Dai R, Iwama A, Wang S, Kapila Y L
Department of Stomatology, School of Dentistry, University of California, San Francisco, CA 94143-0512, USA.
Apoptosis. 2005 May;10(3):503-12. doi: 10.1007/s10495-005-1880-5.
Inflammation in periodontal disease is characterized by the breakdown of the extracellular matrix. This study shows that an inflammation-associated matrix breakdown fragment of fibronectin (FN) induces anoikis of human periodontal ligament (PDL) cells. This 40 kDa fragment was identified in human inflammatory crevicular fluid and is associated with disease status. Previously, we reported that a similar recombinant FN fragment triggered apoptosis of PDL cells by an alternate apoptotic signaling pathway that requires transcriptional downregulation of p53 and c-myc. Thus, to determine whether the physiologically relevant 40 kDa fragment triggers apoptosis in these cells, the 40 kDa fragment was generated and studied for its apoptotic properties. The 40 kDa fragment induces apoptosis of PDL cells, and preincubation of cells with intact vitronectin, FN, and to a limited extent collagen I, rescue this apoptotic phenotype. These data suggest that the 40 kDa fragment prevents PDL cell spreading, thereby inducing anoikis. The signaling pathway also involves a downregulation in p53 and c-myc, as determined by Western blotting and real time quantitative PCR. These data indicate that an altered FN matrix as is elaborated in inflammation induces anoikis of resident cells and thus may contribute to disease progression.
牙周疾病中的炎症以细胞外基质的破坏为特征。本研究表明，一种与炎症相关的纤连蛋白（FN）基质降解片段可诱导人牙周膜（PDL）细胞发生失巢凋亡。该40 kDa片段在人炎症龈沟液中被鉴定出来，且与疾病状态相关。此前，我们报道过一种类似的重组FN片段通过一条需要p53和c-myc转录下调的替代性凋亡信号通路触发PDL细胞凋亡。因此，为了确定生理相关的40 kDa片段是否会在这些细胞中触发凋亡，我们制备了该40 kDa片段并研究其凋亡特性。40 kDa片段可诱导PDL细胞凋亡，而用完整的玻连蛋白、FN以及在一定程度上用I型胶原对细胞进行预孵育可挽救这种凋亡表型。这些数据表明，40 kDa片段可阻止PDL细胞铺展，从而诱导失巢凋亡。通过蛋白质免疫印迹和实时定量PCR确定，该信号通路还涉及p53和c-myc的下调。这些数据表明，炎症中所形成的改变的FN基质可诱导驻留细胞发生失巢凋亡，因此可能促进疾病进展。
