Further Investigation of casein kinase 2 (CK2) activity in epimastigotes of Trypanosoma cruzi Colombiana strain.
Souza, J.E.O1., Lima, A.K.C.1, Guerra, R.J.A.1, Lopes, A.H.C.S.2, Silva-Neto, M.A.C.3 & Dutra, P.M.L.1
1Disciplina de Parasitologia, DPL, FCM, UERJ.
2Instituto de Microbiologia Prof. Paulo de Góes, UFRJ;
3Instituto de Bioquímica, UFRJ.
The protozoan Trypanosoma cruzi is the etiologic agent of Chagas disease. It's the major endemic disease in Latin America where nearly 20 million people are infected, 5 million only in Brazil. T.cruzi is transmitted by the faeces of insects haematophagous of the subfamily Triatominae (Hemiptera, Reduviidae).
T. cruzi parasites undergoes complex morphological changes throughout its life cycle in both the insect vector and the vertebrate host. This cell differentiation is highly regulated and includes significant changes in biochemical pathways. Therefore, studies related to enzymes responsible for the phosphorylation and dephosphorylations of proteins present on the external surface of these parasites are extremely important.
Casein kinase 2 activities were depicted on the cell surface and as secreted enzymes of Leshmania major, L. braziliensis, L. tropica and L. amazonensis, where these enzymes seem to be involved with cell growth, morphology and infectivity. Here we demonstrate CK2 activities in T. cruzi (Colombiana strain CTC-IOC 004) present on the surface of this parasite, in the cytoplasmic content and as a secreted form. The addition of dephosphorylated casein promoted an increase of 53% only in the secreted CK2 activity of T. cruzi. The addition of CK2 inhibitors, heparin and TBB, completely inhibited the growth of the parasites, while the addition of CK2 activators, spermine, spermidine and putrescine, stimulated their growth, showing the importance of this enzyme for their life cycle. The secreted CK2 showed a specific activity of 1.37 nmoles Pi per mg x min after purification by HPLC. This activity was abrogated by heparin. We have tested the modulation of CK2 secretion by the addition of protein extract from BALB/c peritoneal macrophages, BSA, FCS and inactivated human serum. Only protein extracts from macrophages and from human serum were able to promote an enhancement (by 67% and 36%, respectively) on the secreted CK2 activity. We have also incubated the parasite with midgut content of triatomine insect and it promoted an increase of 75% on the secreted CK2 activity.
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