Biology subjects

Dow, J. A. T.

Publications and source records attributed to Dow, J. A. T..

7 recordsLinked to original sources

bioRxiv2026

RNAseK is vital for epithelial proton pump activity in Drosophila melanogaster

The transporting epithelial tissues comprising the Drosophila melanogaster alimentary and renal systems are known to share a common set of enriched genes sometimes referred to as the "epitheliome", reflecting their shared transport functions. Core amongst these genes are the vha genes, which encode subunits of the large Vacuolar-type ATPase (V-ATPase) proton pump complex. However, many of the non-vha components of the epitheliome remain broadly uncharacterised. Here, we explore the role of RNAseK, a gene identified during unbiased epithelial screens in Drosophila whose function within insects is not yet known, though evidence from mammalian systems suggest a role in supporting proton pump activity. We demonstrate computationally that RNAseK is strongly conserved across evolutionary history, and that expression is regulated by the highly epithelial-specific dCLEAR motif. Seeking to understand why epithelial expression is so emphasised, we have assayed the effects of RNAseK knockdown in different epithelia throughout the fly. Across hindgut, midgut, and Malpighian tubules, we note profound defects in gross tissue morphology, transport activity, and fly survival. Mechanistically, our findings that RNAseK may co-localise with the V-ATPase complex, and that V-ATPase inhibition phenocopies RNAseK knockdown, suggest that RNAseK is a critical component of the proton transport axis across Drosophila tissues. Summary statementRNAseK is enriched throughout, and required in, Drosophila melanogaster epithelial tissues. Molecular evidence and evolutionary inferences suggest this is due to a role in the proton transport axis.

cell biology↗

bioRxiv2024

ScGOclust: leveraging gene ontology to compare cell types across distant species using scRNA-seq data

Basic biological processes are shared among animal species, yet their cellular mechanisms are profoundly diverse. Comparing cell type expression profiles across species reveals the conservation and divergence of cellular functions. With the increase of phylogenetic distance between species of interest, a gene-based comparison becomes limited. The Gene Ontology (GO) knowledgebase is the most comprehensive resource of gene functions, providing a bridge for comparing cell types between remote species. Here, we present scGOclust, a computational tool to construct cellular functional profiles using GO terms and facilitates systematic, robust comparisons within and across species. We use scGOclust to analyse and compare the heart, gut and kidney between mouse and fly. We show that scGOclust recapitulates the function spectrum of different cell types, characterises functional similarities between homologous cell types, and reveals functional convergence between unrelated cell types. Furthermore, we identify subpopulations in the fly crop by cross-species comparison of GO profiles. Finally, scGOclust resolved the analogy between Malpighian tubule and kidney segments.

bioinformatics↗

bioRxiv2021

A cell atlas of the fly kidney

Like humans, insects rely on precise regulation of their internal environments to survive. The insect renal system consists of Malpighian tubules and nephrocytes that share similarities to the mammalian kidney. Studies of the Drosophila Malpighian tubules and nephrocytes have provided many insights into our understanding of the excretion of waste products, stem cell regeneration, protein reabsorption, and as human kidney disease models. Here, we analyzed single-nucleus RNA sequencing (snRNA-seq) data sets to characterize the cell types of the adult fly kidney. We identified 11 distinct clusters representing renal stem cells (RSCs), stellate cells (SCs), regionally specific principal cells (PCs), garland nephrocyte cells (GCs) and pericardial nephrocytes (PNs). Analyses of these clusters revealed many new interesting features. For example, we found a new, previously unrecognized cell cluster: lower segment PCs that express Esyt2. In addition, we find that the SC marker genes RhoGEF64c, Frq2, Prip and CG10939 regulate their unusual cell shape. Further, we identified transcription factors specific to each cluster and built a network of signaling pathways that are potentially involved in mediating cell-cell communication between Malpighian tubule cell types. Finally, cross-species analysis allowed us to match the fly kidney cell types to mouse kidney cell types and planarian protonephridia - knowledge that will help the generation of kidney disease models. To visualize this dataset, we provide a web-based resource for gene expression in single cells (https://www.flyrnai.org/scRNA/kidney/). Altogether, our study provides a comprehensive resource for addressing gene function in the fly kidney and future disease studies.

