Biology subjects

Barnett, R. J.

Publications and source records attributed to Barnett, R. J..

2 recordsLinked to original sources

bioRxiv2022

Remodeling and compaction of the inactive X is regulated by Xist during female B cell activation

X Chromosome Inactivation (XCI) equalizes X-linked gene expression between sexes. B cells exhibit unusually dynamic XCI, as Xist RNA/heterochromatic marks on the inactive X (Xi) are absent in naive B cells, but return following mitogenic stimulation. Xi gene expression analysis supports dosage compensation, but reveals high levels of XCI escape genes in both naive and activated B cells. Allele-specific OligoPaints indicate similar Xi and Xa territories in B cells that is less compact than in fibroblasts. Allele-specific Hi-C maps reveal a lack of TAD-like structures on the Xi of naive B cells, and alterations in TADs and stronger TAD boundaries at Xi escape genes after mitogenic stimulation. Notably, Xist deletion in B cells reduces Xi compaction and changes TAD boundaries, independent of its localization to the Xi. Our findings provide the first evidence that Xi compaction/small scale organization in lymphocytes impact XCI maintenance and female biased X-linked gene expression.

genetics↗

bioRxiv2022

High-throughput Oligopaint screen identifies druggable regulators of genome folding

Although the molecular rules governing genome organization are being quickly elucidated, relatively few proteins regulating this process have been identified. To address this gap, we developed a fully automated imaging pipeline, called HiDRO (high-throughput DNA or RNA labeling with optimized Oligopaints), that permits quantitative measurement of chromatin interactions across a large number of samples. Using HiDRO, we screened the human druggable genome and identified >300 factors that regulate chromatin folding during interphase, including 43 validated hits that either increase or decrease interactions between topological associating domains (TADs). We discovered that genetic or chemical inhibition of the ubiquitous kinase GSK3A enhances long-range interactions by dysregulating cohesin-mediated chromatin looping. Collectively, these results highlight a noncanonical role for GSK3A signaling in nuclear architecture and underscore the broader utility of HiDRO-based screening to identify novel mechanisms that drive the spatial organization of the genome.

genetics↗