Haemonchus contortus glutamate-gated chloride channel alpha subunit (HcGluClα)

Haemonchus contortus glutamate-gated chloride channel alpha subunit (HcGluClα) is a critical component of the inhibitory neurotransmission system in the parasitic nematode Haemonchus contortus, commonly known as the barber's pole worm (Wolstenholme, 2012). As a member of the Cys-loop ligand-gated ion channel superfamily, HcGluClα forms pentameric chloride-selective channels that are activated by the neurotransmitter L-glutamate (McCavera et al., 2007). These channels are found exclusively in invertebrates, providing a high degree of selective toxicity for anthelmintic agents compared to vertebrate hosts. HcGluClα is the primary molecular target for macrocyclic lactones, including ivermectin and moxidectin, which bind to an allosteric site within the transmembrane domain to keep the channel in a constitutively open state (Forrester et al., 2003). This persistent activation leads to the hyperpolarization of nerve and muscle cells, resulting in flaccid paralysis and the eventual death or expulsion of the parasite from the host. Due to its central role in parasite control, mutations and expression changes in HcGluClα are frequently investigated as primary drivers of anthelmintic resistance in global livestock populations (Beech et al., 2011).

Other names

Hc-glc-3Hc-glc-5Hc-avr-14Glutamate-gated chloride channel subunit alphaH. contortus GluCl alpha

Macrocyclic lactones act as positive allosteric modulators and agonists of HcGluClα, binding to the transmembrane domain to stabilize the open state of the chloride channel, leading to persistent chloride influx, hyperpolarization, and flaccid paralysis of the parasite (Wolstenholme, 2012; McCavera et al., 2007).