Li Hongyu, Wang Shengnan, Zhang Shuai, Dong Rui, Miao Congcong, Tian Zhenchuan, Hu Ying
Beijing Institute of Dental Research, Beijing Stomatological Hospital, Capital Medical University, Beijing 100050, China.
Bone Rep. 2025 Jan 6;24:101825. doi: 10.1016/j.bonr.2025.101825. eCollection 2025 Mar.
Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant genetic disease characterized by osteosclerosis of the tubular bones and cemento-osseous lesions of the mandibles. () is the pathogenic gene, however, the specific molecular mechanism of GDD remains unclear. Herein, a knockin ( ) mouse model expressing the human mutation p.Cys360Tyr was used to investigate the role of Akt signaling in enhanced osteogenesis and decreased osteoclastogenesis in GDD.
Bone marrow-derived macrophages (BMMs) and mouse calvarial osteoblasts (mCOBs) were isolated from homozygous mice and treated with SC79, a specific Akt activator. The differentiation and F-actin ring formation of osteoclasts were examined by TRAP and phalloidin staining, respectively. Osteoblast differentiation and mineralization were examined by ALP and alizarin red staining. The expression of bone remodeling-related factors was measured by qRT-PCR.
Akt activation promoted the generation of TRAP-positive multinucleated osteoclasts and the formation of actin rings in BMMs cultures, accompanied by increased expression of , , , , , and . Additionally, mutation down-regulated the Akt phosphorylation level in osteoblast. ALP activity and matrix mineralization capacity in osteoblast cultures were inhibited after SC79 stimulation, with reduced expression of , .
Akt activation by SC79 stimulation can obviously rescue abnormal increased osteogenesis and decreased osteoclastogenesis in mouse model, which demonstrated that disturbed Akt signaling pathway may play a pivotal role in the pathogenesis of GDD, and an Akt activator is probable a therapeutic target for GDD.
颌骨干骺端发育异常（GDD）是一种罕见的常染色体显性遗传病，其特征为管状骨骨硬化和下颌骨的牙骨质 - 骨病变。（）是致病基因，然而，GDD的具体分子机制仍不清楚。在此，使用表达人类突变p.Cys360Tyr的敲入（）小鼠模型来研究Akt信号在GDD中增强成骨和减少破骨细胞生成中的作用。
从纯合子小鼠中分离出骨髓来源的巨噬细胞（BMMs）和小鼠颅骨成骨细胞（mCOBs），并用特异性Akt激活剂SC79处理。分别通过抗酒石酸酸性磷酸酶（TRAP）和鬼笔环肽染色检测破骨细胞的分化和F - 肌动蛋白环形成。通过碱性磷酸酶（ALP）和茜素红染色检测成骨细胞分化和矿化。通过定量逆转录 - 聚合酶链反应（qRT - PCR）测量骨重塑相关因子的表达。
Akt激活促进了TRAP阳性多核破骨细胞的生成以及BMMs培养物中肌动蛋白环的形成，同时伴有、、、、和表达增加。此外，突变下调了成骨细胞中Akt的磷酸化水平。SC79刺激后，成骨细胞培养物中的ALP活性和基质矿化能力受到抑制，、表达降低。
SC79刺激激活Akt可明显挽救小鼠模型中异常增加的成骨和减少的破骨细胞生成，这表明Akt信号通路紊乱可能在GDD的发病机制中起关键作用，Akt激活剂可能是GDD的治疗靶点。
