Department of Biochemistry and Molecular Biology, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan; Department of Dental Anesthesiology, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan.
Biochem Biophys Res Commun. 2013 Oct 4;439(4):506-10. doi: 10.1016/j.bbrc.2013.09.014. Epub 2013 Sep 8.
The neuropeptide Y (NPY) system is known as one of the major neural signaling pathways. NPY, produced by peripheral tissues including osteoblasts, is known to bind to the Y1 receptor. Recently, osteoblast-specific Y1 receptor knockout mice were developed and were found to have a high bone mass phenotype, indicating a role for the NPY-Y1 receptor axis as a regulator of bone homeostasis. However, regulation of Y1 receptor expression during osteoblastic differentiation remains unexplored. In the present study, we examined the role of bone morphogenetic protein (BMP) 2 signaling in regulating Y1 receptor expression. In C2C12 cells, expression of Y1 receptor mRNA was induced by BMP2. This induction was also observed after co-transfection with Smad1 and Smad4, the intracellular signaling molecules of the BMP2 signaling pathway. In a transfection assay, Smad1/4 up-regulated transcriptional activity through interaction with the Y1 receptor gene promoter. Following transfection of MC3T3-E1 cells with siRNA for the Y1 receptor, the expression of alkaline phosphatase, osteocalcin, Runx2 and osterix were increased. These results show that BMP2 signaling regulates Y1 receptor gene expression, and raises the possibility that NPY acts in osteoblasts via an autocrine mechanism.
神经肽 Y（NPY）系统是主要的神经信号通路之一。已知 NPY 由包括成骨细胞在内的外周组织产生，与 Y1 受体结合。最近，开发了成骨细胞特异性 Y1 受体敲除小鼠，发现其具有高骨量表型，表明 NPY-Y1 受体轴作为骨稳态调节剂的作用。然而，成骨细胞分化过程中 Y1 受体表达的调节仍未得到探索。在本研究中，我们研究了骨形态发生蛋白（BMP）2 信号在调节 Y1 受体表达中的作用。在 C2C12 细胞中，Y1 受体 mRNA 的表达受 BMP2 诱导。这种诱导也观察到在用 BMP2 信号通路的细胞内信号分子 Smad1 和 Smad4 共转染后。在转染实验中，Smad1/4 通过与 Y1 受体基因启动子相互作用上调转录活性。在用 Y1 受体的 siRNA 转染 MC3T3-E1 细胞后，碱性磷酸酶、骨钙素、Runx2 和osterix 的表达增加。这些结果表明 BMP2 信号调节 Y1 受体基因表达，并提出 NPY 通过自分泌机制在成骨细胞中发挥作用的可能性。
