Unravelling the molecular mechanisms regulating cell division in the malaria parasite

Lead Research Organisation: University of Nottingham
Department Name: School of Life Sciences

Abstract

Malaria is the third largest global health problem caused by a single infectious agent after HIV and TB, affecting millions of people, and resulting in one million deaths annually (http://www.who.int/topics/malaria/). The emergence of resistance to antimalarial drugs and the lack of any effective vaccine highlight the great need to develop new tools to control the disease. The symptoms of the disease are caused when the malaria parasite invades human red blood cells and multiplies many times every two days eventually leading to destruction of red blood cells and followed by further invasion and cell division. Some of these parasite cells may cease to divide and they become sex cells (male and female gametocytes). When a female mosquito bites an infected person they ingest parasites along with the blood and this acts as a trigger to activate the parasite sex cells within the mosquito gut. The male gametocytes undergo rapid cell division to produce eight male gametes, which then fertilise the female gametes and the parasite life cycle continues in the mosquito gut. After further development and multiplication the parasite moves to the mosquito's salivary glands and is passed again to a new human host.

The divisions made by parasites in blood cells and during sexual development are very different, but both are essential for the parasite If the parasite was unable to multiply and divide in the blood stream then it would not cause disease and if the male gametocytes were unable to divide then parasite transmissionwould be blocked. Therefore it is critically important to understand how the parasite multiplies and divides at these two stages so that we can develop ways to interfere with them by developing appropriate drugs.

The molecules that control these two types of cell division in the parasite are very poorly understood. The project proposed here is to identify what they are and how they work. We can start by using the knowledge gathered in model systems and applying this in the parasite. For example in yeast and other well-studied systems, a complex of proteins called the anaphase promoting complex/cyclosome (APC/C), plays a key role in cell multiplication and division. It is activated by the action of other proteins for example one called the cell division cycle protein-20 (CDC20). These proteins are also further regulated by the addition or removal of small 'tags', for example phosphate groups that can turn on or turn off particular functions.

We have recently identified one of these proteins (CDC20) in the malaria parasite and shown that it has a key role in regulating male gamete formation, and also that it is itself regulated by addition of phosphate tags. In preliminary work showing that our approach is feasible, we have obtained evidence for the presence of components of the APC/C protein complex in both the parasite multiplying within the red blood cell and in the male sex cell. Recent advances in analysing genes in malaria allow us to study the function of these molecules. For example, we can see what happens if the proteins are no longer made, and if they are tagged experimentally with a fluorescent marker we can see where they are located in the parasite under the microscope. Therefore, we are now in a position where we can explore further to understand how cell division in malaria is controlled by these different molecules. We will also study how these molecules interact together.

This research will enable us to identify mechanisms essential for parasite growth and multiplication that might be targeted in the development of new anti-malarial treatments. Our study may identify molecular targets important in parasite cell division in red blood cells and in the formation of male gametes, and therefore effective against either the stage responsible for the disease in humans or the transmission from one individual to another through the mosquito.

Technical Summary

Malaria is caused by unicellular parasites belonging to the genus Plasmodium. These parasites invade red blood cells and divide asexually in a developmental process termed as schizogony, causing the disease. In addition, some parasites within red blood cells arrest cell division and differentiate to form sexual gametocytes. Following ingestion by Anopheles mosquitoes, the male gametocyte undergoes rapid cell division to produce 8 male gametes in a process of microgametogenesis. Schizogony and microgametogenesis are distinct types of mitotic cell division, and both also differ from classical cell division as studied in yeast, mammalian or other cells. The molecular mechanisms that regulate cell division in the malaria parasite are not well elucidated. Our main aim in this project is to unravel the molecular pathways controlling these types of cell division and establish how they differ from classical cell division.

Major molecular components regulating cell division in yeast and other eukaryotic cells are the anaphase promoting complex/cyclosome (APC/C) protein complex, its activators such as cell division proteins CDC20 and CDH1, and protein kinases and phosphatases that control the reversible phosphorylation of the complex/activators. We recently identified and partially characterized the single homologue of CDC20/CDH1 in Plasmodium, and have shown that many of the structural protein components of APC/C are not present in these parasites.

