A Detailed Gene Expression Map of Giardia Encystation.

Laura Rojas-López,Staffan G Svärd,Sascha Krakovka,Feifei Xu,Jon Jerlström-Hultqvist,Ulf Ribacke,Elin Einarsson

doi:10.3390/genes12121932

Laura Rojas-López, Staffan G Svärd + Show 5 more

Open Access

https://doi.org/10.3390/genes12121932

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Abstract

Giardia intestinalis is an intestinal protozoan parasite that causes diarrheal infections worldwide. A key process to sustain its chain of transmission is the formation of infectious cysts in the encystation process. We combined deep RNAseq of a broad range of encystation timepoints to produce a high-resolution gene expression map of Giardia encystation. This detailed transcriptomic map of encystation confirmed a gradual change of gene expression along the time course of encystation, showing the most significant gene expression changes during late encystation. Few genes are differentially expressed early in encystation, but the major cyst wall proteins CWP-1 and -2 are highly up-regulated already after 3.5 h encystation. Several transcription factors are sequentially up-regulated throughout the process, but many up-regulated genes at 7, 10, and 14 h post-induction of encystation have binding sites in the upstream regions for the Myb2 transcription factor, suggesting that Myb2 is a master regulator of encystation. We observed major changes in gene expression of several meiotic-related genes from 10.5 h of encystation to the cyst stage, and at 17.5 h encystation, there are changes in many different metabolic pathways and protein synthesis. Late encystation, 21 h to cysts, show extensive gene expression changes, most of all in VSP and HCMP genes, which are involved in antigenic variation, and genes involved in chromatin modifications. This high-resolution gene expression map of Giardia encystation will be an important tool in further studies of this important differentiation process.

Highlights

Giardia intestinalis is a significant cause of diarrheal disease worldwide in humans and other mammals [1]
This study aimed to expand and complement the current knowledge of what is occurring during encystation in G. intestinalis
Non-clustered heat maps of known gene expression regulators show (Figure 2) that there is a gradual change in expression of transcription factors (Figure 2A) and chromatin regulators (Figure 2B)

Summary

Introduction

Giardia intestinalis is a significant cause of diarrheal disease worldwide in humans and other mammals [1]. This parasitic protozoan has been reported to cause more than 300 million cases of diarrhea in children less than five years old [2] and 28.2 million cases of foodborne infections, accounting for 26,270 disability-adjusted life years (DALYs) [3,4]. During the early encystation phase, the adhesive disc is disassembled [8], the flagella are internalized, the cells round up, and the cyst wall formation starts [6].

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