Signaling transcript profile of the asexual intraerythrocytic development cycle of Plasmodium falciparum induced by melatonin and cAMP

Abstract

According to the World Health Organization (WHO), Plasmodium falciparum is the deadliest parasite among all species. This parasite possesses the ability to sense molecules, including melatonin (MEL) and cAMP, and modulate its cell cycle accordingly. MEL synchronizes the development of this malaria parasite by activating several cascades, including the generation of the second messenger cAMP. Therefore, we performed RNA sequencing (RNA-Seq) analysis in P. falciparum erythrocytic stages (ring, trophozoite and schizont) treated with MEL and cAMP. To investigate the expression profile of P. falciparum genes regulated by MEL and cAMP, we performed RNA-Seq analysis in three P. falciparum strains (control, 3D7; protein kinase 7 knockout, PfPK7-; and PfPK7 complement, PfPK7C). In the 3D7 strain, 38 genes were differentially expressed upon MEL treatment; however, none of the genes in the trophozoite (T) stage PfPK7- knockout parasites were differentially expressed upon MEL treatment for 5 hours compared to untreated controls, suggesting that PfPK7 may be involved in the signaling leading to differential gene expression. Moreover, we found that MEL modified the mRNA expression of genes encoding membrane proteins, zinc ion-binding proteins and nucleic acid-binding proteins, which might influence numerous functions in the parasite. The RNA-Seq data following treatment with cAMP show that this molecule modulates different genes throughout the intraerythrocytic cycle, namely, 75, 101 and 141 genes, respectively, in the ring (R), T and schizont (S) stages. Our results highlight P. falciparum's perception of the external milieu through the signaling molecules MEL and cAMP, which are able to drive to changes in gene expression in the parasite.

Cyclic nucleotide signalling in malaria parasites

“…Addition of melatonin led to a change in expression of 38 genes in trophozoites (101 with cAMP) which was dependent on the presence of an intact P. falciparum protein kinase 7 (PK7; PF3D7_0213400) gene; P. falciparum PK7 knockout line is unable to respond to melatonin. Gene ontology and KEGG pathway analysis indicated that components of the ubiquitin–proteasome system (UPS) pathway were regulated by both treatments in trophozoites [ 99 ].…”

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

“…Fennel et al 28 has previously reported that PfeIK1 phosphorylates the eukaryotic initiation factor 2 in its α subunit (eIF 2α) in response to aminoacid starvation. Lima et al 44 investigated the effect of melatonin in the gene expression of 3D7 and PfPK7by RNA-seq. The authors observed 38 genes modulated by melatonin in 3D7 parasites, including F I G U R E 5 Effect of indole compounds in melatonin action on Plasmodium falciparum parasitemia.…”

Role of Melatonin in the Synchronization of Asexual Forms in the Parasite Plasmodium falciparum

“…In addition, few synthetic indole derivatives can regulate the cell cycles of parasites [ 35 ], suggesting that not all indole derivatives confer cell cycle modulation. More recently, RNA-seq analysis of melatonin-treated P. falciparum parasites revealed 38 differentially expressed genes, among which several genes were related to post-translational modification (PTM), Zn-binding proteins and nucleic acid-binding proteins [ 36 ].…”

“…Additionally, the upregulation of 14 UPS genes, including E1, E2, E3, ubiquitin-like, deubiquitinase, and proteasome subunits, by melatonin has been shown in wild-type P. falciparum and abolished in PfPK7 − parasites [ 28 ]. Further evidence that PfPK7 is pivotal for melatonin signalling came from two studies that performed RNA-seq analysis and examined mitochondrial genes related to mitochondrial fission [ 36 , 47 ]. Lima et al, in the RNA-seq study, compared the effects of 5 h melatonin treatment on differentially expressed genes in wild-type P. falciparum 3D7 and in PfPK7 − parasites.…”

“…They found that 5 h melatonin treatment at the trophozoite stage resulted in 38 differentially expressed genes in wild-type parasites but not in PfPK7 − or untreated parasites. Additionally, 6 h cAMP treatment differentially modulated 75 genes in rings, 101 genes in trophozoites, and 141 genes in schizonts [ 36 ]. A study by Scarpelli et al, however, showed the relevance of PfPK7 to the alteration of mitochondrial fission genes PfFIS1, PfDYN1, and PfDYN2 upon melatonin treatment.…”