Korb Katja, Katsikogianni Eleni, Zingler Sebastian, Daum Edith, Lux Christopher J, Hohenstein Axel, Erber Ralf
Department of Orthodontics, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
Bioassay GmbH, Im Neuenheimer Feld 515, 69120, Heidelberg, Germany.
Clin Oral Investig. 2016 Dec;20(9):2333-2341. doi: 10.1007/s00784-016-1740-4. Epub 2016 Feb 19.
Root resorptions are common undesirable side effects of orthodontic treatment. In most patients, these defects are repaired by cementoblasts. However, in 1-5 % of patients, the repair fails. The repair mechanism is not well understood. Apoptosis of cementoblasts might contribute to an impaired repair of root resorptions induced by orthodontic forces.
To gain insight into putative molecular pathways leading to compression-induced apoptosis of human primary cementoblasts (HPCBs), three independent cell populations were subjected to compressive loading at 5, 20, and 30 g/cm for 1, 6, and 10 h. The mRNA expression of AXUD1, a novel pro-apoptotic gene, was monitored by quantitative reverse transcription PCR (qRT-PCR). To identify a possible function in compression-dependent apoptosis, AXUD1 was silenced in cementoblasts using an siRNA approach. Apoptosis of cementoblasts was measured by annexin V staining and flow cytometry. The phosphorylation of c-Jun-N-terminal kinases (JNKs) was investigated by Western blotting.
AXUD1 was significantly induced in a time- and force-dependent manner. The rate of apoptotic HPCBs increased by 20-40 % after 10 h of compression (30 g/cm). Phosphorylation of JNKs was detected after 10 h at 30 g/cm. SiRNA-mediated knockdown of AXUD1 led to decreased phosphorylation of JNKs and reduced apoptosis rates in compressed HPCBs.
Compression-induced apoptosis of HPCBs is mediated by AXUD1 via a JNK-dependent pathway.
AXUD1-dependent apoptosis of human cementoblasts might contribute to an impaired repair of root resorptions during orthodontic tooth movement. Further studies are needed to develop treatment strategies aiming to minimize root resorption during orthodontic tooth movement.
牙根吸收是正畸治疗常见的不良副作用。在大多数患者中，这些缺损由成牙骨质细胞修复。然而，1%至5%的患者修复失败。修复机制尚不清楚。成牙骨质细胞凋亡可能导致正畸力引起的牙根吸收修复受损。
为深入了解导致人原代成牙骨质细胞（HPCBs）受压诱导凋亡的潜在分子途径，对三个独立的细胞群体分别施加5、20和30 g/cm的压缩负荷，持续1、6和10小时。通过定量逆转录PCR（qRT-PCR）监测新型促凋亡基因AXUD1的mRNA表达。为确定AXUD1在压缩依赖性凋亡中的可能作用，采用小干扰RNA（siRNA）方法使成牙骨质细胞中的AXUD1沉默。通过膜联蛋白V染色和流式细胞术检测成牙骨质细胞的凋亡情况。通过蛋白质免疫印迹法研究c-Jun氨基末端激酶（JNKs）的磷酸化情况。
AXUD1以时间和力依赖性方式显著诱导表达。压缩10小时（30 g/cm）后，凋亡的HPCBs比例增加了20%至40%。在30 g/cm压缩10小时后检测到JNKs的磷酸化。siRNA介导的AXUD1敲低导致JNKs磷酸化减少，压缩的HPCBs凋亡率降低。
HPCBs的压缩诱导凋亡由AXUD1通过JNK依赖性途径介导。
人成牙骨质细胞的AXUD1依赖性凋亡可能导致正畸牙齿移动过程中牙根吸收修复受损。需要进一步研究以制定旨在减少正畸牙齿移动过程中牙根吸收的治疗策略。
