The importance of p38 mitogen-activated protein kinase (p38 MAPK) to Schistosoma mansoni miracidium to mother-sporocyst development was investigated. Western blotting revealed that phosphorylation (activation) of p38 MAPK was low in larvae after 4h development in vitro but increased markedly during transformation, with ∼2.7- and ∼3.7-fold increases after 19h and 28h culture, respectively. Immunohistochemistry of larvae undergoing transformation revealed activated p38 MAPK associated with regions including the tegument, neural mass and germinal cells. Inhibition of larval p38 MAPK with SB203580 reduced significantly the rate of development of miracidia to mother sporocysts, whereas activation of p38 MAPK with anisomycin had the opposite effect. These results provide insight into p38 MAPK signalling in schistosomes and support a role for p38 MAPK in the early post-embryonic development of S. mansoni.
"Despite such challenges, we do have some insight into the changes in gene expression that occur during schistosome development [38,39] and of potential regulators of reproductive development (above). In addition, knowledge gleaned from studies into the regulation of development of early post-embryonic snail-host life-stages [40,41] could inform similar research on definitive-host stages and vice-versa. As with other organisms, molecular regulation of schistosome development will be complex, but studies this area are important to develop a complete understanding of schistosome developmental biology, crucial for drug development work, and to inform research in comparative developmental biology including that on other trematode parasites such as Fasciola spp. "
[Show abstract][Hide abstract] ABSTRACT: The need to discover new treatments for human schistosomiasis has been an important driver for molecular research on schistosomes, a major breakthrough being the publication of the Schistosoma mansoni and Schistosoma japonicum genomes in 2009. This 'Primer' considers recent advances in the understanding of schistosome biology by providing a snapshot of selected areas of contemporary functional schistosome research, including that on the genome, the tegument, cell signalling and developmental biology, offering biologists a valuable insight into the life of these fascinating parasites at the basic and molecular level.
[Show abstract][Hide abstract] ABSTRACT: Schistosome parasites are the causative pathogens of schistosomiasis (bilharzia), a disease of worldwide significance. In terms of patient numbers, schistosomiasis ranks second to malaria as a parasitosis affecting more than 200 million people of the tropics and subtropics. Since the 1970s Praziquantel (PZQ) is the drug of choice and nearly exclusively used for treatment. However, drug resistance is an increasing threat, particularly with respect to large-scale PZQ administration programs. Last decade's research indicated that resistance against PZQ can be induced under laboratory conditions, and field studies provided first indications for the possibility of reduced PZQ efficacy. Furthermore, clear evidence for the molecular armamentarium of schistosomes with multidrug transporters was found, one of which was responding to PZQ challenge. Also the development of a vaccine still represents an elusive goal, although effort and time have been invested in this subject. In light of these facts it is commonly accepted that new drugs are urgently needed. Research on signal transduction processes in Schistosoma mansoni has provided an unexpected and novel perspective towards this end. Molecular, biochemical, and physiological studies elucidating principles of schistosome development have demonstrated the essential role of protein kinases (PKs). In humans, PKs are known to be involved in cancer development. Since a variety of approved anticancer drugs targeting PKs exist, first studies have been performed to investigate whether these drugs are able to also inhibit schistosome PKs. Indeed, promising results have been obtained indicating the potential of PKs as privileged targets for new concepts in fighting schistosomes.
Current pharmaceutical design 05/2012; 18(24):3579-94. · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cyclic AMP (cAMP)-dependent protein kinase/protein kinase A (PKA) is the major transducer of cAMP signalling in eukaryotic cells. Here, using laser scanning confocal microscopy and 'smart' anti-phospho PKA antibodies that exclusively detect activated PKA, we provide a detailed in situ analysis of PKA signalling in intact adult Schistosoma mansoni, a causative agent of debilitating human intestinal schistosomiasis. In both adult male and female worms, activated PKA was consistently found associated with the tegument, oral and ventral suckers, oesophagus and somatic musculature. In addition, the seminal vesicle and gynaecophoric canal muscles of the male displayed activated PKA whereas in female worms activated PKA localized to the ootype wall, the ovary, and the uterus particularly around eggs during expulsion. Exposure of live worms to the PKA activator forskolin (50 µM) resulted in striking PKA activation in the central and peripheral nervous system including at nerve endings at/near the tegument surface. Such neuronal PKA activation was also observed without forskolin treatment, but only in a single batch of worms. In addition, PKA activation within the central and peripheral nervous systems visibly increased within 15 min of worm-pair separation when compared to that observed in closely coupled worm pairs. Finally, exposure of adult worms to forskolin induced hyperkinesias in a time and dose dependent manner with 100 µM forskolin significantly increasing the frequency of gross worm movements to 5.3 times that of control worms (P≤0.001). Collectively these data are consistent with PKA playing a central part in motor activity and neuronal communication, and possibly interplay between these two systems in S. mansoni. This study, the first to localize a protein kinase when exclusively in an activated state in adult S. mansoni, provides valuable insight into the intricacies of functional protein kinase signalling in the context of whole schistosome physiology.
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