Epigenetic regulation in African trypanosomes: a new kid on the block

• Published in: Nature reviews. Microbiology Vol. 7; no. 7; pp. 504 - 513
• Main Authors: Figueiredo, Luisa M, Cross, George A. M, Janzen, Christian J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-07-2009; Nature Publishing Group
• Subjects: Animals; Biomedical and Life Sciences; Cell cycle; Chromatin; Chromatin - genetics; Enzymes; Epigenesis, Genetic - genetics; Epigenesis, Genetic - physiology; Epigenetic inheritance; Epigenetics; Genes; Genetic aspects; Glycoproteins; Health aspects; Histones - genetics; Humans; Infectious Diseases; Life Sciences; Medical Microbiology; Microbiology; Parasites; Parasitology; Physiological aspects; Proteins; Protozoa; review-article; Ribosomal DNA; RNA polymerase; Trypanosoma; Trypanosoma - genetics; Trypanosoma - pathogenicity; Trypanosomiasis, African - genetics; Trypanosomiasis, African - parasitology; Virology; United States; Germany; New York; United States > US
• ISSN: 1740-1526; 1740-1534
• DOI: 10.1038/nrmicro2149

Key Points
Trypanosoma brucei
, the causative agent of sleeping sickness in humans, diverged from the highest eukaryotic lineage several hundred million years ago. Understanding epigenetic regulation in
T. brucei
could shed light on important basic questions in the chromatin field.
Edman degradation and mass spectrometry studies revealed a striking absence of many well-conserved histone post-translational modifications (PTMs). By contrast, some unusual and apparently trypanosome-specific PTMs were identified. DNA can also carry epigenetic information, either in the form of methylcytosine or base J.
Consistent with a simplified histone code, the genome of
T. brucei
contains few candidate genes that encode for histone-modifying or chromatin-remodelling enzymes. Readers of the histone code can also be identified, and they seem to have a single PTM-binding domain.
Characterization of some of these epigenetic factors revealed that they are involved in the regulation of
VSG
monoallelic expression and cell differentiation cell cycle control.
Future studies should lead to the identification of more players involved in epigenetics in
T. brucei
, as well as the mechanistic details of how they regulate basic biological processes.
The identification of post-translational histone modifications and chromatin-modifying enzymes in eukaryotic parasites has widened the field of research into epigenetic regulation. Figueiredo, Cross and Janzen compare the role of epigenetics in
Trypanosoma brucei
and humans and discuss how studies in such parasites might yield useful information about the evolution of epigenetic processes.
Epigenetic regulation is important in many facets of eukaryotic biology. Recent work has suggested that the basic mechanisms underlying epigenetic regulation extend to eukaryotic parasites. The identification of post-translational histone modifications and chromatin-modifying enzymes is beginning to reveal both common and novel functions for chromatin in these parasites. In this Review, we compare the role of epigenetics in African trypanosomes and humans in several biological processes. We discuss how the study of trypanosome chromatin might help us to better understand the evolution of epigenetic processes.