Biology subjects

Wigoda, N.

Publications and source records attributed to Wigoda, N..

7 recordsLinked to original sources

bioRxiv2025

Aberrant inheritance of extrachromosomal DNA amplifications promotes cancer evolution

Gene amplification in the form of extrachromosomal DNA (ecDNA) is a frequent driver in multiple cancer types. As ecDNA lack centromeres, their mitotic segregation does not follow traditional inheritance principles. However, the mechanisms that govern ecDNA fate following mitosis remain unclear. We found that ecDNA undergo numerical and structural optimization under increased selective pressure, with mitotic chromosomal tethering, or detachment, dictating ecDNA fate. When tethered, ecDNA aggregates promote uneven distribution into the newly formed daughter cells, thereby driving inter-cellular numerical heterogeneity and rapid increase of amplification under selective pressure. Mitotically detached ecDNA frequently encapsulate within micronuclei of variable size and content that appear to be highly fragile. Strikingly, ecDNA enclosed in very small micronuclei, which we term nanonuclei, are being actively degraded through autophagy. Together with ongoing structural rearrangements, nanonuclear ecDNA degradation promotes their structural evolution, which facilitates cancer cell adaptation. Our work highlights ecDNA aggregation, micronucleation, and degradation, as pivotal events in directing cancer genome evolution trajectories.

cancer biology↗

bioRxiv2025

Comparative developmental transcriptomics of Drosophila mushroom body neurons highlights the mevalonate pathway as a regulator of axon growth

The ability of neurons to extend axons is governed by tightly regulated genetic programs that vary across developmental stages and cell types. Understanding the molecular features that control axon growth potential is critical for uncovering how neural circuits form, mature, and respond to injury or disease. The Drosophila mushroom body (MB) offers a powerful model to dissect axon growth programs, as lineage-related Kenyon cells (KCs) undergo different developmental events under shared spatiotemporal conditions. During metamorphosis, {gamma}-KCs undergo axon pruning, followed by developmental regrowth at the same time-frame as /{beta}-KCs initiate axon growth - thus providing a unique opportunity to compare these distinct growth paradigms. We thus performed RNA-sequencing of /{beta}-and {gamma}-KCs during their initial growth and developmental regrowth, respectively, revealing dynamic transcriptional changes and identifying 300 shared genes upregulated during both growth states. A targeted loss-of-function screen revealed genes specifically required for either /{beta} initial growth, {gamma} regrowth, or both. Focusing on one such candidate, Pmvk, we found that it plays a crucial role in axon regrowth by acting within the mevalonate pathway. Notably, other enzymes in this pathway were also required, suggesting that the entire metabolic pathway is essential for supporting regrowth. Genetic mutant analyses and rescue exepriements suggest that Pmvk likely controls axon regrowth via Rheb, an effector of the TOR pathway, which we previously found to be required for regrowth. Our developmental transcriptomic atlas not only advances understanding of intrinsic axon growth programs, but also provides candidate genes and a valuable framework for future studies aimed at enhancing axon regeneration in the adult nervous system.

neuroscience↗

bioRxiv2024

Wnt/β-Catenin coordinates muscle spindle development by regulating capsule differentiation, intrafusal fiber nuclei aggregation and proprioceptive nerve endings

Proprioception is essential for the regulation of posture, movement, and musculoskeletal integrity. The muscle spindle, a mechanosensory organ composed of multiple specialized tissues, detects stretch and provides proprioceptive feedback. Despite its importance, the molecular mechanisms that orchestrate the development of the spindle components remain poorly understood. Here, we reveal the involvement of the Wnt/{beta}-catenin pathway in muscle spindle development. We show that Wnt ligands and their Frizzled receptors are expressed in the developing spindle and that {beta}-catenin is active throughout development in capsule cells and in bag2 intrafusal fibers. Embryonic deletion of {beta}-catenin from capsule and intrafusal fibers induced widespread transcriptomic changes, which led to significant malformations, including impaired capsule cell differentiation, disrupted nuclear organization in intrafusal fibers, and disorganized proprioceptive nerve endings. Postnatal deletion of {beta}-catenin from intrafusal fibers resulted in abnormal nerve endings and impaired proprioceptive function, indicating that the development of proprioceptive afferents is regulated by {beta}-catenin through a non-cell-autonomous mechanism acting in bag2 fibers. Collectively, our findings position the Wnt/{beta}-catenin pathway as a central regulator that acts through both cell-autonomous and non-cell-autonomous mechanisms to coordinate the development of the various spindle tissues into a functional organ.

developmental biology↗

bioRxiv2024

Elucidating early intestinal stem cell response to bacterial infection

Intestinal stem cells (ISCs) are the regenerative force of the gut epithelium. Lgr5+-ISC have been shown to respond to changes in their microenvironment by coping with different metabolites, adapting to caloric changes, and recovering from injury and inflammation. However, how pathogenic bacteria affect adult stem cell regeneration and, as a consequence, the overall tissue adaption to infection has yet to be explored in depth. Here, we interrogated early Lgr5+ ISC responses to an enteric intracellular pathogen by profiling individual IECs from the mouse small intestine. Utilizing GFP-labeled Salmonella enterica, we isolated intracellular invaded cells to elucidate invasion programs of epithelial cell subsets. In particular, we identified a Salmonella-specific infection signature comprised of antimicrobial peptide (AMP) genes, including the Defensin gene family. Our findings demonstrate that Salmonella enterica targets differentiated Paneth, enterocytes, and stem/progenitor cells at these early stages of infection. In response, a rapid Lg5+ ISC-driven cellular remodeling to enterocyte and Paneth lineages expressing AMP genes is initiated to combat the intruders. Importantly, we uncovered an ISC differentiation program via inflammasome activation to protect the crypt environment, while eliminating infected stem cells from the overall stem cell pool. This novel Lgr5+ stem cell defense mechanism not only protects the gut epithelium from persistent bacterial infection but also promotes tissue regeneration. We propose epithelial remodeling to AMP-secreting cells as a novel innate immune response to handle different gut stresses mediated by Lgr5+ ISCs to maintain organizational principles of gut homeostasis and physiology.

