scholarly journals Signaling Dynamics Control Cell Fate in the Early Drosophila Embryo

2019 ◽  
Vol 48 (3) ◽  
pp. 361-370.e3 ◽  
Author(s):  
Heath E. Johnson ◽  
Jared E. Toettcher
Keyword(s):  
Cell Fate ◽  
Control Cell ◽  
Drosophila Embryo ◽  
Signaling Dynamics ◽  
Early Drosophila Embryo

scholarly journals Signaling dynamics control cell fate in the early Drosophila embryo

2018 ◽  
Author(s):  
Heath E. Johnson ◽  
Stanislav Y. Shvartsman ◽  
Jared E. Toettcher
Keyword(s):  
Cell Fate ◽  
Time Window ◽  
Activity Patterns ◽  
Control Cell ◽  
High Amplitude ◽  
Mitogen Activated Protein Kinase ◽  
Drosophila Embryo ◽  
Erk Signaling ◽  
Early Drosophila Embryo ◽  
Erk Activity

The Erk mitogen-activated protein kinase plays diverse roles in animal development, where its activity is associated with phenomena including cell migration, proliferation and differentiation. Its widespread reuse raises a conundrum: when a single kinase like Erk is activated, how does a developing cell know which fate to adopt? Here, we combine precise optogenetic control with genetic perturbations to dissect Erk-dependent cellular responses in the early Drosophila embryo. We find that light-stimulated Erk activity is sufficient to ‘posterior-ize’ the majority of the embryo, leading to massive apical constriction through expression of the autocrine receptor-ligand pair mist and fog. Ectopic contraction at non-terminal positions requires at least 1 h of high-amplitude Erk signaling, whereas a 30 min pulse of Erk activity patterns non-contractile neurogenic ectoderm during the same time window. In contrast to the canonical ‘transient versus sustained’ model, the cell fate switch is triggered by the cumulative load of Erk signaling, not the duration of a single persistent pulse. Our results reveal that the early fly embryo harbors a classic example of dynamic cell fate control, where the total dose of Erk activity selects between two distinct physiological outcomes.

scholarly journals Decoding temporal interpretation of the morphogen Bicoid in the early Drosophila embryo

2017 ◽  
Author(s):  
Anqi Huang ◽  
Christopher Amourda ◽  
Shaobo Zhang ◽  
Nicholas S. Tolwinski ◽  
Timothy E. Saunders
Keyword(s):  
Cell Fate ◽  
Spatial Information ◽  
Drosophila Embryo ◽  
High Temporal Resolution ◽  
Local Concentration ◽  
Cell Fates ◽  
Cell Fate Decisions ◽  
Gap Gene ◽  
Early Drosophila Embryo ◽  
Time Specific

SUMMARYMorphogen gradients provide essential spatial information during development. Not only the local concentration but also duration of morphogen exposure is critical for correct cell fate decisions. Yet, how and when cells temporally integrate signals from a morphogen remains unclear. Here, we use optogenetic manipulation to switch off Bicoid-dependent transcription in the early Drosophila embryo with high temporal resolution, allowing time-specific and reversible manipulation of morphogen signalling. We find that Bicoid transcriptional activity is dispensable for embryonic viability in the first hour after fertilization, but persistently required throughout the rest of the blastoderm stage. Short interruptions of Bicoid activity alter the most anterior cell fate decisions, while prolonged inactivation expands patterning defects from anterior to posterior. Such anterior susceptibility correlates with high reliance of anterior gap gene expression on Bicoid. Therefore, cell fates exposed to higher Bicoid concentration require input for longer duration, demonstrating a previously unknown aspect of morphogen decoding.

scholarly journals Decoding temporal interpretation of the morphogen Bicoid in the early Drosophila embryo

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Anqi Huang ◽  
Christopher Amourda ◽  
Shaobo Zhang ◽  
Nicholas S Tolwinski ◽  
Timothy E Saunders
Keyword(s):  
Cell Fate ◽  
Spatial Information ◽  
Drosophila Embryo ◽  
High Temporal Resolution ◽  
Local Concentration ◽  
Cell Fates ◽  
Cell Fate Decisions ◽  
Gap Gene ◽  
Early Drosophila Embryo ◽  
Time Specific

