scholarly journals A Plasmodium yoelii Mei2-Like RNA Binding Protein Is Essential for Completion of Liver Stage Schizogony

2016 ◽  
Vol 84 (5) ◽  
pp. 1336-1345 ◽  
Author(s):  
Dorender A. Dankwa ◽  
Marshall J. Davis ◽  
Stefan H. I. Kappe ◽  
Ashley M. Vaughan
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Plasmodium Yoelii ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Wild Type ◽  
Liver Stage ◽  
Content Type ◽  
Stage Development

Plasmodiumparasites employ posttranscriptional regulatory mechanisms as their life cycle transitions between host cell invasion and replication within both the mosquito vector and mammalian host. RNA binding proteins (RBPs) provide one mechanism for modulation of RNA function. To explore the role ofPlasmodiumRBPs during parasite replication, we searched for RBPs that might play a role during liver stage development, the parasite stage that exhibits the most extensive growth and replication. We identified a parasite ortholog of theMei2(Meiosisinhibited 2) RBP that is conserved amongPlasmodiumspecies (PlasMei2) and exclusively transcribed in liver stage parasites. Epitope-taggedPlasmodium yoeliiPlasMei2 was expressed only during liver stage schizogony and showed an apparent granular cytoplasmic location. Knockout ofPlasMei2(plasmei2−) inP. yoeliionly affected late liver stage development. TheP. yoeliiplasmei2−liver stage size increased progressively until late in development, similar to wild-type parasite development. However,P. yoeliiplasmei2−liver stage schizonts exhibited an abnormal DNA segregation phenotype and failed to form exoerythrocytic merozoites. Consequently the cellular integrity ofP. yoeliiplasmei2−liver stages became increasingly compromised late in development and the majority ofP. yoeliiplasmei2−underwent cell death by the time wild-type liver stages mature and release merozoites. This resulted in a complete block ofP. yoeliiplasmei2−transition from liver stage to blood stage infection in mice. Our results show for the first time the importance of aPlasmodiumRBP in the coordinated progression of late liver stage schizogony and maturation of new invasive forms.

scholarly journals Inhibition of Plasmodium Liver Infection by Ivermectin

2016 ◽  
Vol 61 (2) ◽  
Author(s):  
António M. Mendes ◽  
Inês S. Albuquerque ◽  
Marta Machado ◽  
Joana Pissarra ◽  
Patrícia Meireles ◽  
...  
Keyword(s):  
Control Strategies ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Content Type ◽  
Vector Borne Diseases ◽  
Host Infection ◽  
Liver Infection

ABSTRACT Avermectins are powerful endectocides with an established potential to reduce the incidence of vector-borne diseases. Here, we show that several avermectins inhibit the hepatic stage of Plasmodium infection in vitro. Notably, ivermectin potently inhibits liver infection in vivo by impairing parasite development inside hepatocytes. This impairment has a clear impact on the ensuing blood stage parasitemia, reducing disease severity and enhancing host survival. Ivermectin has been proposed as a tool to control malaria transmission because of its effects on the mosquito vector. Our study extends the effect of ivermectin to the early stages of mammalian host infection and supports the inclusion of this multipurpose drug in malaria control strategies.

scholarly journals In VitroAlterations Do Not Reflect a Requirement for Host Cell Cycle Progression during Plasmodium Liver Stage Infection

2014 ◽  
Vol 14 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Kirsten K. Hanson ◽  
Sandra March ◽  
Shengyong Ng ◽  
Sangeeta N. Bhatia ◽  
Maria M. Mota
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Hepatoma Cells ◽  
Plasmodium Yoelii ◽  
Host Cells ◽  
Cycle Progression ◽  
Liver Stage ◽  
Content Type ◽  
Stage Development ◽  
Stage Infection

