Biology subjects

Fuller, A. D.

Publications and source records attributed to Fuller, A. D..

5 recordsLinked to original sources

bioRxiv2026

NIX-associated mitochondrial remodeling contributes to esophageal epithelial differentiation

Mitochondria are increasingly recognized as regulators of cellular differentiation, but their role in esophageal epithelial homeostasis remains poorly understood. Here, we investigated mitochondrial remodeling during esophageal epithelial differentiation and whether mitochondrial depletion contributes to the acquisition of the differentiated phenotype. Mitochondrial abundance was assessed across normal human esophageal epithelium and in non-transformed immortalized human esophageal epithelial cells (EPC2-hTERT) using two differentiation models. Mitochondrial architecture was quantified, and the functional role of mitochondrial abundance was examined using doxycycline-inducible depletion of transcription factor A, mitochondrial (TFAM). Mitochondrial abundance progressively decreased from basal to superficial compartments of normal human esophageal epithelium and during in vitro differentiation, accompanied by fragmentation and remodeling of the mitochondrial network. TFAM depletion reduced mitochondrial abundance and increased squamous differentiation markers, indicating that mitochondrial depletion was sufficient to promote differentiation. Analysis of candidate mitochondrial clearance pathways identified Bcl2-interacting protein 3-like (BNIP3L)/NIX (NIP3-like protein X) as preferentially associated with differentiated epithelial cells and induced during differentiation. NIX was associated with mitochondria and increased as mitochondrial abundance declined. NIX depletion prevented differentiation-associated mitochondrial depletion and attenuated differentiation marker induction. In human esophageal epithelium, NIX expression increased across the basal-to-suprabasal compartment before declining superficially. BNIP3L expression was reduced in active eosinophilic esophagitis (EoE) and increased following corticosteroid-associated remission. Interleukin-13 similarly reduced BNIP3L expression and suppressed epithelial differentiation in EPC2-hTERT cells. These findings identify NIX-associated mitochondrial remodeling as an important component of esophageal epithelial differentiation and suggest that disruption of mitochondrial quality control may contribute to impaired epithelial differentiation in EoE.

cell biology↗

bioRxiv2025

Interleukin-13-mediated alterations in esophageal epithelial mitochondria contribute to tissue remodeling in eosinophilic esophagitis

BackgroundThe significance of mitochondria in EoE pathobiology remains elusive. ObjectiveTo determine the impact of EoE inflammatory mediators upon mitochondrial biology in esophageal epithelium, the mechanisms mediating these effects, and their functional significance to EoE pathobiology. MethodsMitochondria were evaluated in human biopsies, MC903/Ovalbumin-induced murine EoE, and human esophageal keratinocytes. Esophageal keratinocytes were treated with EoE-relevant cytokines and JAK/STAT inhibitor ruxolitinib. To deplete mitochondria, 3D organoids generated from TFAMloxp/loxp mice were subjected ex vivo to Cre or siRNA against Transcription factor A, mitochondria (TFAM) was transfected into esophageal keratinocytes. Mitochondrial respiration, membrane potential, and superoxide levels were measured. ResultsWe find evidence of increased mitochondria in esophageal epithelium of patients with EoE and mice with EoE-like inflammation. In esophageal keratinocytes, IL-4 and IL-13 increase mitochondrial mass. IL-13 increases mitochondrial biogenesis in a JAK/STAT-dependent manner. In 3D organoids, IL-13 limits squamous cell differentiation (SCD), and this is blunted upon TFAM depletion. IL-13 decreases mitochondrial respiration and superoxide level, although mitochondria remain intact. IL-13-mediated suppression of superoxide was abrogated upon TFAM depletion in esophageal keratinocytes. ConclusionsWe report that increased mitochondrial mass is a feature of EoE. Among EoE-relevant cytokines, IL-13 is the primary driver of increased mitochondrial mass in esophageal keratinocytes by promoting mitochondrial biogenesis in a JAK/STAT-dependent manner. IL-13-mediated accumulation of mitochondria impairs SCD in esophageal keratinocytes and also suppresses oxidative stress, a factor that is known to induce SCD. These findings identify a novel mechanism through which IL-13 promotes EoE-associated epithelial remodeling. Clinical ImplicationThese findings further lay a foundation for exploration of level of esophageal epithelial mitochondria as a predictive biomarker for response to dupilumab. Capsule summaryIL-13 promotes mitochondrial biogenesis in esophageal epithelium, contributing to impaired squamous cell differentiation.

