Cytonemes coordinate asymmetric signaling and organization in the Drosophila muscle progenitor niche

Asymmetric signaling and organization in the stem-cell niche determine stem-cell fates. We investigated the basis of asymmetric signaling and stem-cell organization using the Drosophila wing-disc that creates an adult muscle progenitor (AMP) niche. We uncovered that AMPs extend polarized cytonemes to contact the disc epithelial junctions and adhere themselves to the disc/niche. Niche-adhering cytonemes localize an FGF-receptor to selectively adhere to the FGF-producing disc and receive FGFs in a contact-dependent manner. Activation of FGF-signaling in AMPs, in turn, reinforces disc-specific cytoneme polarity/adhesion, which maintains their disc-proximal positions. The wing-disc produces two FGFs in distinct zones and restricts their signaling only through cytonemes. Consequently, although both FGFs use the same receptor, their cytoneme-mediated signaling asymmetrically distributes different muscle-specific AMPs into different FGF-producing niches. Loss of cytoneme-mediated adhesion and FGF-signaling promotes AMPs to lose niche occupancy, occupy a disc-distal position, and acquire morphological hallmarks of differentiation. Thus, cytonemes are essential for asymmetric signaling and niche-specific AMP organization.

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Plant stem cell organization and differentiation at single-cell resolution

10.1101/2020.08.25.267427 ◽

2020 ◽

Cited By ~ 1

Author(s):

James W. Satterlee ◽

Josh Strable ◽

Michael J. Scanlon

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Single Cell ◽

Cell Fates ◽

Organizing Center ◽

Cell Organization ◽

Plant Stem ◽

Cell Niche ◽

Transcriptional Landscape

Plants maintain populations of pluripotent stem cells in shoot apical meristems (SAMs), which continuously produce new aboveground organs. We used single-cell RNA sequencing to achieve an unbiased characterization of the transcriptional landscape of the maize shoot stem-cell niche and its differentiating cellular descendants. Stem cells housed in the SAM tip are engaged in genome integrity maintenance and exhibit a low rate of cell division, consistent with their contributions to germline and somatic cell fates. Surprisingly, we find no evidence for a canonical stem cell organizing center subtending these cells. In addition, we use trajectory inference to trace the gene expression changes that accompany cell differentiation. These data provide a valuable scaffold on which to better dissect the genetic control of plant shoot morphogenesis.

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Ionizing radiation induces stem cell-like properties in a caspase-dependent manner in Drosophila

10.1101/316497 ◽

2018 ◽

Author(s):

Shilpi Verghese ◽

Tin Tin Su

Keyword(s):

Stem Cell ◽

Ionizing Radiation ◽

Cancer Cells ◽

Wing Disc ◽

Lineage Tracing ◽

Dependent Manner ◽

Cancer Treatments ◽

Therapeutic Success ◽

Wing Discs ◽

Regenerative Cells

ABSTRACTCancer treatments including ionizing radiation (IR) can induce cancer stem cell-like properties in non-stem cancer cells, an outcome that can interfere with therapeutic success. Yet, we understand little about what consequences of IR induces stem cell like properties and why some cancer cells show this response but not others. In previous studies, we identified a pool of epithelial cells in Drosophila larval wing discs that display IR-induced stem cell-like properties. These cells are resistant to killing by IR and, after radiation damage, change fate and translocate to regenerate parts of the disc that suffered more cell death. Here, we addressed how IR exposure results in the induction of stem cell-like behavior, and found a requirement for caspase activity. Unexpectedly, this requirement was mapped to the regenerative cells, suggesting a non-apoptotic role for caspases in the induction of stem cell-like behavior. We also performed a systematic probing of different regions of the wing disc by lineage tracing, in order to identify additional pools of cells with IR-induced regenerative properties. We identified two new populations of such cells. Unlike the original pool that helps regenerate the disc, the new pools of cells undergo abnormal regeneration to produce an ectopic, supernumerary wing disc. We also identified cells that lack the ability to display IR-induced regenerative behavior. Identification of different cell populations with different IR-induced regenerative potential will allow us to probe the molecular basis for these differences in the future.AUTHOR SUMMARYIonizing Radiation (IR), alone or in combination with other therapies, is used to treat an estimated half of all cancer patients. Yet, we understand little about why some tumors cells respond to treatment while others grow back (regenerate). We identified specific pools of cells within a Drosophila organ that are capable of regeneration after damage by IR. We also identified what it is about IR damage that allows these cells to regenerate. These results help us understand how cells regenerate after IR damage and will aid in designing better therapies that involve radiation.

