Patterning of the angiosperm female gametophyte through the prism of theoretical paradigms

2014 ◽  
Vol 42 (2) ◽  
pp. 332-339 ◽  
Author(s):  
Dmytro S. Lituiev ◽  
Ueli Grossniklaus
Keyword(s):  
Cell Fate ◽  
Female Gametophyte ◽  
Positional Information ◽  
Cell Types ◽  
Theoretical Frameworks ◽  
Cell Specification ◽  
Distinct Cell ◽  
Dynamical Nature ◽  
Theoretical Paradigms ◽  
Lines Of Evidence

The FG (female gametophyte) of flowering plants (angiosperms) is a simple highly polar structure composed of only a few cell types. The FG develops from a single cell through mitotic divisions to generate, depending on the species, four to 16 nuclei in a syncytium. These nuclei are then partitioned into three or four distinct cell types. The mechanisms underlying the specification of the nuclei in the FG has been a focus of research over the last decade. Nevertheless, we are far from understanding the patterning mechanisms that govern cell specification. Although some results were previously interpreted in terms of static positional information, several lines of evidence now show that local interactions are important. In the present article, we revisit the available data on developmental mutants and cell fate markers in the light of theoretical frameworks for biological patterning. We argue that a further dissection of the mechanisms may be impeded by the combinatorial and dynamical nature of developmental cues. However, accounting for these properties of developing systems is necessary to disentangle the diversity of the phenotypic manifestations of the underlying molecular interactions.

scholarly journals Regulatory network characterization in development: challenges and opportunities

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1477
Author(s):  
Guangdun Peng ◽  
Jing-Dong J. Han
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Regulatory Networks ◽  
Stem Cell Differentiation ◽  
Cell Types ◽  
Mammalian Development ◽  
Distinct Cell ◽  
Challenges And Opportunities ◽  
Cell Processes ◽  
Early Mammalian Development

Embryonic development and stem cell differentiation, during which coordinated cell fate specification takes place in a spatial and temporal context, serve as a paradigm for studying the orderly assembly of gene regulatory networks (GRNs) and the fundamental mechanism of GRNs in driving lineage determination. However, knowledge of reliable GRN annotation for dynamic development regulation, particularly for unveiling the complex temporal and spatial architecture of tissue stem cells, remains inadequate. With the advent of single-cell RNA sequencing technology, elucidating GRNs in development and stem cell processes poses both new challenges and unprecedented opportunities. This review takes a snapshot of some of this work and its implication in the regulative nature of early mammalian development and specification of the distinct cell types during embryogenesis.

scholarly journals Recent advances in understanding female gametophyte development

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 804 ◽  
Author(s):  
Debra J Skinner ◽  
Venkatesan Sundaresan
Keyword(s):  
Cell Fate ◽  
Female Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Cell Types ◽  
Egg Cell ◽  
Male Gametes ◽  
Reproductive Unit ◽  
Genetic Mechanisms ◽  
Female Gametophyte Development

The haploid female gametophyte (embryo sac) is an essential reproductive unit of flowering plants, usually comprising four specialized cell types, including the female gametes (egg cell and central cell). The differentiation of these cells relies on spatial signals which pattern the gametophyte along a proximal-distal axis, but the molecular and genetic mechanisms by which cell identities are determined in the embryo sac have long been a mystery. Recent identification of key genes for cell fate specification and their relationship to hormonal signaling pathways that act on positional cues has provided new insights into these processes. A model for differentiation can be devised with egg cell fate as a default state of the female gametophyte and with other cell types specified by the action of spatially regulated factors. Cell-to-cell communication within the gametophyte is also important for maintaining cell identity as well as facilitating fertilization of the female gametes by the male gametes (sperm cells).

scholarly journals Control of neural crest multipotency by Wnt signaling and the Lin28/let-7 axis

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Debadrita Bhattacharya ◽  
Megan Rothstein ◽  
Ana Paula Azambuja ◽  
Marcos Simoes-Costa
Keyword(s):  
Cell Differentiation ◽  
Neural Crest ◽  
Positional Information ◽  
Cell Types ◽  
Transcriptional Networks ◽  
Dependent Manner ◽  
Regulatory Circuit ◽  
Distinct Cell ◽  
Cell Niche ◽  
Migratory Cells

