Ubiquitin Proteasome System as a Potential Drug Target for Malaria

Parasites of Plasmodium genus are responsible for causing malaria in humans. Resistant strains to all available antimalarials can be found in several locations around the globe, including parasites resistant to the latest generation of combination drugs, such as piperaquine + artemisinin. Plasmodium develops between two completely different hosts such as a vertebrate one and the mosquito vector, thus it has the ability to adapt to very extreme and different environments. Through the complex life cycle in the hosts, Plasmodium invades and replicates in totally different cells thus making the study of the biology of the parasite and the identification of targets for drug development affecting all stages very difficult. It was shown that host molecules, such as melatonin and derivatives, have a role in the progression and regulation of the parasite cell cycle; In fact, when the parasite is exposed to melatonin there is an increase in transcription levels of genes encoding for proteins related to the Ubiquitin Proteasome (UPS) System. This system is essential for the survival of the parasite, and drugs such as bortezomib, MLN-273, ZL3B, epoxomicins and salinosporamides are capable of eliminating the parasite by inhibiting the degradation of proteins via the proteasome system. In addition, the Plasmodium UPS shows low similarity to the ubiquitin proteasome system in Humans; the identification of unique targets to be used for therapeutic molecules development increases the importance of UPS studies in malaria challenging. Drugs that cause oxidative stress, such as artemisinin, show a strong synergistic effect with proteasome inhibitors, increasing the possibilities of combined therapies, which are more effective with lower concentration of drugs. Thus, the study of the mechanism of action of the UPS and the identification of potential targets for new drugs development are promising alternative strategies to fight the drug-resistance problem in malaria parasites.