In this project we aim to investigate the role of putative APC/C components and their interaction with CDC20 during malaria parasite cell division at the two stages of the life cycle. This project will primarily use the rodent malaria model P. berghei since the whole life cycle can be completed in the laboratory and it is highly amenable to experimental manipulation. We will use reverse genetics, cell biological methods such as microscopy, protein biochemistry, and proteomics approaches to achieve our goal.

Planned Impact

Cell division is a prerequisite for any organism to proliferate and develop during its life cycle. To understand how chromosomes are duplicated and segregated and how cell division occurs in a proper manner are basic questions in cell biology. Although various systems have been used to provide our understanding of these processes, including yeast, human and plant cells, very little is known about such processes and their regulation in parasitic protozoa, especially malaria parasites belonging to the genus Plasmodium.

Malaria is a major infectious disease of humans, with 300 million clinical cases and around a million deaths each year, mostly of children (http://www.who.int/topics/malaria/). Currently there is no effective vaccine, and the continual emergence of resistance to antimalarial drugs has resulted in human suffering, a strain on health care resources, and economic disadvantage. With a global agenda to substantially reduce malaria-related childhood mortality, to block transmission and eliminate malaria from large parts of the world, and eventually to eradicate the parasite, new tools are desperately needed both now and in the longer term.

Our research proposal is directed towards a better understanding of the molecular mechanisms involved in parasite multiplication and more specifically parasite cell division at two stages of its life cycle. One is the asexual multiplication (schizogony) that takes place within the red blood cell and results in the pathology of the disease, and the other is male gamete formation that commences within the host in the development of gametocytes, which further develop, divide and differentiate within the mosquito gut after being ingested by a mosquito. This stage of the parasite's life cycle is important in terms of transmission blocking interventions.

It is clear that important targets of intervention to stop parasite multiplication and the causation of disease are likely to be expressed within the red blood cell stage and targets of intervention to block transmission are likely to be expressed during development and differentiation within mosquito gut. Understanding the molecular mechanisms controlling multiplication in these stages is crucial to help develop intervention and control strategies. Our research will give us a better understanding of the molecules that are involved in these two processes of cell division and hence the identification of probable targets for intervention.

Our multifaceted approach will employ technologies that are at the cutting edge of research in the areas of parasite genetics, cell biology, protein chemistry and proteomics. This study will further strengthen the research potential of the malaria community. Most of the resources generated during the course of the project will be deposited in research data bases like PlasmoDB or the RGM data base. The research in malaria parasites may also impact on our understanding of the cell division in other parasites such as Trypanosoma, Giardia and others.

The research output from the proposed project could be used to identify strategic targets and these could be used by Nottingham Innovation scientists and companies involved in designing, making and testing antimalarial agents. Hence the project could identify new strategies towards drug development.
In addition another important impact will be the training of the named researchers in the project, allowing them to advance their own research careers and development. They will gain knowledge in a cutting edge area of research in the subject of malaria, a disease that is of great health and socio-economic importance.

Publications

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Bunnik EM (2019) Comparative 3D genome organization in apicomplexan parasites. in Proceedings of the National Academy of Sciences of the United States of America

 
Title Rodent Malaria Data base 
Description This is reasearch data base where all the malaria transgenic parasite information is provided 
Type Of Material Database/Collection of data 
Year Produced 2010 
Provided To Others? Yes  
Impact Many of the mutant are distributed to various researcher across europe and USA 
URL http://www.pberghei.eu/.
 
Title Rodent malaria data base 
Description All the information for phosphatase mutants for malaria model is deposited. It is a rodent malaria transgenic data base 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact The parasites are provided to different group in France and USA 
URL http://www.pberghei.eu/.
 