ABSTRACTPrior to invading nonreplicative erythrocytes,Plasmodiumparasites undergo their first obligate step in the mammalian host inside hepatocytes, where each sporozoite replicates to generate thousands of merozoites. While normally quiescent, hepatocytes retain proliferative capacity and can readily reenter the cell cycle in response to diverse stimuli. Many intracellular pathogens, including protozoan parasites, manipulate the cell cycle progression of their host cells for their own benefit, but it is not known whether the hepatocyte cell cycle plays a role duringPlasmodiumliver stage infection. Here, we show thatPlasmodiumparasites can be observed in mitotic hepatoma cells throughout liver stage development, where they initially reduce the likelihood of mitosis and ultimately lead to significant acquisition of a binucleate phenotype. However, hepatoma cells pharmacologically arrested in S phase still support robust and completePlasmodiumliver stage development, which thus does not require cell cycle progression in the infected cellin vitro. Furthermore, murine hepatocytes remain quiescent throughoutin vivoinfection with eitherPlasmodium bergheiorPlasmodium yoelii, as doPlasmodium falciparum-infected primary human hepatocytes, demonstrating that the rapid and prodigious growth of liver stage parasites is accomplished independent of host hepatocyte cell cycle progression during natural infection.

scholarly journals Use of a Selective Inhibitor To Define the Chemotherapeutic Potential of the Plasmodial Hexose Transporter in Different Stages of the Parasite's Life Cycle

2011 ◽  
Vol 55 (6) ◽  
pp. 2824-2830 ◽  
Author(s):  
Ksenija Slavic ◽  
Michael J. Delves ◽  
Miguel Prudêncio ◽  
Arthur M. Talman ◽  
Ursula Straschil ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Specific Inhibitor ◽  
Parasite Development ◽  
Mosquito Vector ◽  
Hexose Transporter ◽  
Asexual Blood Stage ◽  
Liver Stage ◽  
Content Type ◽  
Green Fluorescent ◽  
Malaria Model

ABSTRACTDuring blood infection, malarial parasites used-glucose as their main energy source. ThePlasmodium falciparumhexose transporter (PfHT), which mediates the uptake ofd-glucose into parasites, is essential for survival of asexual blood-stage parasites. Recently, genetic studies in the rodent malaria model,Plasmodium berghei, found that the orthologous hexose transporter (PbHT) is expressed throughout the parasite's development within the mosquito vector, in addition to being essential during intraerythrocytic development. Here, using ad-glucose-derived specific inhibitor of plasmodial hexose transporters, compound 3361, we have investigated the importance ofd-glucose uptake during liver and transmission stages ofP. berghei. Initially, we confirmed the expression of PbHT during liver stage development, using a green fluorescent protein (GFP) tagging strategy. Compound 3361 inhibited liver-stage parasite development, with a 50% inhibitory concentration (IC50) of 11 μM. This process was insensitive to the externald-glucose concentration. In addition, compound 3361 inhibited ookinete development and microgametogenesis, with IC50s in the region of 250 μM (the latter in ad-glucose-sensitive manner). Consistent with our findings for the effect of compound 3361 on vector parasite stages, 1 mM compound 3361 demonstrated transmission blocking activity. These data indicate that novel chemotherapeutic interventions that target PfHT may be active against liver and, to a lesser extent, transmission stages, in addition to blood stages.

scholarly journals Plasmodium falciparum PF10_0164 (ETRAMP10.3) Is an Essential Parasitophorous Vacuole and Exported Protein in Blood Stages

2010 ◽  
Vol 9 (5) ◽  
pp. 784-794 ◽  
Author(s):  
Drew C. MacKellar ◽  
Matthew T. O'Neill ◽  
Ahmed S. I. Aly ◽  
John B. Sacci ◽  
Alan F. Cowman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasitophorous Vacuole ◽  
Structural Similarity ◽  
Plasmodium Yoelii ◽  
Parasitophorous Vacuole Membrane ◽  
Liver Stage ◽  
Content Type ◽  
Vacuole Membrane ◽  
Stage Development ◽  
Gene 4

