Cho Sun Wook, Yang Jae-Yeon, Sun Hyun Jin, Jung Ju Yeon, Her Sun Ju, Cho Hwa Young, Choi Hyung Jin, Kim Sang Wan, Kim Seong Yeon, Shin Chan Soo
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Bone. 2009 Jun;44(6):1069-77. doi: 10.1016/j.bone.2009.02.012. Epub 2009 Feb 27.
Wnt inhibitory factor (WIF)-1 belongs to the members of secreted modulators of Wnt proteins. Secreted frizzled-related proteins (sFRPs), another member of Wnt modulators, have been shown to play differential roles in Wnt signaling depending on the subtypes and cell models. This study was undertaken to investigate the functional role of WIF-1 in osteoblastic differentiation of mouse mesenchymal C3H10T1/2 cells. C3H10T1/2 cells express endogenous WIF-1 and its expression level decreases during osteoblastogenesis. Treatment of C3H10T1/2 cells with WIF-1 significantly reduced alkaline phosphatase (ALP) activities induced by either osteogenic medium (OM, ascorbic acid and beta-glycerophosphate) or Wnt-3a conditioned medium (CM) in a dose-dependent manner. In contrast, the expression level of endogenous WIF-1 increased during adipogenesis and WIF-1 treatment resulted in increased adipogenesis. C3H10T1/2 cells transduced with WIF-1 retrovirus also exhibited reduced ALP activity and decreased mRNA expression of Runx2, collagen type 1, ALP and osteocalcin during osteoblastic differentiation compared to empty virus-transduced cells. Moreover, treatment with WIF-1 dose-dependently attenuates beta-catenin/T-cell factor (TCF) transcriptional activity in this cell line. Finally, knockdown of WIF-1 in C3H10T1/2 cells by RNA interference leads to increase in ALP activities. Collectively, these results indicate that WIF-1 plays as a negative regulator of osteoblastic differentiation in mouse mesenchymal C3H10T1/2 cells in vitro.
Wnt抑制因子（WIF）-1属于Wnt蛋白分泌调节剂成员。Wnt调节剂的另一个成员——分泌型卷曲相关蛋白（sFRP），已被证明根据亚型和细胞模型在Wnt信号传导中发挥不同作用。本研究旨在探讨WIF-1在小鼠间充质C3H10T1/2细胞成骨分化中的功能作用。C3H10T1/2细胞表达内源性WIF-1，其表达水平在成骨过程中降低。用WIF-1处理C3H10T1/2细胞可显著降低由成骨培养基（OM，抗坏血酸和β-甘油磷酸）或Wnt-3a条件培养基（CM）诱导的碱性磷酸酶（ALP）活性，且呈剂量依赖性。相反，内源性WIF-1的表达水平在脂肪生成过程中增加，WIF-1处理导致脂肪生成增加。与空病毒转导的细胞相比，用WIF-1逆转录病毒转导的C3H10T1/2细胞在成骨分化过程中也表现出ALP活性降低以及Runx2、1型胶原蛋白、ALP和骨钙素的mRNA表达减少。此外，用WIF-1处理可剂量依赖性地减弱该细胞系中的β-连环蛋白/T细胞因子（TCF）转录活性。最后，通过RNA干扰敲低C3H10T1/2细胞中的WIF-1导致ALP活性增加。总的来说，这些结果表明WIF-1在体外作为小鼠间充质C3H10T1/2细胞成骨分化的负调节因子发挥作用。
