Einicker-Lamas Marcelo, Nascimento Michelle T C, Masuda Cláudio A, Oliveira Mecia M, Caruso-Neves Celso
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.
Exp Parasitol. 2007 Oct;117(2):171-7. doi: 10.1016/j.exppara.2007.04.011. Epub 2007 May 10.
Inositol is the precursor for most Trypanosoma cruzi surface molecules, including phosphoinositides, glycosylinositolphospholipids and glycosylphosphatidylinositol anchors. As the parasite is an inositol auxotroph, the inositol transport system might be a potential target for new trypanocide drugs, as some of its properties are different from its mammalian counterpart. Here, we investigated the modulation exerted by effectors of PKA and PKC on this transport system to comply with the parasite physiology. Pre-incubation of the cells with either dibutyryl-cyclic AMP (25 microM) or forskolin (30 microM) decreased the myo-inositol uptake by half, this effect being reversed by KT5720 (PKA inhibitor). Conversely, pre-incubation of the cells with PMA (2.8 microg/ml) or serum (5%) had a approximately 50% stimulation in myo-inositol uptake, being this effect reversed by staurosporine (0.5 microM) or sphingosine (10 microM). These results allow us to conclude that the myo-inositol transport system in T. cruzi epimastigotes is inhibited by PKA and stimulated by PKC effectors.
肌醇是大多数克氏锥虫表面分子的前体，包括磷酸肌醇、糖基肌醇磷脂和糖基磷脂酰肌醇锚定物。由于该寄生虫是肌醇营养缺陷型，肌醇转运系统可能是新型杀锥虫药物的潜在靶点，因为其某些特性与哺乳动物的对应物不同。在此，我们研究了蛋白激酶A（PKA）和蛋白激酶C（PKC）的效应物对该转运系统的调节作用，以符合寄生虫的生理学特性。用二丁酰环磷酸腺苷（25微摩尔）或福斯可林（30微摩尔）对细胞进行预孵育可使肌醇摄取量减半，这种效应可被KT5720（PKA抑制剂）逆转。相反，用佛波酯（2.8微克/毫升）或血清（5%）对细胞进行预孵育可使肌醇摄取量有大约50%的刺激作用，这种效应可被星形孢菌素（0.5微摩尔）或鞘氨醇（10微摩尔）逆转。这些结果使我们得出结论，克氏锥虫前鞭毛体中的肌醇转运系统受到PKA的抑制和PKC效应物的刺激。
