A MORC protein complex modulates epigenetic control of gene expression through interaction with heterochromatin.

Dynamic control of gene expression is critical for blood stage development of malaria parasites. Here, we used multi-omic analyses to investigate transcriptional regulation by the chromatin-associated microrchidia protein, MORC, during asexual blood stage development of the human malaria parasite . We show that MORC (PF3D7_1468100) interacts with a suite of nuclear proteins, including APETALA2 (ApiAP2) transcription factors (AP2-G5, AP2-O5, AP2-I, PF3D7_0420300, PF3D7_0613800, PF3D7_1107800, and PF3D7_1239200), a DNA helicase DS60 (PF3D7_1227100), and other chromatin remodelers (CHD1 and EELM2).

The genetically encoded calcium indicator GCaMP3 reveals spontaneous calcium oscillations at asexual stages of the human malaria parasite Plasmodium falciparum.

Most protocols used to study the dynamics of calcium (Ca) in the malaria parasite are based on dyes, which are invasive and do not allow discrimination between the signal from the host cell and the parasite. To avoid this pitfall, we have generated a parasite line expressing the genetically encoded calcium sensor GCaMP3. The PfGCaMP3 parasite line is an innovative tool for studying spontaneous intracellular Ca oscillations without external markers.

Melatonin as a Circadian Marker for Rhythms.

, a digenetic parasite, requires a host and a vector for its life cycle completion. Most species display circadian rhythmicity during their intraerythrocytic cycle within the host, aiding in immune evasion. This rhythmicity, however, diminishes in in vitro cultures, highlighting the importance of host-derived signals for synchronizing the parasite's asexual cycle.

Changes in K Concentration as a Signaling Mechanism in the Apicomplexa Parasites and .

During their life cycle, apicomplexan parasites pass through different microenvironments and encounter a range of ion concentrations. The discovery that the GPCR-like SR25 in is activated by a shift in potassium concentration indicates that the parasite can take advantage of its development by sensing different ionic concentrations in the external milieu. This pathway involves the activation of phospholipase C and an increase in cytosolic calcium.

Combining IP affinity chromatography and bioinformatics reveals a novel protein-IP binding site on MDR1 transporter.

Intracellular Ca mobilization induced by second messenger IP controls many cellular events in most of the eukaryotic groups. Despite the increasing evidence of IP-induced Ca in apicomplexan parasites like , responsible for malaria infection, no protein with potential function as an IP-receptor has been identified. The use of bioinformatic analyses based on previously known sequences of IP-receptor failed to identify potential IP-receptor candidates in any .

Decoding the Role of Melatonin Structure on Human Malaria Parasites Synchronization Using 2-Sulfenylindoles Derivatives.

Melatonin acts to synchronize the parasite's intraerythrocytic cycle by triggering the phospholipase -inositol 1,4,5-trisphosphate (PLC-IP) signaling cascade. Compounds with an indole scaffold impair in vitro proliferation of blood-stage malaria parasites, indicating that this class of compounds is potentially emerging antiplasmodial drugs. Therefore, we aimed to study the role of the alkyl and aryl thiol moieties of 14 synthetic indole compounds against chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) strains of .

Contribution of Transcriptome to Elucidate the Biology of Plasmodium spp.

The present review discusses some of the new technologies that have been applied to elucidate how Plasmodium spp escape from the immune system and subvert the host physiology to orchestrate the regulation of its biological pathways. Our manuscript describes how techniques such as microarray approaches, RNA-Seq, and single-cell RNA sequencing have contributed to the discovery of transcripts and changed the concept of gene expression regulation in closely related malaria parasite species. Moreover, the text highlights the contributions of high-throughput RNA sequencing for the current knowledge of malaria parasite biology, physiology, vaccine target, and the revelation of new players in parasite signaling.

Malaria parasites and circadian rhythm: New insights into an old puzzle.

•Discuss molecular components for the coordination of circadian rhythm of malaria parasites inside the vertebrate host.•Synthetic indole compounds show antimalarial activity against 3D7.• synchronizes in cell culture upon melatonin treatment.

Evidence of G-Protein-Coupled Receptors (GPCR) in the Parasitic Protozoa -Sensing the Host Environment and Coupling within Its Molecular Signaling Toolkit.

