Biology subjects

Tillotson, R.

Publications and source records attributed to Tillotson, R..

4 recordsLinked to original sources

bioRxiv2025

ATRX Deficiency Drives Aberrant Type I Interferon Signalling Through cGAS-Dependent Transcriptional Dysregulation

The X-linked -thalassaemia intellectual disability syndrome (ATRX) protein is a chromatin remodeller involved in transcriptional regulation and genome stability. While the importance of ATRX in development and malignancy is well recognised, its role in innate immunity is less well defined. In two unrelated patients demonstrating cerebral white matter disease, learning difficulties and a persistent upregulation of interferon stimulated gene expression in whole blood, we identified the same Y1758C missense substitution in ATRX. Using patient-derived cells, engineered fibroblasts and neuronal models, we show that this substitution, and other loss of function mutations in ATRX, result in enhanced type I interferon signalling through a cGAS-dependent mechanism uncoupled from the DNA sensing activity of cGAS. Loss of ATRX function leads to alterations in the chromatin distribution of DAXX and H3.3, with cGAS essential for the changes in nucleosome composition and gene expression mediated by ATRX deficiency. Thus, our study highlights a previously unrecognized link between ATRX dysfunction and inflammation involving a non-canonical role of cGAS.

immunology↗

bioRxiv2025

Visible traits demonstrate that crispant founder mice can be used for phenotypic assessment

Genes can be knocked out in model organisms by introducing a single guide RNA and Cas9 into one cell zygotes. Recently, the zebrafish and Xenopus communities have employed this method in genetic screening pipelines that assess phenotypes in founders (F0), referred to as "crispants". In contrast, phenotyping crispant mice has been avoided as results are believed to be confounded by genetic mosaicism, requiring that only established mouse lines undergo phenotypic assessment. Here, we targeted seven genes associated with visible recessive phenotypes. We observed the expected null phenotype in up to 100% founders per gene. Crucially, we achieved 100% editing efficiency in all but two animals. Genetic mosaicism was common, but did not confound an animals phenotype when comprised of mutations that all disrupted the targeted gene. Mosaicism included short in-frame mutations, but these were sufficient to disrupt function of five genes. Several founders were compound heterozygotes carrying a null and a non-null allele (short in-frame mutation or late truncation), enabling functional assessment of the non-null allele to dissect protein function. Our results set the stage for using crispant founders for initial phenotypic assessment in genetic screening, before selecting candidates for further study. This will dramatically reduce animal numbers.

genetics↗

bioRxiv2023

A new mouse model of ATR-X syndrome carrying a common patient mutation exhibits neurological and morphological defects

ATRX is a chromatin remodelling ATPase that is involved in transcriptional regulation, DNA damage repair and heterochromatin maintenance. It has been widely studied for its role in ALT-positive cancers, but its role in neurological function remains elusive. Hypomorphic mutations in the X-linked ATRX gene cause a rare form of intellectual disability combined with alpha-thalassemia called ATR-X syndrome in hemizygous males. Patients also have facial dysmorphism, microcephaly, musculoskeletal defects and genital abnormalities. Since complete deletion of ATRX in mice results in early embryonic lethality, the field has largely relied on conditional knockout models to assess the role of ATRX in multiple tissues. Given that null alleles are not found in patients, a more patient-relevant model was needed. Here, we have produced and characterised the first patient mutation knock-in model of ATR-X syndrome, carrying the most common patient mutation, R246C. This is one of a cluster of missense mutations located in the chromatin interaction domain that disrupts its function. The knock-in mice recapitulate several aspects of the patient disorder, including craniofacial defects, microcephaly and impaired neurological function. They provide a powerful model for understanding the molecular mechanisms underlying ATR-X syndrome and for testing potential therapeutic strategies.

neuroscience↗

bioRxiv2020

Neuronal non-CG methylation is an essential target for MeCP2 function

SUMMARYDNA methylation is implicated in neuronal biology via the protein MeCP2, mutation of which causes Rett syndrome. MeCP2 recruits the NCOR1/2 corepressor complexes to methylated cytosine in the CG dinucleotide, but also to non-CG methylation, which is abundant specifically in neuronal genomes. To test the biological significance of its dual binding specificity, we replaced the MeCP2 DNA binding domain with an orthologous domain whose specificity is restricted to mCG motifs. Knock-in mice expressing the domain-swap protein displayed severe Rett syndrome-like phenotypes, demonstrating that interaction with sites of non-CG methylation, specifically the mCAC trinucleotide, is critical for normal brain function. The results support the notion that the delayed onset of Rett syndrome is due to the late accumulation of both mCAC and its reader MeCP2. Intriguingly, genes dysregulated in both Mecp2-null and domain-swap mice are implicated in other neurological disorders, potentially highlighting targets of particular relevance to the Rett syndrome phenotype.Competing Interest StatementThe authors have declared no competing interest.View Full Text

genetics↗