Polo-like kinases are important regulators of cell cycle progression and mitosis. They constitute a family of conserved serine/threonine kinases which are highly related in their catalytic domains and contain polo boxes involved in protein-protein interactions and subcellular localization. In mammals, five Plks (Plk 1-5) encompass diverse roles in centrosome dynamics, spindle formation, intra S-phase and G2/M checkpoints and DNA damage response. Plk1 is a key positive regulator of mitosis and is overexpressed in various types of cancers. Plk4 is a divergent member of the Plk family, with essential functions in centriole duplication. Homozygous disruption of Plk1 or Plk4 in mice is lethal in embryos. Two Plk members SmPlk1 and SmSak, homologous to Plk1 and Plk4 respectively, are present in the parasitic platyhelminth Schistosoma mansoni. Structural and functional analyses of SmPlk1 have demonstrated its conserved function in the regulation of cell cycle G2/M transition in Xenopus oocytes. The anti-cancer drug BI 2536 (the most potent and selective Plk1 inhibitor) inhibits specifically the catalytic activity of SmPlk1 and induced profound alterations in schistosome gonads, indicating a role of SmPlk1 in parasite gametogenesis and its potential as a novel chemotherapeutic target against schistosomiasis. Functions of SmSak in cell cycle regulation and schistosome gonad development are currently investigated.Key words: cell cycle, Polo-like kinases, reproduction, Schistosoma mansoni.
SCHISTOSOME BIOLOGY AND PROTEIN KINASESSchistosomiasis is a water-borne disease and one of the most important parasitic diseases worldwide, with more than 200 million people infected. Transmission of schistosomes is endemic in over 70 tropical and subtropical countries. Control of schistosomiasis relies in priority on mass treatment of human populations with Praziquantel (PZQ), a drug which has been proven for decades to be efficient to reduce morbidity and mortality due to schistosomiasis. However, its widespread use and its inefficacy on juvenile parasites raise fears that schistosomes will develop resistance to PZQ, and there is an urgent need to Correspondence to: Colette Dissous E-mail: colette.dissous@pasteur-lille.fr find alternative drugs and novel concepts to fight schistosomes (Doenhoff et al. 2008).Mating and sexual maturation of adult male and female worms of S. mansoni in the human host lead to the production of numerous eggs which are responsible for transmission, but also for the pathology of schistosomiasis. Eggs are eliminated in faeces, and they assure parasite transmission through the infection of fresh water molluscs as intermediate hosts. Aside, a large proportion of eggs become trapped into human tissues, and granulomas formed around these eggs have serious pathogenic consequences (Ross et al. 2002). In this context, any strategy that aims to reduce worm fecundity and schistosome reproduction represents a valuable concept to combat schistosomiasis.An Acad Bras Cienc (2011) 83 (2) 628 COLETTE DISSOUS, CHRISTO...