Apoptosis Regulated by Fibronectin and Its Receptors

这些研究的目的是了解纤维连接蛋白水解片段（FN）介导牙周韧带（PDL）细胞凋亡的机制。虽然牙周病的病因已归因于细菌病原体，但这种疾病发病机制的几个组成部分仍然知之甚少。其中一个领域是由细菌蛋白酶和炎症宿主源性酶产生的基质片段在牙周病进展中的作用。几种假定的牙周病原体表达的蛋白酶很容易将FN切割成多个片段，这些片段在体内发现并与牙周病部位有关。其中一个片段是40 kDa的凝乳胰蛋白酶片段，它包含肝素结合域和部分FN的选择性剪接的V区，可以由普雷沃氏菌中间体产生的凝乳胰蛋白酶样酶产生。这个40kda片段和一个更长的重组片段（V+H-）也具有肝素结合域和FN的V区选择性剪接诱导PDL细胞凋亡。此外，FN片段改变了PDL细胞的运动，增强了蛋白酶的表达。这些发现导致这样一种假设，即细菌和/或宿主炎症细胞蛋白酶产生的FN蛋白水解片段影响了PDL细胞的几种功能，包括存活，从而加剧了牙周组织的降解并导致疾病进展。具体目的是：(1)表征40kda FN片段诱导PDL细胞凋亡的基质参数；(2)鉴定40kda FN片段的细胞表面受体，以及40kda -含重组FN片段参与调节PDL细胞凋亡的细胞表面受体；(3)表征40kda FN片段和其他包含40kda区域的片段调控PDL细胞凋亡的信号通路。这些发现将有助于我们了解牙周病的发病机制，并有助于我们对细胞外基质调控细胞凋亡的基本认识。

The goal of these studies is to understand the mechanism by which proteolytic fragments of fibronectin (FN) mediate apoptosis in periodontal ligament (PDL) cells. Although the etiology of periodontal disease has been attributed to bacterial pathogens, several components in the pathogenesis of this disease remain poorly understood. One such area is the role of matrix fragments generated by bacterial proteinases and by inflammatory host-derive enzymes in the progression of periodontal disease. Proteases expressed by several putative periodontal pathogens readily cleave FN into multiple fragments, which are found in vivo and in association with periodontally disease sites. One such fragment is a 40 kDa chymotryptic fragment which contains the heparin-binding domain and part of the alternatively spliced V region of FN and can be generated by the chymotrypsin-like enzyme produced b Prevotella intermedia. Both this 40 kDa fragment and a longer recombinant (V+H-) fragment that also has the heparin-binding domain and the alternatively spliced V region of FN induce apoptosis in PDL cells. In addition, fragments of FN alter cell motility and enhance proteinase expression in PDL cells. These findings lead to the hypothesis that proteolytic fragments of FN generated by bacterial and/or host inflammatory cell proteinases affect several PDL cell functions including, survival, thereby exacerbating the degradation of periodontal tissues and contributing to disease progression. The specific aims are to: (1) Characterize the matrix parameters by which the 40 kDa FN fragment induces apoptosis in PDL cells; (2) Identify the cell surface receptors for the 40 kDa FN fragment, and for the 40 kDa-containing recombinant FN fragments that are involved in regulating apoptosis in PDL cells; and (3) characterize the signaling pathways by which the 40 kDa FN fragment and other fragments containing the 40 kDa region regulate apoptosis of PDL cells. These findings will contribute to our understanding of the pathogenesis of periodontal disease and to our basic understanding of the regulation of apoptosis by the extracellular matrix.