Large-scale chromatin structure of inducible genes: Transcription on a condensed, linear template

Yan Hu, Igor Kireev, Matt Plutz, Nazanin Ashourian, Andrew S. Belmont

Research output: Contribution to journalArticlepeer-review


The structure of interphase chromosomes, and in particular the changes in large-scale chromatin structure accompanying transcriptional activation, remain poorly characterized. Here we use light microscopy and in vivo immunogold labeling to directly visualize the interphase chromosome conformation of 1-2 Mbp chromatin domains formed by multi-copy BAC transgenes containing 130-220 kb of genomic DNA surrounding the DHFR, Hsp70, or MT gene loci. We demonstrate near-endogenous transcription levels in the context of large-scale chromatin fibers compacted nonuniformly well above the 30-nm chromatin fiber. An approximately 1.5-3-fold extension of these large-scale chromatin fibers accompanies transcriptional induction and active genes remain mobile. Heat shock-induced Hsp70 transgenes associate with the exterior of nuclear speckles, with Hsp70 transcripts accumulating within the speckle. Live-cell imaging reveals distinct dynamic events, with Hsp70 transgenes associating with adjacent speckles, nucleating new speckles, or moving to preexisting speckles. Our results call for re-examination of classical models of interphase chromosome organization.

Original languageEnglish (US)
Pages (from-to)87-100
Number of pages14
JournalJournal of Cell Biology
Issue number1
StatePublished - Apr 6 2009

ASJC Scopus subject areas

  • Cell Biology


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