Lemonnier J, Haÿ E, Delannoy P, Fromigué O, Lomri A, Modrowski D, Marie P J
INSERM U 349 Affiliated CNRS, Lariboisière Hospital, Paris, France.
Am J Pathol. 2001 May;158(5):1833-42. doi: 10.1016/S0002-9440(10)64139-9.
Apert syndrome is an autosomal dominant disorder characterized by premature cranial ossification resulting from fibroblast growth factor receptor-2 (FGFR-2)-activating mutations. We have studied the effects of the prominent S252W FGFR-2 Apert mutation on apoptosis and the underlying mechanisms in human mutant osteoblasts. In vivo analysis of terminal deoxynucleotidyl transferase-mediated nick-end labeling revealed premature apoptosis of mature osteoblasts and osteocytes in the Apert suture compared to normal coronal suture. In vitro, mutant osteoblasts showed increased apoptosis, as demonstrated by terminal deoxynucleotidyl transferase-mediated nick-end labeling analysis, trypan blue staining, and DNA fragmentation. Mutant osteoblasts also showed increased activity of caspase-8 and effector caspases (-3, -6, -7) constitutively. This was related to protein kinase C activation because the selective protein kinase C inhibitor calphostin C inhibited caspase-8, effector caspases, and apoptosis in mutant osteoblasts. Apert osteoblasts also showed increased expression of interleukin (IL)-1alpha, IL-1beta, Fas, and Bax, and decreased Bcl-2 levels. Specific neutralizing anti-IL-1 antibody reduced Fas levels, Bax expression, effector caspases activity, and apoptosis in mutant cells. Thus, the Apert S252W FGFR-2 mutation promotes apoptosis in human osteoblasts through activation of protein kinase C, overexpression of IL-1 and Fas, activation of caspase-8, and increased Bax/Bcl-2 levels, leading to increased effector caspases and DNA fragmentation. This identifies a complex FGFR-2 signaling pathway involved in the premature apoptosis induced by the Apert S252W FGFR-2 mutation in human calvaria osteoblasts.
Apert综合征是一种常染色体显性疾病，其特征为成纤维细胞生长因子受体2（FGFR - 2）激活突变导致的颅骨过早骨化。我们研究了显著的S252W FGFR - 2 Apert突变对人突变成骨细胞凋亡的影响及其潜在机制。对末端脱氧核苷酸转移酶介导的缺口末端标记进行的体内分析显示，与正常冠状缝相比，Apert缝中成熟成骨细胞和骨细胞存在过早凋亡。在体外，末端脱氧核苷酸转移酶介导的缺口末端标记分析、台盼蓝染色和DNA片段化分析表明，突变成骨细胞的凋亡增加。突变成骨细胞还显示出组成性的半胱天冬酶 - 8和效应半胱天冬酶（-3、-6、-7）活性增加。这与蛋白激酶C激活有关，因为选择性蛋白激酶C抑制剂calphostin C可抑制突变成骨细胞中的半胱天冬酶 - 8、效应半胱天冬酶和凋亡。Apert成骨细胞还显示白细胞介素（IL）-1α、IL - 1β、Fas和Bax表达增加，而Bcl - 2水平降低。特异性中和抗IL - 1抗体可降低突变细胞中的Fas水平、Bax表达、效应半胱天冬酶活性和凋亡。因此，Apert S252W FGFR - 2突变通过激活蛋白激酶C、IL - 1和Fas的过表达、半胱天冬酶 - 8的激活以及Bax/Bcl - 2水平升高，促进人成骨细胞凋亡，导致效应半胱天冬酶增加和DNA片段化。这确定了一条复杂的FGFR - 2信号通路，该通路参与Apert S252W FGFR - 2突变诱导的人颅骨成骨细胞过早凋亡。
