- 學位論文
玻尿酸藉由結合CD44活化中性白血球的分子機轉研究
Studies on the Molecular Basis of CD44 and Hyaluronan in Neutrophils Activation
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摘要
CD44是一個具有多重功能且位於細胞表面的醣蛋白質，其功能涉及細胞之間的相互作用、細胞附著、遷移、增殖和血管新生，而且在大多數的哺乳動物細胞中皆有表現。玻尿酸（hyaluromic acid; HA）是CD44一個非常重要的配體，廣泛分佈在整個結締組織、上皮細胞或神經組織中。CD44與玻尿酸結合會活化其下游訊息傳遞路徑而引發許多作用。在之前的研究中已經證明CD44具有誘導淋巴細胞活化、再循環和吸引淋巴細胞的功能。一些研究報告更指出CD44和玻尿酸的結合可以調控發炎反應、拮抗組織損傷和修復由發炎所造成的細胞傷害、減少發炎因子的釋放和增加幹細胞遷移。然而CD44與玻尿酸結合後對於中性白血球的影響目前仍不清楚。在我們初步的研究中，發現了一些有趣的結果。首先，脂多醣（LPS）和anti-CD44會誘導多核型白血球 (PMN)中CD44的表現量增加。而玻尿酸的刺激可以增加多核型白血球的吞噬作用並誘導細胞骨架的重組。CD44與玻尿酸的結合能誘導IL-8的產生。接下來我們更發現，玻尿酸可以誘導MAP kinase (p38)、ERK1/2磷酸化增加。在未來的研究方面，我們將添加不同的促發炎因子，觀察多核型白血球CD44的表現量。並使用抑製劑阻斷訊息傳遞路徑研究其對多核型白血球的吞噬作用和cytokine產生的影響以及所扮演的角色。此外，我們也將使用玻尿酸酶分解玻尿酸，以研究CD44-HA的結合對於多核型白血球的影響。最後，我們藉由降低CD44的表現量確認玻尿酸與CD44結合對於發炎反應的調解具有重要性。
並列摘要
CD44 is a multifunctional cell-surface glycoprotein that is involved in cell-cell interaction, cell adhesion, migration, proliferation and angiogenesis and is widely expressed in a large number of mammalian cell types. Hyaluronic acid (HA), one of important ligand of CD44, is distributed widely throughout connective, epithelial, and neural tissues. After CD44-HA binding initiates CD44 downstream signaling pathways, the signaling induces multiple functions. Previous studies have demonstrated that CD44 induces the lymphocyte activation, recirculation, and homing. Some paper have shown that CD44-HA interaction could regulate inflammation, tissue injury and repair through regulating inflammatory cell recruitment, release of inflammatory cytokines, and stem cell migration. However, the effects of CD44-HA interaction on neutrophils remained unclear. In our preliminary study, several interesting results were found. First, we found that the LPS and anti-CD44 could increase the expression of CD44 on PMN. HA could also enhance the phagocytosis activity and cytoskeleton rearrangement of PMN and its binding to CD44 could induce the interlukin-8 (IL-8) production. Furthermore, we found that HA could induce phosphorylation of MAP kinase (p38), and ERK1/2 signaling pathways. In the future, we will test the effect of different pro-inflammatory cytokines on the surface expression of CD44 on PMN. The signaling pathways will be selectively blocked for the observation of their effects on phagocytosis and cytokines production of PMN. In addition, the hyaluronidase will be used to evaluate the CD44-HA interaction on PMN. Lastly, the knockdown of CD44 expression in PMN will be carried out to define the CD44-independent mechanisms by which HA can mediate inflammation.
並列關鍵字
CD44 ； hyaluronic acid ； MAP kinase (p38) ； ERK1/2 ； PMN phagocytosis ； cytoskeleton rearrangement參考文獻
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