Effect of cAMP on macromolecule synthesis in the pathogenic protozoa Trypanosoma cruzi

Abstract

Macromolecule synthesis of Trypanosoma cruzi in culture was monitored using radioactive tracers. Cells of different days in culture displayed a preferential incorporation of precursors as follows: 1 day for (³H)-thymidine cells; 3 days for (³H)-uridine cells, and 4 days for (³H)-leucine cells. Autoradiographic studies showed that (³H)-thymidine was incorporated in the DNA of both kinetoplast and nucleus in this order. Shifts in the intracellular content of cAMP either by addition of dibutyryl-cAMP or by stimulation of the adenylcyclase by isoproterenol, caused an inhibition in the synthesis of DNA, RNA and proteins. Addition to the T. cruzi cultures of these agents which elevate the intracellular content ofcAMP provoked an interruption of cell proliferation as a result of the impairment of macromolecule synthesis. A discrimination was observed among the stereoisomers of isoproterenol, the L configuration showing to be most active.<br>A síntese de macromoléculas de T. cruzi em cultura foi monitorada usando traçadores radioativos. Células de diferentes dias em cultura mostraram uma incorporação preferencial de precursores comco se seguez: 1 dia para (3H)-timidina; 3 dias para (3H)-uridina e 4 dias para (3H)-leucina. Estudos autoradiográficos mostraram que (3H)-leucina. Estudos autoradiográficos mostraram que (3H)-timidina foi incorporada no DNA de ambos, cinetoplasto e núcleo, nesta ordem. Alterações no conteúdo intracelular de cAMP seja por adição de dibutiril-cAMP ou por estimulação de adenilciclase por isoproterenol, causav am inibição na síntese de DNA, RNA e proteínas. A adição destes agentes que elevam o conteúdo intracelular de cAMP em culturas de T.cruzi provocou inibição de crescimento, com resultado da síntese macromolecular imperfeita. Foi observada uma discriminação entre os estereoisômeros de isoproterenol, sendo a configuração L, a mais ativa

Quantitative Proteomic and Phosphoproteomic Analysis of Trypanosoma cruzi Amastigogenesis

“…These enzymes regulate the intracellular levels of cAMP and cGMP, intracellular second messengers of pathways whose importance to T. cruzi cell proliferation is already known (68,72). The decrease in their expression after the period during which the parasite remains inside phagolysosomes in vivo reinforces the hypothesis that key processes of induction/regulation of amastigogenesis are achieved within these 2 h. After that point, the process may be irreversibly triggered, with the remaining time possibly necessary for ultrastructural adjustments.…”

The myriad roles of cyclic AMP in microbial pathogens: from signal to sword

“…In T. cruzi , cAMP regulates PKA with striking effects on cell survival 122 and cell proliferation through the inhibition of DNA, RNA and protein synthesis 123 . cAMP has also been implicated in the transition of the human-infective form to the insect-infective form of T. cruzi 124,125 .…”

Intracellular cyclic AMP levels modulate differential adaptive responses on epimastigotes and cell culture trypomastigotes of Trypanosoma cruzi

“…Initially, higher intracellular cAMP and T. cruzi Adenylyl cyclase (AC) activity were shown to stimulate metacyclogenesis (Fraidenraich et al, 1993;Gonzales-Perdomo et al, 1988;Rangel-Aldao et al, 1988). Additional studies demonstrated that elevated intracellular cAMP could arrest DNA, RNA and protein synthesis (Santos and Oliveira, 1988), which concomitantly led to a proliferation arrest in epimastigotes. Later, a new family of phosphodiesterases (PDEs) was identified in trypanosomatids, and they were connected with certain stress response transduction pathways (Alonso et al, 2007;Bhattacharya et al, 2009), and in T. brucei TbPDEB1 and TbPDEB2 have even been validated as drug targets (Bland et al, 2011;De Koning et al, 2012;Oberholzer et al, 2007;Torphy and Page, 2000).…”