Gangliosides act as co-receptors for Salmonella enteritidis FliC and promote FliC induction of human β-defensin-2 expression in Caco-2 cells
Gangliosides act as co-receptors for Salmonella enteritidis FliC and promote FliC induction of human β-defensin-2 expression in Caco-2 cells
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DOI：
10.1074/jbc.m307944200
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发表时间：
2004-03-26
影响因子：
4.8
通讯作者：
Hirayama, T
中科院分区：
文献类型：
--
作者：
Ogushi, K;Wada, A;Hirayama, T
抗微生物肽如防御素对宿主粘膜表面的防御至关重要。我们以前报道过，肠炎沙门氏菌鞭毛蛋白（FliC）通过NF-kappaB激活在Caco-2细胞中诱导人β -防御素-2 (hBD-2) mRNA表达（Ogushi， K, Wada， A., Niidome， T., Mori， N., Oishi， K., Nagatake， T., Takahashi， A., Asakura， H., Makino， S., Hojo， H., Nakahara， Y., Ohsaki， M., Hatakeyama， T., Aoyagi， H., Kurazono， H., Moss， J., Hirayama， T.）。化学，276,30521-30526)。在这项研究中，我们研究了神经节苷脂作为toll样受体5 （TLR5）的共受体在FliC诱导Caco-2细胞hBD-2表达中的作用。外源性神经节苷抑制FliC诱导hBD-2启动子活性和FliC与Caco-2细胞的结合。外源性神经节苷脂GD1a掺入Caco-2细胞膜增加了FliC对hBD-2启动子活性的影响。为了支持内源性神经节苷的作用，Caco-2细胞与DL-threo-2-hexadecanoylamino-3-morpholino-1-phenylpropanol（一种葡萄糖神经酰胺合成酶抑制剂）一起培养，降低了FliC对hBD-2启动子活性的诱导。与不表达TLR5的CHO-K1细胞相比，负载gd1a的CHO-K1细胞在flc刺激后具有更高的诱导hBD-2的潜力。FliC增加了丝裂原活化蛋白激酶p38和ERK1/2的磷酸化。外源性神经节苷脂GD1a、GD1b和GT1b均抑制FliC诱导的p38和ERK1/2磷酸化。此外，在含有突变激活蛋白1结合位点的质粒转染的Caco-2细胞中，flc并没有增强荧光素酶的活性。这些结果表明，神经节苷脂作为TLR5在FliC中的共受体，通过丝裂原活化蛋白激酶促进hBD-2的表达。
Antimicrobial peptides such as defensins are crucial for host defense at mucosal surfaces. We reported previously that Salmonella enteritidis flagellin (FliC) induced human beta-defensin-2 (hBD-2) mRNA expression in Caco-2 cells via NF-kappaB activation (Ogushi, K., Wada, A., Niidome, T., Mori, N., Oishi, K., Nagatake, T., Takahashi, A., Asakura, H., Makino, S., Hojo, H., Nakahara, Y., Ohsaki, M., Hatakeyama, T., Aoyagi, H., Kurazono, H., Moss, J., and Hirayama, T. (2001) J. Biol. Chem. 276, 30521-30526). In this study, we examined the role of ganglioside as co-receptors with Toll-like receptor 5 (TLR5) on FliC induction of hBD-2 expression in Caco-2 cells. Exogenous gangliosides suppressed FliC induction of hBD-2 promoter activity and binding of FliC to Caco-2 cells. Incorporation of exogenous ganglioside GD1a into Caco-2 cell membranes increased the effect of FliC on hBD-2 promoter activity. In support of a role for endogenous gangliosides, incubation of Caco-2 cells with DL-threo-2-hexadecanoylamino-3-morpholino-1-phenylpropanol, a glucosylceramide synthase inhibitor, reduced FliC induction of hBD-2 promoter activity. GD1a-loaded CHO-K1-expressing TLR5 cells had a higher potential for hBD-2 induction following FliC stimulation than GD1a-loaded CHO-K1 cells not expressing TLR5. FliC increased phosphorylation of mitogen-activated protein kinase, p38, and ERK1/2. Exogenous gangliosides GD1a, GD1b, and GT1b each suppressed FliC induction of p38 and ERK1/2 phosphorylation. Furthermore, FliC did not enhance luciferase activity in Caco-2 cells transfected with a plasmid containing a mutated activator protein 1-binding site. These results suggest that gangliosides act as co-receptors with TLR5 for FliC and promote hBD-2 expression via mitogen-activated protein kinase.