Shanmugarajan Srinivasan, Youssef Rimon F, Pati Parmita, Ries William L, Rao D Sudhaker, Reddy Sakamuri V
Charles P. Darby Children's Research Institute, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
J Cell Biochem. 2008 Jul 1;104(4):1500-8. doi: 10.1002/jcb.21723.
Paget's disease (PD) of bone is characterized by increased activity of large abnormal osteoclasts (OCLs) which contain paramyxoviral nuclear and cytoplasmic inclusions. MVNP gene expression has been shown to induce pagetic phenotype in OCLs. We previously characterized the osteoclast inhibitory peptide-1 (OIP-1/hSca) which inhibits OCL formation/bone resorption. OIP-1 is a glycophosphatidylinositol (GPI)-linked membrane protein containing a 79 amino acid extra cellular peptide and a 32 amino acid carboxy terminal GPI-linked peptide (c-peptide) which is critical for OCL inhibition. In this study, we demonstrate that OIP-1 c-peptide significantly decreased (43%) osteoclast differentiation of peripheral blood mononuclear cells from patients with PD. Also, OIP-1 treatment to normal human bone marrow mononuclear cells transduced with the MVNP inhibited (41%) osteoclast precursor (CFU-GM) growth in methyl-cellulose cultures. We further tested if OIP-1 overexpression in the OCL lineage in transgenic mice inhibits MVNP stimulated OCL formation. MVNP transduction and RANKL stimulation of OIP-1 mouse bone marrow cells showed a significant decrease (43%) in OCL formation and inhibition (38%) of bone resorption area compared to wild-type mice. Western blot analysis identified that OIP-1 decreased (3.5-fold) MVNP induced TRAF2 expression during OCL differentiation. MVNP or OIP-1 expression did not affect TRAF6 levels. Furthermore, OIP-1 expression resulted in a significant inhibition of MVNP stimulated ASK1, Rac1, c-Fos, p-JNK, and NFATc1 expression during OCL differentiation. These results suggest that OIP-1 inhibits MVNP induced pagetic OCL formation/activity through suppression of RANK signaling. Thus, OIP-1 may have therapeutic utility against excess bone resorption in patients with PD.
骨佩吉特病（PD）的特征是大型异常破骨细胞（OCL）活性增加，这些破骨细胞含有副粘病毒核和胞质内含物。已证明MVNP基因表达可诱导破骨细胞出现佩吉特病表型。我们之前鉴定了破骨细胞抑制肽-1（OIP-1/hSca），它可抑制破骨细胞形成/骨吸收。OIP-1是一种糖基磷脂酰肌醇（GPI）连接的膜蛋白，包含一个79个氨基酸的细胞外肽和一个32个氨基酸的羧基末端GPI连接肽（c肽），该c肽对破骨细胞抑制至关重要。在本研究中，我们证明OIP-1 c肽可显著降低（43%）PD患者外周血单核细胞的破骨细胞分化。此外，用MVNP转导的正常人骨髓单核细胞经OIP-1处理后，在甲基纤维素培养物中破骨细胞前体（CFU-GM）生长受到抑制（41%）。我们进一步测试了转基因小鼠破骨细胞谱系中OIP-1的过表达是否抑制MVNP刺激的破骨细胞形成。与野生型小鼠相比，对OIP-1小鼠骨髓细胞进行MVNP转导和RANKL刺激后，破骨细胞形成显著减少（43%），骨吸收面积受到抑制（38%）。蛋白质印迹分析表明，在破骨细胞分化过程中，OIP-1可使MVNP诱导的TRAF2表达降低（3.5倍）。MVNP或OIP-1表达不影响TRAF6水平。此外，OIP-1表达导致在破骨细胞分化过程中MVNP刺激的ASK1、Rac1、c-Fos、p-JNK和NFATc1表达受到显著抑制。这些结果表明，OIP-1通过抑制RANK信号传导来抑制MVNP诱导的佩吉特病破骨细胞形成/活性。因此，OIP-1可能对PD患者过度的骨吸收具有治疗作用。