Throughout evolution, the need for single-celled organisms to associate and form a single cluster of cells has had several evolutionary advantages. In complex, multicellular organisms, each tissue or organ has a specialty and function that make life together possible, and the organism as a whole needs to act in balance and adapt to changes in the environment. Sensory organs are essential for connecting external stimuli into a biological response, through the senses: sight, smell, taste, hearing, and touch.

Identifying Plasmodium falciparum receptor activation using bioluminescence resonance energy transfer (BRET)-based biosensors in HEK293 cells.

Throughout evolution the need for unicellular organisms to associate and form a single cluster of cells had several evolutionary advantages. G protein coupled receptors (GPCRs) are responsible for a large part of the senses that allow this clustering to succeed, playing a fundamental role in the perception of cell's external environment, enabling the interaction and coordinated development between each cell of a multicellular organism. GPCRs are not exclusive to complex multicellular organisms.

The Knockout for G Protein-Coupled Receptor-Like PfSR25 Increases the Susceptibility of Malaria Parasites to the Antimalarials Lumefantrine and Piperaquine but Not to Medicine for Malaria Venture Compounds.

Previously we have reported that the G protein-coupled receptor (GPCR)-like PfSR25 in is a potassium (K) sensor linked to intracellular calcium signaling and that knockout parasites (PfSR25-) are more susceptible to oxidative stress and antimalarial compounds. Here, we explore the potential role of PfSR25 in susceptibility to the antimalarial compounds atovaquone, chloroquine, dihydroartemisinin, lumefantrine, mefloquine, piperaquine, primaquine, and pyrimethamine and the Medicine for Malaria Venture (MMV) compounds previously described to act on egress/invasion (MMV006429, MMV396715, MMV019127, MMV665874, MMV665878, MMV665785, and MMV66583) through comparative assays with PfSR25- and 3D7 parasite strains, using flow cytometry assays. The IC and IC results show that lumefantrine and piperaquine have greater activity on the PfSR25- parasite strain when compared to 3D7.

A nuclear protein, PfMORC confers melatonin dependent synchrony of the human malaria parasite P. falciparum in the asexual stage.

The host hormone melatonin is known to modulate the asexual cell-cycle of the human malaria parasite Plasmodium falciparum and the kinase PfPK7 is fundamental in the downstream signaling pathways. The nuclear protein PfMORC displays a histidine kinase domain and is involved in parasite cell cycle control. By using a real-time assay, we show a 24 h (h) rhythmic expression of PfMORC at the parasite asexual cycle and the expression is dramatically changed when parasites were treated with 100 nM melatonin for 17 h.

Intracellular Ca Signaling in Protozoan Parasites: An Overview with a Focus on Mitochondria.

Ca signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca storage inside the cell, but mitochondria have long been recognized as a fundamental Ca pool. Protozoan parasites such as , , and display a Ca signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca-dependent signaling events.

Melatonin action in Plasmodium infection: Searching for molecules that modulate the asexual cycle as a strategy to impair the parasite cycle.

Half of the world's population lives in countries at risk of malaria infection, which results in approximately 450,000 deaths annually. Malaria parasites infect erythrocytes in a coordinated manner, with cycle durations in multiples of 24 hours, which reflects a behavior consistent with the host's circadian cycle. Interference in cycle coordination can help the immune system to naturally fight infection.

Role of Melatonin in the Synchronization of Asexual Forms in the Parasite .

The indoleamine compound melatonin has been extensively studied in the regulation of the circadian rhythm in nearly all vertebrates. The effects of melatonin have also been studied in Protozoan parasites, especially in the synchronization of the human malaria parasite via a complex downstream signalling pathway. Melatonin activates protein kinase A (PfPKA) and requires the activation of protein kinase 7 (PfPK7), PLC-IP, and a subset of genes from the ubiquitin-proteasome system.

Evidences of G Coupled-Protein Receptor (GPCR) Signaling in the human Malaria Parasite for Sensing its Microenvironment and the Role of Purinergic Signaling in Malaria Parasites.

The nucleotides were discovered in the early 19th century and a few years later, the role of such molecules in energy metabolism and cell survival was postulated. In 1972, a pioneer work by Burnstock and colleagues suggested that ATP could also work as a neurotransmitter, which was known as the "purinergic hypothesis". The idea of ATP working as a signaling molecule faced initial resistance until the discovery of the receptors for ATP and other nucleotides, called purinergic receptors.

