期刊
JOURNAL OF CELL SCIENCE
卷 116, 期 17, 页码 3611-3622出版社
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jcs.00666
关键词
phosphatidylinositol; phagocytosis; invasion; Trypanosoma cruzi; maturation
类别
资金
- NIAID NIH HHS [R01 AI47960] Funding Source: Medline
- NIGMS NIH HHS [R01 GM041890] Funding Source: Medline
Mammalian cell invasion by the protozoan parasite, Trypanosoma cruzi, is facilitated by the activation of host cell phosphatidylinositol 3 (PI 3)-kinases. We demonstrate that the well-characterized Ca2+-regulated lysosome-mediated parasite entry pathway is abolished by wortmannin pretreatment. In addition, we have characterized a novel route of T cruzi invasion unexpectedly revealed in the course of this study. For over a decade, targeted exocytosis of lysosomes at the host cell plasma membrane was considered as the primary mechanism for T cruzi entry into non-professional phagocytic cells. We now provide evidence that a significant fraction (50% or greater) of invading T cruzi trypomastigotes exploit an alternate actin-independent entry pathway that involves formation of a tightly associated host cell plasma membrane-derived vacuole enriched in the lipid products of class I PI 3-kinases, PtdInsP(3)/PtdIns(3,4)P-2- Initially devoid of lysosomal markers, the resultant parasite-containing vacuoles gradually acquire lysosome associated membrane protein 1 (lamp-1) and fluid phase endocytic tracer from the lysosomal compartment. In striking contrast to latex bead phagosomes, few T cruzi vacuoles associate with the early endosomal marker, EEA1 and the 'maturation' process becomes refractory to PI 3-kinase inhibition immediately following parasite internalization. Jointly, these data provide a new paradigm for T cruzi invasion of nonprofessional phagocytic cells and reveal a novel vacuole maturation process that appears to bypass the requirement for EEA1.
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