The Schistosoma mansoni Src kinase TK3 is expressed in the gonads and likely involved in cytoskeletal organization

Characterization of the Src/Abl Hybrid Kinase SmTK6 of Schistosoma mansoni

“…It has been hypothesized that SmVKR1 might be involved in the recognition of a male pheromone signal necessary for the development and maturation of the ovary because it possesses a Venus Flytrap module, also present in mammalian pheromone receptors (14,23,49). SmVKR1 transcripts were predominantly found in mature oocytes of female schistosomes by in situ hybridization, which coincided with the transcript localizations of SmTK4 (17), SmTK3 (15), and SmTK6 (13). In addition to the SmTK4-SmTK6 binding confirmed previously (13), we showed in this study by co-immunoprecipitation experiments that SmTK6 interacts with SmTK3 as well as with SmVKR1.…”

“…This finding and the results of the phylogenetic analyses suggested a hybrid character of this unusual kinase. Functional evidence in support of this hypothesis was obtained by GVBD assays in Xenopus oocytes expressing the catalytic TK domains of SmTK6 and other schistosome kinases representing members of the Src (SmTK3) or Abl (SmAbl1) kinase families (15,18). Using inhibitors specific for each of these CTK families demonstrated the hybrid character also at the biochemical level.…”

“…Interactions-Previous studies showed that SmTK3 and SmVKR1 are expressed in the gonads of schistosomes co-localizing in the ovary (15,23). Because SmTK4 and SmTK6 are also transcribed in the ovary of females, and because by Y2H library screening SmTK6 was found as a binding partner, whose interaction with SmTK4 was confirmed by co-immunoprecipitation experiments (13), a kinase complex acting in the gonads was first hypothesized (13,14).…”

“…Among these are the Src kinase SmTK3 and the Syk kinase SmTK4 (13,14). SmTK3 contains all Src-typical features, and expression products were localized in vitelline cells, oocytes, and spermatocytes suggesting a role in reproductive activity (15). Studies with the Src kinase-specific inhibitor herbimycin A provided strong evidence for a role of SmTK3 in the control of mitotic activity and egg production of adult schistosomes in vitro (16).…”

Protein tyrosine kinases in Schistosoma mansoni

“…It is now clear that the ability of S. mansoni to survive for decades in the blood-stream of its host and the sexual maturation of the female that depends on a close contact with the male are processes that require molecular communication (Schussler et al 1997, Kunz 2001, Kapp et al 2004.…”