Cysteine Peptidase B Regulates Leishmania mexicana Virulence through the Modulation of GP63 Expression.
Cysteine Peptidase B Regulates Leishmania mexicana Virulence through the Modulation of GP63 Expression.
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DOI：
10.1371/journal.ppat.1005658
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发表时间：
2016-05
期刊：
影响因子：
6.7
通讯作者：
Descoteaux A
中科院分区：
文献类型：
--
作者：
Casgrain PA;Martel C;McMaster WR;Mottram JC;Olivier M;Descoteaux A
半胱氨酸肽酶在利什曼原虫的生物学中起着核心作用。在这项工作中，我们试图进一步阐明半胱氨酸肽酶CPB对L。mexicana毒力和CPB是否参与这些寄生虫引起的大型公共寄生虫空泡的形成。我们首先研究了L. mexicana感染对VAMP3和VAMP8的运输的影响，这两种内吞SNARE蛋白与吞噬溶酶体生物发生和功能相关。使用CPB缺陷突变体，我们发现VAMP3和VAMP8都以CPB依赖性方式下调。我们还发现，表达的毒性相关的GPI锚定的金属蛋白酶GP63在CPB的情况下被抑制。CPB缺陷突变体中GP63的表达足以下调VAMP3和VAMP8。类似地，GP63的附加型表达使CPB缺陷突变体能够在巨噬细胞中建立感染，诱导大的公共寄生虫空泡的形成，并在小鼠中引起病变。这些发现暗示CPB参与了GP63表达的调节，并为GP63和CPB都是L.墨西哥。寄生虫墨西哥利什曼原虫表达木瓜蛋白酶家族的几种半胱氨酸肽酶，其参与诸如毒力和逃避宿主免疫应答的过程。半胱氨酸肽酶CPB是在巨噬细胞内存活和易感小鼠病变形成所必需的。当它们被巨噬细胞内化后，L。mexicana复合体诱导大型公共寄生虫空泡的形成，它们在其中复制，并且这些大型空泡的扩张与寄生虫在巨噬细胞内存活的能力相关。在这里，我们发现CPB有助于L。墨西哥利什曼原虫毒力（巨噬细胞存活、公共寄生虫空泡的形成和扩张、小鼠中的病变形成）通过毒力因子GP 63的调节，GP 63是一种通过切割关键宿主细胞蛋白而起作用的利什曼原虫锌金属蛋白酶。因此，这项工作阐明了一种新的利什曼原虫毒力调节机制，CPB控制GP63的表达。
Cysteine peptidases play a central role in the biology of Leishmania. In this work, we sought to further elucidate the mechanism(s) by which the cysteine peptidase CPB contributes to L. mexicana virulence and whether CPB participates in the formation of large communal parasitophorous vacuoles induced by these parasites. We initially examined the impact of L. mexicana infection on the trafficking of VAMP3 and VAMP8, two endocytic SNARE proteins associated with phagolysosome biogenesis and function. Using a CPB-deficient mutant, we found that both VAMP3 and VAMP8 were down-modulated in a CPB-dependent manner. We also discovered that expression of the virulence-associated GPI-anchored metalloprotease GP63 was inhibited in the absence of CPB. Expression of GP63 in the CPB-deficient mutant was sufficient to down-modulate VAMP3 and VAMP8. Similarly, episomal expression of GP63 enabled the CPB-deficient mutant to establish infection in macrophages, induce the formation of large communal parasitophorous vacuoles, and cause lesions in mice. These findings implicate CPB in the regulation of GP63 expression and provide evidence that both GP63 and CPB are key virulence factors in L. mexicana. The parasite Leishmania mexicana expresses several cysteine peptidases of the papain family that are involved in processes such as virulence and evasion of host immune responses. The cysteine peptidase CPB is required for survival within macrophages and for lesion formation in susceptible mice. Upon their internalization by macrophages, parasites of the L. mexicana complex induce the formation of large communal parasitophorous vacuoles in which they replicate, and expansion of those large vacuoles correlates with the ability of the parasites to survive inside macrophages. Here, we found that CPB contributes to L. mexicana virulence (macrophage survival, formation and expansion of communal parasitophorous vacuoles, lesion formation in mice) through the regulation of the virulence factor GP63, a Leishmania zinc-metalloprotease that acts by cleaving key host cell proteins. This work thus elucidates a novel Leishmania virulence regulatory mechanism whereby CPB controls the expression of GP63.