Biology subjects

Hanssen, L. L. P.

Publications and source records attributed to Hanssen, L. L. P..

4 recordsLinked to original sources

bioRxiv2026

In vivo lineage tracing across human tissues using methylation barcodes in the protocadherin gene cluster

Resolving the lineage history of human cells is fundamental to understanding ageing and cancer but remains hampered by a lack of native, high-resolution markers. Here, we identify the protocadherin (PCDH) gene cluster as a naturally occurring, highly diverse methylation barcode. While PCDH methylation creates neuronal diversity in the brain, we show that stochastic methylation patterns in this region are maintained as heritable, evolvable lineage markers across multiple non-neuronal tissues, including blood, kidney, prostate, and bladder. By tracking these barcodes in serial samples over a decade, we reveal clonal dynamics with high fidelity, quantitatively recapitulating genetic clone sizes. Crucially, PCDH barcodes identify "cryptic" clonal expansions invisible to standard driver-mutation sequencing and resolve subclonal architectures via continuous epimutation. This native barcoding system provides a scalable, driver-agnostic framework for reconstructing somatic evolution in humans.

genomics↗

bioRxiv2020

CaptureCompendium: a comprehensive toolkit for 3C analysis.

DNA folding within nuclei is a highly ordered process, with implications for gene regulation and development. An array of chromosome conformation capture (3C) methods have been developed to investigate how DNA is packaged within nuclei and to interrogate specific interactions. While these methods use different approaches to examine target loci (many-versus-all) or the entire genome (all-versus-all), they all rely on the core principle of endonuclease digestion and proximity-based ligation to re-arrange genomic order to reflect the three-dimensional nuclear conformation. This sequence reorganization creates novel chimeric DNA fragments which require specialist bioinformatic tools to analyze and visualize. Despite this need for specialist bioinformatic skills, the core biological importance of genome folding has seen widespread methodological uptake. To service the needs of experimentalists using the many-versus-all Capture-C family of methods we have developed CaptureCompendium; a toolkit of software to simplify the design, analysis and presentation of 3C experiments.

bioinformatics↗

bioRxiv2019

A revised model for promoter competition based on multi-way chromatin interactions

Specific communication between gene promoters and enhancers is critical for accurate regulation of gene expression. However, it remains unclear how specific interactions between multiple regulatory elements and genes contained within a single chromatin domain are coordinated. Recent technological advances allow for the investigation of multi-way chromatin interactions at single alleles in individual nuclei. This can provide insights into how multiple regulatory elements cooperate or compete for transcriptional activation. We have used these techniques in a mouse model in which the -globin domain is extended to include several additional genes. This allows us to determine how the interactions of the -globin super-enhancer are distributed between multiple promoters in a single domain. Our data show that gene promoters do not form mutually exclusive interactions with the super-enhancer, but all interact simultaneously in a single complex. These finding show that promoters within the same domain do not structurally compete for interactions with enhancers, but form a regulatory hub structure, consistent with the recent model of transcriptional activation in phase-separated nuclear condensates.

genomics↗

bioRxiv2018

Single-cell chromatin interactions reveal regulatory hubs in dynamic compartmentalized domains

The promoters of mammalian genes are commonly regulated by multiple distal enhancers, which physically interact within discrete chromatin domains. How such domains form and how the regulatory elements within them interact within single cells is not understood. To address this we developed Tri-C, a new Chromosome Conformation Capture (3C) approach to identify concurrent chromatin interactions at individual alleles within single cells. The heterogeneity of interactions observed between such cells shows that CTCF-mediated formation of chromatin domains and interactions within them are dynamic processes. Importantly, our analyses reveal higher-order structures involving simultaneous interactions between multiple enhancers and promoters within individual cells. This provides a structural basis for understanding how multiple cis-elements act together to establish robust regulation of gene expression.

genetics↗