Project 1 – Role and function of molecular chaperones during the Leishmania life cycle

Heat shock proteins are traditionally seen as protecting against environmental stress, e.g. non-physiological temperatures, acidic milieu and reactive oxygen species. In the Leishmania parasites, heat shock proteins have evolved according to the needs of their life cycle.

The chaperones HSP100 and Cyclophilin 40 are essential for the intracellular survival of the parasites inside their macrophage host cells, the former by affecting the immune modulation of the mammalian host.

HSP23 is required for the survival of temperatures > 34°C and for resistance against acidic milieu and metalloid compounds, the latter being a mainstay of anti-Leishmania therapy.

We currently investigate the impact of Casein Kinase 1-dependent phosphorylation of  HSP23 and analyse phenotype alterations due to phosphorylation site mutations.  

Moreover, we investigate the roles of the mitochondrial and ER-specific HSP90 family members in the context of life cycle control and stress tolerance.

Project 2 - Regulation of life cycle stage differentiation

Leishmania parasites undergo a shape change when transmitted from sandflies to mammals: spindle shaped insect forms, promastigotes, transform into ovoid amastigotes inside their target cells, macrophages. This process is critical for parasite survival and pathogenicity because only the amastigotes are able to colonise macrophages. The differentiation can be mimicked by the pharmacological inhibition of a key protein, the 90 kD heat shock protein (HSP90).

New systems biology strategies, e.g. ribosome profiling-based, genome-wide quantification of protein synthesis, allowed us to investigate the processes induced during stage differentiation, and we found that i) stage-specific protein synthesis is regulated at the level of translation, ii) inhibition of HSP90 indeed induces the synthesis of several groups of amastigote-specific proteins, and iii) quantitative RNA analysis cannot predict protein synthesis rates.

We are currently looking into the implications of elevated synthesis of histone and  proteins, determining their impact on chromatin structure and transcriptional activity.

Project 3 - Influence of Leishmania infection on host cell biology

In this collaboration with the AG Lotter (BNITM) we investigate the impact of Leishmania infection on the gene expression of host cells, human ex-vivo macrophages, using high throughput imaging and genome-wide transcriptome analysis. In particular, we aim at identifying gender-specific changes of the transcriptome, which may hint at the molecular basis of the observed sex-specific manifestation of Leishmania infections in humans.