Robert A. Coleman, PhD (Asst. Prof., Department of Anatomy and Structural Biology in the Gruss-Lipper Biophotonics Center at the Albert Einstein College of Medicine) will present the following abstract: Years of biochemical experiments have led to the identification of the eukaryotic transcription machinery and a static view of gene regulation. However, mechanisms controlling the dynamics of transcriptional regulation inside a crowded nucleus remains poorly understood. Recent advances in single molecule imaging have begun to shine light on these mechanisms, providing an unprecedented dynamic view of transcriptional regulation in live cells. We and others have found that transcription factors form dynamic hubs of activity in select nuclear compartments. I will discuss how formation of these hubs and recognition of genomic targets is regulated by interactions between transcription factors and the histone tails of chromatin. Transcription factors cycle on and off of their chromatin targets within these hubs on the order of seconds that likely reflect dynamic rates of chromatin remodeling, RNA Polymerase II convoy formation and transcriptional output of a gene. These findings are put into context describing how expression of the p21 cell cycle arrest gene is dynamically regulated by the tumor suppressor p53 protein and chromatin remodelers.