Protein kinase activities in Leishmania aethiopica: control by growth, transformation and inhibitors

Assefa, Daniel; Worku, Yoseph; Skoglund, Göran

doi:10.1016/0925-4439(94)00080-a

Cited by 11 publications

(9 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In accordance with the data of Assefa and collaborators 26 which defined a decrease in protein kinases activity in amastigote-like forms of L. aethiopica, we also pka activity in L. AMAZONENSIS 317 observed discrete PKA activity in axenic amastigotes, being higher in the SF and significantly lower than in infective promastigotes. Indeed, protein kinase activities do not seem to be essential for amastigote metabolism, since Becker and Jaffe 6 who cultivated L. amazonensis in the presence of staurosporin observed that parasite proliferation was not affected at all.…”

Section: Resultssupporting

confidence: 92%

See 1 more Smart Citation

Protein kinase A activity is associated with metacyclogenesis in Leishmania amazonensis

Genestra

Cysne-Finkelstein

Leon

2004

Cell Biochemistry & Function

View full text Add to dashboard Cite

Because of the importance of cell signalling processes in proliferation and differentiation, the adenylate cyclase pathway was studied, specifically the protein kinase A (PKA) in Leishmania amazonensis. The PKAs of soluble (SF) and enriched membrane fractions (MF) from infective/non-infective promastigotes and axenic amastigotes were assayed. In order to purify the PKA molecule, fractions were chromatographed on DEAE-cellulose columns and the phosphorylative activity was evaluated using [gamma(32)P]-ATP as the phosphate source. These experiments were performed in the presence of cyclic adenosine monophosphate (cAMP) and an inhibitor of PKA. Our data demonstrated that the PKA activity was significantly higher (about two times) in SF from promastigotes with a high concentration of metacyclic forms, when compared with the non-infective promastigotes, suggesting an association of this activity and the metacyclogenesis process. A discrete phosphorylative activity in axenic amastigotes was observed. As the adenylate cyclase/cAMP pathway would be involved in the parasite-host interiorization, the PKA activity may constitute a good intracellular target for studies of leishmanicidal drugs.

show abstract

Section: Resultssupporting

confidence: 92%

“…6,[25][26][27][28][29][30] Parsons and collaborators 10 suggested a possible modulation of the cell host functions by the parasite kinases. A least two PKA isoforms in mammalian 316 m. genestra ET AL.…”

Section: Resultsmentioning

confidence: 99%

Protein kinase A activity is associated with metacyclogenesis in Leishmania amazonensis

Genestra

Cysne-Finkelstein

Leon

2004

Cell Biochemistry & Function

View full text Add to dashboard Cite

show abstract

“…The phosphorylation of PS by Leishmania aethiopica promastigotes, either particulate or soluble fractions or live parasites, is strongly inhibited by staurosporine. Low concentrations of drug (50 nM) inhibited the phosphorylation of PS by Ͼ80% when parasite fractions were used and by approximately 45% using live parasites (28). Furthermore, staurosporine concentrations similar to those that inhibit the constitutively shed ecto-PK are cytostatic and/or cytotoxic to the promastigotes and induce pronounced morphological changes (29).…”

Section: Discussionmentioning

confidence: 99%

Release of Ecto-protein Kinases by the Protozoan ParasiteLeishmania major

Sacerdoti‐Sierra¹,

Jaffe²

1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

Leishmania major promastigotes have externally oriented ecto-protein kinases (PK) that are capable of phosphorylating both endogenous membrane substrates and foreign proteins. Live parasites phosphorylate protamine sulfate, casein, and phosvitin but not bovine serum albumin. Addition of exogenous PK substrates, such as phosvitin or casein, induced the shedding of ecto-PK that are capable of phosphorylating protamine sulfate. No phosphorylation of protamine sulfate was seen when cell-free supernatants from promastigotes incubated with either buffer alone or bovine serum albumin were used. A second enzyme, a constitutively released PK that phosphorylates casein or phosvitin and not protamine sulfate or mixed histones, was identified and characterized. This PK is inhibited by 5 M staurosporine, 50 g/ml heparin, and 75 M CKI-7, concentrations typical of the IC 50 found for other eukaryotic casein kinases (CK). The constitutively shed ecto-PK specifically phosphorylated a peptide substrate for CK1 but not for CK2, suggesting that this shed PK is similar to CK1.

show abstract

“…An increasing number of PKs of parasitic protozoa are being evaluated as drug targets. Some inhibitors of PKs have been shown to display antiproliferative effects on the protozoa (Assefa et al, 1995;Becker & Jaffe, 1997;Straarup et al, 1997;Doerig et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Effects of protein kinase and phosphatidylinositol-3 kinase inhibitors on growth and ultrastructure of Trypanosoma cruzi

Braga

Souza

2006

FEMS Microbiology Letters

View full text Add to dashboard Cite

An increasing number of protein kinases (PKs) of parasitic protozoa are being evaluated as drug targets. Some PK inhibitors display antiproliferative effects on protozoa. We tested three PK inhibitors on the growth and ultrastructure of epimastigotes of Trypanosoma cruzi and the effect of these drugs on intracellular amastigotes. They were staurosporine (serine/threonine kinase inhibitor), genistein (tyrosine kinase inhibitor), and wortmannin (phosphatidylinositol 3' (PI3) kinase inhibitor). All drugs inhibited epimastigote growth at the concentrations tested. Wortmannin inhibited parasite growth at the lowest concentrations. However, staurosporine was the most effective after 24 h treatment and genistein caused the stronger inhibition during the whole treatment (60-70% inhibition). The IC50 were: staurosporine: 6.43+/-1.28 microM; genistein: 6.54+/-1.86 microM; and wortmannin: 0.056+/-0.014 microM. These PK inhibitors had strong ultrastructural effects on the epimastigotes: abnormal chromatin condensation of the nucleus; loose flagellar membrane with the formation of blebs; incomplete cell division; autophagosomes and myelin-like figures. These drugs did not interfere with the division of intracellular amastigotes or with its differentiation to trypomastigotes. However, as trypanosomes have kinomes that contain a large set of protein kinases and phosphatases, PKs should not be disregarded as an important target for chemotherapy of Chagas disease.

show abstract

Protein kinase activities in Leishmania aethiopica: control by growth, transformation and inhibitors

Cited by 11 publications

References 16 publications

Protein kinase A activity is associated with metacyclogenesis in Leishmania amazonensis

Protein kinase A activity is associated with metacyclogenesis in Leishmania amazonensis

Release of Ecto-protein Kinases by the Protozoan ParasiteLeishmania major

Effects of protein kinase and phosphatidylinositol-3 kinase inhibitors on growth and ultrastructure of Trypanosoma cruzi

Contact Info

Product

Resources

About