Deng Zhennan, Liu Yang, Wang Chaopeng, Fan Hongyi, Ma Jianfeng, Yu Haiyang
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China; Wenzhou Medical University, Wenzhou 325027, China.
State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
Arch Oral Biol. 2014 Oct;59(10):1032-41. doi: 10.1016/j.archoralbio.2014.04.012. Epub 2014 Apr 28.
The aim of this study was to explore the mutual communication of the parathyroid hormone-related peptide (PTHrP) and phosphatidylinositol 3-kinase/threonine protein kinase (PI3K/Akt) pathway on the proliferation and differentiation of condylar chondrocytes from Sprague-Dawley (SD) rats.
Condylar chondrocytes from the condylar cartilage were cultured and an organ culture system of mandibular condyles was employed. The distribution of PI3K, phospho-Akt (p-Akt), and PTHrP in condylar cartilage was detected by either immunohistochemistry or immunofluorescence. The second passage chondrocytes and condyle specimens in the organ culture system were treated with PTHrP, LY294002, PTHrP and LY294002 in combination, or dimethyl sulfoxide (DMSO), separately. The mRNA and protein levels of type II (Col II) and type X collagen (Col X) were investigated by real-time polymerase chain reaction (PCR) and Western blot analysis. The condyle growth in organ culture system was analysed by haematoxylin-eosin staining.
PTHrP, PI3K, and p-Akt were mainly located in the proliferative and hypertrophic zones. PTHrP promoted the proliferation of condylar chondrocytes, while LY294002 limited this effect. The mRNA and protein levels of Col II and Col X in these cells were reduced by PTHrP and enhanced by LY294002. Organ culture showed a significant enhancement of condyle elongation with PTHrP treatment or a combination of PTHrP and LY294002 treatment. After treatment with LY294002, the length of condyles was reduced compared with the samples treated with DMSO.
We conclude that the PI3K/Akt pathway plays an essential role in the proliferation and differentiation of condylar chondrocytes and is a potential target for PTHrP in regulating chondrocyte differentiation at condylar cartilage.
本研究旨在探讨甲状旁腺激素相关肽（PTHrP）与磷脂酰肌醇3激酶/苏氨酸蛋白激酶（PI3K/Akt）信号通路在Sprague-Dawley（SD）大鼠髁突软骨细胞增殖和分化过程中的相互作用。
培养髁突软骨的髁突软骨细胞，并采用下颌髁突器官培养系统。通过免疫组织化学或免疫荧光检测PI3K、磷酸化Akt（p-Akt）和PTHrP在髁突软骨中的分布。将第二代软骨细胞和器官培养系统中的髁突标本分别用PTHrP、LY294002、PTHrP与LY294002联合处理或二甲基亚砜（DMSO）处理。通过实时聚合酶链反应（PCR）和蛋白质免疫印迹分析研究Ⅱ型胶原（Col II）和X型胶原（Col X）的mRNA和蛋白水平。通过苏木精-伊红染色分析器官培养系统中髁突的生长情况。
PTHrP、PI3K和p-Akt主要位于增殖区和肥大区。PTHrP促进髁突软骨细胞的增殖，而LY294002抑制这种作用。PTHrP降低了这些细胞中Col II和Col X的mRNA和蛋白水平，而LY294002则增强了它们的表达。器官培养显示，PTHrP处理或PTHrP与LY294002联合处理可显著促进髁突伸长。与DMSO处理的样本相比，LY294002处理后髁突长度缩短。
我们得出结论，PI3K/Akt信号通路在髁突软骨细胞的增殖和分化中起重要作用，是PTHrP调节髁突软骨细胞分化的潜在靶点。
