Understanding gene regulation in nuclear space

ongoing

There is accumulating evidence for a new gene expression paradigm, in which genes and transcription factors cooperate to create specialized nuclear hotspots optimized for transcription. How hotspots form, and how they impact transcription, however, is unclear. This is mostly because mechanistic and functional approaches have been limited by the large number of hotspots per nucleus, their small size, and their transient nature. Here, wThere is accumulating evidence for a new gene expression paradigm, in which genes and transcription factors cooperate to create specialized nuclear hotspots optimized for transcription. How hotspots form, and how they impact transcription, however, is unclear. This is mostly because mechanistic and functional approaches have been limited by the large number of hotspots per nucleus, their small size, and their transient nature. Here, we will take advantage of two hotspots that precede all other transcription during zebrafish embryogenesis. The hotspots are large, isolated, and relatively long-lived, and we can interfere with their formation specifically. They therefore provide an excellent opportunity to study nuclear hotspots. The stereotyped activation of transcription during embryogenesis further provides the opportunity to determine the effect of hotspots on gene expression. In Aim 1, we will determine what triggers hotspot formation, identify the components of hotspots and the order in which they come together, and determine the enrichment of components in hotspots compared to nucleoplasm. In Aim 2, we turn our attention to the genes that come together in these hotspots. We will develop a method to visualize single copy genes live and use this to determine how genes come together in transcription hotspots to be activated. Together, the work we propose will reveal how stable gene expression programs can emerge from the self- organizing interactions between chromatin, transcription factors and emergent properties of transcribed sites.