Biology subjects

Moore, E. L.

Publications and source records attributed to Moore, E. L..

7 recordsLinked to original sources

bioRxiv2025

NR6A1 is essential for neural crest cell specification, formation and survival

Neural crest cells (NCC) are a migratory progenitor cell population considered unique to vertebrates. Derived from the neuroepithelium during early embryogenesis, NCC contribute to nearly every tissue and organ system throughout the body, and disruptions in NCC development can result in congenital disorders, termed neurocristopathies. Despite decades of research, we have a poor understanding of the cellular mechanisms and signals that govern mammalian NCC formation. We discovered nuclear receptor superfamily 6 group member 1 (NR6A1/GCNF/RTR), is a novel, critical regulator of mammalian NCC specification, formation and survival. Nr6a1 is expressed throughout the neuroepithelium in mouse embryos from E8.0 to E9.5 and briefly in newly delaminated NCC. Nr6a1 loss-of-function perturbs anterior cranial NCC formation and survival, and results in the complete agenesis of migratory NCC caudal to the first pharyngeal arch. Using mouse ESC and human iPSC differentiation into NCC, chromatin immunoprecipitation, and multiomic approaches, we demonstrate that these phenotypes are associated with perturbation of NCC specification (Foxd3, Sox9, Sox10) and epithelial-mesenchymal transition (EMT; Snail1, Zeb2), in concert with persistent expression of pluripotency-associated factors (Oct4 and Nanog) in the neuroepithelium. Conditional deletion revealed that Nr6a1 is required during mid-late gastrulation, demonstrating that murine NCC specification occurs earlier than previously thought. Consistent with these observations, in vivo overexpression of Oct4 in gastrulating mouse embryos disrupts NCC specification and formation. Therefore, Nr6a1 is essential for mammalian NCC formation and moreover, may function as a bimodal switch repressing pluripotency-associated factors in the neuroepithelium, while concomitantly activating NCC specifiers and regulators of EMT.

developmental biology↗

bioRxiv2024

Cell extrusion - a novel mechanism driving neural crest cell delamination

Neural crest cells (NCC) comprise a heterogeneous population of cells with variable potency, that contribute to nearly every tissue and organ system throughout the body. Considered unique to vertebrates, NCC are transiently generated within the dorsolateral region of the neural plate or neural tube, during neurulation. Their delamination and migration are crucial events in embryo development as the differentiation of NCC is heavily influenced by their final resting locations. Previous work in avian and aquatic species has shown that NCC delaminate via an epithelial-mesenchymal transition (EMT), which transforms these stem and progenitor cells from static polarized epithelial cells into migratory mesenchymal cells with fluid front and back polarity. However, the cellular and molecular drivers facilitating NCC delamination in mammals are poorly understood. We performed live timelapse imaging of NCC delamination in mouse embryos and discovered a group of cells that exit the neuroepithelium as isolated round cells, which then halt for a short period prior to acquiring the mesenchymal migratory morphology classically associated with most delaminating NCC. High magnification imaging and protein localization analyses of the cytoskeleton, together with measurements of pressure and tension of delaminating NCC and neighboring neuroepithelial cells, revealed these round NCC are extruded from the neuroepithelium prior to completion of EMT. Furthermore, we demonstrate that cranial NCC are extruded through activation of the mechanosensitive ion channel, PIEZO1, a key regulator of the live cell extrusion pathway, revealing a new role for PIEZO1 in neural crest cell development. Our results elucidating the cellular and molecular dynamics orchestrating NCC delamination support a model in which high pressure and tension in the neuroepithelium results in activation of the live cell extrusion pathway and delamination of a subpopulation of NCC in parallel with EMT. This model has broad implications for our understanding of cell delamination in development and disease.

developmental biology↗

bioRxiv2023

Identification and characterization of intermediate states in mammalian neural crest cell epithelial to mesenchymal transition and delamination