The genetic Ca sensor GCaMP3 reveals multiple Ca stores differentially coupled to Ca entry in the human malaria parasite .

Cytosolic Ca regulates multiple steps in the host-cell invasion, growth, proliferation, and egress of blood-stage , yet our understanding of Ca signaling in this endemic malaria parasite is incomplete. By using a newly generated transgenic line of (PfGCaMP3) that expresses constitutively the genetically encoded Ca indicator GCaMP3, we have investigated the dynamics of Ca release and influx elicited by inhibitors of the sarcoplasmic/endoplasmic reticulum Ca-ATPase pumps, cyclopiazonic acid (CPA), and thapsigargin (Thg). Here we show that in isolated trophozoite phase parasites: (i) both CPA and Thg release Ca from intracellular stores in parasites; (ii) Thg is able to induce Ca release from an intracellular compartment insensitive to CPA; (iii) only Thg is able to activate Ca influx from extracellular media, through a mechanism resembling store-operated Ca entry, typical of mammalian cells; and (iv) the Thg-sensitive Ca pool is unaffected by collapsing the mitochondria membrane potential with the uncoupler carbonyl cyanide -chlorophenyl hydrazone or the release of acidic Ca stores with nigericin.

Knockout for the GPCR-Like PfSR25 Receptor Displays Greater Susceptibility to 1,2,3-Triazole Compounds That Block Malaria Parasite Development.

The search for new compounds with antimalarial activity is urgent, as resistance to ones in the classical drug, has already been described in more than one continent. Compounds derived from 1,2,3-triazoles are effective against parasites and bacteria. Here, we evaluated the potential antimalarial activity against the human malaria parasite in a culture of fifty-four triazole compounds derived from 1-and 2-1,2,3-triazole.

The Plasmodium falciparum eIK1 kinase (PfeIK1) is central for melatonin synchronization in the human malaria parasite. Melatotosil blocks melatonin action on parasite cell cycle.

Melatonin and its indoles derivatives are central in the synchronization of malaria parasites. In this research, we discovered that melatonin is unable to increase the parasitemia in the human malaria Plasmodium falciparum that lacks the kinase PfeIK1. The PfeIK1 knockout strain is a valuable tool in the screening of indol-related compound that blocks the melatonin effect in wild-type (WT) parasite development.

Porphyrin Derivative Nanoformulations for Therapy and Antiparasitic Agents.

Porphyrins and analogous macrocycles exhibit interesting photochemical, catalytic, and luminescence properties demonstrating high potential in the treatment of several diseases. Among them can be highlighted the possibility of application in photodynamic therapy and antimicrobial/antiparasitic PDT, for example, of malaria parasite. However, the low efficiency generally associated with their low solubility in water and bioavailability have precluded biomedical applications.

Employing Transgenic Parasite Strains to Study the Ca Dynamics in the Human Malaria Parasite Plasmodium falciparum.

Studying Ca dynamics in protozoan parasites is not an easy task. Loading of parasites with commonly used Ca fluorescent dyes (such as Fuo4-AM) remains as the major protocol to measure the Ca oscillations inside the cell. In this chapter, we describe an alternative method to study Ca signaling in Plasmodium falciparum parasite.

Identification of Plasmodium berghei Oocyst Rupture Protein 2 (ORP2) domains involved in sporozoite egress from the oocyst.

Sporozoites are the infective form of malaria parasites which are transmitted from the mosquito salivary glands to a new host in a mosquito blood meal. The sporozoites develop inside the sporogonic oocyst and it is crucial for the continuation of the life cycle that the oocyst ruptures to release sporozoites. We recently described two Plasmodium Oocyst Rupture Proteins (ORP1 and ORP2), localized at the oocyst capsule, that are each essential for rupture of the oocysts.

Evidence for Regulation of Hemoglobin Metabolism and Intracellular Ionic Flux by the Plasmodium falciparum Chloroquine Resistance Transporter.

Plasmodium falciparum multidrug resistance constitutes a major obstacle to the global malaria elimination campaign. Specific mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) mediate resistance to the 4-aminoquinoline drug chloroquine and impact parasite susceptibility to several partner agents used in current artemisinin-based combination therapies, including amodiaquine. By examining gene-edited parasites, we report that the ability of the wide-spread Dd2 PfCRT isoform to mediate chloroquine and amodiaquine resistance is substantially reduced by the addition of the PfCRT L272F mutation, which arose under blasticidin selection.