A crucial step in cell differentiation is the silencing of developmental programs underlying multipotency. While much is known about how lineage-specific genes are activated to generate distinct cell types, the mechanisms driving suppression of stemness are far less understood. To address this, we examined the regulation of the transcriptional network that maintains progenitor identity in avian neural crest cells. Our results show that a regulatory circuit formed by Wnt, Lin28a and let-7 miRNAs controls the deployment and the subsequent silencing of the multipotency program in a position-dependent manner. Transition from multipotency to differentiation is determined by the topological relationship between the migratory cells and the dorsal neural tube, which acts as a Wnt-producing stem cell niche. Our findings highlight a mechanism that rapidly silences complex regulatory programs, and elucidate how transcriptional networks respond to positional information during cell differentiation.

scholarly journals Co-ordinating retinal histogenesis: early cell cycle exit enhances early cell fate determination in the Xenopus retina

Development ◽  
2002 ◽  
Vol 129 (10) ◽  
pp. 2435-2446 ◽  
Author(s):  
Shin-ichi Ohnuma ◽  
Susannah Hopper ◽  
Kevin C. Wang ◽  
Anna Philpott ◽  
William A. Harris
Keyword(s):  
Cell Cycle ◽  
Cell Fate ◽  
Kinase Inhibitor ◽  
Cell Types ◽  
Retinal Ganglion ◽  
Cell Cycle Exit ◽  
Cyclin E1 ◽  
Distinct Cell ◽  
Cyclin Kinase Inhibitor ◽  
Notch Activation

The laminar arrays of distinct cell types in the vertebrate retina are built by a histogenic process in which cell fate is correlated with birth order. To explore this co-ordination mechanistically, we altered the relative timing of cell cycle exit in the developing Xenopus retina and asked whether this affected the activity of neural determinants. We found that Xath5, a bHLH proneural gene that promotes retinal ganglion cell (RGC) fate, (Kanekar, S., Perron, M., Dorsky, R., Harris, W. A., Jan, L. Y., Jan, Y. N. and Vetter, M. L. (1997) Neuron19, 981-994), does not cause these cells to be born prematurely. To drive cells out of the cell cycle early, therefore, we misexpressed the cyclin kinase inhibitor, p27Xic1. We found that early cell cycle exit potentiates the ability of Xath5 to promote RGC fate. Conversely, the cell cycle activator, cyclin E1, which inhibits cell cycle exit, biases Xath5-expressing cells toward later neuronal fates. We found that Notch activation in this system caused cells to exit the cell cycle prematuely, and when it is misexpressed with Xath5, it also potentiates the induction of RGCs. The potentiation is counteracted by co-expression of cyclin E1. These results suggest a model of histogenesis in which the activity of factors that promote early cell cycle exit enhances the activity of factors that promote early cellular fates.

scholarly journals Single-cell transcriptomics identifies divergent developmental lineage trajectories during human pituitary development

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Shu Zhang ◽  
Yueli Cui ◽  
Xinyi Ma ◽  
Jun Yong ◽  
Liying Yan ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Fate ◽  
Developmental Trajectories ◽  
Cell Types ◽  
Cellular Heterogeneity ◽  
Human Pituitary ◽  
Pituitary Development ◽  
Physiological Processes ◽  
Distinct Cell ◽  
Transcriptional Landscape

Abstract The anterior pituitary gland plays a central role in regulating various physiological processes, including body growth, reproduction, metabolism and stress response. Here, we perform single-cell RNA-sequencing (scRNA-seq) of 4113 individual cells from human fetal pituitaries. We characterize divergent developmental trajectories with distinct transitional intermediate states in five hormone-producing cell lineages. Corticotropes exhibit an early intermediate state prior to full differentiation. Three cell types of the PIT-1 lineage (somatotropes, lactotropes and thyrotropes) segregate from a common progenitor coexpressing lineage-specific transcription factors of different sublineages. Gonadotropes experience two multistep developmental trajectories. Furthermore, we identify a fetal gonadotrope cell subtype expressing the primate-specific hormone chorionic gonadotropin. We also characterize the cellular heterogeneity of pituitary stem cells and identify a hybrid epithelial/mesenchymal state and an early-to-late state transition. Here, our results provide insights into the transcriptional landscape of human pituitary development, defining distinct cell substates and subtypes and illustrating transcription factor dynamics during cell fate commitment.

scholarly journals Single-cell analysis of cell fate bifurcation in the chordate Ciona

2020 ◽  
Author(s):  
Konner M. Winkley ◽  
Wendy M. Reeves ◽  
Michael T. Veeman
Keyword(s):  
Single Cell ◽  
Cell Fate ◽  
Single Cell Analysis ◽  
Cell Types ◽  
Embryonic Cell ◽  
Major Mechanism ◽  
Divergent Gene ◽  
Distinct Cell ◽  
Hourglass Model ◽  
Almost All

AbstractInductive signaling interactions between different cell types are a major mechanism for the further diversification of embryonic cell fates. Most blastomeres in the model chordate Ciona robusta become restricted to a single predominant fate between the 64-cell and mid-gastrula stages. We used single-cell RNAseq spanning this period to identify 53 distinct cell states, 25 of which are dependent on a MAPK-mediated signal critical to early Ciona patterning. Divergent gene expression between newly bifurcated sibling cell types is dominated by upregulation in the induced cell type. These upregulated genes typically include numerous transcription factors and not just one or two key regulators. The Ets family transcription factor Elk1/3/4 is upregulated in almost all the putatively direct inductions, indicating that it may act in an FGF-dependent feedback loop. We examine several bifurcations in detail and find support for a ‘broad-hourglass’ model of cell fate specification in which many genes are induced in parallel to key tissue-specific transcriptional regulators via the same set of transcriptional inputs.

scholarly journals On the edge: Evolution of polarity protein BASL and the capacity for stomatal lineage asymmetric divisions

2021 ◽  
Author(s):  
Ido Nir ◽  
Gabriel O Amador ◽  
Yan Gong ◽  
Nicole K Smoot ◽  
Le Cai ◽  
...  
Keyword(s):  
Cell Fate ◽  
Cell Types ◽  
Cell Fates ◽  
Division Plane ◽  
Asymmetric Cell Divisions ◽  
Cell Divisions ◽  
Distinct Cell ◽  
Asymmetric Divisions ◽  
Stem Cell Divisions ◽  
Stomatal Lineage

Asymmetric and oriented stem cell divisions enable the continued production of patterned tissues. The molecules that guide these divisions include several polarity proteins that are localized to discrete plasma membrane domains, are differentially inherited during asymmetric divisions, and whose scaffolding activities can guide division plane orientation and subsequent cell fates. In the stomatal lineages on the surfaces of plant leaves, asymmetric and oriented divisions create distinct cell types in physiologically optimized patterns. The polarity protein BASL is a major regulator of stomatal lineage division and cell fate asymmetries in Arabidopsis, but its role in the stomatal lineages of other plants was unclear. Here, using phylogenetic and functional assays, we demonstrate that BASL is a dicot specific polarity protein. Among dicots, divergence in BASLs roles may reflect some intrinsic protein differences, but more likely reflects previously unappreciated differences in how asymmetric cell divisions are employed for pattern formation in different species. This multi-species analysis therefore provides insight into the evolution of a unique polarity regulator and into the developmental choices available to cells as they build and pattern tissues.

scholarly journals spalt-dependent switching between two cell fates that are induced by the Drosophila EGF receptor

Development ◽  
2001 ◽  
Vol 128 (5) ◽  
pp. 723-732 ◽  
Author(s):  
P.R. Elstob ◽  
V. Brodu ◽  
A.P. Gould
Keyword(s):  
Cell Fate ◽  
Animal Species ◽  
Egf Receptor ◽  
Zinc Finger Protein ◽  
Cell Types ◽  
Chordotonal Organ ◽  
Egfr Signaling ◽  
Cell Fates ◽  
Finger Protein ◽  
Distinct Cell