Morphogen gradients provide essential spatial information during development. Not only the local concentration but also duration of morphogen exposure is critical for correct cell fate decisions. Yet, how and when cells temporally integrate signals from a morphogen remains unclear. Here, we use optogenetic manipulation to switch off Bicoid-dependent transcription in the early Drosophila embryo with high temporal resolution, allowing time-specific and reversible manipulation of morphogen signalling. We find that Bicoid transcriptional activity is dispensable for embryonic viability in the first hour after fertilization, but persistently required throughout the rest of the blastoderm stage. Short interruptions of Bicoid activity alter the most anterior cell fate decisions, while prolonged inactivation expands patterning defects from anterior to posterior. Such anterior susceptibility correlates with high reliance of anterior gap gene expression on Bicoid. Therefore, cell fates exposed to higher Bicoid concentration require input for longer duration, demonstrating a previously unknown aspect of Bicoid decoding.

scholarly journals The endoplasmic reticulum is partitioned asymmetrically during mitosis before cell fate selection in proneuronal cells in the early Drosophila embryo

2017 ◽  
Vol 28 (11) ◽  
pp. 1530-1538 ◽  
Author(s):  
Anthony S. Eritano ◽  
Arturo Altamirano ◽  
Sarah Beyeler ◽  
Norma Gaytan ◽  
Mark Velasquez ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Cell Fate ◽  
Asymmetric Cell Division ◽  
Asymmetric Division ◽  
Drosophila Embryo ◽  
Early Drosophila Embryo ◽  
Dividing Cells ◽  
Fate Determinants ◽  
Selection Of

Asymmetric cell division is the primary mechanism to generate cellular diversity, and it relies on the correct partitioning of cell fate determinants. However, the mechanism by which these determinants are delivered and positioned is poorly understood, and the upstream signal to initiate asymmetric cell division is unknown. Here we report that the endoplasmic reticulum (ER) is asymmetrically partitioned during mitosis in epithelial cells just before delamination and selection of a proneural cell fate in the early Drosophila embryo. At the start of gastrulation, the ER divides asymmetrically into a population of asynchronously dividing cells at the anterior end of the embryo. We found that this asymmetric division of the ER depends on the highly conserved ER membrane protein Jagunal (Jagn). RNA inhibition of jagn just before the start of gastrulation disrupts this asymmetric division of the ER. In addition, jagn-deficient embryos display defects in apical-basal spindle orientation in delaminated embryonic neuroblasts. Our results describe a model in which an organelle is partitioned asymmetrically in an otherwise symmetrically dividing cell population just upstream of cell fate determination and updates previous models of spindle-based selection of cell fate during mitosis.

scholarly journals Preformation and epigenesis converge to specify primordial germ cell fate in the early Drosophila embryo

PLoS Genetics ◽  
2022 ◽  
Vol 18 (1) ◽  
pp. e1010002
Author(s):  
Megan M. Colonnetta ◽  
Yogesh Goyal ◽  
Heath E. Johnson ◽  
Sapna Syal ◽  
Paul Schedl ◽  
...  
Keyword(s):  
Cell Fate ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Bmp Signaling ◽  
Drosophila Embryo ◽  
Animal Development ◽  
Early Drosophila Embryo ◽  
Bmp Pathway ◽  
Necessary And Sufficient

A critical step in animal development is the specification of primordial germ cells (PGCs), the precursors of the germline. Two seemingly mutually exclusive mechanisms are implemented across the animal kingdom: epigenesis and preformation. In epigenesis, PGC specification is non-autonomous and depends on extrinsic signaling pathways. The BMP pathway provides the key PGC specification signals in mammals. Preformation is autonomous and mediated by determinants localized within PGCs. In Drosophila, a classic example of preformation, constituents of the germ plasm localized at the embryonic posterior are thought to be both necessary and sufficient for proper determination of PGCs. Contrary to this longstanding model, here we show that these localized determinants are insufficient by themselves to direct PGC specification in blastoderm stage embryos. Instead, we find that the BMP signaling pathway is required at multiple steps during the specification process and functions in conjunction with components of the germ plasm to orchestrate PGC fate.

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