immunology↗

bioRxiv2022

Stress resilience is established during development and is regulated by complement factors

Individuals in a population respond differently to stressful situations. While resilient individuals recover efficiently, others are susceptible to the same stressors. However, it remains challenging to identify resilience in mammalian embryos to determine if stress resilience is established as a trait during development or acquired later in life. Using a new behavioural paradigm in zebrafish larvae, we show that resilience is a trait that is determined and exhibited early in life. Resilient and susceptible individuals retained these traits throughout life and passed them on to the next generation. Resilient larvae showed higher expression of resilience-associated genes and larvae lacking neuropeptide Y and miR218 were significantly under-represented in the resilient population. Unbiased transcriptome analysis revealed that multiple factors of the innate immune complement cascade were downregulated in resilient larvae in response to stressors. Pharmacological inhibition and genetic knockouts of critical complement factors led to an increase in resilience. We conclude that resilience is established early during development as a stable trait, and that neuropeptides and the complement pathway play positive and negative roles in determining resilience respectively. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/478444v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@359261org.highwire.dtl.DTLVardef@11d1e62org.highwire.dtl.DTLVardef@b5d346org.highwire.dtl.DTLVardef@141bae1_HPS_FORMAT_FIGEXP M_FIG C_FIG Why some individual individuals recover better than others from stressful situations is unclear. We show that resilience to stress is established during zebrafish development as a stable and heritable trait. Resilience is augmented by brain-derived neuropeptides and attenuated by innate immune complement factors specifically expressed in the liver. HighlightsO_LIWildtype zebrafish larvae show differences in their dynamics of recovering from stress, with some being more resilient than others. C_LIO_LIResilience is a stable and heritable trait. C_LIO_LIResilient fish show specific stress-responsive transcriptional changes. C_LIO_LINeuropeptide Y and miRNA218 positively affect resilience, while innate immune complement factors attenuate resilience. C_LI

neuroscience↗

bioRxiv2021

Dendritic cell ICAM-1 strengthens immune synapses but is dispensable for effector and memory responses

Lymphocyte priming in lymph nodes (LNs) depends on the formation of functional TCR specific immune synapses (ISs) with antigen (Ag) presenting dendritic cells. The high affinity LFA-1 ligand ICAM-1 has been implicated in different ISs studied in vitro. The in vivo roles of DC ICAM-1 in Ag stimulated T cell differentiation have been unclear. In newly generated DC conditional ICAM-1 knockout mice, we report that under Th1 polarizing conditions, ICAM-1 deficient DCs could not engage in stable conjugates with newly generated CD8 blasts. Nevertheless, these DCs triggered normal lymphocyte priming, proliferation and differentiation into functional cytotoxic T cells (CTLs) and central memory lymphocytes (Tcm) in both vaccinated and virus infected skin. Single cell RNAseq analysis confirmed that Tcm were normally generated in these mice and gave rise to normal T effectors during a recall skin response. Our results suggest that although CD8 T cell blasts tightly bind DC-ICAM-1, strongly adhesive DC-T ISs are not necessary for functional TCR dependent DC mediated CD8 T cell proliferation and differentiation into productive effector and memory lymphocytes. SummarySapoznikov et al generated a new genetic murine model deficient in dendritic cell expression of the key adhesion molecule ICAM-1 and found that CD8 lymphocytes do not require strong adhesion to dendritic cells for antigen-dependent differentiation into effector and memory T cells.

immunology↗

bioRxiv2017

Bundle-sheath cells are internal leaf "water valves" controlled via xylem acidification by H+-ATPase

O_LIThe leaf vascular bundle sheath cells (BSCs) that tightly envelop the leaf veins, are a selective and dynamic barrier to xylem-sap water and solutes radially entering the mesophyll cells. Under normal conditions, xylem-sap pH of <6 is presumably important for driving and regulating the transmembranal solute transport. Having discovered recently a differentially high expression of a BSCs proton pump, AHA2, we now test the hypothesis that it regulates this pH and leaf radial water fluxes. C_LIO_LIWe monitored the xylem-sap pH in the veins of detached leaves of WT Arabidopsis, AHA mutants, and aha2 mutants complemented with AHA2 gene solely in BSCs. We tested an AHA inhibitor and stimulator, and different pH buffers. We monitored their impact on the xylem-sap pH and the whole leaf hydraulic conductance (Kleaf), and the effect of pH on the water osmotic permeability (Pf) of isolated BSCs protoplasts. C_LIO_LIOur results demonstrated that AHA2 is necessary for xylem-sap acidification, and in turn, for elevating Kleaf. Conversely, knocking out AHA2 alkalinized the xylem-sap. Also, elevating xylem sap pH to 7.5 reduced Kleaf and elevating external pH to 7.5 decreased the BSCs Pf. C_LIO_LIAll these demonstrate a causative link between AHA2 activity in BSCs and leaf radial water conductance. C_LI One-sentence summaryBundle-sheath cells can control the leaf hydraulic conductance by proton-pump-regulated xylem sap pH

plant biology↗