Biology subjects

Marshall, K. L.

Publications and source records attributed to Marshall, K. L..

11 recordsLinked to original sources

bioRxiv2026

The role of urothelial PIEZO ion channels in urinary function

The urothelium is increasingly recognized as a dynamic sensory interface that contributes to the regulation of urinary tract function. Mechanosensitive PIEZO ion channels expressed by urothelial cells have been proposed to play important roles in bladder fullness sensation and urinary reflexes. However, the functional contribution of urothelial PIEZO channels to these processes remains unclear. Here, we investigated the consequences of urothelial Piezo1 and Piezo2 deletion using the commonly used Upk2-cre transgenic line. Surprisingly, combined deletion of urothelial PIEZO channels did not alter urinary behavior, and mice lacking urothelial PIEZO1/2 exhibited normal bladder pressure-volume relationships, indicating preserved bladder filling and voiding function. Notably, Upk2-cre; Piezo1fl/fl mice displayed enhanced external urethral sphincter reflex activity during voiding, suggesting that loss of PIEZO1 from cells targeted by Upk2-cre may influence sensory signaling outside of the bladder urothelium. Consistent with this possibility, we identified substantial off-target Cre expression in dorsal root ganglia. These findings demonstrate that the Upk2-cre line is not restricted to the urothelium and therefore raises important considerations for interpreting associated phenotypes attributed specifically to urothelial gene deletion. Biologically, this raises the possibility that PIEZO1 does not influence bladder pressure-volume handling but might contribute to urinary reflexes.

neuroscience↗

bioRxiv2026

Maladaptive Piezo1 Mechanotransduction Drives Smooth Muscle Aging in the Gut

Age-related gastrointestinal dysfunction is common, but the mechanisms of aging-associated smooth muscle failure remain unclear. We show that aging in mice slows whole gut and colonic transit, increases regional stiffness, and reduces smooth muscle contractility. Inducible smooth muscle cell (SMC) specific deletion of Piezo1 preserved youthful transit and force generation, whereas Piezo1 activation in young mice phenocopied aging-associated transit delay. Single cell transcriptomics, RNA velocity, stiffness-controlled cell and tissue cultures, and pharmacologic studies revealed that Piezo1 couples increased stiffness to Ca2+, calcineurin, NFAT signaling, loss of contractile gene programs, leading to age-related contractile loss and contractile to synthetic SMC remodeling and gut wall stiffening. Human intestinal SMCs supported conservation of this pathway, and PIEZO1 gain of function carriers showed a trend toward delayed colonic transit. Thus, maladaptive SMC Piezo1 mechanotransduction is a targetable mechanism of aging-associated gut dysmotility.

physiology↗

bioRxiv2026

PIEZO1-mediated mechanosensation links aging to bladder dysfunction

Aging is accompanied by profound changes in bladder function, leading to increased urinary frequency and incontinence that impair quality of life in humans and are recapitulated in mouse models. Bladder filling and emptying rely on precise mechanosensory feedback, yet how aging alters this sensory control remains unclear. PIEZO ion channels convert mechanical forces into cellular signals essential for bladder fullness sensation. Using inducible smooth-muscle specific Piezo1 deletion, we find that loss of Piezo1 attenuates aging-related bladder dysfunction. Dietary enrichment with margaric acid, a membrane-active fatty acid previously shown to inhibit PIEZO channels, reduced urinary dysfunction in aged mice. In humans, genotype-phenotype analyses reveal an association between a PIEZO1 gain-of-function variant and early-onset neuromuscular bladder dysfunction. Together, these findings define a smooth-muscle, PIEZO1-mediated mechanosensory basis for aging-related bladder dysfunction and introduce a non-invasive strategy for targeting PIEZO channels in vivo.

physiology↗

bioRxiv2026

Complementary constraints in germ and immune cells shape evolution of gene regulation and phenotype

New mutations arise in germ cells and must preserve fertility while altering somatic phenotype to confer a fitness advantage. To understand how whole organisms balance these constraints, we generated mice with humanized noncoding promoter sequence at Traf6, an NF-{kappa}B pathway component with recently diverged chromatin state in mouse germ cells. The humanized allele (Traf6h) reinstated human-like expression in germ and immune cells, which we traced to a 13 base pair deletion that impairs CTCF binding. Traf6h had no effect on fertility but induced a sensitized innate immune response to endotoxin. Other NF-{kappa}B pathway genes followed a similar pattern, suggesting that their expression has evolved in tandem and consistent with known mouse-human differences in inflammatory response. Our results reveal distinct roles for germ and immune cells in shaping gene regulatory evolution, where immune cells quickly adjust phenotype, enabling selection, while germ cells robustly maintain fertility despite changing expression levels, enabling inheritance.

genetics↗

bioRxiv2025

One Number to Rule Them All: The Wildlife Sperm Index for Standardized Gamete Assessment

In wildlife conservation, breeding programs focused on reintroduction are critical to recovering endangered species. Assisted reproductive technologies (ARTs) and biobanking play pivotal roles in these efforts but depend on high-quality gametes. Spermatozoa, due to their structural simplicity and well documented quality assessments are often considered the preferred cell type for cryopreservation and ARTs, especially in rare or exotic species. However, inconsistent retrieval of sperm samples with sufficient volume and concentration, especially for critically endangered species, can pose major limitations to assessing overall sperm quality. To address this information gap, we have developed the Wildlife Sperm Index (WSI), a standardized scoring system that integrates key sperm quality metrics--such as motility, viability, and DNA integrity--into a weighted composite score. While this study applies the WSI to sperm, the framework is adaptable to other cell types used in biobanking and reproductive technologies, broadening its potential utility. Unlike traditional sperm assessments that rely solely on microscopy, the WSI provides a scalable and quantitative framework for evaluating samples across species, including those that yield low-volume or concentration sperm samples. We validated the WSI against traditional means of sperm quality assessments, demonstrating its reliability as both a quality assessment and decision-making tool, enabling users to evaluate sample suitability for cryopreservation, ARTs, or downstream applications. By enabling standardized quality tracking, the WSI provides a foundation for more informed reproductive decisions to support global conservation efforts. Summary sentenceWe present the Wildlife Sperm Index (WSI), a standardized, composite scoring system that integrates key sperm quality metrics to improve gamete assessment and supports assisted reproduction and biobanking in wildlife conservation.

cell biology↗

bioRxiv2025

Differential Bioenergetic Profile of Human Glioblastoma following Transplantation of Myocyte-derived Mitochondria

Glioblastoma (GBM) exhibits profound plasticity, enabling adaptation to fluctuating microenvironmental stressors such as hypoxia and nutrient deprivation. However, this metabolic rewiring also creates subtype-specific vulnerabilities that may be exploited therapeutically. Here, we investigate whether mitochondrial transplantation using non-neoplastic, human myocyte-derived mitochondria alters the metabolic architecture of GBM cells and modulates their response to ionizing radiation. Using a cell-penetrating peptide-mediated delivery system, we successfully introduced mitochondria into two mesenchymal-subtype GBM cell lines, U3035 and U3046. Transplanted cells exhibited enhanced mitochondrial polarization and respiratory function, particularly in the metabolically flexible U3035 line. Bioenergetic profiling revealed significant increases in basal respiration, spare respiratory capacity, and glycolytic reserve in U3035 cells post-transplantation, whereas U3046 cells showed minimal bioenergetic augmentation. Transcriptomic analyses using oxidative phosphorylation (OXPHOS) and glycolysis gene sets confirmed these functional findings. At baseline, U3035 cells expressed high levels of both glycolytic and OXPHOS genes, while U3046 cells were metabolically suppressed. Following radiation, U3035 cells downregulated key OXPHOS and glycolysis genes, suggesting metabolic collapse. In contrast, U3046 cells transcriptionally upregulated both pathways, indicating compensatory adaptation. These results identify and establish mitochondrial transplantation as a metabolic priming strategy that sensitizes adaptable GBM subtypes like U3035 to therapeutic stress by inducing bioenergetic overextension. Conversely, rigid subtypes like U3046 may require inhibition of post-radiation metabolic compensation for effective targeting. Our findings support a novel stratified approach to GBM treatment which integrates metabolic subtype profiling with bioenergetic modulation.

neuroscience↗

bioRxiv2023

Evolutionary innovations in germline biology of placental mammals revealed by transcriptomics of first wave spermatogenesis in opossum

Mammalian spermatogenesis is a deeply conserved developmental program that is essential for fitness. Paradoxically, spermatogenic development also allows rapid divergence in gene expression and is thought to be a source of evolutionary novelty and gene birth. How mammalian spermatogenic cells protect a conserved developmental program while enabling exceptionally rapid divergence in gene expression and function is unknown. Here, we comprehensively profile the spermatogenic gene expression program in grey short-tailed opossum (Monodelphis domestica, a model marsupial) and compare it to equivalent data from the mouse (Mus musculus, a model placental mammal) to discover contrasting forces underlying the unique evolutionary dynamics of gene expression during mammalian spermatogenesis. For the first time, we describe the timing of the first wave of opossum spermatogenesis, and we combine bulk transcriptomic data from first-wave juvenile testes with single-cell transcriptomic data from adult testes to define conserved and divergent gene expression programs across the placental-marsupial split. We substantiate and extend our findings using genome-wide chromatin and multi-species transcriptome data and identify three classes of genes with different evolutionary trajectories: a deeply conserved central gene regulatory program governing spermatogenic progression; a separate class of spermatogenic genes exhibiting dynamic expression across placental mammals; and a third set of genes with evidence for directional selection in the placental mammal ancestor and constraint on expression levels within the placental mammalian lineage, representing placental innovations in germline gene expression and including biologically critical modules such as the DNA recombination and repair machinery.

genomics↗

bioRxiv2022

PIEZO2 in somatosensory neurons controls gastrointestinal transit

The gastrointestinal tract is in a state of constant motion. These movements are tightly regulated by the presence of food and help digestion by mechanically breaking down and propelling gut content. Mechanical sensing in the gut is thought to be essential for regulating motility; however, the identity of the neuronal populations, the molecules involved, and the functional consequences of this sensation are unknown. Here, we show that humans lacking PIEZO2 exhibit impaired bowel sensation and motility. Piezo2 in mouse dorsal root but not nodose ganglia is required to sense gut content, and this activity slows down food transit rates in the stomach, small intestine, and colon. Indeed, Piezo2 is directly required to detect colon distension in vivo. Our study unveils the mechanosensory mechanisms that regulate the transit of luminal contents throughout the gut, which is a critical process to ensure proper digestion, nutrient absorption, and waste removal. HighlightsO_LIIndividuals with PIEZO2 syndrome present impaired bowel sensation and gastrointestinal dysfunction. C_LIO_LIPIEZO2 in DRG neurons plays an important role in regulating gut motility. C_LIO_LILack of PIEZO2 from sensory neurons accelerates gastric emptying and intestinal transit. C_LIO_LIDRG neurons detect colon distension via PIEZO2. C_LI

neuroscience↗

bioRxiv2022

Excessive Mechanotransduction in Sensory Neurons Causes Joint Contractures in a Mouse Model of Arthrogryposis

Distal arthrogryposis (DA) is a collection of rare disorders characterized by congenital joint contractures. Most DA mutations are in muscle- and joint-related genes, and the anatomical defects originate cell-autonomously within the musculoskeletal system. However, gain-of-function (GOF) mutations in PIEZO2, a principal mechanosensor in somatosensation, cause DA subtype 5 via unknown mechanisms. We show that expression of a GOF PIEZO2 mutation in proprioceptive sensory neurons mainly innervating muscle spindles and tendons is sufficient to induce DA5-like phenotypes in mice. Overactive PIEZO2 causes anatomical defects via increased activity within the peripheral nervous system during postnatal development. Remarkably, Botox and a dietary fatty acid that modulates PIEZO2 activity markedly reduce DA5-like deficits. This reveals an unexpected role for somatosensory neurons: excessive mechanosensation within these neurons disrupts musculoskeletal development.

neuroscience↗

bioRxiv2022

Lighting Up Mechanosensation: dyeing to see PIEZO2

Sensory neurons gather information about mechanical forces from both the environment and internal organs to regulate physiology. PIEZO2 is a mechanosensory ion channel critical for touch, proprioception and bladder stretch sensation, yet its broad expression in sensory neurons and elsewhere suggests it may have undiscovered physiological roles. To fully understand mechanosensory physiology, we must know where and when PIEZO2-expressing neurons detect force. The fluorescent styryl dye FM 1-43 was shown to permeate several ion channels in cell culture and label sensory neurons. Surprisingly, we find that the vast majority of FM 1-43 somatosensory neuron labeling in vivo is dependent on PIEZO2-activity within nerve endings. We illustrate the potential of FM 1-43 by using it to identify novel Piezo2-expressing urethral neurons that are engaged by urination. These data reveal that FM 1-43 is a functional probe for mechanosensitivity via PIEZO2 activation in vivo and will facilitate the characterization of known and novel mechanosensory processes.

neuroscience↗

bioRxiv2018

Camphor white oil induces tumor regression through cytotoxic T cell-dependent mechanisms

Bioactive derivatives from the camphor laurel tree, Cinnamomum camphora, are posited to exhibit chemopreventive properties but the efficacy and mechanism of these natural products have not been established. We tested an essential-oil derivative, camphor white oil (CWO), for anti-tumor activity in a mouse model of keratinocyte-derived skin cancer. Daily topical treatment with CWO induced dramatic regression of pre-malignant skin tumors and a two-fold reduction in cutaneous squamous cell carcinomas. We next investigated underlying cellular and molecular mechanisms. In cultured keratinocytes, CWO stimulated calcium signaling, resulting in calcineurin-dependent activation of nuclear factor of activated T cells (NFAT). In vivo, CWO induced transcriptional changes in immune-related genes, resulting in cytotoxic T cell-dependent tumor regression. Finally, we identified chemical constituents of CWO that recapitulated effects of the admixture. Together, these studies identify T cell-mediated tumor regression as the mechanism through which a plant-derived essential oil diminishes established tumor burden.\n\nSUMMARY BLURBEssential oil derived from the camphor tree acts by stimulating immune cell-dependent regression of skin tumors in a mouse model of cutaneous squamous cell carcinoma.

physiology↗