The WD40-Protein PfWLP1 Ensures Stability of the PfCCp-Based Adhesion Protein Complex in Plasmodium falciparum Gametocytes

Members of the WD40-repeat protein family can be found in all eukaryotic proteomes where they usually serve as interaction platforms for the assembly of large protein complexes and are therefore essential for the integrity of these complexes. In the malaria parasite Plasmodium falciparum, the WD40-repeat protein PfWLP1 has been shown to interact with members of distinct adhesion protein complexes in the asexual blood stages and gametocyte stages. In this study, we demonstrate that the presence of PfWLP1 is crucial for both the stability of these gametocyte-specific adhesion complexes as well as for gametocyte maturation and gametogenesis. Using reverse genetics, we generated a PfWLP1-knockdown parasite line for functional characterization of the protein. Knockdown of PfWLP1 resulted in a slight reduction of gametocyte numbers and significantly the impaired ability of the gametocytes to exflagellate. PfWLP1-knockdown further led to reduced protein levels of the Limulus coagulation factor C-like (LCCL)-domain proteins PfCCp1 and PfCCp2, which are key components of the adhesion complexes. These findings suggest that the interaction of PfWLP1 with members of the PfCCp-based adhesion complex ensures complex stability and thereby contributes to gametocyte viability and exflagellation

Portuguese history storyboard

This paper intends to present relevant facts about the Portuguese culture and history, so as to enable a better understanding of who the Portuguese are and provide an overall perspective of the course of history in this westernmost part of Europe. Although the choice of historical facts was subjective by nature, it is believed it achieves the aim of presenting information in a critical but blithesome way, with a view to also deconstructing national stereotypes, such as that Portuguese people are always late or are crazy about football. Finally, it focuses on some information about the Portuguese language mainly to serve as a term of comparison with other European languages

In-Vivo Biodistribution and Safety of 99mTc-LLP2A-HYNIC in Canine Non-Hodgkin Lymphoma

Theranostic agents are critical for improving the diagnosis and treatment of non-Hodgkin Lymphoma (NHL). The peptidomimetic LLP2A is a novel peptide receptor radiotherapy candidate for treating NHL that expresses the activated α4β1 integrin. Tumor-bearing dogs are an excellent model of human NHL with similar clinical characteristics, behavior, and compressed clinical course. Canine in vivo imaging studies will provide valuable biodistribution and affinity information that reflects a diverse clinical population of lymphoma. This may also help to determine potential dose-limiting radiotoxicity to organs in human clinical trials. To validate this construct in a naturally occurring model of NHL, we performed in-vivo molecular targeted imaging and biodistribution in 3 normal dogs and 5 NHL bearing dogs. 99mTc-LLP2A-HYNIC-PEG and 99mTc-LLP2A-HYNIC were successfully synthesized and had very good labeling efficiency and radiochemical purity. 99mTc-LLP2A-HYNIC and 99mTc-LLP2A-HYNIC-PEG had biodistribution in keeping with their molecular size, with 99mTc-LLP2A-HYNIC-PEG remaining longer in the circulation, having higher tissue uptake, and having more activity in the liver compared to 99mTc-LLP2A-HYNIC. 99mTc-LLP2A-HYNIC was mainly eliminated through the kidneys with some residual activity. Radioactivity was reduced to near-background levels at 6 hours after injection. In NHL dogs, tumor showed moderately increased activity over background, with tumor activity in B-cell lymphoma dogs decreasing after chemotherapy. This compound is promising in the development of targeted drug-delivery radiopharmaceuticals and may contribute to translational work in people affected by non-Hodgkin lymphoma

Funktionale Charakterisierung sexualstadienspezifischer Proteine während der Gametogenese des humanpathogenen Malariaerregers Plasmodium falciparum

