Developmental regulation of protein kinase A expression and activity in Schistosoma mansoni.
cAMP-dependent protein kinases (PKAs) are the main transducers of cAMP signalling in eukaryotic cells. Recently we reported the identification and characterisation of a PKA catalytic subunit (SmPKA-C) in Schistosoma mansoni that is required for adult schistosome viability in vitro. To gain further insights into the role of SmPKA-C in biological processes during the schistosome life cycle, we undertook a quantitative analysis of SmPKA-C mRNA expression in different life cycle stages. Our data shows that SmPKA-C mRNA expression is developmentally regulated, with the highest levels of expression in cercariae and adult female worms. To evaluate the biological role of SmPKA-C in these developmental stages, cercariae and adult worms were treated with various concentrations of PKA inhibitors. Treatment of cercariae with H-89 or PKI 14-22 amide resulted in loss of viability suggesting that, as in adults, PKA is an essential enzyme activity in this infectious larval stage. In adult worms, in vitro exposure to sub-lethal concentrations of H-89 or PKI 14-22 amide resulted in inhibition of egg production in a dose-dependent manner. Furthermore, using a murine model of schistosome infection where S. mansoni fecundity is impaired, we show that reduced rates of egg production in vivo correlate with significant reductions in SmPKA-C mRNA expression and PKA activity. Finally, restoration of parasite egg production in vivo also resulted in normalisation of SmPKA-C mRNA expression and PKA activity. Taken together, our data suggest that PKA signalling is required for cercarial viability and may play a specific role in the reproductive activity of adult worms.
Swierczewski
Brett E
BE
Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
Davies
Stephen J
SJ
D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology; D016019:Survival Analysis
D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide