scholarly journals Brachyury controls Ciona notochord fate as part of a feedforward network

Development ◽  
2021 ◽  
pp. dev.195230
Author(s):  
Wendy M. Reeves ◽  
Kotaro Shimai ◽  
Konner M. Winkley ◽  
Michael T. Veeman

The notochord is a defining feature of the chordates. The transcription factor Brachyury (Bra) is a key regulator of notochord fate but here we show that it is not a unitary master regulator in the model chordate Ciona. Ectopic Bra expression only partially reprograms other cell types to a notochord-like transcriptional profile and a subset of notochord-enriched genes are unaffected by CRISPR Bra disruption. We identify Foxa.a and Mnx as potential co-regulators and find that combinatorial cocktails are more effective at reprograming other cell types than Bra alone. We reassess the network relationships between Bra, Foxa.a, and other components of the notochord gene regulatory network and find that Foxa.a expression in the notochord is regulated by vegetal FGF signaling. It is a direct activator of Bra expression and has a binding motif that is significantly enriched in the regulatory regions of notochord-enriched genes. These and other results indicate that Bra and Foxa.a act together in a regulatory network dominated by positive feed-forward interactions, with neither being a classically-defined master regulator.

Author(s):  
Wendy M. Reeves ◽  
Kotaro Shimai ◽  
Konner M. Winkley ◽  
Michael T. Veeman

AbstractThe notochord is a defining feature of the chordates. The transcription factor Brachyury (Bra) is a key regulator of notochord fate but here we show that it is not a unitary master regulator in the model chordate Ciona. Ectopic Bra expression only partially reprograms other cell types to a notochord-like transcriptional profile and a subset of notochord-enriched genes are unaffected by CRISPR Bra disruption. We identify Foxa.a and Mnx as potential co-regulators and find that combinatorial cocktails are more effective at reprograming other cell types than Bra alone. We reassess the network relationships between Bra, Foxa.a and other components of the notochord gene regulatory network and find that Foxa.a expression in the notochord is regulated by vegetal FGF signaling. It is a direct activator of Bra expression and has a binding motif that is significantly enriched in the regulatory regions of notochord-enriched genes. These and other results indicate that Bra and Foxa.a act together in a regulatory network dominated by positive feed-forward interactions, with neither being a classically-defined master regulator.


2018 ◽  
Vol 12 (9) ◽  
pp. 1014-1026 ◽  
Author(s):  
Masoumeh Farahani ◽  
Mostafa Rezaei–Tavirani ◽  
Hakimeh Zali ◽  
Afsaneh Arefi Oskouie ◽  
Meisam Omidi ◽  
...  

2018 ◽  
Author(s):  
Brooke E. Chambers ◽  
Gary F. Gerlach ◽  
Karen H. Chen ◽  
Eleanor G. Clark ◽  
Ignaty Leshchiner ◽  
...  

AbstractRenal functional units known as nephrons undergo patterning events during development that create a segmental array of cellular populations with discrete physiological tasks. Knowledge about the terminal differentiation programs of each nephron segment has central importance for understanding kidney disease and to advance regenerative medicine, as mammalian nephrons grown in organoid cultures from pluripotent cells fail to terminally differentiate. Here, from a novel forward genetic screen using zebrafish we report the discovery that transcription factor AP-2 alpha (tfap2a) coordinates a gene regulatory network that controls the progression of nephron distal segment progenitors into the differentiated state. Overexpression of tfap2a rescued differentiation in mutants and caused ectopic expression of distal segment markers in wild-type nephrons, indicating tfap2a is sufficient to instigate the distal segment differentiation program. tfap2a/2b deficiency exacerbated distal nephron segment differentiation defects, revealing functional redundancy where tfap2a has a dominant role upstream of its family member. With further genetic studies, we assembled a blueprint of the tfap2a gene regulatory network during nephrogenesis. We demonstrate that tfap2a acts downstream of Iroquois homeobox 3b, a conserved distal lineage transcription factor. tfap2a controls a circuit consisting of irx1a, tfap2b, and genes encoding solute transporters that dictate the specialized metabolic functions of the distal nephron segments, and we show for the first time that this regulatory node is distinct from the pathway circuits controlling aspects such as apical-basal polarity and ciliogenesis during the differentiation process. Thus, our studies reveal new insights into the genetic control of differentiation, where tfap2a regulates the suite of segment transporter traits. These findings have relevance for understanding renal birth defects, as well as efforts to recapitulate nephrogenesis in vivo to make functional units that can facilitate organoid applications such as drug discovery and regenerative therapies.Summary StatementHere, we report for the first time that transcription factor AP-2 alpha (tfap2a) controls the progression from nephron progenitor into the fully differentiated state. This fundamentally deepens our knowledge about the genetic control of kidney development.


2021 ◽  
Author(s):  
Matthias Christian Vogg ◽  
Jaroslav Ferenc ◽  
Wanda Christa Buzgariu ◽  
Chrystelle Perruchoud ◽  
Panagiotis Papasaikas ◽  
...  