ABSTRACT Upregulated in infectious sporozoites gene 4 (UIS4) encodes a parasitophorous vacuole membrane protein expressed in the sporozoite and liver stages of rodent malaria parasites. Parasites that lack UIS4 arrest in early liver-stage development, and vaccination of mice with uis4 − sporozoites confers sterile protection against challenge with infectious sporozoites. Currently, it remains unclear whether an ortholog of UIS4 is carried in the human malaria parasite Plasmodium falciparum, although the gene PF10_0164 has been identified as a candidate ortholog for UIS4 on the basis of synteny and structural similarity of the encoded protein. We show that PF10_0164 is expressed in sporozoites and blood stages of P. falciparum, where it localizes to the parasitophorous vacuole, and is also exported to the host erythrocyte. PF10_0164 is refractory to disruption in asexual blood stages. Functional complementation was tested in Plasmodium yoelii by replacing the endogenous copy of UIS4 with PF10_0164. PF10_0164 localized to the parasitophorous vacuole membrane of liver stages, but transgenic parasites did not complete liver-stage development in mice. We conclude that PF10_0164 is a parasitophorous vacuole protein that is essential in asexual blood stages and that does not complement P. yoelii UIS4, and it is thus likely not a functional ortholog of UIS4.

scholarly journals Plasmodium yoelii Macrophage Migration Inhibitory Factor Is Necessary for Efficient Liver-Stage Development

2012 ◽  
Vol 80 (4) ◽  
pp. 1399-1407 ◽  
Author(s):  
Jessica L. Miller ◽  
Anke Harupa ◽  
Stefan H. I. Kappe ◽  
Sebastian A. Mikolajczak
Keyword(s):  
Life Cycle ◽  
Immune Responses ◽  
Macrophage Migration Inhibitory Factor ◽  
Plasmodium Yoelii ◽  
Blood Stage ◽  
Macrophage Migration ◽  
Liver Stage ◽  
Content Type ◽  
Host Immune Responses ◽  
Stage Development

ABSTRACTMammalian macrophage migration inhibitory factor (MIF) is a multifaceted cytokine involved in both extracellular and intracellular functions. Malaria parasites express a MIF homologue that might modulate host immune responses against blood-stage parasites, but the potential importance of MIF against other life cycle stages remains unstudied. In this study, we characterized the MIF homologue ofPlasmodium yoeliithroughout the life cycle, with emphasis on preerythrocytic stages.P. yoeliiMIF (Py-MIF) was expressed in blood-stage parasites and detected at low levels in mosquito salivary gland sporozoites. MIF expression was strong throughout liver-stage development and localized to the cytoplasm of the parasite, with no evidence of release into the host hepatocyte. To examine the importance of Py-MIF for liver-stage development, we generated a Py-mifknockout parasite (P. yoeliiΔmif).P. yoeliiΔmifparasites grew normally as asexual erythrocytic-stage parasites and showed normal infection of mosquitoes. In contrast, theP. yoeliiΔmifstrain was attenuated during the liver stage. Mice infected withP. yoeliiΔmifsporozoites either did not develop blood-stage parasitemia or exhibited a delay in the onset of blood-stage patency. Furthermore,P. yoeliiΔmifparasites exhibited growth retardationin vivo. Combined, the data indicate thatPlasmodiumMIF is important for liver-stage development ofP. yoelii, during which it is likely to play an intrinsic role in parasite development rather than modulating host immune responses to infection.

scholarly journals A Plasmodium Parasite with Complete Late Liver Stage Arrest Protects against Preerythrocytic and Erythrocytic Stage Infection in Mice

2018 ◽  
Vol 86 (5) ◽  
pp. e00088-18 ◽  
Author(s):  
Ashley M. Vaughan ◽  
Brandon K. Sack ◽  
Dorender Dankwa ◽  
Nana Minkah ◽  
Thao Nguyen ◽  
...  
Keyword(s):  
Inbred Mice ◽  
Specific Protein ◽  
Plasmodium Yoelii ◽  
Blood Stage ◽  
Susceptible Mouse ◽  
Liver Stage ◽  
Content Type ◽  
Synthetic Lethal ◽  
Stage Development ◽  
Stage Infection