Epithelial to mesenchymal transition (EMT) is a cellular process that converts epithelial cells to mesenchymal cells with migratory potential in both developmental and pathological processes. Although originally considered a binary event, EMT in cancer progression involves intermediate states between a fully epithelial and a fully mesenchymal phenotype, which are characterized by distinct combinations of epithelial and mesenchymal markers. This phenomenon has been termed epithelial to mesenchymal plasticity (EMP), however, the intermediate states remain poorly described and its unclear whether they exist during developmental EMT. Neural crest cells (NCC) are an embryonic progenitor cell population that gives rise to numerous cell types and tissues in vertebrates, and their formation is a classic example of developmental EMT. An important feature of NCC development is their delamination from the neuroepithelium via EMT, following which NCC migrate throughout the embryo and undergo differentiation. NCC delamination shares similar changes in cellular state and structure with cancer cell invasion. However, whether intermediate states also exist during NCC EMT and delamination remains unknown. Through single cell RNA sequencing, we identified intermediate NCC states based on their transcriptional signature and then spatially defined their locations in situ in the dorsolateral neuroepithelium. Our results illustrate the progressive transcriptional and spatial transitions from premigratory to migratory cranial NCC during EMT and delamination. Of note gene expression and trajectory analysis indicate that distinct intermediate populations of NCC delaminate in either S phase or G2/M phase of the cell cycle, and the importance of cell cycle regulation in facilitating mammalian cranial NCC delamination was confirmed through cell cycle inhibition studies. Additionally, transcriptional knockdown revealed a functional role for the intermediate stage marker Dlc1 in regulating NCC delamination and migration. Overall, our work identifying and characterizing the intermediate cellular states, processes, and molecular signals that regulate mammalian NCC EMT and delamination furthers our understanding of developmental EMP and may provide new insights into mechanisms regulating pathological EMP.

developmental biology↗

bioRxiv2022

rRNA transcription is integral to liquid-liquid phase separation and maintenance of nucleolar structure

Beginning with transcription of ribosomal RNA (rRNA) by RNA Polymerase (Pol) I in the nucleolus, ribosome biogenesis is intimately tied to cell growth and proliferation. Perturbation of ribosome biogenesis has been previously shown to affect nucleolar structure, yet the underlying mechanism is unknown. We generated loss-of-function mouse mutants of Pol I subunits, Polr1a, Polr1b, Polr1c and Polr1d, thereby genetically inhibiting rRNA transcription and ribosome biogenesis. Pol I mutant embryos are preimplantation lethal and have fewer nucleoli. Using hiPSCs triple labeled for the three nucleolar compartments, we observe two phenotypes upon Pol I inhibition: a single condensed nucleolus, and fragmented nucleoli. We find that when rRNA transcription is inhibited, the viscosity of the granular compartment of the nucleolus is increased disrupting its liquid-liquid phase separation properties, which results in a condensed nucleolus. Taken together, our data suggests that Pol I function and rRNA transcription are required for maintaining nucleolar structure and integrity.

developmental biology↗

bioRxiv2022

Nr6a1 controls axially-restricted body elongation, segmentation, patterning and lineage allocation

The vertebrate main-body axis is laid down during embryonic stages in an anterior-to-posterior (head-to-tail) direction, driven and supplied by posteriorly located progenitors. For the vertebral column, the process of axial progenitor cell expansion that drives elongation, and the process of segmentation which allocates progenitor-descendants into repeating pre-vertebral units, occurs seemingly uninterrupted from the first to the last vertebra. Nonetheless, there is clear developmental and evolutionary support for two discrete modules controlling processes within different axial regions: a trunk and a tail module. Here, we identify Nuclear receptor subfamily 6 group A member 1 (Nr6a1) as a master regulator of elongation, segmentation, patterning and lineage allocation specifically within the trunk region of the mouse. Both gain- and loss-of-function in vivo analyses revealed that the precise level of Nr6a1 acts as a rheostat, expanding or contracting vertebral number of the trunk region autonomously from other axial regions. Moreover, Nr6a1 was found to be required for segmentation, but only for trunk-forming somites, with the timely clearance of Nr6a1 critical in supporting tail formation. In parallel with these morphological outcomes, we reveal Nr6a1 as a novel regulator of global Hox signatures within axial progenitors, preventing the precocious expression of multiple posterior Hox genes as the trunk is being laid down and thus reinforcing that patterning and elongation are coordinated. Finally, our data supports a crucial role for Nr6a1 in regulating gene regulatory networks that guide cell lineage choice of axial progenitors between neural and mesodermal fate. Collectively, these data reveal an axially-restricted role for Nr6a1 in all major cellular and tissue-level events required for vertebral column formation, supporting the view that modulation of Nr6a1 expression level or function is likely to underpin evolutionary changes in axial formulae that exclusively alter the trunk region.

