Mechanically Induced Chromatin Condensation Requires Cellular Contractility in Mesenchymal Stem Cells

Su Jin Heo, Woojin M. Han, Spencer Szczesny, Brian D. Cosgrove, Dawn M. Elliott, David A. Lee, Randall L. Duncan, Robert L. Mauck

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Mechanical cues play important roles in directing the lineage commitment of mesenchymal stem cells (MSCs). In this study, we explored the molecular mechanisms by which dynamic tensile loading (DL) regulates chromatin organization in this cell type. Our previous findings indicated that the application of DL elicited a rapid increase in chromatin condensation through purinergic signaling mediated by ATP. Here, we show that the rate and degree of condensation depends on the frequency and duration of mechanical loading, and that ATP release requires actomyosin-based cellular contractility. Increases in baseline cellular contractility via the addition of an activator of G-protein coupled receptors (lysophosphatidic acid) induced rapid ATP release, resulting in chromatin condensation independent of loading. Conversely, inhibition of contractility through pretreatment with either a RhoA/Rock inhibitor (Y27632) or MLCK inhibitor (ML7) abrogated ATP release in response to DL, blocking load-induced chromatin condensation. With loading, ATP release occurred very rapidly (within the first 10–20 s), whereas changes in chromatin occurred at a later time point (∼10 min), suggesting a downstream biochemical pathway mediating this process. When cells were pretreated with blockers of the transforming growth factor (TGF) superfamily, purinergic signaling in response to DL was also eliminated. Further analysis showed that this pretreatment decreased contractility, implicating activity in the TGF pathway in the establishment of the baseline contractile state of MSCs (in the absence of exogenous ligands). These data indicate that chromatin condensation in response to DL is regulated through the interplay between purinergic and RhoA/Rock signaling, and that ligandless activity in the TGF/bone morphogenetic proteins signaling pathway contributes to the establishment of baseline contractility in MSCs.

Original languageEnglish (US)
Pages (from-to)864-874
Number of pages11
JournalBiophysical journal
Volume111
Issue number4
DOIs
StatePublished - Aug 23 2016

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Mesenchymal Stromal Cells
Chromatin
Adenosine Triphosphate
Transforming Growth Factors
Actomyosin
Bone Morphogenetic Proteins
G-Protein-Coupled Receptors
Cues
Ligands

All Science Journal Classification (ASJC) codes

  • Biophysics

Cite this

Heo, Su Jin ; Han, Woojin M. ; Szczesny, Spencer ; Cosgrove, Brian D. ; Elliott, Dawn M. ; Lee, David A. ; Duncan, Randall L. ; Mauck, Robert L. / Mechanically Induced Chromatin Condensation Requires Cellular Contractility in Mesenchymal Stem Cells. In: Biophysical journal. 2016 ; Vol. 111, No. 4. pp. 864-874.
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Heo, SJ, Han, WM, Szczesny, S, Cosgrove, BD, Elliott, DM, Lee, DA, Duncan, RL & Mauck, RL 2016, 'Mechanically Induced Chromatin Condensation Requires Cellular Contractility in Mesenchymal Stem Cells', Biophysical journal, vol. 111, no. 4, pp. 864-874. https://doi.org/10.1016/j.bpj.2016.07.006

Mechanically Induced Chromatin Condensation Requires Cellular Contractility in Mesenchymal Stem Cells. / Heo, Su Jin; Han, Woojin M.; Szczesny, Spencer; Cosgrove, Brian D.; Elliott, Dawn M.; Lee, David A.; Duncan, Randall L.; Mauck, Robert L.

In: Biophysical journal, Vol. 111, No. 4, 23.08.2016, p. 864-874.

Research output: Contribution to journalArticle

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