Transcriptional burst fraction and size dynamics during lens fiber cell differentiation and detailed insights into the denucleation process

Saima Limi, Adrien Senecal, Robert A. Coleman, Melissa Lopez-Jones, Peng Guo, Christina Polumbo, Robert H. Singer, Arthur I. Skoultchi, Ales Cvekl

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Genes are transcribed in irregular pulses of activity termed transcriptional bursts. Cellular differentiation requires coordinated gene expression; however, it is unknown whether the burst fraction (i.e. the number of active phases of transcription) or size/intensity (the number of RNA molecules produced within a burst) changes during cell differentiation. In the ocular lens, the positions of lens fiber cells correlate precisely with their differentiation status, and the most advanced cells degrade their nuclei. Here, we examined the transcriptional parameters of the -actin and lens differentiation–specific -, -, and -crystallin genes by RNA fluorescent in situ hybridization (FISH) in the lenses of embryonic day (E) E12.5, E14.5, and E16.5 mouse embryos and newborns. We found that cellular differentiation dramatically alters the burst fraction in synchronized waves across the lens fiber cell compartment with less dramatic changes in burst intensity. Surprisingly, we observed nascent transcription of multiple genes in nuclei just before nuclear destruction. Nuclear condensation was accompanied by transfer of nuclear proteins, including histone and nonhistone proteins, to the cytoplasm. Although lens-specific deletion of the chromatin remodeler SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 5 (Smarca5/Snf2h) interfered with denucleation, persisting nuclei remained transcriptionally competent and exhibited changes in both burst intensity and fraction depending on the gene examined. Our results uncover the mechanisms of nascent transcriptional control during differentiation and chromatin remodeling, confirm the burst fraction as the major factor adjusting gene expression levels, and reveal transcriptional competence of fiber cell nuclei even as they approach disintegration.

Original languageEnglish (US)
Pages (from-to)13176-13190
Number of pages15
JournalJournal of Biological Chemistry
Volume293
Issue number34
DOIs
StatePublished - Jan 1 2018

Fingerprint

Lenses
Cell Differentiation
Fibers
Genes
Chromatin
Transcription
Actins
Gene expression
RNA
Gene Expression
Crystalline Lens
Crystallins
Chromatin Assembly and Disassembly
Nuclear Proteins
Cell Nucleus
Fluorescence In Situ Hybridization
Disintegration
Histones
Mental Competency
Cytoplasm

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Transcriptional burst fraction and size dynamics during lens fiber cell differentiation and detailed insights into the denucleation process. / Limi, Saima; Senecal, Adrien; Coleman, Robert A.; Lopez-Jones, Melissa; Guo, Peng; Polumbo, Christina; Singer, Robert H.; Skoultchi, Arthur I.; Cvekl, Ales.

In: Journal of Biological Chemistry, Vol. 293, No. 34, 01.01.2018, p. 13176-13190.

Research output: Contribution to journalArticle

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