Biology subjects

Ferreira, H. C.

Publications and source records attributed to Ferreira, H. C..

3 recordsLinked to original sources

bioRxiv2025

ATRX safeguards cellular identity during C. elegans development

ATRX is a member of the SWI/SNF family of ATP-dependent chromatin remodellers. In humans, loss of ATRX function leads to ATRX syndrome, a neurodevelopmental disorder. ATRX mutation in human cell lines is associated with multiple phenotypes including activation of the alternative lengthening of telomere (ALT) pathway, upregulation of retrotransposons and increased sensitivity to replication stress. However, the principal role of ATRX and the reason why its mutation causes such diverse phenotypes is currently unclear. To address this, we studied the role of ATRX in the model organism Caenorhabditis elegans. We find that loss of XNP-1, the C. elegans homologue of ATRX, recapitulates many human phenotypes. Loss of XNP-1 causes ectopic activation of germline genes in somatic cells, indicating a loss of cellular identity control. Strikingly, mutation of the germline transcription factor gsox-1 suppresses both this misexpression and multiple xnp-1 phenotypes, including developmental delay and telomeric defects. These findings suggest that ectopic germline gene expression underlies the majority of XNP-1-dependent phenotypes, consistent with a role for XNP-1 in maintaining cellular identity, offering insights into the functions of ATRX in humans.

molecular biology↗

bioRxiv2022

POT-3 preferentially binds the terminal DNA-repeat on the telomeric G-overhang

Eukaryotic chromosomes typically end in 3 telomeric overhangs. The safeguarding of telomeric single-stranded DNA overhangs is carried out by factors related to the Protection of Telomeres 1 (POT1) protein in humans. Of the three POT1-like proteins in C. elegans, POT-3 was the only member thought to not play a role at telomeres. Here, we provide evidence that POT-3 is a bona fide telomere-binding protein. Using a new loss-of-function mutant, we show that the absence of POT-3 causes telomere lengthening and increased levels of telomeric C-circles. We find that POT-3 directly binds the telomeric G-strand in vitro and map its minimal DNA binding site to the six-nucleotide motif, GCTTAG. We further show that the closely related POT-2 protein binds the same motif, but that POT-3 shows higher sequence selectivity. Crucially, in contrast to POT-2, POT-3 prefers binding sites immediately adjacent to the 3 end of DNA. These differences are significant as genetic analyses reveal that pot-2 and pot-3 do not function redundantly with each other in vivo. Our work highlights the rapid evolution and specialisation of telomere binding proteins and places POT-3 in a unique position to influence activities that control telomere length.

molecular biology↗

bioRxiv2018

The ATP-dependent chromatin remodelling enzyme Uls1 prevents Topoisomerase II poisoning

Topoisomerase II (Top2) is an essential enzyme that decatenates DNA via a transient Top2-DNA covalent intermediate. This intermediate can be stabilised by a class of drugs termed Top2 poisons, resulting in massive DNA damage. Thus, Top2 activity is a double-edged sword that needs to be carefully controlled to maintain genome stability. We show that Uls1, an ATP-dependent chromatin remodelling (Snf2) enzyme, can alter Top2 chromatin binding and prevent Top2 poisoning in yeast. Deletion mutants of ULS1 are hypersensitive to the Top2 poison acriflavine (ACF), activating the DNA damage checkpoint. We map Uls1s Top2 interaction domain and show that this, together with its ATPase activity, is essential for Uls1 function. By performing ChIP-seq, we show that ACF leads to a general increase in Top2 binding across the genome. We map Uls1 binding sites and identify tRNA genes as key regions where Uls1 associates after ACF treatment. Importantly, the presence of Uls1 at these sites prevents ACF-dependent Top2 accumulation. Our data reveal the effect of Top2 poisons on the global Top2 binding landscape and highlights the role of Uls1 in antagonising Top2 function. Remodelling Top2 binding is thus an important new means by which Snf2 enzymes promote genome stability.

molecular biology↗