developmental biology↗

bioRxiv2021

Microbial communities in retail draft beers and the biofilms they produce

In the beer brewing industry, microbial spoilage presents a consistent threat that must be monitored and controlled to ensure the palatability of a finished product. Many of the predominant beer spoilage microbes have been identified and characterized, but the mechanisms of contamination and persistence remain an open area of study. Post-production, many beers are distributed as kegs that are attached to draft delivery systems in retail settings where ample opportunities for microbial spoilage are present. As such, restaurants and bars can experience substantial costs and downtime for cleaning when beer draft lines become heavily contaminated. Spoilage monitoring on the retail side of the beer industry is often overlooked, yet this arena may represent one of the largest threats to the profitability of a beer if its flavor profile becomes substantially distorted. In this study, we sampled and cultured microbial communities found in beers dispensed from a retail draft system to identify the contaminating bacteria and yeasts. We also evaluated their capability to establish new biofilms in a controlled setting. Among four tested beer types, we identified over a hundred different contaminant bacteria and nearly twenty wild yeasts. The culturing experiments demonstrated that most of these microbes were viable and capable of joining new biofilm communities. From these data, we provide an important starting point for the efficient monitoring of beer spoilage in draft systems and provide suggestions for cleaning protocol improvements that can benefit the retail community. ImportanceBeer production, packaging, and service are each vulnerable to contamination by microbes that metabolize beer chemicals and impart undesirable flavors, which can result in the disposal of entire batches. Therefore, great effort is taken by brewmasters to reduce and monitor contamination during production and packaging. A commonly overlooked quality control stage of a beer supply chain is at the retail service end, where beer kegs supply draft lines in bars and restaurants under non-sterile conditions. We found that retail draft line contamination is rampant and that routine line cleaning methods are insufficient to efficiently suppress beer spoilage. Thus, many customers unknowingly experience spoiled versions of the beers they consume. This study identified the bacteria and yeast that were resident in draft beer samples and also assessed their abilities to colonize tubing material as members of stable biofilm communities.

microbiology↗

bioRxiv2017

Osterix functions downstream of anti-Mullerian hormone signaling to regulate Mullerian duct regression

In mammals, the developing reproductive tract primordium of male and female fetuses consists of the Wolffian duct and the Mullerian duct (MD), two epithelial tube pairs surrounded by mesenchyme. During male development, mesenchyme-epithelia interactions mediate MD regression to prevent its development into a uterus, oviduct and upper vagina. It is well established that transforming growth factor-beta family member anti-Mullerian hormone (AMH) secreted from the fetal testis and its type 1 and 2 receptors expressed in MD mesenchyme regulate MD regression. However, little is known about the molecular network regulating downstream actions of AMH signaling. To identify potential AMH-induced genes and regulatory networks controlling MD regression in a global non-biased manner, we examined transcriptome differences in MD mesenchyme between males (AMH signaling on) and females (AMH signaling off) by RNA-Seq analysis of purified fetal MD mesenchymal cells. This analysis found 82 genes up-regulated in males during MD regression and identified Osterix (Osx)/Sp7, a key transcriptional regulator of osteoblast differentiation and bone formation, as a novel downstream effector of AMH signaling during MD regression. Osx/OSX was expressed in a male-specific pattern in MD mesenchyme during MD regression. OSX expression was lost in mutant males without AMH signaling. In addition, transgenic mice ectopically expressing human AMH in females induced a male pattern of Osx expression. Together these results indicate that AMH signaling is necessary and sufficient for Osx expression in the MD mesenchyme. In addition, MD regression was delayed in Osx null males, identifying Osx as a new factor that regulates MD regression.\n\nSignificanceIn mammals, each embryo forms both male and female reproductive tract organ progenitor tissues. Anti-Mullerian hormone (AMH) secreted by fetal testes acts on mesenchyme cells adjacent to the Mullerian duct (MD) epithelium, the progenitor tissue of the female reproductive tract, to induce MD regression. While AMH and early AMH signaling components are elucidated, downstream gene networks directing this process are largely unknown. A global non-biased approach using whole transcriptome sequencing of fetal MD mesenchymal cells identified 82 factors as potential target genes of AMH including Osterix (Osx). Our findings provide in vivo evidence Osx is an AMH-induced gene that regulates MD regression. Identification of Osx may provide key insights into gene regulatory networks underlying MD regression and male sex differentiation.

developmental biology↗