The sexual reproduction phase of Plasmodium falciparum is essential for the successful transmission of the malaria parasite and represents an optimal target for transmission blocking intervention strategies. It is initiated by the formation of intra erythrocytic gametocytes in the human host. The aim of this thesis was to decipher different molecular and cellular processes during the sexual reproduction phase of P. falciparum and to describe the roles of proteins involved in these processes. In order to pre-adapt to the change of hosts, the parasite stores transcripts coding for proteins needed in the mosquito midgut stages in stress granules of female gametocytes thereby stalling translation. After transmission to the mosquito the translational repression is released during gametogenesis and protein synthesis is initiated. In the present thesis, the protein 7-Helix-1 was shown to play a crucial role in this process. The detailed analysis of transcriptome studies performed in a 7-Helix-1-deficient parasite line indicated that the loss of 7-Helix-1 results in a deregulation of translation associated genes. Via co-localization studies and Western blots, 7-Helix-1 was shown to be a component of stress granules. Co-immunoprecipitations verified 7-Helix-1 as an interaction partner of serveral known translational repressors and unveiled the binding of repressed transcripts to the complex. In accordance with these data, it was shown that the protein synthesis of repressed transcripts is reduced in 7-Helix-1-KO gametocytes, pointing to a role of 7-Helix-1 in the re-initiation of translation after the release of translational repression. Furthermore, the parasite has to egress from the enveloping red blood cell during gametogenesis in order to facilitate physical contact of the male and female gametes. The host cell egress is among others accompanied by the fusion of egress vesicles, that contain for example the perforin-like protein PPLP2, with the plasmamembrane and the secretion of their content into the host cytosol. To identify the proteome of the egress vesicles, a PPLP2-BirA parasite line has been generated, that will be employed in BioID-based approaches in order to decipher interaction partners of PPLP2. To further analyse the process of vesicle fusion and proteins involved in this exocytotic process, an expression analysis of putative SNARE proteins, that usually mediate vesicle fusion, has been performed using RT-PCR and IFA. The results revealed both stage unspecific and gametocyte specific members of the SNARE protein family. The results of this thesis contribute to the understanding of the molecular mechanisms during the sexual reproduction phase of the malaria parasite P. falciparum and can serve as a basis for the discovery of new drug and vaccine targets

The Multiple Roles of LCCL Domain-Containing Proteins for Malaria Parasite Transmission

Multi-protein complexes are crucial for various essential biological processes of the malaria parasite Plasmodium, such as protein synthesis, host cell invasion and adhesion. Especially during the sexual phase of the parasite, which takes place in the midgut of the mosquito vector, protein complexes are required for fertilization, sporulation and ultimately for the successful transmission of the parasite. Among the most noticeable protein complexes of the transmission stages are the ones formed by the LCCL domain-containing protein family that play critical roles in the generation of infective sporozoites. The six members of this protein family are characterized by numerous adhesive modules and domains typically found in secreted proteins. This review summarizes the findings of expression and functional studies on the LCCL domain-containing proteins of the human pathogenic P. falciparum and the rodent-infecting P. berghei and discusses the common features and differences of the homologous proteins

Perforin-like protein PPLP4 is crucial for mosquito midgut infection by Plasmodium falciparum

The genomes of Plasmodium parasites encode for five perforin-like proteins, PPLP1-5, and four of them have previously been demonstrated to be involved in disruption of host cell barriers. We now show that the fifth perform, PPLP4, is crucial for infection of the mosquito vector by Plasmodium falciparum parasites. PPLP4 is expressed in the blood and mosquito midgut stages in granular structures. In gametocytes, PPLP4 expression is specific to the female gender, while ookinetes show a PPLP4 localization at the apical pole. Gene disruption of pplp4 results in no phenotypical change during blood stage replication, gametocyte development or gametogenesis, while mosquitoes fed with PPLP4-deficient gametocytes display a severe reduction in oocyst numbers, and an accumulation of ookinetes in the mosquito midguts was observed. In conclusion, we propose an essential role for PPLP4 in infection of the mosquito midgut, presumably by mediating ookinete traversal through the midgut epithelium