The Akt-like kinase of Leishmania panamensis: As a new molecular target for drug discovery

- A novel therapeutic target against Leishmania was identified from the specific inhibition of the Akt-like kinase; kinase involved in cell survival of the parasite under stress conditions.
- Allosteric inhibition of the PH domain of the Akt-like kinase of Leishmania panamensis, blocks the phosphorylation of this kinase, causing the death of the parasite by a mechanism similar to apoptosis .
- The use of specific inhibitors against the PH domain of the Akt-like kinase of Leishmania panamensis, does not affect the phosphorylation of the human Akt and therefore its functionality.
- All Akt-like kinases of Leishmania are highly conserved, making it a common target in all Leishmania species.

The Akt-like kinase of Leishmania spp. is a cytoplasmic orthologous protein of the serine/threonine kinase B-PKB/human-Akt group, which is involved in the cellular survival of these parasites. By the application of a computational strategy we obtained two specific inhibitors of the Akt-like protein of L. panamensis (UBMC1 and UBMC4), which are predicted to bind specifically to the pleckstrin domain (PH) of the enzyme. We show that the Akt-like of Leishmania panamensis is phospho-activated in parasites under nutritional and thermic stress, this phosphorylation is blocked by the UBMC1 and UMBC2 and such inhibition leads to cell death. Amongst the effects caused by the inhibitors on the parasites we found high percentage of hypodiploidy and loss of mitochondrial membrane potential. Ultrastructural studies showed highly vacuolated cytoplasm, as well as shortening of the flagellum, loss of nuclear membrane integrity and DNA fragmentation. Altogether the presented results suggest that the cell death caused by UMBC1 and UMBC4 may be associated to an apoptosis-like process. The compounds present an inhibitory concentration (IC50) over intracellular amastigotes of L. panamensis of 9.2 ± 0.8 μM for UBMC1 and 4.6 ± 1.9 μM for UBMC4. The cytotoxic activity for UBMC1 and UBMC4 in human macrophages derived from monocytes (huMDM) was 29 ± 1.2 μM and >40 μM respectively. Our findings strongly support that the presented compounds can be plausible candidates as a new therapeutic alternative for the inhibition of specific kinases of the parasite.

Schematic model of the putative action of the Lp-RAC/Akt-like protein in response to death and survival in Leishmania panamensis under cell stress conditions.105