Live imaging of nascent RNA dynamics reveals distinct types of transcriptional pulse regulation

Proc Natl Acad Sci U S A. 2012 May 8;109(19):7350-5. doi: 10.1073/pnas.1117603109. Epub 2012 Apr 23.

Abstract

Transcription of genes can be discontinuous, occurring in pulses or bursts. It is not clear how properties of transcriptional pulses vary between different genes. We compared the pulsing of five housekeeping and five developmentally induced genes by direct imaging of single gene transcriptional events in individual living Dictyostelium cells. Each gene displayed its own transcriptional signature, differing in probability of firing and pulse duration, frequency, and intensity. In contrast to the prevailing view from both prokaryotes and eukaryotes that transcription displays binary behavior, strongly expressed housekeeping genes altered the magnitude of their transcriptional pulses during development. These nonbinary "tunable" responses may be better suited than stochastic switch behavior for housekeeping functions. Analysis of RNA synthesis kinetics using fluorescence recovery after photobleaching implied modulation of housekeeping-gene pulse strength occurs at the level of transcription initiation rather than elongation. In addition, disparities between single cell and population measures of transcript production suggested differences in RNA stability between gene classes. Analysis of stability using RNAseq revealed no major global differences in stability between developmental and housekeeping transcripts, although strongly induced RNAs showed unusually rapid decay, indicating tight regulation of expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Blotting, Northern
  • Dictyostelium / cytology
  • Dictyostelium / genetics*
  • Dictyostelium / growth & development
  • Fluorescence Recovery After Photobleaching
  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental*
  • Genes, Protozoan / genetics
  • Kinetics
  • Models, Genetic
  • RNA Stability
  • RNA, Protozoan / genetics*
  • RNA, Protozoan / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Single-Cell Analysis / methods
  • Transcription, Genetic / genetics*

Substances

  • RNA, Protozoan