Live imaging reveals chromatin compaction transitions and dynamic transcriptional bursting during stem cell differentiation in vivo
- Yale University, United States
- Michigan State University, United States
- McGill University, Canada
Abstract
Stem cell differentiation requires dramatic changes in gene expression and global remodeling of chromatin architecture. How and when chromatin remodels relative to the transcriptional, behavioral, and morphological changes during differentiation remain unclear, particularly in an intact tissue context. Here, we develop a quantitative pipeline which leverages fluorescently-tagged histones and longitudinal imaging to track large-scale chromatin compaction changes within individual cells in a live mouse. Applying this pipeline to epidermal stem cells, we reveal that cell-to-cell chromatin compaction heterogeneity within the stem cell compartment emerges independent of cell cycle status, and instead is reflective of differentiation status. Chromatin compaction state gradually transitions over days as differentiating cells exit the stem cell compartment. Moreover, establishing live imaging of Keratin-10 (K10) nascent RNA, which marks the onset of stem cell differentiation, we find that Keratin-10 transcription is highly dynamic and largely precedes the global chromatin compaction changes associated with differentiation. Together, these analyses reveal that stem cell differentiation involves dynamic transcriptional states and gradual chromatin rearrangement.
Data availability
All coding scripts and source datasheets for figure quantifications are made accessible through the Dryad data repository: https://doi.org/10.5061/dryad.5hqbzkh94. Representative raw imaging data are accessible through the same link and full datasets available upon request with no restrictions (due to size) by contacting VG. Source datasheets are included in supplemental information.
Article and author information
Author details
Funding
National Institute of Arthritis and Musculoskeletal and Skin Diseases (1R01AR063663-01)
- Valentina Greco
National Institute of Arthritis and Musculoskeletal and Skin Diseases (1R01AR067755-01A1)
- Valentina Greco
National Institute on Aging (1DP1AG066590-01)
- Valentina Greco
National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01AR072668)
- Valentina Greco
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All procedures involving animal subjects were performed under the approval of the Institutional Animal Care and Use Committee (IACUC) of the Yale School of Medicine (Protocol #2021-11303). All live imaging was performed under 1-2% isoflurane, and ever effort was made to minimize suffering.
Copyright
© 2023, May et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Live imaging reveals chromatin compaction transitions and dynamic transcriptional bursting during stem cell differentiation in vivo
eLife 12:e83444.
https://doi.org/10.7554/eLife.83444
Further reading
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- Developmental Biology
- Stem Cells and Regenerative Medicine
Niches are often found in specific positions in tissues relative to the stem cells they support. Consistency of niche position suggests that placement is important for niche function. However, the complexity of most niches has precluded a thorough understanding of how their proper placement is established. To address this, we investigated the formation of a genetically tractable niche, the Drosophila Posterior Signaling Center (PSC), the assembly of which had not been previously explored. This niche controls hematopoietic progenitors of the lymph gland (LG). PSC cells were previously shown to be specified laterally in the embryo, but ultimately reside dorsally, at the LG posterior. Here, using live-imaging, we show that PSC cells migrate as a tight collective and associate with multiple tissues during their trajectory to the LG posterior. We find that Slit emanating from two extrinsic sources, visceral mesoderm and cardioblasts, is required for the PSC to remain a collective, and for its attachment to cardioblasts during migration. Without proper Slit-Robo signaling, PSC cells disperse, form aberrant contacts, and ultimately fail to reach their stereotypical position near progenitors. Our work characterizes a novel example of niche formation and identifies an extrinsic signaling relay that controls precise niche positioning.
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- Developmental Biology
- Stem Cells and Regenerative Medicine
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