Limits...
Adenylyl cyclase alpha and cAMP signaling mediate Plasmodium sporozoite apical regulated exocytosis and hepatocyte infection.

Ono T, Cabrita-Santos L, Leitao R, Bettiol E, Purcell LA, Diaz-Pulido O, Andrews LB, Tadakuma T, Bhanot P, Mota MM, Rodriguez A - PLoS Pathog. (2008)

Bottom Line: We have generated P. berghei parasites deficient in adenylyl cyclase alpha (ACalpha), a gene containing regions with high homology to adenylyl cyclases.PbACalpha-deficient sporozoites do not exocytose in response to migration through host cells and present more than 50% impaired hepatocyte infectivity in vivo.These effects are specific to ACalpha, as re-introduction of ACalpha in deficient parasites resulted in complete recovery of exocytosis and infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America.

ABSTRACT
Malaria starts with the infection of the liver of the host by Plasmodium sporozoites, the parasite form transmitted by infected mosquitoes. Sporozoites migrate through several hepatocytes by breaching their plasma membranes before finally infecting one with the formation of an internalization vacuole. Migration through host cells induces apical regulated exocytosis in sporozoites. Here we show that apical regulated exocytosis is induced by increases in cAMP in sporozoites of rodent (P. yoelii and P. berghei) and human (P. falciparum) Plasmodium species. We have generated P. berghei parasites deficient in adenylyl cyclase alpha (ACalpha), a gene containing regions with high homology to adenylyl cyclases. PbACalpha-deficient sporozoites do not exocytose in response to migration through host cells and present more than 50% impaired hepatocyte infectivity in vivo. These effects are specific to ACalpha, as re-introduction of ACalpha in deficient parasites resulted in complete recovery of exocytosis and infection. Our findings indicate that ACalpha and increases in cAMP levels are required for sporozoite apical regulated exocytosis, which is involved in sporozoite infection of hepatocytes.

Show MeSH

Related in: MedlinePlus

PbACα- has normal blood-stage growth rates and sporozoite motility.(A) Growth curves of P. berghei WT (black squares), PbACα- C1 (black circles) and C2 (white circles) in mice. (B) Gliding motility of sporozoites from WT, PbACα- C1 and C2 in the presence (right panel) or absence (left panel) of mouse albumin. Percentage of sporozoites that do not glide or do less than a complete circle (black bars), gliding sporozoites exhibiting 1 (dark gray bars), 2 to 10 (light gray bars), or >10 (white bars) circles per trail. (C) Migration through Hepa1-6 cells was measured as the number of dextran positive cells per coverslip. The difference between C1 or C2 and WT is not significantly different (p>0.05).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2279260&req=5

ppat-1000008-g006: PbACα- has normal blood-stage growth rates and sporozoite motility.(A) Growth curves of P. berghei WT (black squares), PbACα- C1 (black circles) and C2 (white circles) in mice. (B) Gliding motility of sporozoites from WT, PbACα- C1 and C2 in the presence (right panel) or absence (left panel) of mouse albumin. Percentage of sporozoites that do not glide or do less than a complete circle (black bars), gliding sporozoites exhibiting 1 (dark gray bars), 2 to 10 (light gray bars), or >10 (white bars) circles per trail. (C) Migration through Hepa1-6 cells was measured as the number of dextran positive cells per coverslip. The difference between C1 or C2 and WT is not significantly different (p>0.05).

Mentions: We examined the phenotype of PbACα- parasites during the Plasmodium life cycle. We compared the two PbACα- lines with WT P. berghei parasites also cloned independently. PbACα- parasites were indistinguishable from WT parasites in growth during red blood cell stages in mice (Fig. 6A). We next analyzed parasite growth in the mosquito by determining oocyst development and sporozoite salivary gland invasion. Similar oocyst and salivary gland sporozoite numbers were obtained for PbACα- and the WT control, indicating that PbACα is not involved in oocyst development and sporozoite salivary gland invasion (Table 1).