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Bi-compartmentalized stem cell organization of the corneal limbal niche

10.1101/2020.06.25.171462 ◽

2020 ◽

Author(s):

Olivia Farrelly ◽

Yoko Suzuki-Horiuchi ◽

Megan Brewster ◽

Paola Kuri ◽

Sixia Huang ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Stem Cell Niche ◽

Tissue Architecture ◽

Corneal Regeneration ◽

Cell Organization ◽

Cell Niche ◽

Slow Cycling ◽

And Function

AbstractStem cells exist in precise locations within tissues, yet how their organization supports tissue architecture and function is poorly understood. The limbus is the presumptive stem cell niche of the corneal epithelium. Here, we visualize the live limbus and track the activity of single stem cells in their native environment by 2-photon microscopy. We identify previously unknown niche compartments and show that long implicated slow-cycling cells form separate lineages in the outer limbus, with only local clonal dynamics. Instead, we find distinct stem cells in the pericorneal limbus to be required for corneal regeneration. Unbiased photolabeling captures their progeny exiting the niche, then moving centripetally in unison before undergoing terminal differentiation. This study demonstrates how a compartmentalized stem cell organization coordinates tissue regeneration.One Sentence SummaryIn vivo live imaging of the regenerating cornea reveals distinct stem cell activities in the limbal niche

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In vivo relevance of intercellular calcium signaling in Drosophila wing development

10.1101/187401 ◽

2017 ◽

Cited By ~ 2

Author(s):

Qinfeng Wu ◽

Pavel A. Brodskiy ◽

Francisco Huizar ◽

Jamison J. Jangula ◽

Cody Narciso ◽

...

Keyword(s):

Ex Vivo ◽

Wing Disc ◽

Chemical Stimulus ◽

Wing Development ◽

Dependent Manner ◽

Drosophila Wing ◽

Wing Discs ◽

Vein Patterning ◽

Dose Dependent

AbstractRecently, organ-scale intercellular Ca2+ transients (ICTs) were reported in the Drosophila wing disc. However, the functional in vivo significance of ICTs remains largely unknown. Here we demonstrate the in vivo relevance of intercellular Ca2+ signaling and its impact on wing development. We report that Ca2+ signaling in vivo decreases as wing discs mature. Ca2+ signaling ex vivo responds to fly extract in a dose-dependent manner. This suggests ICTs occur in vivo due to chemical stimulus that varies in concentration during development. RNAi mediated inhibition of genes required for ICTs results in defects in the size, shape, and vein patterning of adult wings. It also leads to reduction or elimination of in vivo Ca2+ transients. Further, perturbations to the extracellular matrix along the basal side of the wing disc stimulates intercellular Ca2+ waves. This is the first identified chemically defined, non-wounding stimulus of ICTs. Together, these results point toward specific in vivo functions of intercellular Ca2+ signaling to mediate mechanical stress dissipation and ensure robust patterning during development.

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Wnt target genes and where to find them

F1000Research ◽

10.12688/f1000research.11034.1 ◽

2017 ◽

Vol 6 ◽

pp. 746 ◽

Cited By ~ 28

Author(s):

Aravinda-Bharathi Ramakrishnan ◽

Ken M. Cadigan

Keyword(s):

Gene Regulation ◽

Stem Cell ◽

Transcriptional Activation ◽

Cell Biology ◽

Target Genes ◽

Dependent Manner ◽

Binding Partners ◽

The Rich ◽

Cell Niche

Wnt/β-catenin signaling is highly conserved throughout metazoans, is required for numerous essential events in development, and serves as a stem cell niche signal in many contexts. Misregulation of the pathway is linked to several human pathologies, most notably cancer. Wnt stimulation results in stabilization and nuclear import of β-catenin, which then acts as a transcriptional co-activator. Transcription factors of the T-cell family (TCF) are the best-characterized nuclear binding partners of β-catenin and mediators of Wnt gene regulation. This review provides an update on what is known about the transcriptional activation of Wnt target genes, highlighting recent work that modifies the conventional model. Wnt/β-catenin signaling regulates genes in a highly context-dependent manner, and the role of other signaling pathways and TCF co-factors in this process will be discussed. Understanding Wnt gene regulation has served to elucidate many biological roles of the pathway, and we will use examples from stem cell biology, metabolism, and evolution to illustrate some of the rich Wnt biology that has been uncovered.

