Plasmodium secretion induces hepatocyte lysosome exocytosis and promotes parasite entry

Abstract

20The invasion of a suitable host hepatocyte by Plasmodium sporozoites is an essential step in 21 malaria infection. We demonstrate that in infected hepatocytes, lysosomes are redistributed away 22 from the nucleus, and surface exposure of lysosomal-associated membrane protein (LAMP1) is 23 increased. Lysosome exocytosis in infected cells occurs independently of sporozoite traversal. 24Instead, a sporozoite-secreted factor is sufficient for the process. Knockdown of the SNARE 25 proteins involved in lysosome-plasma membrane fusion reduces lysosome exocytosis and 26 Plasmodium infection. In contrast, promoting fusion between the lysosome and plasma membrane 27 dramatically increases infection. Our work demonstrates new parallels between Plasmodium 28 sporozoite entry of hepatocytes and infection by the excavate pathogen, Trypanosoma cruzi and 29 raises the question of whether convergent evolution has shaped host cell invasion by divergent 30 pathogens. 31 32 33 34 35 36 37 38 Vijayan et. al., page 3 Plasmodium parasites, the causative agents of malaria, are transmitted to humans by the bite of 39 infected female Anopheles mosquitoes. The sporozoite form of the parasite is deposited into human 40 skin during a blood meal. Sporozoites are motile, and rapidly migrate through the skin to enter a 41 capillary, which allows the parasite to travel to the liver. Plasmodium sporozoites have the capacity 42 to transmigrate through cells using a process termed cell traversal (CT)(1). Once in the liver, 43 sporozoites invade a single hepatocyte, form a parasitophorous vacuole (PV) and develop into a 44 liver stage (LS) schizont, from which merozoites are released into the bloodstream and invade 45 erythrocytes. The secretion of a multitude of sporozoite factors has been demonstrated to occur 46 during motility, CT and, invasion, yet a precise role for most secreted factors remains undefined. 47 129effects. To partially circumvent this, we evaluated the impact of a range of small molecules that 130 modulate lysosome exocytosis (Table S1). We treated Hepa1-6 cells with each compound for 15 131 min, washed the cells, and then infected with P. yoelii sporozoites, T. gondii tachyzoites or T. cruzi 132 trypomastigotes for 90 min. Molecules that increase lysosome exocytosis or redistribution 133 (Ionomycin, Thapsigargin, Brefeldin A, Table S1 and Fig. S3C), significantly increased P. yoelii 134 and T. cruzi infection (Fig. 3d). In contrast, molecules that reduced lysosome exocytosis or 135 redistribution (Nocodazole, MβCD) diminished P. yoelii and T. cruzi infections. No inhibitors 136 substantially altered T. gondii infection (Fig. 3d). Overall, changes in P. yoelii and T. cruzi 137 infections were tightly correlated (Pearson Correlation Coefficient = 0.8297) (Fig. 3e), while other 138 pairwise comparisons were less correlated. Our data suggest that T. cruzi and P. yoelii, but not T. 139 gondii, rely on a lysosome-mediated mechanism to enter the host cell. The extent of these parallels, 140 and ways in which the entry stra...

Plasmodium translocon component EXP2 facilitates hepatocyte invasion

“…4 ). This is in agreement with recent findings showing that Plasmodium sporozoites trigger exocytosis of host lysosomes, to facilitate invasion 56 . Notably, other pathogens including another eukaryotic parasite, T. cruzi 48 , but also the bacteria Listeria monocytogenes 57 and Neisseria gonorrhoeae 58 as well as human adenoviruses 59 have also been reported to invade cells by hijacking host cell plasma membrane-repair pathways resulting in ceramide generation.…”

A genome-wide CRISPR-Cas9 screen identifies CENPJ as a host regulator of altered microtubule organization during Plasmodium liver infection

“…Multiple screening efforts and other reports (Lopes da Silva et al, 2012;Niklaus et al, 2019;Petersen et al, 2017;Prudencio et al, 2008;Raphemot et al, 2019;Real et al, 2018;Rodrigues et al, 2008;Vijayan et al, 2019) have pointed to the critical role of vesicular transport, including retrograde trafficking (Raphemot et al, 2019), throughout Plasmodium LS infection. Here, we observe an association of Golgi and post-Golgi anterograde vesicles with the parasite, suggesting the parasite sequesters both anterograde and retrograde trafficking of host derived vesicles.…”

“…The cytoskeleton is a key regulator of deformability, and Plasmodium has been demonstrated to alter host cell actin cytoskeleton during LS development (Gomes-Santos et al, 2012), egress (Burda et al, 2017), and blood stage development (Hale et al, 2017;Warncke and Beck, 2019). We and others previously have demonstrated that the Plasmodium liver stage PV membrane interacts with late endosomes (Petersen et al, 2017), lysosomes (Lopes da Silva et al, 2012;Niklaus et al, 2019;Prado et al, 2015;Risco-Castillo et al, 2015;Vijayan et al, 2019), retrograde vesicles (Raphemot et al, 2019) and autophagic vesicles (Prado et al, 2015;Real et al, 2018;Wacker et al, 2017). As many intracellular pathogens target the host microtubule network to subvert host vesicle trafficking events for their own benefit (Alix et al, 2011;Asrat et al, 2014), we hypothesized that Plasmodium LS parasites actively alters the host cytoskeleton to traffic the host vesicles to PVM.…”

Protein Regulation Strategies of Mouse Spleen in Response to Babesia Microti Infection

“…After hosts are infected with common parasitic protozoans such as Babesia, Plasmodium, and Leishmania, lysosomes in host cells can engulf a large number of parasites [18][19][20]. CTSD belongs to the aspartic protease family.…”