Latino Studies at New York University

Timothee Lionnet

Albert Einstein College of Medicine

October 25, 2011

Probing transcription regulation in live cells, one mRNA at a time

In order to ensure stable expression of an endogenous protein, the cell has to regulate each step of gene expression, starting with transcription.  How transcription is temporally regulated is still an open question.  Here we observe in live cells the real-time transcription of an endogeneous gene, b-actin.  To achieve this, we use a transgenic mouse model where RNA stem loops knocked in the untranslated region of b-actin mRNA are bound to a flourescent MS2 reporter protein.  Using the unique capability of following transcriptional events in single cells in real time, we are able to describe the regulation strategies evolved to control mRNA synthesis: whether alleles are synchronous, whether transcription occurs continuously or in bursts, or how transcription is modulated through the cell cycle.  Importantly, we also investigate how cells respond transciptionally to various signaling cues, and test models of gene activation.