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The cytokine FAM3B/PANDER is an FGFR ligand that promotes posterior development in Xenopus

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2100342118 ◽

2021 ◽

Vol 118 (20) ◽

pp. e2100342118

Author(s):

Fangfang Zhang ◽

Xuechen Zhu ◽

Pan Wang ◽

Qing He ◽

Huimei Huang ◽

...

Keyword(s):

Messenger Rna ◽

Sequence Similarity ◽

Erk Signaling ◽

Dependent Manner ◽

Cell Fates ◽

Fgf Receptor ◽

Axial Patterning ◽

Culture Cells ◽

Extracellular Signal ◽

Morpholino Oligonucleotides

Fibroblast growth factor (FGF)/extracellular signal-regulated kinase (ERK) signaling plays a crucial role in anterior–posterior (A–P) axial patterning of vertebrate embryos by promoting posterior development. In our screens for novel developmental regulators in Xenopus embryos, we identified Fam3b as a secreted factor regulated in ectodermal explants. Family with sequence similarity 3 member B (FAM3B)/PANDER (pancreatic-derived factor) is a cytokine involved in glucose metabolism, type 2 diabetes, and cancer in mammals. However, the molecular mechanism of FAM3B action in these processes remains poorly understood, largely because its receptor is still unidentified. Here we uncover an unexpected role of FAM3B acting as a FGF receptor (FGFR) ligand in Xenopus embryos. fam3b messenger RNA (mRNA) is initially expressed maternally and uniformly in the early Xenopus embryo and then in the epidermis at neurula stages. Overexpression of Xenopus fam3b mRNA inhibited cephalic structures and induced ectopic tail-like structures. Recombinant human FAM3B protein was purified readily from transfected tissue culture cells and, when injected into the blastocoele cavity, also caused outgrowth of tail-like structures at the expense of anterior structures, indicating FGF-like activity. Depletion of fam3b by specific antisense morpholino oligonucleotides in Xenopus resulted in macrocephaly in tailbud tadpoles, rescuable by FAM3B protein. Mechanistically, FAM3B protein bound to FGFR and activated the downstream ERK signaling in an FGFR-dependent manner. In Xenopus embryos, FGFR activity was required epistatically downstream of Fam3b to mediate its promotion of posterior cell fates. Our findings define a FAM3B/FGFR/ERK-signaling pathway that is required for axial patterning in Xenopus embryos and may provide molecular insights into FAM3B-associated human diseases.

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Quantitative EM of gap junction distribution in mutant drosophila wing discs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077177 ◽

1983 ◽

Vol 41 ◽

pp. 720-721

Author(s):

J.S. Ryerse

Keyword(s):

Gap Junctions ◽

Growth Control ◽

Intercellular Junctions ◽

Wing Disc ◽

En Bloc ◽

Metabolic Cooperation ◽

Drosophila Wing ◽

Adult Wing ◽

Wing Discs ◽

Wing Pouch

Gap junctions are intercellular junctions found in both vertebrates and invertebrates through which ions and small molecules can pass. Their distribution in tissues could be of critical importance for ionic coupling or metabolic cooperation between cells or for regulating the intracellular movement of growth control and pattern formation factors. Studies of the distribution of gap junctions in mutants which develop abnormally may shed light upon their role in normal development. I report here the distribution of gap junctions in the wing pouch of 3 Drosophila wing disc mutants, vg (vestigial) a cell death mutant, 1(2)gd (lethal giant disc) a pattern abnormality mutant and 1(2)gl (lethal giant larva) a neoplastic mutant and compare these with wildtype wing discs.The wing pouch (the anlagen of the adult wing blade) of a wild-type wing disc is shown in Fig. 1 and consists of columnar cells (Fig. 5) joined by gap junctions (Fig. 6). 14000x EMs of conventionally processed, UA en bloc stained, longitudinally sectioned wing pouches were enlarged to 45000x with a projector and tracings were made on which the lateral plasma membrane (LPM) and gap junctions were marked.

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