PT  - JOURNAL ARTICLE
AU  - Sarah Lensch
AU  - Michael H. Herschl
AU  - Connor H. Ludwig
AU  - Joydeb Sinha
AU  - Michaela M. Hinks
AU  - Adi Mukund
AU  - Taihei Fujimori
AU  - Lacramioara Bintu
TI  - Dynamic spreading of chromatin-mediated gene silencing and reactivation between neighboring genes in single cells
AID  - 10.1101/2021.11.04.467237
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.11.04.467237
4099  - http://biorxiv.org/content/early/2021/11/04/2021.11.04.467237.short
4100  - http://biorxiv.org/content/early/2021/11/04/2021.11.04.467237.full
AB  - In mammalian cells genes that are in close proximity are coupled transcriptionally: silencing or activating one gene can affect its neighbors. Understanding these dynamics is important for natural processes, such as heterochromatin spreading during development and aging, and when designing synthetic gene regulation. Here, we systematically dissect this process in single cells by recruiting and releasing repressive chromatin regulators at dual-gene synthetic reporters, and measuring how fast gene silencing and reactivation spread as a function of intergenic distance and configuration of insulator elements. We find that silencing by KRAB, associated with histone methylation, spreads between two genes within hours, with a time delay that increases with distance. This fast KRAB-mediated spreading is not blocked by the classical cHS4 insulators. Silencing by histone deacetylase HDAC4 of the upstream gene can also lead to downstream gene silencing, but with a days-long delay that does not change with distance. This slower silencing can sometimes be stopped by insulators. Gene reactivation of neighboring genes is also coupled, with strong promoters and insulators determining the order of reactivation. We propose a new model of multi-gene regulation, where both gene silencing and gene reactivation can act at a distance, allowing for coordinated dynamics via chromatin regulator recruitment.Competing Interest StatementThe authors have declared no competing interest.