title: The regulation of gene expression during onset of differentiation by nuclear mechanical heterogeneity.
abstract: Embryonic stem (ES) cells exhibit plasticity in nuclear organization as well as variability in gene expression. Although such physicochemical features are important in lineage commitment, mechanistic insights coupling nuclear plasticity and gene expression have not been elucidated. To probe this, we developed single cell micro-patterned assay to map nuclear deformation and its correlation with gene expression. We found an inherent heterogeneity in nuclear pliability of ES cells. Softer nuclei deformed to the underlying substrate geometry while the stiffer ones remained spherical. Stiffer nuclei were strongly correlated with decreased global histone (H3) acetylation and an increase in Lamin A/C expression. Interestingly, these cells also have higher nuclear accumulation of the transcription cofactor MRTF-A (myocardin-related transcription factor A) and an upregulation of its downstream target genes. Taken together, our results provide compelling evidence to show that the mechanical heterogeneity of stem cell nucleus can regulate transcriptional programs during onset of cellular differentiation.
authors.affiliation: Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore, T-Lab #05-01, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Shefali
authors.initials: S
authors.lastname: Talwar
authors.affiliation: Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore, T-Lab #05-01, 5A Engineering Drive 1, Singapore 117411, Singapore; Centre for Bio-Imaging Sciences, NUS, Singapore, T-Lab #05-01, 5A Engineering Drive 1, Singapore 117411, Singapore.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Jain
authors.affiliation: Mechanobiology Institute and Department of Biological Sciences, NUS, Singapore, T-Lab #05-01, 5A Engineering Drive 1, Singapore 117411, Singapore; Centre for Bio-Imaging Sciences, NUS, Singapore, T-Lab #05-01, 5A Engineering Drive 1, Singapore 117411, Singapore. Electronic address: shiva.gvs@gmail.com.
authors.forename: G V
authors.initials: GV
authors.lastname: Shivashankar
mesh_terms: D000107:Acetylation; D000818:Animals; D002454:Cell Differentiation; D019070:Cell Lineage / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D005353:Fibronectins / Q000737:chemistry; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D046228:Microarray Analysis; D018613:Microscopy, Confocal; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome; D015854:Up-Regulation; D000099251:Myocardin
chemical_list: D005353:Fibronectins; D006657:Histones; D009687:Nuclear Proteins; D015534:Trans-Activators; D000099251:Myocardin
keywords: Global gene expression; Micro-patterns; Nuclear mechanics; Stem cells; Transcription factor compartmentalization