Functional genomics in sand fly-derived Leishmania promastigotes

Area of Science:

• Parasitology
• Molecular Biology
• Genomics

Background:

• Leishmania parasites develop into infective metacyclic promastigotes within the sand fly gut.
• This developmental process can be replicated in laboratory cultures.
• Gene expression profiling via transcriptome analysis is used to study these promastigote forms.

Purpose of the Study:

• To investigate the differences in gene expression between sand fly gut-derived and culture-derived Leishmania promastigotes.
• To understand the role of the sand fly's microenvironment in parasite development.
• To identify specific genes and pathways differentially regulated during development in vivo versus in vitro.

Main Methods:

• Transcriptome analysis (RNA sequencing) of Leishmania promastigotes.
• Comparison of gene expression profiles from sand fly gut and culture conditions.
• Analysis of differential gene expression, including specific gene clusters and pathways.

Main Results:

• Substantial differences and moderate correlation found between transcriptomes of cultured and sand fly-derived promastigotes.
• Sand fly-derived metacyclic promastigotes exhibit higher infectivity than cultured ones.
• Genes related to hydrophilic acidic surface protein/small endoplasmic reticulum protein (HASP/SHERP), glycoprotein 63 (gp63), and autophagy are upregulated in sand fly-derived promastigotes.
• Leishmania major upregulates cell cycle and glucose metabolism genes in the gut, while metacyclics upregulate fatty acid biosynthesis and proton transport genes.

Conclusions:

• Transcriptome analysis is effective for studying differential gene expression in sand fly gut promastigotes.
• Transcript and protein levels show poor quantitative correlation but better qualitative correlation, suggesting post-transcriptional regulation.
• Differences in gene expression highlight the importance of the sand fly microenvironment and caution against direct extrapolation from culture studies.