developmental biology↗

bioRxiv2021

Fly Cell Atlas: a single-cell transcriptomic atlas of the adult fruit fly

The ability to obtain single cell transcriptomes for stable cell types and dynamic cell states is ushering in a new era for biology. We created the Tabula Drosophilae, a single cell atlas of the adult fruit fly which includes 580k cells from 15 individually dissected sexed tissues as well as the entire head and body. Over 100 researchers from the fly community contributed annotations to >250 distinct cell types across all tissues. We provide an in-depth analysis of cell type-related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types that are shared between tissues, such as blood and muscle cells, allowed the discovery of rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the entire Drosophila community and serves as a comprehensive reference to study genetic perturbations and disease models at single cell resolution.

genomics↗

bioRxiv2020

The septate junction protein Snakeskin is critical for epithelial barrier function and tissue homeostasis in the Malpighian tubules of adult Drosophila

Transporting epithelia provide a protective physical barrier while directing appropriate transport of ions, solutes and water. In invertebrates, epithelial integrity is dependent on formation, and maintenance, of tight septate junctions (SJs). We demonstrated that Drosophila Malpighian (renal) tubules undergo an age-dependent decline in secretory transport capacity, which correlates with mislocalisation of SJ proteins and coincident progressive degeneration in cellular morphology and tissue homeostasis. By restrictively impairing, in adult tubules, the cell adhesion protein Snakeskin, which is essential for smooth SJ formation, we observed progressive changes in cellular and tissue morphology that phenocopied these effects, including mislocalisation of junctional proteins with concomitant loss of cell polarity and barrier function. Resulting in significant accelerated decline in tubule secretory capacity and organismal viability. Our investigations highlight the tubules essential role in maintenance of organismal health, while providing measurable markers of compromised epithelial barrier and tissue function that manifest in advanced morbidity and death. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/422678v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@68e080org.highwire.dtl.DTLVardef@16af9ddorg.highwire.dtl.DTLVardef@3a399eorg.highwire.dtl.DTLVardef@9cc393_HPS_FORMAT_FIGEXP M_FIG Model for epithelial dysfunction arising from failure of smooth septate junctional complexes as a consequence of impaired Snakeskin expression. C_FIG

physiology↗

bioRxiv2020

A nutrient-responsive hormonal circuit controls energy and water homeostasis in Drosophila

The regulation of systemic energy balance involves the coordinated activity of specialized organs, which control nutrient uptake, utilization and storage to promote metabolic homeostasis during environmental challenges. The humoral signals that drive such homeostatic programs are largely unidentified. Here we show that three pairs of central neurons in adult Drosophila respond to internal water and nutrient availability by releasing Capa-1 and -2 hormones that signal through the Capa receptor (CapaR) to exert systemic metabolic control. Loss of Capa/CapaR signaling leads to intestinal hypomotility and impaired nutrient absorption, which gradually deplete internal nutrient stores and reduce organismal lifespan. Conversely, hyperactivation of the Capa circuitry stimulates fluid and waste excretion. Furthermore, we demonstrate that Capa/CapaR regulates energy metabolism by modulating the release of the glucagon-like adipokinetic hormone, which governs lipolysis in adipose tissue to stabilize circulating energy levels. Altogether, our results uncover a novel inter-tissue program that plays a central role in coordinating post-prandial responses that are essential to maintain adult viability.

physiology↗

bioRxiv2019

When two cells are better than one: specialized stellate cells provide a privileged route for uniquely rapid water flux in Drosophila renal tubule

Insects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 members of the Major Intrinsic Protein family are expressed at very high level in the fly renal tissue; the aquaporins Drip and Prip, and the aquaglyceroporins Eglp2 and Eglp4. As predicted from their structure and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes impacts tubule performance resulting in impaired hormone-induced fluid secretion. The Drosophila tubule has two main secretory cell types: active cation-transporting principal cells with the aquaglyceroporins localize to opposite plasma membranes and small stellate cells, the site of the chloride shunt conductance, with these aquaporins localising to opposite plasma membranes. This suggests a model in which cations are pumped by the principal cells, causing chloride to follow through the stellate cells in order to balance the charge. As a consequence, osmotically obliged water follows through the stellate cells. Consistent with this model, fluorescently labelled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects.\n\nSignificance statementThe tiny insect renal (Malpighian) tubule can transport fluid at unparalleled speed, suggesting unique specialisations. Here we show that strategic allocation of Major Intrinsic Proteins (MIPs) to specific cells within the polarized tubule allow the separation of metabolically intense active cation transport from chloride and water conductance. This body plan is general to at least many higher insects, providing a clue to the unique success of the class Insecta.

physiology↗