ABSTRACT Genetically attenuated malaria parasites (GAP) that arrest during liver stage development are powerful immunogens and afford complete and durable protection against sporozoite infection. Late liver stage-arresting GAP provide superior protection against sporozoite challenge in mice compared to early live stage-arresting attenuated parasites. However, very few late liver stage-arresting GAP have been generated to date. Therefore, identification of additional loci that are critical for late liver stage development and can be used to generate novel late liver stage-arresting GAPs is of importance. We further explored genetic attenuation in Plasmodium yoelii by combining two gene deletions, PlasMei2 and liver-specific protein 2 (LISP2), that each cause late liver stage arrest with various degrees of infrequent breakthrough to blood stage infection. The dual gene deletion resulted in a synthetic lethal phenotype that caused complete attenuation in a highly susceptible mouse strain. P. yoelii plasmei2− lisp2− arrested late in liver stage development and did not persist in livers beyond 3 days after infection. Immunization with this GAP elicited robust protective antibody responses in outbred and inbred mice against sporozoites, liver stages, and blood stages as well as eliciting protective liver-resident T cells. The immunization afforded protection against both sporozoite challenge and blood stage challenge. These findings provide evidence that completely attenuated late liver stage-arresting GAP are achievable via the synthetic lethal approach and might enable a path forward for the creation of a completely attenuated late liver stage-arresting P. falciparum GAP.

scholarly journals The fibrinolytic system enables the onset of Plasmodium infection in the mosquito vector and the mammalian host

2021 ◽  
Vol 7 (6) ◽  
pp. eabe3362 ◽  
Author(s):  
Thiago Luiz Alves e Silva ◽  
Andrea Radtke ◽  
Amanda Balaban ◽  
Tales Vicari Pascini ◽  
Zarna Rajeshkumar Pala ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Fibrinolytic System ◽  
Matrix Proteins ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Plasminogen Activation ◽  
Plasmodium Infection ◽  
Human Plasminogen ◽  
Vertebrate Hosts

Plasmodium parasites must migrate across proteinaceous matrices to infect the mosquito and vertebrate hosts. Plasmin, a mammalian serine protease, degrades extracellular matrix proteins allowing cell migration through tissues. We report that Plasmodium gametes recruit human plasminogen to their surface where it is processed into plasmin by corecruited plasminogen activators. Inhibition of plasminogen activation arrests parasite development early during sexual reproduction, before ookinete formation. We show that increased fibrinogen and fibrin in the blood bolus, which are natural substrates of plasmin, inversely correlate with parasite infectivity of the mosquito. Furthermore, we show that sporozoites, the parasite form transmitted by the mosquito to humans, also bind plasminogen and plasminogen activators on their surface, where plasminogen is activated into plasmin. Surface-bound plasmin promotes sporozoite transmission by facilitating parasite migration across the extracellular matrices of the dermis and of the liver. The fibrinolytic system is a potential target to hamper Plasmodium transmission.

scholarly journals Investigating the Roles of RNA Binding Protein Combinations in Neuronal Function and Organismal Behavior

2019 ◽  
Vol 4 (Spring 2019) ◽  
Author(s):  
Alexa Vandenburg
Keyword(s):  
Binding Sites ◽  
Neuronal Development ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Wild Type ◽  
C Elegans ◽  
Neuronal Gene ◽  
Touch Response

The Norris lab recently identified two RNA binding proteins required for proper neuron-specific splicing. The lab conducted touch- response behavioral assays to assess the function of these proteins in touch-sensing neurons. After isolating C. elegans worms with specific phenotypes, the lab used automated computer tracking and video analysis to record the worms’ behavior. The behavior of mutant worms differed from that of wild-type worms. The Norris lab also discovered two possible RNA binding protein sites in SAD-1, a neuronal gene implicated in the neuronal development of C. elegans1. These two binding sites may control the splicing of SAD-1. The lab transferred mutated DNA into the genome of wild-type worms by injecting a mutated plasmid. The newly transformed worms fluoresced green, indicating that the two binding sites control SAD-1 splicing.