Signaling from the EGF receptor (EGFR) can trigger the differentiation of a wide variety of cell types in many animal species. We have explored the mechanisms that generate this diversity using the Drosophila peripheral nervous system. In this context, Spitz (SPI) ligand can induce two alternative cell fates from the dorsolateral ectoderm: chordotonal sensory organs and non-neural oenocytes. We show that the overall number of both cell types that are induced is controlled by the degree of EGFR signaling. In addition, the spalt (sal) gene is identified as a critical component of the oenocyte/chordotonal fate switch. Genetic and expression analyses indicate that the SAL zinc-finger protein promotes oenocyte formation and supresses chordotonal organ induction by acting both downstream and in parallel to the EGFR. To explain these findings, we propose a prime-and-respond model. Here, sal functions prior to signaling as a necessary but not sufficient component of the oenocyte prepattern that also serves to raise the apparent threshold for induction by SPI. Subsequently, sal-dependent SAL upregulation is triggered as part of the oenocyte-specific EGFR response. Thus, a combination of SAL in the responding nucleus and increased SPI ligand production sets the binary cell-fate switch in favour of oenocytes. Together, these studies help to explain how one generic signaling pathway can trigger the differentiation of two distinct cell types.

scholarly journals Neuronal cell fate diversification controlled by sub-temporal action of Kruppel

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Johannes Stratmann ◽  
Hugo Gabilondo ◽  
Jonathan Benito-Sipos ◽  
Stefan Thor
Keyword(s):  
Cell Fate ◽  
System Development ◽  
Neuronal Cell ◽  
Cell Types ◽  
Nervous System Development ◽  
Spatial Cues ◽  
Distinct Cell ◽  
Embryonic Nervous System ◽  
The Many ◽  
Temporal Program

During Drosophila embryonic nervous system development, neuroblasts express a programmed cascade of five temporal transcription factors that govern the identity of cells generated at different time-points. However, these five temporal genes fall short of accounting for the many distinct cell types generated in large lineages. Here, we find that the late temporal gene castor sub-divides its large window in neuroblast 5–6 by simultaneously activating two cell fate determination cascades and a sub-temporal regulatory program. The sub-temporal program acts both upon itself and upon the determination cascades to diversify the castor window. Surprisingly, the early temporal gene Kruppel acts as one of the sub-temporal genes within the late castor window. Intriguingly, while the temporal gene castor activates the two determination cascades and the sub-temporal program, spatial cues controlling cell fate in the latter part of the 5–6 lineage exclusively act upon the determination cascades.

scholarly journals Resolving Transcriptional States and Predicting Lineages in the Annelid Capitella teleta Using Single-Cell RNAseq

2021 ◽  
Vol 8 ◽  
Author(s):  
Abhinav Sur ◽  
Néva P. Meyer
Keyword(s):  
Single Cell ◽  
Cell Fate ◽  
Cell Types ◽  
Neurosecretory Cells ◽  
Animal Evolution ◽  
Distinct Cell ◽  
Capitella Teleta ◽  
Unique Cell ◽  
Changes Over Time ◽  
Larval Cell

Evolution and diversification of cell types has contributed to animal evolution. However, gene regulatory mechanisms underlying cell fate acquisition during development remains largely uncharacterized in spiralians. Here we use a whole-organism, single-cell transcriptomic approach to map larval cell types in the annelid Capitella teleta at 24- and 48-h post gastrulation (stages 4 and 5). We identified eight unique cell clusters (undifferentiated precursors, ectoderm, muscle, ciliary-band, gut, neurons, neurosecretory cells, and protonephridia), thus helping to identify uncharacterized molecular signatures such as previously unknown neurosecretory cell markers in C. teleta. Analysis of coregulatory programs in individual clusters revealed gene interactions that can be used for comparisons of cell types across taxa. We examined the neural and neurosecretory clusters more deeply and characterized a differentiation trajectory starting from dividing precursors to neurons using Monocle3 and velocyto. Pseudotime analysis along this trajectory identified temporally-distinct cell states undergoing progressive gene expression changes over time. Our data revealed two potentially distinct neural differentiation trajectories including an early trajectory for brain neurosecretory cells. This work provides a valuable resource for future functional investigations to better understanding neurogenesis and the transitions from neural precursors to neurons in an annelid.

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