Participação das proteínas hint-like e calmodulina na sinalização de cálcio e proteólise no plasmodium falciparum

• Ano de defesa: 2017
• Autor(a) principal: Gomes, Mayrim Machado [UNIFESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Malaria; Hint-1; Calmodulin; Malária; Calmodulina; Sinalização de cálcio; Atividade proteolítica
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5579359; https://repositorio.unifesp.br/handle/11600/50652

Malaria is a life-threatening disease caused by protozoan parasites of the genus Plasmodium. Many Plasmodium cellular events are regulated by cytosolic calcium fluctuations. The available information regarding calcium signalling pathways in Plasmodium, although fragmented, suggests a pathway that is unique to the parasite. Identification and characterization of these calcium signalling elements in Plasmodium, that control important cellular processes of the parasite, are considered potential antimalarial targets. Therefore, the aim of the project was to study the calcium signalling pathway in Plasmodium parasites, focusing on proteins that may be involved in this pathway. In this work we verified that Calmodulin (PfCaM) plays an important role in calcium homeostasis of the parasite. The use of Calmidazolium, a Calmodulin inhibitor, increased the concentration of cytosolic calcium drastically, due to the opening of calcium channels of plasma membrane of the parasite, besides calcium mobilization of acidic compartments. It was also observed that the mitochondria uptakes part of this cytosolic calcium. Our results suggest that PfCaM may also act as a "reservoir" of cytosolic calcium. In this context, it is important to identify possible molecular partners of Calmodulin associated with calcium mobilization in Plasmodium. In our laboratory, we identified possible ligands of PfCaM in P.falciparum. Among the potential molecular partners of PfCaM identified was the Hint-1 protein. There is only one gene for Hint-1 (PfHint-1) annotated in P. falciparum genome, and its function is unknown. Our results showed that PfHint-1 is expressed at all intraerythrocytic stages and appears to be localized to the endoplasmic reticulum. Knockout of Hint-1 in P. berghei suggests that the Hint-1 gene is essential. Overexpression of PfHint-1 displayed lower parasite cytosolic calcium rise induced by the ER-Ca2+ pump inhibition, while PfCaM overexpressing parasites exhibit a higher cytosolic calcium rise after challenge with CZ. Overexpression of PfCaM and PfHint-1 are able to modulate intracellular calcium-sensitive proteolysis.