Study on Interaction between Osteoclast Progenitors and Osteoblastic Cells in Osteoclast Development.

我们建立了小鼠成骨细胞和脾细胞的共培养体系，以研究破骨祖细胞与成骨细胞在其分化为破骨细胞过程中的相互作用。利用该共培养体系，我们研究了成骨细胞在破骨细胞发育中的作用，[2]OP/OP(骨质疏松症)和oc/oc(骨硬化性)突变小鼠的骨化性疾病的发病机制，以及[3]p60^&lt；c-src&GT；[1]成骨细胞在破骨细胞发育中的作用在小鼠成骨细胞和脾细胞共培养体系中，研究了成骨细胞在破骨细胞发育中的作用。我们已经证明，成骨细胞通过细胞与细胞之间的相互作用机制在调节破骨细胞前体细胞的分化中发挥重要作用(5，6，8)。成骨细胞表达破骨细胞诱导因子(S)似乎受到骨吸收…的严格调控更多的因素，如1α，25-二羟基维生素D_3和甲状旁腺激素(1，2，6，11)。[2]突变小鼠的骨化性疾病的发病机制我们用成骨细胞和脾细胞的共培养系统研究了OP/OP和oc/oc突变小鼠的骨化性疾病的发病机制。研究表明，OP/OP小鼠破骨细胞缺陷是成骨细胞缺陷所致，成骨细胞产生的M-CSF在破骨细胞发育过程中起关键作用。我们还发现，M-CSF对于破骨细胞前体细胞的增殖和向成熟破骨细胞的分化都是不可或缺的(4，10)。在用oc/oc小鼠进行的实验中，我们得出结论：oc/oc小鼠缺乏骨吸收是由于破骨祖细胞的缺陷，在成骨细胞提供的微环境中，破骨祖细胞无法分化为有功能的破骨细胞(7)。[3]p60^&lt；c-src&gt；在破骨细胞中的表达最近有报道称，c-src的靶向干扰在小鼠中诱导了骨化。因此，我们检测了p60^&lt；c-src&gt；在共培养体系中形成的真实破骨细胞和破骨细胞样细胞中的表达。在共培养中，p60^&lt；c-src&gt；的表达显著增加，与破骨细胞样细胞的出现平行(9)。电子显微镜研究表明，p60^&lt；c-src&gt；主要定位于褶皱的边缘膜和液泡上(9)。这些结果表明，p60^&lt；c-src&gt；在破骨细胞性骨吸收中起重要作用。较少

We have developed a co-culture system of mouse osteoblastic cells and spleen cells to investigate the interaction of osteoclast progenitors with osteoblastic cells in their differentiation into osteoclasts.Using this co-culture system, we examined [1] role of osteoblastic cells in osteoclast development, [2] pathogenesis of osteopetrotic disorders in op/op (osteopetrotic) and oc/oc (osteosclerotic) mutant mice, and [3] expression of p60^<c-src> (a product of c-src proto-oncogenen) in osteoclasts.[1] Role of Osteoblastic Cells in Osteoclast Development The role of osteoblastic cells in osteoclast development was investigated in a co-culture system of mouse osteoblastic cells and spleen cells. We have shown that osteoblastic cells play an important role in modulating the differentiation of osteoclast progenitors through a mechanism of cell-to-cell interaction (5,6,8). The expression of an osteoclast-inducing factor (s) by osteoblastic cells appeared to be tightly regulated by bone-resorb … More ing factors such as 1alpha,25-dihydroxyvitamin D_3 and parathyroid hormone (1,2,6,11).[2] Pathogenesis of Osteopetrotic Disorders in Mutant Mice We examined pathogenesis of osteopetrotic disorders in op/op and oc/oc mutant mice using a co-culture system of their osteoblastic cells and spleen cells. It was shown that osteoclast deficiency in op/op mice is due to a defect in osteoblastic cells, and that the M-CSF produced by osteoblastic cells plays a critical role in osteoclast development (3). We also found that M-CSF is indispensable for both proliferation of osteoclast progenitors and their differentiation into mature osteoclasts (4, 10). In experiments using oc/oc mice, we concluded that the lack of bone resorption in oc/oc mice is due to a defect of osteoclast progenitors, which fail to differentiate into functional osteoclasts in the microenvironment provided by osteoblastic cells (7).[3] Expression of p60^<c-src> in Osteoclasts Recently, it was reported that the targeted disruption of c-src in mice induced osteopetrosis. We, therefore, examined expression of p60^<c-src> in authentic osteoclasts and osteoclast-like cells formed in the co-culture system. The expression of p60^<c-src> strikingly increased parallel with the appearance of osteoclast-like cells in the co-culture (9). The electron microscopic study revealed that p60^<c-src> was primarily localized on ruffled border membranes and vacuoles (9). These results indicate that p60^<c-src> is important in osteoclastic bone resorption. Less