Enomoto-Iwamoto M, Nakamura T, Aikawa T, Higuchi Y, Yuasa T, Yamaguchi A, Nohno T, Noji S, Matsuya T, Kurisu K, Koyama E, Pacifici M, Iwamoto M
Department of Biochemistry, Osaka University Faculty of Dentistry, Japan.
J Bone Miner Res. 2000 Sep;15(9):1659-68. doi: 10.1359/jbmr.2000.15.9.1659.
Sonic hedgehog (Shh) and Indian hedgehog (Ihh) are important regulators of skeletogenesis, but their roles in this complex multistep process are not fully understood. Recent studies have suggested that the proteins participate in the differentiation of chondrogenic precursor cells into chondrocytes. In the present study, we have tested this possibility more directly. We found that implantation of dermal fibroblasts expressing hedgehog proteins into nude mice induces ectopic cartilage and bone formation. Immunohistological and reverse-transcription polymerase chain reaction (RT-PCR) analyses revealed that the ectopic tissues derived largely if not exclusively from host cells. We found also that treatment of clonal prechondrogenic RMD-1 and ATDC5 cells in culture with Ihh or recombinant amino half of Shh (recombinant N-terminal portion of Shh [rShh-N]) induced their differentiation into chondrocytes, as revealed by cytoarchitectural changes, Alcian blue staining and proteoglycan synthesis. Induction of RMD-1 cell differentiation by Ihh or rShh-N was synergistically enhanced by cotreatment with bone morphogenetic protein 2 (BMP-2) but was blocked by cotreatment with fibroblast growth factor 2 (FGF-2). Our findings indicate that hedgehog proteins have the ability to promote differentiation of chondrogenic precursor cells and that their action in this process can be influenced and modified by synergistic or antagonist cofactors.
音猬因子（Shh）和印度刺猬因子（Ihh）是骨骼生成的重要调节因子，但其在这一复杂多步骤过程中的作用尚未完全明确。近期研究表明，这些蛋白参与软骨生成前体细胞向软骨细胞的分化过程。在本研究中，我们更直接地验证了这种可能性。我们发现，将表达刺猬因子蛋白的真皮成纤维细胞植入裸鼠体内可诱导异位软骨和骨的形成。免疫组织学和逆转录聚合酶链反应（RT-PCR）分析显示，异位组织很大程度上（若非完全）源自宿主细胞。我们还发现，用Ihh或音猬因子重组氨基端（重组音猬因子N端[rShh-N]）处理培养中的克隆软骨生成前体细胞RMD-1和ATDC5，可诱导它们分化为软骨细胞，细胞结构变化、阿尔新蓝染色和蛋白聚糖合成均证实了这一点。Ihh或rShh-N对RMD-1细胞分化的诱导作用在与骨形态发生蛋白2（BMP-2）共同处理时协同增强，但在与成纤维细胞生长因子2（FGF-2）共同处理时受到抑制。我们的研究结果表明，刺猬因子蛋白具有促进软骨生成前体细胞分化的能力，且在这一过程中的作用可受到协同或拮抗辅助因子的影响和调节。