Description Anaphase promoting complex 
Organisation University College London
Department UCL Cancer Institute
Country United Kingdom 
Sector Academic/University 
PI Contribution This collaboration is with Prof Hiro Yamano to understand the anaphase promoting complex
Collaborator Contribution Prf Hiro Yamano has contributed immensly for undersyanding of cell division in yeat and mammalian system and provided us with various resources.
Impact We have published one paper together in Plos Pathogenes in 2015
Start Year 2014
 
Description Collaboration on Protein Phosphatases and especially PRL and PTPLA 
Organisation International Centre for Genetic Engineering and Biotechnology
Country Italy 
Sector Charity/Non Profit 
PI Contribution We have provided a training to the student from ICGEB India to learn the reverse genetics in P berghei and understand the parasite stages with mosquito host
Collaborator Contribution The partners are working on PRL in P falciparum.
Impact I am colaborating with computational biologist and the proteomics biologist in this collaboration.
Start Year 2015
 
Description Kinesin in Plasmodium 
Organisation Birkbeck, University of London
Country United Kingdom 
Sector Academic/University 
PI Contribution I am collaborating with Prof Carolyn Moores who is an expert on Kinesin in mammalian system and is a reputed Structural Biologist
Collaborator Contribution She will provide us the biochemistry of of the Kinesin 5 and Kininesin 13
Impact We will be writing the paper at the end of the year.
Start Year 2014
 
Description PKG 
Organisation London School of Hygiene and Tropical Medicine (LSHTM)
Country United Kingdom 
Sector Academic/University 
PI Contribution We have collaborated to generate humanised transgenic parasite to be used as drug target for PKG.
Collaborator Contribution Dr Baker has provided us the human cDNA of PfPKG
Impact We have used this transgenic parasite for testing various compounds and for validation of in vivo assay.
Start Year 2010
 
Description Phosphorylation 
Organisation University of Leicester
Department Department of Cell Physiology and Pharmacology
Country United Kingdom 
Sector Academic/University 
PI Contribution significant intellectual input
Collaborator Contribution To provide technical help with Global Phosphorylationtraining of staff
Impact Two manuscript in preparation
Start Year 2010
 
Description Phosphorylation 
Organisation University of Leicester
Country United Kingdom 
Sector Academic/University 
PI Contribution significant intellectual input
Collaborator Contribution To provide technical help with Global Phosphorylationtraining of staff
Impact Two manuscript in preparation
Start Year 2010
 
Description This collaboration is typrosine phosphatases 
Organisation McGill University
Country Canada 
Sector Academic/University 
PI Contribution WE have published the phosphatome screen in 2014 and described that there are three PTP in Plasmodium and PRL is eesential in Plasmodium,
Collaborator Contribution Prof Michel Tremblay is an expert on Tyrosine phosphatases in mammalian system especialy in relation to cancer.
Impact This collaboration is resulted in collaborating on other collaborator who work in crystallography and chemical biology
Start Year 2015
 
Description A seminar at Mredical Erasmus University 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact This helped me to meet scientist who are working with Cohesin in mammalian system.
Year(s) Of Engagement Activity 2017
 
Description BBC media coverage 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact It had wide coverage both in UK and abroad about the malaria cell division
Year(s) Of Engagement Activity 2015
 
Description EMBO research conference on Europhosphatases 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This meeting had particpants from across the world who work on Phosphatases and their role in different diseases like Cancer, alzheimer and infectious diseases
Year(s) Of Engagement Activity 2015
 
Description Gordon Research Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact This is a forum to present unpublished research and have good interaction and collaborative research thinking and discussion

We had very good collaboration set up with scientists
Year(s) Of Engagement Activity 2014
 
Description Media Interest 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact It had good response in the online information about malaria research and the activity of our research in this area.

High interest in media and scientist across the world
Year(s) Of Engagement Activity 2014
URL http://www.nottingham.ac.uk/news/pressreleases/2014/july/the-yin-and-yang-of-malaria-parasite-develo...
 
Description Organised a Midland Cel Cycle Club 2017 for the East Midland 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact This meeting made good network of scientist working in the area of Cel Cycle and Cytoskeleton in various model system like human, drosophila, yeat parasites etc.
Year(s) Of Engagement Activity 2017
 
Description Organising the London Molecular Parasitology Club 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Study participants or study members
Results and Impact Three meeting of London Molecular Parasitology are organised every year. The speakers range from any where in Uk or Europe. It benefots the scientist working in London and adjoining areas.
Year(s) Of Engagement Activity 2007,2008,2009,2010,2011
 
Description School Visit to Loughbourough School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact 50-80 students attended the talk
Year(s) Of Engagement Activity 2015
 
Description Seminar at European Malaria Network at Geneva 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact It is a closed meeting of malaria research in europe and it was very productive for our research activities

Good collaborations set up
Year(s) Of Engagement Activity 2014