Ichikawa Shota, Mishima Yoshitaka, Nagao Mayu, Sakashita Gyosuke, Furukawa Koichi, Sato Takuma, Miyazawa Ken, Hamamura Kazunori
Department of Pharmacology, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
In Vivo. 2025 Jan-Feb;39(1):257-266. doi: 10.21873/invivo.13824.
BACKGROUND/AIM: Gangliosides regulate bone formation and resorption. Bone formation is reduced in mice lacking ganglioside GM2/GD2 synthase due to a decrease in osteoblasts. However, the effects of the loss of complex gangliosides by the deletion of both GM2/GD2 and GD3 synthases are unknown. Therefore, we investigated whether deletion of complex gangliosides in mice affected bone metabolism.
Twenty-six double-knockout mice lacking both GM2/GD2 and GD3 synthases (dKO) and 30 wild-type (WT) mice as controls were used. The mass of cancellous bone and bone strength in femurs were determined using three-dimensional micro-computed tomography and three-point bending test, respectively. Bone formation and resorption were assessed using histomorphometrical analysis with hematoxylin and eosin, and tartrate-resistant acid phosphatase (TRAP), respectively. Osteoblast proliferation was determined by bromodeoxyuridine assay and the differentiation into osteoclasts by TRAP staining; mRNA levels of osteoclast differentiation markers [nuclear factor of activated T-cells, cytoplasmic 1 (Nfatc1); Trap; and cathepsin K (Ctsk)] were also determined.
Bone mass increased in dKO mice, while bone formation and resorption decrease. In terms of bone strength, breaking displacement significantly increased in dKO mice. Furthermore, the proliferation of osteoblasts was suppressed, and the number of TRAP-positive multinucleated cells was reduced in dKO mice. Treatment with receptor activator of NF-[Formula: see text]B ligand significantly reduced Nfatc1, Trap and Ctsk mRNA levels in macrophages from dKO mice.
Bone formation and resorption were reduced by the deletion of genes for complex gangliosides. The slight increase in bone strength in dKO mice may be due to the cancellous bone volume increase in these mice.
背景/目的：神经节苷脂调节骨形成和骨吸收。由于成骨细胞减少，缺乏神经节苷脂GM2/GD2合酶的小鼠骨形成减少。然而，通过删除GM2/GD2和GD3合酶导致复合神经节苷脂缺失的影响尚不清楚。因此，我们研究了小鼠中复合神经节苷脂的缺失是否会影响骨代谢。
使用26只同时缺乏GM2/GD2和GD3合酶的双敲除小鼠（dKO）和30只野生型（WT）小鼠作为对照。分别使用三维微计算机断层扫描和三点弯曲试验测定股骨松质骨质量和骨强度。分别使用苏木精和伊红以及抗酒石酸酸性磷酸酶（TRAP）进行组织形态计量分析来评估骨形成和骨吸收。通过溴脱氧尿苷测定法测定成骨细胞增殖，并通过TRAP染色测定其向破骨细胞的分化；还测定了破骨细胞分化标志物[活化T细胞核因子，细胞质1（Nfatc1）；Trap；和组织蛋白酶K（Ctsk）]的mRNA水平。
dKO小鼠的骨量增加，而骨形成和骨吸收减少。在骨强度方面，dKO小鼠的断裂位移显著增加。此外，dKO小鼠中成骨细胞增殖受到抑制，TRAP阳性多核细胞数量减少。用NF-κB受体激活剂配体处理可显著降低dKO小鼠巨噬细胞中Nfatc1、Trap和Ctsk的mRNA水平。
复合神经节苷脂基因的缺失导致骨形成和骨吸收减少。dKO小鼠骨强度的轻微增加可能是由于这些小鼠的松质骨体积增加。