scholarly journals Cyclic GMP Balance Is Critical for Malaria Parasite Transmission from the Mosquito to the Mammalian Host

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Viswanathan Lakshmanan ◽  
Matthew E. Fishbaugher ◽  
Bob Morrison ◽  
Michael Baldwin ◽  
Michael Macarulay ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Cyclic Gmp ◽  
Cyclic Nucleotide ◽  
Malaria Parasite ◽  
Plasmodium Yoelii ◽  
Pcr Analysis ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Parasite Transmission ◽  
Mosquito Bite

ABSTRACT Transmission of malaria occurs during Anopheles mosquito vector blood meals, when Plasmodium sporozoites that have invaded the mosquito salivary glands are delivered to the mammalian host. Sporozoites display a unique form of motility that is essential for their movement across cellular host barriers and invasion of hepatocytes. While the molecular machinery powering motility and invasion is increasingly well defined, the signaling events that control these essential parasite activities have not been clearly delineated. Here, we identify a phosphodiesterase (PDEγ) in Plasmodium, a regulator of signaling through cyclic nucleotide second messengers. Reverse transcriptase PCR (RT-PCR) analysis and epitope tagging of endogenous PDEγ detected its expression in blood stages and sporozoites of Plasmodium yoelii. Deletion of PDEγ (pdeγ−) rendered sporozoites nonmotile, and they failed to invade the mosquito salivary glands. Consequently, PDEγ deletion completely blocked parasite transmission by mosquito bite. Strikingly, pdeγ− sporozoites showed dramatically elevated levels of cyclic GMP (cGMP), indicating that a perturbation in cyclic nucleotide balance is involved in the observed phenotypic defects. Transcriptome sequencing (RNA-Seq) analysis of pdeγ− sporozoites revealed reduced transcript abundance of genes that encode key components of the motility and invasion apparatus. Our data reveal a crucial role for PDEγ in maintaining the cyclic nucleotide balance in the malaria parasite sporozoite stage, which in turn is essential for parasite transmission from mosquito to mammal. IMPORTANCE Malaria is a formidable threat to human health worldwide, and there is an urgent need to identify novel drug targets for this parasitic disease. The parasite is transmitted by mosquito bite, inoculating the host with infectious sporozoite stages. We show that cellular signaling by cyclic nucleotides is critical for transmission of the parasite from the mosquito vector to the mammalian host. Parasite phosphodiesterase γ is essential for maintaining cyclic nucleotide balance, and its deletion blocks transmission of sporozoites. A deeper understanding of the signaling mechanisms involved in transmission might inform the discovery of novel drugs that interrupt this essential step in the parasite life cycle.

scholarly journals In VitroAnalysis of the Interaction between Atovaquone and Proguanil against Liver Stage Malaria Parasites

2016 ◽  
Vol 60 (7) ◽  
pp. 4333-4335 ◽  
Author(s):  
Lídia Barata ◽  
Pascal Houzé ◽  
Khadija Boutbibe ◽  
Gigliola Zanghi ◽  
Jean-François Franetich ◽  
...  
Keyword(s):  
Plasmodium Yoelii ◽  
Human Hepatocytes ◽  
High Efficacy ◽  
Liver Stage ◽  
Content Type ◽  
Cytochrome P450 Activity ◽  
Main Target ◽  
P450 Activity ◽  
Pharmacological Basis

ABSTRACTThe interaction between atovaquone and proguanil has never been studied against liver stage malaria, which is the main target of this drug combination when used for chemoprevention. Using human hepatocytes lacking cytochrome P450 activity, and thus avoiding proguanil metabolizing into potent cycloguanil, we showin vitrothat the atovaquone-proguanil combination synergistically inhibits the growth of rodentPlasmodium yoeliiparasites. These results provide a pharmacological basis for the high efficacy of atovaquone-proguanil used as malaria chemoprevention.

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