Phosphatidylinositol 3-kinase and frabin mediate Cryptosporidium parvum cellular invasion via activation of Cdc42
Phosphatidylinositol 3-kinase and frabin mediate Cryptosporidium parvum cellular invasion via activation of Cdc42
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DOI：
10.1074/jbc.m401592200
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发表时间：
2004-07-23
影响因子：
4.8
通讯作者：
LaRusso, NF
中科院分区：
文献类型：
--
作者：
Chen, XM;Splinter, PL;LaRusso, NF
微小隐孢子虫通过宿主细胞肌动蛋白重组机制侵入靶上皮细胞。我们之前已经证明了C.小疟原虫激活宿主细胞中Cdc 42/神经Wiskott-Aldrich综合征蛋白网络，导致宿主细胞-寄生虫界面处的肌动蛋白重塑，从而促进C.小孢子细胞侵入。在这里，我们测试了磷脂酰肌醇3-激酶（PI 3 K）和frabin（一种特异性针对Cdc 42的鸟嘌呤核苷酸交换因子）在C.胆道上皮细胞的细小感染。我们发现C. parvum感染培养的人胆管上皮细胞诱导PI 3 K在宿主细胞-寄生虫界面的积累，并导致感染细胞中PI 3 K的活化。Frabin也被招募到宿主细胞-寄生虫界面，这一过程被两种PI 3 K抑制剂Wortmannin和LY 294002抑制。无论是PI 3 K的显性失活突变体（PI 3 K-Deltap 85）还是frabin功能缺陷突变体的细胞表达都抑制了C.寄生虫诱导的Cdc 42在宿主细胞-寄生虫界面的积累。此外，LY 294002还能消除C. parvum诱导感染细胞中Cdc 42活化。通过细胞过度表达PI 3 K-Deltap 85或通过渥曼青霉素或LY 294002抑制PI 3 K，以及通过各种功能缺陷突变体抑制frabin，降低了C. parvum诱导的肌动蛋白积累和抑制C.小孢子细胞侵入。相反，PI 3 K的p85亚基的过表达促进了C.寄生蜂入侵我们的数据表明，C.寄生虫对靶上皮细胞的侵袭是由生物体触发宿主细胞PI 3 K/frabin信号传导以激活Cdc 42途径的能力引起的，导致宿主细胞-寄生虫界面处的宿主细胞肌动蛋白重塑。
Cryptosporidium parvum invades target epithelia via a mechanism that involves host cell actin reorganization. We previously demonstrated that C. parvum activates the Cdc42/neural Wiskott-Aldrich syndrome protein network in host cells resulting in actin remodeling at the host cell-parasite interface, thus facilitating C. parvum cellular invasion. Here, we tested the role of phosphatidylinositol 3-kinase (PI3K) and frabin, a guanine nucleotide exchange factor specific for Cdc42 in the activation of Cdc42 during C. parvum infection of biliary epithelial cells. We found that C. parvum infection of cultured human biliary epithelial cells induced the accumulation of PI3K at the host cell-parasite interface and resulted in the activation of PI3K in infected cells. Frabin also was recruited to the host cell-parasite interface, a process inhibited by two PI3K inhibitors, wortmannin and LY294002. The cellular expression of either a dominant negative mutant of PI3K (PI3K-Deltap85) or functionally deficient mutants of frabin inhibited C. parvum-induced Cdc42 accumulation at the host cell-parasite interface. Moreover, LY294002 abolished C. parvum-induced Cdc42 activation in infected cells. Inhibition of PI3K by cellular overexpression of PI3K-Deltap85 or by wortmannin or LY294002, as well as inhibition of frabin by various functionally deficient mutants, decreased C. parvum-induced actin accumulation and inhibited C. parvum cellular invasion. In contrast, the overexpression of the p85 subunit of PI3K promoted C. parvum invasion. Our data suggest that an important component of the complex process of C. parvum invasion of target epithelia results from the ability of the organism to trigger host cell PI3K/frabin signaling to activate the Cdc42 pathway, resulting in host cell actin remodeling at the host cell-parasite interface.