Dynamics of Notch-dependent transcriptional bursting in its native context

Abstract

Transcription is well known to be inherently stochastic and episodic, but the regulation of transcriptional dynamics is not well understood. Here we analyze how Notch signaling modulates transcriptional bursting during animal development. Our focus is Notch regulation of transcription in germline stem cells of the nematode C. elegans. Using the MS2 system to visualize nascent transcripts and live imaging to record dynamics, we analyze bursting as a function of position within the intact animal. We find that Notch-dependent transcriptional activation is indeed \"bursty\"; that wild-type Notch modulates burst duration (ON-time) rather than duration of pauses between bursts (OFF-time) or mean burst intensity; and that a mutant Notch receptor, which is compromised for assembly into the Notch transcription factor complex, primarily modifies burst size (duration x intensity). To our knowledge, this work is the first to visualize regulation of metazoan transcriptional bursting by a canonical signaling pathway in its native context.\n\nHIGHLIGHTSO_LINotch-dependent transcriptional bursts are spatially graded across the stem cell pool\nC_LIO_LIBurst duration is the key determinant of Notch-dependent transcriptional probability\nC_LIO_LINotch NICD strength influences both burst duration and intensity\nC_LIO_LINotch dynamics are largely stochastic for consecutive bursts at the same chromosomal locus\nC_LI