The molecular mechanisms that maintain cell identities and prevent transdifferentiation remain mysterious. Interestingly, both dedifferentiation and transdifferentiation are transiently reshuffled during regeneration. Therefore, organisms that regenerate readily offer a fruitful paradigm to investigate the regulation of cell fate stability. Here, we used Hydra as a model system and show that Zic4 silencing is sufficient to induce transdifferentiation of tentacle into foot cells. We identified a Wnt-controlled Gene Regulatory Network that controls a transcriptional switch of cell identity. Furthermore, we show that this switch also controls the re-entry into the cell cycle. Our data indicate that maintenance of cell fate by a Wnt-controlled GRN is a key mechanism during both homeostasis and regeneration.


eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Carine Gubelmann ◽  
Petra C Schwalie ◽  
Sunil K Raghav ◽  
Eva Röder ◽  
Tenagne Delessa ◽  
...  

Adipose tissue is a key determinant of whole body metabolism and energy homeostasis. Unraveling the regulatory mechanisms underlying adipogenesis is therefore highly relevant from a biomedical perspective. Our current understanding of fat cell differentiation is centered on the transcriptional cascades driven by the C/EBP protein family and the master regulator PPARγ. To elucidate further components of the adipogenic gene regulatory network, we performed a large-scale transcription factor (TF) screen overexpressing 734 TFs in mouse pre-adipocytes and probed their effect on differentiation. We identified 22 novel pro-adipogenic TFs and characterized the top ranking TF, ZEB1, as being essential for adipogenesis both in vitro and in vivo. Moreover, its expression levels correlate with fat cell differentiation potential in humans. Genomic profiling further revealed that this TF directly targets and controls the expression of most early and late adipogenic regulators, identifying ZEB1 as a central transcriptional component of fat cell differentiation.


PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244794 ◽  
Author(s):  
Kleio Petratou ◽  
Samantha A. Spencer ◽  
Robert N. Kelsh ◽  
James A. Lister

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 specification of all three pigment cell-types, although the melanocyte and xanthophore lineages recover later. We show that Mitfa represses tfec expression, revealing a likely mechanism contributing to the decision between melanocyte and iridophore fate. Our data are consistent with the long-standing proposal of a tripotent progenitor restricted to pigment cell fates. Moreover, we investigate activation, maintenance and function of tfec in multipotent NCSCs, demonstrating for the first time its role in the gene regulatory network forming and maintaining early neural crest cells. In summary, we build on our previous work to characterise the gene regulatory network governing iridophore development, establishing Tfec as the master regulator driving iridophore specification from multipotent progenitors, while shedding light on possible cellular mechanisms of progressive fate restriction.


2020 ◽  
Vol 11 ◽  
Author(s):  
Subham Seal ◽  
Anne H. Monsoro-Burq

The neural crest (NC) cells and cranial placodes are two ectoderm-derived innovations in vertebrates that led to the acquisition of a complex head structure required for a predatory lifestyle. They both originate from the neural border (NB), a portion of the ectoderm located between the neural plate (NP), and the lateral non-neural ectoderm. The NC gives rise to a vast array of tissues and cell types such as peripheral neurons and glial cells, melanocytes, secretory cells, and cranial skeletal and connective cells. Together with cells derived from the cranial placodes, which contribute to sensory organs in the head, the NC also forms the cranial sensory ganglia. Multiple in vivo studies in different model systems have uncovered the signaling pathways and genetic factors that govern the positioning, development, and differentiation of these tissues. In this literature review, we give an overview of NC and placode development, focusing on the early gene regulatory network that controls the formation of the NB during early embryonic stages, and later dictates the choice between the NC and placode progenitor fates.


2010 ◽  
Vol 62 (2) ◽  
pp. 250-264 ◽  
Author(s):  
Salma Balazadeh ◽  
Hamad Siddiqui ◽  
Annapurna D. Allu ◽  
Lilian P. Matallana-Ramirez ◽  
Camila Caldana ◽  
...  

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Wenqing Jean Lee ◽  
Sumantra Chatterjee ◽  
Sook Peng Yap ◽  
Siew Lan Lim ◽  
Xing Xing ◽  
...  

Embryogenesis is an intricate process involving multiple genes and pathways. Some of the key transcription factors controlling specific cell types are the Sox trio, namely, Sox5, Sox6, and Sox9, which play crucial roles in organogenesis working in a concerted manner. Much however still needs to be learned about their combinatorial roles during this process. A developmental genomics and systems biology approach offers to complement the reductionist methodology of current developmental biology and provide a more comprehensive and integrated view of the interrelationships of complex regulatory networks that occur during organogenesis. By combining cell type-specific transcriptome analysis and in vivo ChIP-Seq of the Sox trio using mouse embryos, we provide evidence for the direct control of Sox5 and Sox6 by the transcriptional trio in the murine model and by Morpholino knockdown in zebrafish and demonstrate the novel role of Tgfb2, Fbxl18, and Tle3 in formation of Sox5, Sox6, and Sox9 dependent tissues. Concurrently, a complete embryonic gene regulatory network has been generated, identifying a wide repertoire of genes involved and controlled by the Sox trio in the intricate process of normal embryogenesis.


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