Histone code dictates fate biasing of neural crest cells to melanocyte lineage (original) (raw)
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Histone variant dictates fate biasing of neural crest cells to melanocyte lineage
Development, 2020
In the neural crest lineage, progressive fate-restriction and stem cell assignment are critical for both development and regeneration. While the fate-commitment events have distinct transcriptional footprints, fate-biasing is often transitory and metastable, and is thought to be moulded by epigenetic programs. Hence molecular basis of specification is difficult to define. In this study, we establish a role of a histone variant H2a.z.2 in specification of melanocyte lineage from multipotent neural crest cells. Silencing of H2a.z.2 reduces the number of melanocyte precursors in developing zebrafish embryos, and from mouse embryonic stem cells in vitro. We demonstrate that this histone variant occupies nucleosomes in the promoter of key melanocyte determinant Mitf, and enhances its induction. CRISPR-Cas9 based targeted mutagenesis of this gene in zebrafish drastically reduces adult melanocytes, as well as their regeneration. Thereby our study establishes the role of a histone variant u...
pH controlled histone acetylation amplifies melanocyte differentiation program downstream of MITF
2019
Tanning response and melanocyte differentiation are mediated by the central transcription factor MITF. Enigmatically, these involve rapid and selective induction of melanocyte maturation genes, while concomitantly maintaining the expression of other effectors. In this study using cell-based and zebrafish model systems, we elucidate a pH mediated feed-forward mechanism of epigenetic regulation that enables selective amplification of melanocyte maturation program. We demonstrate that MITF activation directly elevates the expression of Carbonic Anhydrase 14 (Ca14) enzyme. Nuclear localized Ca14 increases the intracellular pH, resulting in the activation of histone acetyl transferase activity of p300/CBP. In turn enhanced H3K27 histone acetylation marks of select differentiation genes facilitates their amplified expression by MITF. CRISPR-mediated targeted missense mutation of CA14 in zebrafish results in immature acidic melanocytes with decreased pigmentation, establishing the centrali...
2019
Understanding how fate specification of distinct cell-types from multipotent progenitors occurs is a fundamental question in embryology. Neural crest stem cells (NCSCs) generate extraordinarily diverse derivatives, including multiple neural, skeletogenic and pigment cell fates. Key transcription factors and extracellular signals specifying NCSC lineages remain to be identified, and we have only a little idea of how and when they function together to control fate. Zebrafish have three neural crest-derived pigment cell types, black melanocytes, light-reflecting iridophores and yellow xanthophores, which offer a powerful model for studying the molecular and cellular mechanisms of fate segregation. Mitfa has been identified as the master regulator of melanocyte fate. Here, we show that an Mitf-related transcription factor, Tfec, functions as master regulator of the iridophore fate. Surprisingly, our phenotypic analysis of tfec mutants demonstrates that Tfec also functions in the initial...
Cell Research, 2008
The neural crest (NC) is a unique embryonic structure and contains a remarkable multipotent stem cell population that arises during vertebrate embryogenesis . NC has been referred to as the fourth germ layer because of its great importance during development . NC stem cells arise from the dorsal neural tube during neurolation in early development, then migrate out from the neural tube and along defined pathways throughout the body, where they contribute to numerous cell types and tissues, including melanocytes, ocular and periocular structures, bone and cartilage cells of the cranial skeleton, odontoblasts, autonomic neurons, sensory neurons, enteric neurons, smooth muscle, endocrine cells, chromaffin cells, and glial cells . Although it has long been thought that the fates of NC-derived lineages are controlled by transcription and growth factors, the physiological functions of these factors are not fully known.
Low-level repressive histone marks fine-tune stemness gene transcription in neural stem cells
Coordinated regulation of stemness gene activity by transcriptional and translational mechanisms poise stem cells for a timely cell-state transition during differentiation. Although important for all stemness-to-differentiation transitions, mechanistic understanding of the fine-tuning of stemness gene transcription is lacking due to the compensatory effect of translational control. We used intermediate neural progenitor (INP) identity commitment to define the mechanisms that fine-tune stemness gene transcription in fly neural stem cells (neuroblasts). We demonstrate that the transcription factor FruitlessC(FruC) bindscis-regulatory elements of most genes uniquely transcribed in neuroblasts. Loss offruCfunction alone has no effect on INP commitment but drives INP dedifferentiation when translational control is reduced. FruCnegatively regulates gene expression by promoting low-level enrichment of the repressive histone mark H3K27me3 in genecis-regulatory regions. Identical tofruCloss-...
