Lipid kinases and Ca(2+) signaling in Trypanosoma cruzi stimulated by a synthetic peptide

The synthetic peptide carrying residues 1-40 of chicken alpha(D)-globin, which promotes differentiation in Trypanosoma cruzi epimastigote, stimulated PPtdIns-k, DAG-k, and PA-k activities in a dose-dependent manner. A biphasic behavior only for PPtdIns-k and DAG-k was demonstrated by changes in (32)P]PPtdIns and PtdOH levels, the earlier phase peaking at 3 min with a return to basal levels by 6 min and then a second phase with a sustained increase in time. This behavior was not observed for PA-k; the DGPP levels peaked at 6 min and were sustained in time. PMA pretreatment only abolished the first peak of PPtdIns-k, DAG-k activities, and InsPs/InsP(3) levels. There was also a transient elevation in intracellular calcium concentration, but this variation was modified only 50% by PMA. The results suggest that peptide 1-40 induces activation of the inositol cycle through lipid kinase activation in a biphasic manner. In this response, the early increase of enzymatic activities would be regulated by PKC and the InsP(3) may only be responsible, in part, for the calcium signaling.