Genome-Wide Expression Patterns of Rhoptry Kinases during the Eimeria tenella Life-Cycle

Abstract

Kinome from apicomplexan parasites is composed of eukaryotic protein kinases and Apicomplexa specific kinases, such as rhoptry kinases (ROPK). Ropk is a gene family that is known to play important roles in host–pathogen interaction in Toxoplasma gondii but is still poorly described in Eimeria tenella, the parasite responsible for avian coccidiosis worldwide. In the E. tenella genome, 28 ropk genes are predicted and could be classified as active (n = 7), inactive (incomplete catalytic triad, n = 12), and non-canonical kinases (active kinase with a modified catalytic triad, n = 9). We characterized the ropk gene expression patterns by real-time quantitative RT-PCR, normalized by parasite housekeeping genes, during the E. tenella life-cycle. Analyzed stages were: non-sporulated oocysts, sporulated oocysts, extracellular and intracellular sporozoites, immature and mature schizonts I, first- and second-generation merozoites, and gametes. Transcription of all those predicted ropk was confirmed. The mean intensity of transcription was higher in extracellular stages and 7–9 ropk were specifically transcribed in merozoites in comparison with sporozoites. Transcriptional profiles of intracellular stages were closely related to each other, suggesting a probable common role of ROPKs in hijacking signaling pathways and immune responses in infected cells. These results provide a solid basis for future functional analysis of ROPK from E. tenella.

Overexpression of Eimeria tenella Rhoptry Kinase 2 Induces Early Production of Schizonts

“…Although rhoptry kinases are restricted to apicomplexans, phylogenetic analysis showed that most of the 28 rhoptry kinases from E. tenella ( 18 , 19 ) constitute a specific clade, organized into seven subfamilies ( 20 ), based on sequence homology and tandem repeat loci. Recently, we confirmed the dynamic transcription of 27 of these ropk genes during the parasite life cycle ( 21 , 22 ). No correlation could be found between subfamilies and stage transcription ( 21 ).…”

“…Recently, we confirmed the dynamic transcription of 27 of these ropk genes during the parasite life cycle ( 21 , 22 ). No correlation could be found between subfamilies and stage transcription ( 21 ). Three distinct transcription profiles were described: (i) with a constant and low expression across the parasite life cycle, (ii) with higher expression in the extracellular stages, and (iii) with higher expression in the intracellular stages.…”

“…EtROP2 is predicted to possess a putative serine/threonine kinase domain at residues 323 to 665, with the conservation of 11 subdomains and most key residues that are essential for the canonical kinase activity ( 27 ). Despite the lack of conserved alanine and glutamic acid residues in subdomain VIII, these bioinformatic predictions suggested that EtROP2 was an active kinase ( 21 ). The analysis indicated an N-terminal extension (NTE), also found in other ROPKs ( 20 ), containing a signal peptide (SP) with a cleavage site between residues 16 and 17.…”

Botanicals: A promising approach for controlling cecal coccidiosis in poultry

“…Cells containing mature schizonts of Eimeria then rupture and release the merozoites ( 128 , 129 ). These merozoites of Eimeria undergo multiple cycles of schizogony, and then, due to unknown reasons, they mature into male and female gametes (micro- and macrogametes) ( 130 , 131 ). These gametes fuse to form zygotes that develop into unsporulated oocysts, which are then shed in the bird's feces ( 132 , 133 ).…”

Released Parasite-Derived Kinases as Novel Targets for Antiparasitic Therapies

“…TgROP16 is localized to the host cell nucleus after invasion ( Ong et al., 2010 ), phosphorylates signal transducer and activator of transcription STAT6 and STAT3 ( Yamamoto et al., 2009 ; Butcher et al., 2011 ) to bypass the protective immune-response of the host cell. In E. tenella , among 28 ROPKs differentially expressed during the life-cycle ( Ribeiro E Silva et al., 2021 ), only EtROP1 has been functionally characterised ( Diallo et al., 2019 ). It interacts with host p53, to inhibit host cell apoptosis and induce G0/G1 cell cycle arrest.…”