Adenylyl cyclase alpha and cAMP signaling mediate Plasmodium sporozoite apical regulated exocytosis and hepatocyte infection.

Ono T, Cabrita-Santos L, Leitao R, Bettiol E, Purcell LA, Diaz-Pulido O, Andrews LB, Tadakuma T, Bhanot P, Mota MM, Rodriguez A - PLoS Pathog. (2008)

PbACα- has normal blood-stage growth rates and sporozoite motility.(A) Growth curves of P. berghei WT (black squares), PbACα- C1 (black circles) and C2 (white circles) in mice. (B) Gliding motility of sporozoites from WT, PbACα- C1 and C2 in the presence (right panel) or absence (left panel) of mouse albumin. Percentage of sporozoites that do not glide or do less than a complete circle (black bars), gliding sporozoites exhibiting 1 (dark gray bars), 2 to 10 (light gray bars), or >10 (white bars) circles per trail. (C) Migration through Hepa1-6 cells was measured as the number of dextran positive cells per coverslip. The difference between C1 or C2 and WT is not significantly different (p>0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2279260&req=5

ppat-1000008-g006: PbACα- has normal blood-stage growth rates and sporozoite motility.(A) Growth curves of P. berghei WT (black squares), PbACα- C1 (black circles) and C2 (white circles) in mice. (B) Gliding motility of sporozoites from WT, PbACα- C1 and C2 in the presence (right panel) or absence (left panel) of mouse albumin. Percentage of sporozoites that do not glide or do less than a complete circle (black bars), gliding sporozoites exhibiting 1 (dark gray bars), 2 to 10 (light gray bars), or >10 (white bars) circles per trail. (C) Migration through Hepa1-6 cells was measured as the number of dextran positive cells per coverslip. The difference between C1 or C2 and WT is not significantly different (p>0.05).
Mentions: We examined the phenotype of PbACα- parasites during the Plasmodium life cycle. We compared the two PbACα- lines with WT P. berghei parasites also cloned independently. PbACα- parasites were indistinguishable from WT parasites in growth during red blood cell stages in mice (Fig. 6A). We next analyzed parasite growth in the mosquito by determining oocyst development and sporozoite salivary gland invasion. Similar oocyst and salivary gland sporozoite numbers were obtained for PbACα- and the WT control, indicating that PbACα is not involved in oocyst development and sporozoite salivary gland invasion (Table 1).

Bottom Line: We have generated P. berghei parasites deficient in adenylyl cyclase alpha (ACalpha), a gene containing regions with high homology to adenylyl cyclases.PbACalpha-deficient sporozoites do not exocytose in response to migration through host cells and present more than 50% impaired hepatocyte infectivity in vivo.These effects are specific to ACalpha, as re-introduction of ACalpha in deficient parasites resulted in complete recovery of exocytosis and infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America.

ABSTRACT
Malaria starts with the infection of the liver of the host by Plasmodium sporozoites, the parasite form transmitted by infected mosquitoes. Sporozoites migrate through several hepatocytes by breaching their plasma membranes before finally infecting one with the formation of an internalization vacuole. Migration through host cells induces apical regulated exocytosis in sporozoites. Here we show that apical regulated exocytosis is induced by increases in cAMP in sporozoites of rodent (P. yoelii and P. berghei) and human (P. falciparum) Plasmodium species. We have generated P. berghei parasites deficient in adenylyl cyclase alpha (ACalpha), a gene containing regions with high homology to adenylyl cyclases. PbACalpha-deficient sporozoites do not exocytose in response to migration through host cells and present more than 50% impaired hepatocyte infectivity in vivo. These effects are specific to ACalpha, as re-introduction of ACalpha in deficient parasites resulted in complete recovery of exocytosis and infection. Our findings indicate that ACalpha and increases in cAMP levels are required for sporozoite apical regulated exocytosis, which is involved in sporozoite infection of hepatocytes.

Show MeSH
Related in: MedlinePlus