Deviating from the norm: Nuclear organisation in trypanosomes

Field, Mark C.

doi:10.1016/j.ceb.2023.102234

Cited by 2 publications

(2 citation statements)

References 35 publications

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“…ESB1 has recently been identified to be essential for the active ES transcription and is responsible for recruiting RNA pol I and forming a local, highly SUMOylated focus at ESB [233], where SUMOylation has been shown to positively regulate VSG expression [234,235]. On the other hand, silent ESs are dispersed in the nucleus, away from ESB [236]. Nearly all genes in T. brucei are organized in polycistronic transcription units [112,237,238], and the polycistronic transcripts are trans-spliced to have a spliced leader added at the 5 ′ end of the individual gene transcript [239,240].…”

Section: Multiple Mechanisms Are Employed To Ensure Vsg Monoallelic E...mentioning

confidence: 99%

Unwrap RAP1’s Mystery at Kinetoplastid Telomeres

2024

Biomolecules

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Although located at the chromosome end, telomeres are an essential chromosome component that helps maintain genome integrity and chromosome stability from protozoa to mammals. The role of telomere proteins in chromosome end protection is conserved, where they suppress various DNA damage response machineries and block nucleolytic degradation of the natural chromosome ends, although the detailed underlying mechanisms are not identical. In addition, the specialized telomere structure exerts a repressive epigenetic effect on expression of genes located at subtelomeres in a number of eukaryotic organisms. This so-called telomeric silencing also affects virulence of a number of microbial pathogens that undergo antigenic variation/phenotypic switching. Telomere proteins, particularly the RAP1 homologs, have been shown to be a key player for telomeric silencing. RAP1 homologs also suppress the expression of Telomere Repeat-containing RNA (TERRA), which is linked to their roles in telomere stability maintenance. The functions of RAP1s in suppressing telomere recombination are largely conserved from kinetoplastids to mammals. However, the underlying mechanisms of RAP1-mediated telomeric silencing have many species-specific features. In this review, I will focus on Trypanosoma brucei RAP1’s functions in suppressing telomeric/subtelomeric DNA recombination and in the regulation of monoallelic expression of subtelomere-located major surface antigen genes. Common and unique mechanisms will be compared among RAP1 homologs, and their implications will be discussed.

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Section: Multiple Mechanisms Are Employed To Ensure Vsg Monoallelic E...mentioning

confidence: 99%

Unwrap RAP1’s Mystery at Kinetoplastid Telomeres

2024

Biomolecules

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“…5A ). An alternate view, expressed by one of us recently (Mark C. Field in [ 115 ]), is that there are so many differences within RNA processing pathways and NPC composition between trypanosomes and other lineages that this may reflect a more fundamental distinction, and that trypanosomes could be examples of an earlier eukaryotic state [ 115 ]; however, the validity of either argument remains unestablished. Apart from variations in the NPC architecture among eukaryotes, variations in composition have been detected among tissues and even in the same cell.…”

Section: The Nuclear Pore Complexmentioning

confidence: 99%

Evolutionary, structural and functional insights in nuclear organisation and nucleocytoplasmic transport in trypanosomes

Padilla‐Mejia,

Field

2023

FEBS Letters

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One of the remarkable features of eukaryotes is the nucleus, delimited by the nuclear envelope (NE), a complex structure and home to the nuclear lamina and nuclear pore complex (NPC). For decades, these structures were believed to be mainly architectural elements and, in the case of the NPC, simply facilitating nucleocytoplasmic trafficking. More recently, the critical roles of the lamina, NPC and other NE constituents in genome organisation, maintaining chromosomal domains and regulating gene expression have been recognised. Importantly, mutations in genes encoding lamina and NPC components lead to pathogenesis in humans, while pathogenic protozoa disrupt the progression of normal development and expression of pathogenesis‐related genes. Here, we review features of the lamina and NPC across eukaryotes and discuss how these elements are structured in trypanosomes, protozoa of high medical and veterinary importance, highlighting lineage‐specific and conserved aspects of nuclear organisation.

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Deviating from the norm: Nuclear organisation in trypanosomes

Cited by 2 publications

References 35 publications

Unwrap RAP1’s Mystery at Kinetoplastid Telomeres

Unwrap RAP1’s Mystery at Kinetoplastid Telomeres

Evolutionary, structural and functional insights in nuclear organisation and nucleocytoplasmic transport in trypanosomes

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