p63 and Brg1 control developmentally regulated higher-order chromatin remodelling at the epidermal differentiation complex locus in epidermal progenitor cells

Abstract

Chromatin structural states and their remodelling, including higher-order chromatin folding and three-dimensional (3D) genome organisation, play an important role in the control of gene expression. The role of 3D genome organisation in the control and execution of lineage-specific transcription programmes during the development and differentiation of multipotent stem cells into specialised cell types remains poorly understood. Here, we show that substantial remodelling of the higher-order chromatin structure of the epidermal differentiation complex (EDC), a keratinocyte lineage-specific gene locus on mouse chromosome 3, occurs during epidermal morphogenesis. During epidermal development, the locus relocates away from the nuclear periphery towards the nuclear interior into a compartment enriched in SC35-positive nuclear speckles. Relocation of the EDC locus occurs prior to the full activation of EDC genes involved in controlling terminal keratinocyte differentiation and is a lineage-specific, developmentally regulated event controlled by transcription factor p63, a master regulator of epidermal development. We also show that, in epidermal progenitor cells, p63 directly regulates the expression of the ATP-dependent chromatin remodeller Brg1, which binds to distinct domains within the EDC and is required for relocation of the EDC towards the nuclear interior. Furthermore, Brg1 also regulates gene expression within the EDC locus during epidermal morphogenesis. Thus, p63 and its direct target Brg1 play an essential role in remodelling the higher-order chromatin structure of the EDC and in the specific positioning of this locus within the landscape of the 3D nuclear space, as required for the efficient expression of EDC genes in epidermal progenitor cells during skin development.

The cytolinker plectin regulates nuclear mechanotransduction in keratinocytes

“…In addition, histone de-acetylation correlates with decreased cell spreading, reduced nuclear size and terminal differentiation on micro-patterned substrates (Connelly et al, 2011). During terminal differentiation in the mouse epidermis, increased clusters of heterochromatin accompany decreased nuclear volume (Gdula et al, 2013), and regulators of nuclear architecture and chromatin remodelling, such as Ezh2, Satb1 and Brg1, are required for positioning and expression of genes within the epidermal differentiation complex (EDC) (Botchkarev et al, 2012;Ezhkova et al, 2009;Fessing et al, 2011;Mardaryev et al, 2014). Thus, decreased nuclear volume on small micro-patterns might facilitate terminal differentiation by physically forcing chromatin condensation.…”

p53/p63/p73 in the Epidermis in Health and Disease

“…For instance, p63 directly regulates expression of several genes encoding the genome organizer and AT-rich-binding protein Satb1, as well as ATP-dependent chromatin remodelers Lsh and Brg1 in epidermal keratinocytes (Fessing et al 2011;Keyes et al 2011;Mardaryev et al 2014). Both Brg1 and Satb1 play important roles in mediating a p63-regulated program of higherorder chromatin remodeling within the epidermal differentiation complex (EDC) locus.…”

“…Brg1 regulates relocation of the EDC away from the nuclear periphery into the nuclear interior and propinquity with nuclear speckles. This is followed by Satb1-regulated arrangement of chromatin conformation within the central domain of the locus, which contains a large number of genes activated during terminal keratinocyte differentiation (Fessing et al 2011;Mardaryev et al 2014). In turn, Lsh regulates chromatin remodeling and mediates DNp63-dependent proliferation and survival of Keratin 15-positive stem cells in the skin (Keyes et al 2011).…”

The Epigenetic Regulation of Wound Healing

“…53 In developing epidermis, Brg1 serves as direct target for p63 transcription factor and regulates relocation of the epidermal differentiation complex (EDC) locus toward nuclear interior associated with marked increase of gene expression within the locus. 54 Higher-order chromatin remodeling and 3D genome organization Higher-order chromatin structure refers to the chromatin folding beyond ''beads on the string'' repeat. The position of chromosomes and subchromosomal regions is nonrandom within the interphase nucleus.…”