PLoS Genetics, 2011
The mechanisms generating stably differentiated cell-types from multipotent precursors are key to understanding normal development and have implications for treatment of cancer and the therapeutic use of stem cells. Pigment cells are a major derivative of neural crest stem cells and a key model cell-type for our understanding of the genetics of cell differentiation. Several factors driving melanocyte fate specification have been identified, including the transcription factor and master regulator of melanocyte development, Mitf, and Wnt signalling and the multipotency and fate specification factor, Sox10, which drive mitf expression. While these factors together drive multipotent neural crest cells to become specified melanoblasts, the mechanisms stabilising melanocyte differentiation remain unclear. Furthermore, there is controversy over whether Sox10 has an ongoing role in melanocyte differentiation. Here we use zebrafish to explore in vivo the gene regulatory network (GRN) underlying melanocyte specification and differentiation. We use an iterative process of mathematical modelling and experimental observation to explore methodically the core melanocyte GRN we have defined. We show that Sox10 is not required for ongoing differentiation and expression is downregulated in differentiating cells, in response to Mitfa and Hdac1. Unexpectedly, we find that Sox10 represses Mitf-dependent expression of melanocyte differentiation genes. Our systems biology approach allowed us to predict two novel features of the melanocyte GRN, which we then validate experimentally. Specifically, we show that maintenance of mitfa expression is Mitfa-dependent, and identify Sox9b as providing an Mitfa-independent input to melanocyte differentiation. Our data supports our previous suggestion that Sox10 only functions transiently in regulation of mitfa and cannot be responsible for long-term maintenance of mitfa expression; indeed, Sox10 is likely to slow melanocyte differentiation in the zebrafish embryo. More generally, this novel approach to understanding melanocyte differentiation provides a basis for systematic modelling of differentiation in this and other cell-types.
Cells
Keratinocytes undergo a complex differentiation process, coupled with extensive changes in gene expression through which they acquire distinctive features indispensable for cells that form the external body barrier—epidermis. Disturbed epidermal differentiation gives rise to multiple skin diseases. The involvement of epigenetic factors, such as DNA methylation or histone modifications, in the regulation of epidermal gene expression and differentiation has not been fully recognized yet. In this work we performed a CRISPR/Cas9-mediated knockout of SUV39H1, a gene-encoding H3K9 histone methyltransferase, in HaCaT cells that originate from spontaneously immortalized human keratinocytes and examined changes in the expression of selected differentiation-specific genes located in the epidermal differentiation complex (EDC) and other genomic locations by RT-qPCR. The studied genes revealed a diverse differentiation state-dependent or -independent response to a lower level of H3K9 methylatio...
Development, 2013
Understanding when and how multipotent progenitors segregate into diverse fates is a key question during embryonic development. The neural crest (NC) is an exemplary model system with which to investigate the dynamics of progenitor cell specification, as it generates a multitude of derivatives. Based on 'in ovo' lineage analysis, we previously suggested an early fate restriction of premigratory trunk NC to generate neural versus melanogenic fates, yet the timing of fate segregation and the underlying mechanisms remained unknown. Analysis of progenitors expressing a Foxd3 reporter reveals that prospective melanoblasts downregulate Foxd3 and have already segregated from neural lineages before emigration. When this downregulation is prevented, late-emigrating avian precursors fail to upregulate the melanogenic markers Mitf and MC/1 and the guidance receptor Ednrb2, generating instead glial cells that express P0 and Fabp. In this context, Foxd3 lies downstream of Snail2 and Sox9, constituting a minimal network upstream of Mitf and Ednrb2 to link melanogenic specification with migration. Consistent with the gain-of-function data in avians, loss of Foxd3 function in mouse NC results in ectopic melanogenesis in the dorsal tube and sensory ganglia. Altogether, Foxd3 is part of a dynamically expressed gene network that is necessary and sufficient to regulate fate decisions in premigratory NC. Their timely downregulation in the dorsal neural tube is thus necessary for the switch between neural and melanocytic phases of NC development.
Turkish Journal of Biochemistry
Objectives Gene expression changes during embryonic stem cell (ESC) differentiation is regulated by epigenetic mechanisms. Understanding these can help uncover how cell fate decisions are made during early embryonic development. Comparison of chromatin of ESCs with lineage-committed cells can implicate chromatin factors functional in exit from pluripotency and the choice of proper lineages. Therefore, we quantitatively analyzed histone modifications in mouse ESC differentiation towards neuroectoderm and endoderm. Methods We cultured mouse ESCs (mESCs) and differentiated them towards neuroectoderm or endoderm lineages and performed mass spectrometry on total histones. Subsequent Western blots verified significantly altered H3K36me2. RT-qPCR analyses showed changes in H3K36-specific methyltransferases, demethylases and readers at mESC stage or during neuroectoderm/endoderm commitment. Results We presented quantitative histone modification levels in mESCs and lineage-committed cells. H...