Biology subjects

Rodermund, L.

Publications and source records attributed to Rodermund, L..

4 recordsLinked to original sources

bioRxiv2026

A key role for chromosome compartment interactions in directing Xist RNA localisation

X-chromosome inactivation, the mechanism for dosage compensation in mammals, is orchestrated by the long non-coding RNA Xist which localises across the X chromosome in cis. The basis for in cis localisation remains poorly understood. To investigate in situ Xist localisation, we established MCPH1-deficient cell models that retain compacted interphase chromosomes, enabling visualisation of individualised chromosome territories. We find that Xist RNA is directed to sites around the periphery of compacted chromosome territories, and moreover that these sites correlate closely with A1-sub-compartments on the X chromosome. We further show that peripheral positioning of A1-sub-compartments occurs on all chromosomes and is a hallmark of early prophase. A key role for compartment interactions in Xist localisation is further supported by analysis of MCPH1-deficient models where Xist is overexpressed (from the X chromosome or an autosomal Xist transgene), and following depletion of HNRNPU, a key factor that anchors Xist RNA to chromosome territories.

genetics↗

bioRxiv2025

N6-methyladenosine and the NEXT complex direct Xist RNA turnover and X inactivation dynamics

X chromosome inactivation (XCI) in mammals is orchestrated by the non-coding RNA Xist which together with specific interacting proteins, functions in cis to silence an entire X chromosome. Defined sites on Xist RNA carry the N6-methyladenosine (m6A) modification, and perturbation of the m6A writer complex has been found to abrogate Xist-mediated gene-silencing. However, the relative contribution of m6A and its mechanism of action remain unclear. Here we investigate the role of m6A in XCI by applying rapid degron-mediated depletion of METTL3, the catalytic subunit of the m6A writer complex, an approach that minimises indirect effects due to transcriptome-wide depletion of m6A. We find that acute loss of METTL3/m6A accelerates Xist-mediated gene silencing, and that this correlates with increased levels and stability of Xist transcripts. We show that Xist RNA turnover is mediated by the nuclear exosome targeting (NEXT) complex but is independent of the principal nuclear m6A reader protein YTHDC1. Our findings demonstrate that the primary function of m6A on Xist RNA is to promote Xist RNA turnover which in turn regulates XCI dynamics.

biochemistry↗

bioRxiv2021

Xist-mediated silencing requires additive functions of SPEN and Polycomb together with differentiation-dependent recruitment of SmcHD1

X chromosome inactivation (XCI) is mediated by the non-coding RNA Xist which directs chromatin modification and gene silencing in cis. The RNA binding protein SPEN and associated corepressors have a central role in Xist-mediated gene silencing. Other silencing factors, notably the Polycomb system, have been reported to function downstream of SPEN. In recent work we found that SPEN has an additional role in correct localisation of Xist RNA in cis, indicating that its contribution to chromatin-mediated gene silencing needs to be reappraised. Making use of a SPEN separation-of-function mutation we show that SPEN and Polycomb pathways in fact function in parallel to establish gene silencing. Additionally, we find that differentiation-dependent recruitment of the chromosomal protein SmcHD1 is required for silencing many X-linked genes. Our results provide important insights into the mechanism of X inactivation and the coordination of chromatin-based gene regulation with cellular differentiation and development.

molecular biology↗

bioRxiv2020

Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading

Xist RNA directs the process of X-chromosome inactivation in mammals by spreading in cis along the chromosome from which it is transcribed and recruiting chromatin modifiers to silence gene transcription. To elucidate mechanisms of Xist RNA cis-confinement, we established a sequential dual color labeling, super-resolution imaging approach to trace individual Xist RNA molecules over time, enabling us to define fundamental parameters of spreading. We demonstrate a feedback mechanism linking Xist RNA synthesis and degradation, and an unexpected physical coupling between preceding and newly synthesized Xist RNA molecules. Additionally, we show that the protein SPEN, a key factor for Xist-mediated gene-silencing, has a distinct function in Xist RNA localization, stability and in coupling behavior. Our results provide important insights towards understanding the unique dynamic properties of Xist RNA. One Sentence SummaryVisualizing Xist RNA dynamics in single cells during X chromosome inactivation

developmental biology↗