Apoptosis Regulated by Fibronectin and Its Receptors

这些研究的目的是了解纤维连接蛋白(FN)的蛋白水解性片段介导牙周膜(PDL)细胞凋亡的机制。虽然牙周病的病因被归因于细菌病原体，但这种疾病的发病机制中的几个组成部分仍然知之甚少。一个这样的领域是由细菌蛋白酶和炎性宿主衍生酶产生的基质片段在牙周病进展中的作用。几种可能的牙周病原体表达的蛋白酶很容易将FN裂解成多个片段，这些片段在体内被发现，并与牙周疾病部位有关。其中一个这样的片段是一个40 kDa的胰凝乳酶片段，它包含Fn的肝素结合结构域和部分选择性剪接的V区，可以由中间普氏杆菌产生的类凝乳蛋白酶产生。这个40 kDa的片段和一个更长的重组(V+H-)片段都可以诱导PDL细胞的凋亡。此外，FN片段改变了细胞的运动能力，增强了PDL细胞中的蛋白酶表达。这些发现导致了一种假设，即细菌和/或宿主炎症细胞蛋白酶产生的FN的蛋白水解性片段会影响PDL细胞的几种功能，包括生存，从而加剧牙周组织的退化并促进疾病的进展。其具体目的是：(1)鉴定40 kDa FN片段诱导PDL细胞凋亡的基质参数；(2)鉴定40 kDa FN片段的细胞表面受体，以及参与调控PDL细胞凋亡的40 kDa重组FN片段；(3)鉴定40 kDa FN片段和其他含有40 kDa片段的片段调控PDL细胞凋亡的信号通路。这些发现将有助于我们理解牙周病的发病机制，并有助于我们对细胞外基质对细胞凋亡的调控的基本理解。

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.