Structural model, functional modulation by ivermectin and tissue localization of Haemonchus contortus P-glycoprotein-13

Abstract

Haemonchus contortus, one of the most economically important parasites of small ruminants, has become resistant to the anthelmintic ivermectin. Deciphering the role of P-glycoproteins in ivermectin resistance is desirable for understanding and overcoming this resistance. In the model nematode, Caenorhabditis elegans, P-glycoprotein-13 is expressed in the amphids, important neuronal structures for ivermectin activity. We have focused on its ortholog in the parasite, Hco-Pgp-13. A 3D model of Hco-Pgp-13, presenting an open inward-facing conformation, has been constructed by homology with the Cel-Pgp-1 crystal structure. In silico docking calculations predicted high affinity binding of ivermectin and actinomycin D to the inner chamber of the protein. Following in vitro expression, we showed that ivermectin and actinomycin D modulated Hco-Pgp-13 ATPase activity with high affinity. Finally, we found in vivo Hco-Pgp-13 localization in epithelial, pharyngeal and neuronal tissues. Taken together, these data suggest a role for Hco-Pgp-13 in ivermectin transport, which could contribute to anthelmintic resistance.

Sub-lethal doses of albendazole induce drug metabolizing enzymes and increase albendazole deactivation in Haemonchus contortus adults

“…In our study, exposure to ABZ and ABZSO affected transcription levels of six (out of eight tested) transporter genes in H. contortus adults. However, IVMinduced changes in P-gps expression were more pronounced; particularly the expression of pgp-9.2 in the males and pgp-10, pgp-11 in the females was increased substantially [30], a result which is in agreement with the clear relationship of P-gps with IVM metabolism and resistance in nematodes [39,40]. Nevertheless, increased transcription of several P-gps after ABZ and ABZSO exposure suggests a particular role of these transporters in the metabolism of these drugs as well.…”

Assessment of P-glycoprotein gene expression in adult stage of Haemonchus contortus in vivo exposed to ivermectin

“…The best match between each P-gp and the transcript sequences of H.contortus is displayed in Table 1. This analysis showed that the sequence HM635772 reported by Williamson and Wolstenholme (2012) as P-gp1 and used in this work for the quantification of Hco-pgp-1 by qPCR, matches the exons 26-27 from gene HCOI00233200, corresponding to P-gp17 (David et al, 2018;Laing et al, 2013). Unfortunately, the sequence HM635770 used for the design of the Hco-pgp-11 primers includes exons 5 to 7 of the same gene.…”

“…reported by Williamson and Wolstenholme (2012) as P-gp12 and P-gp14, respectively, both match the complete P-gp13 mRNA sequence KX844966 published in GenBank (David et al, 2018) and corresponding to gene HCOI01115500 on the H. contortus reference genome (Laing et al, 2013).…”

“…Williamson and Wolstenholme (2012) were able to quantify P-gp13 expression (reported in the manuscript as P-gp12 and P-gp14) by qPCR in the L3 stage of H. contortus. Recently, David et al (David et al, 2018) reported the P-gp13 protein localization in several organs of the digestive, neuronal, excretory and epithelial systems in larvae and adult H. contortus cryosections by immunohistochemistry. By contrast, we were not able to quantify P-gp13 expression neither by qPCR nor RNA-seq analysis in female specimens of the H. contortus isolate here studied.…”

ABCB1 (P‐glycoprotein) regulates vitamin D absorption and contributes to its transintestinal efflux

“…With the use of the in silico docking approach, we provide computational evidence that the 2 forms of vitamin D can bind efficiently a close ortholog of human ABCB1. ABCB protein structures and functions are well conserved within all living kingdoms, including nematodes and mammals (31), and the nematode ABCB1 (i.e., Cel-Pgp-1) has been previously described to share similar structural features with the mammalian ABCB1 in ligand binding (22,32). Therefore, we confidently used the Cel-Pgp-1 3-dimensional structure as a relevant model for human ABCB1 in an open-inward configuration, which is supposed to be the first conformational state recognized by a substrate (21).…”