Dynamic microenvironments shape nuclear organization and gene expression

Live imaging has revealed that the regulation of gene expression is largely driven by transient interactions. For example, many regulatory proteins bind chromatin for just seconds, and loop-like genomic contacts are rare and last only minutes. These discoveries have been difficult to reconcile with our canonical models that are predicated on stable and hierarchical interactions. Proteomic microenvironments that concentrate nuclear factors may explain how brief interactions can still mediate gene regulation by creating conditions where reactions occur more frequently. Here, we summarize new imaging technologies and recent discoveries implicating microenvironments as a potential driver of nuclear function. Finally, we propose that key properties of proteomic microenvironments, such as their size, enrichment, and lifetimes, are directly linked to regulatory function.