A Novel Receptor Binding Progesterone, a Possible Transregulation Mechanism in the -Host Interaction.

Background: Hormone receptors exert their function through binding with their ligands, which results in cellular signaling activation mediated by genomic or non-genomic mechanisms. The intrinsic molecular communication of tick and its host comprises an endocrine regulation involving hormones. In the present study, we performed a molecular and analysis of a Membrane Associated Progesterone Receptor in (RmMAPRC).

Methods: The RmMAPRC protein sequence was analyzed with bioinformatics tools, and its structure was characterized by three-dimensional (3D) modeling and molecular docking. A semi-quantitative reverse transcription and polymerase chain reaction (sqRT-PCR) assessed the gene presence and relative expression in tick organs and embryonic cells.

Results: relative expression in salivary glands, ovaries, and embryonic cells showed overexpression of 3%, 13%, and 24%, respectively. Bioinformatic analysis revealed that RmMAPRC corresponded to a Progesterone Receptor Membrane Component 1 (RmPGRMC1) of ~23.7 kDa, with an N-terminal transmembrane domain and a C-terminal Cytochrome b5-like heme/steroid binding domain. The docking results suggest that RmPGRMC1 could bind to progesterone (P4), some progestins, and P4 antagonists. The phylogenetic reconstruction showed that spp. MAPRC receptors were clustered in a clade that includes , , and (RmMAPRC), and mammals and helminths MAPRC receptors clustered in two separated clades away from ticks.

Conclusions: The presence of RmPGRMC1 highlights the importance of transregulation as a conserved adaptive mechanism that has succeeded for arthropod parasites, making it a target for tick control.