因突变的早发性骨质疏松症(EOOP)患者，从而证实了之前的研究，即半合子失活PLS3突变是X连锁骨质疏松症的原因，而PLS3杂合子突变是EOOP女性患者的原因。PLS3如何参与骨骼重塑尚不清楚，但已有研究表明，该蛋白可能是成骨细胞向骨细胞转变相关的形态变化所必需的。然而，这是否真的是pls-3在骨骼重塑中的主要功能仍有待确定，同样的情况也适用于PLS3失活对其他细胞类型的潜在影响。这种知识的匮乏可能是由于缺乏描述PLS3缺陷小鼠的生成和表型的研究。为了在细胞和分子水平上分析PLS3失活对骨量的影响，我们利用了EUCOMM提供的PLS3缺陷小鼠模型。到目前为止，我们已经对第一组6周龄和12周龄的PLS3-/0雄性及其对应的PLS3+/0胎仔进行了股骨微CT扫描。在这里，我们可以清楚地证明，PLS3缺乏影响骨量，主要是在皮质室，从而为其他几个实验提供了基础。更具体地说，我们将使用静态、细胞和动态组织形态计量学，结合骨重建生物标志物的基因表达研究和血清分析，比较不同年龄的PLS3-/0雄性和PLS3+/-雌性与野生型窝仔的表型。我们还将分析PLS3失活对骨细胞网络的影响，并研究PLS3缺陷骨细胞(成骨细胞和破骨细胞)的体外行为。最后，我们将利用这个小鼠模型来优化PLS3突变导致的X连锁骨质疏松症患者的治疗。由于我们之前已经在其他项目中使用了这些方法中的大多数，我们希望在接下来的36个月内对纤溶酶-3在骨骼重塑中的作用获得重要的见解。

The skeleton is a highly complex tissue being constantly remodeled in a process mediated by the coordinated activities of bone-forming osteoblasts and bone-resorbing osteoclasts. A relative increase of bone resorption is the cause of osteoporosis, one of the most prevalent disorders in the aged population. We have previously identified two individuals with early-onset osteoporosis (EOOP) carrying mutations of the PLS3 gene, thereby confirming previous studies describing hemizygous inactivating PLS3 mutations as a cause of X-linked osteoporosis and heterozygous PLS3 mutations in women with EOOP. How Pls3 is involved in skeletal remodeling is still unknown, yet it has been suggested that the protein might be required for morphological changes associated with osteoblast to osteocyte transition. Whether this is truly the primary function of Pls-3 in skeletal remodeling however remains to be determined, and the same applies for potential effects of Pls3 inactivation on other cell types. This paucity of knowledge is likely explained by the lack of studies describing the generation and phenotyping of Pls3-deficient mice. To analyze the impact of Pls3 inactivation on bone mass at a cellular and molecular level we took advantage of a commercially available Pls3-deficient mouse model from EUCOMM. Until now we have analyzed the first set of 6 weeks and 12 weeks old Pls3-/0 males and their corresponding Pls3+/0 littermates by µCT scanning of the femora. Here we could clearly demonstrate that Pls3-deficiency affects bone mass, primarily in the cortical compartment, thereby providing the basis for several additional experiments. More specifically, we will compare the phenotype of Pls3-/0 males and Pls3+/- females towards wildtype littermates at various ages using static, cellular and dynamic histomorphometry, paired with gene expression studies and serum analysis for bone remodeling biomarkers. We will also analyze the impact of Pls3 inactivation on the osteocyte network, and we will study the behavior of Pls3-deficient bone cells (osteoblasts and osteoclasts) ex vivo. Finally, we will utilize this mouse model in order to optimize the treatment for individuals with X-linked osteoporosis due to PLS3 mutation. Since we have previously used most of these methods for other projects, we expect to obtain significant insights into the role of role of plastin-3 in skeletal remodeling within the next 36 months.