molecular biology↗

bioRxiv2023

Autophagy contributes to homeostasis in esophageal epithelium where high autophagic vesicle content marks basal cells with limited proliferation and enhanced self-renewal potential

Background & AimsAutophagy has been demonstrated to play roles in esophageal pathologies both benign and malignant. Here, we aim to define the role of autophagy in esophageal epithelium under homeostatic conditions. MethodsWe generated tamoxifen-inducible, squamous epithelial-specific Atg7 (autophagy related 7) conditional knockout mice to evaluate effects on esophageal homeostasis and response to the carcinogen 4-nitroquinoline 1-oxide (4NQO) using histological and biochemical analyses. We FACS sorted esophageal basal cells based upon fluorescence of the autophagic vesicle (AV)-identifying dye Cyto-ID, then subjected these cells to transmission electron microscopy, image flow cytometry, 3D organoid assays, RNA-Sequencing (RNA-Seq), and cell cycle analysis. 3D organoids were subjected to passaging, single cell (sc) RNA-Seq, cell cycle analysis, and immunostaining. ResultsGenetic autophagy inhibition in squamous epithelium resulted in increased proliferation of esophageal basal cells. Esophageal basal cells with high AV level (Cyto-IDHigh) displayed limited organoid formation capability upon initial plating but passaged more efficiently than their counterparts with low AV level (Cyto-IDLow). RNA-Seq suggested increased autophagy in Cyto- IDHigh esophageal basal cells along with decreased cell cycle progression, the latter of which was confirmed by cell cycle analysis. scRNA-Seq of 3D organoids generated by Cyto-IDLow and Cyto- IDHigh cells identified expansion of 3 cell populations, enrichment of G2/M-associated genes, and aberrant localization of cell cycle-associated genes beyond basal cell populations in the Cyto- IDHigh group. Ki67 expression was also increased in organoids generated by Cyto-IDHigh cells, including in cells beyond the basal cell layer. Squamous epithelial-specific autophagy inhibition induced significant weight loss in mice treated with 4NQO that further displayed perturbed epithelial tissue architecture. ConclusionsHigh AV level identifies esophageal epithelium with limited proliferation and enhanced self-renewal capacity that contributes to maintenance of the esophageal proliferation- differentiation gradient in vivo.

physiology↗

bioRxiv2022

Eosinophilic esophagitis-associated epithelial remodeling may limit esophageal carcinogenesis

Under homeostatic conditions, esophageal epithelium displays a proliferation/differentiation gradient that is generated as proliferative basal cells give rise to suprabasal cells then terminally differentiated superficial cells. This proliferation/differentiation gradient is perturbed in esophageal pathologies both benign and malignant. Esophageal cancer is among the deadliest forms of human malignancy with 5-year survival rates of <20%. Esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) are the two most common subtypes of esophageal cancer. Gastroesophageal reflux disease (GERD) is a primary risk factor for EAC. Although GERD and the food allergy-mediated condition eosinophilic esophagitis (EoE) are both associated with chronic esophageal inflammation and epithelial remodeling, including basal cell hyperplasia, epidemiological evidence suggests that EoE patients do not develop esophageal malignancy. Here, we perform single cell RNA-sequencing in murine models of EoE and ESCC to delineate the effects that these two conditions have specifically upon the cellular landscape of esophageal epithelium. In mice with EoE or ESCC, we find expansion of cell populations as compared to normal esophageal epithelium. In mice with EoE, we detect expansion of 4 suprabasal populations coupled with depletion of 4 basal cell populations. By contrast, mice with ESCC display expansion of 4 basal populations as well as depletion of 3 superficial populations. We further evaluated modules of co-expressed genes in EoE- and ESCC-enriched epithelial cell clusters. Senescence, glucocorticoid receptor signaling, and granulocyte-macrophage colony-stimulating factor pathways were associated with EoE-enriched clusters while pathways associated with cell proliferation and metabolism were identified in ESCC-enriched clusters. Finally, by pairing murine models of EoE and ESCC, we demonstrate that exposure to EoE inflammation limits esophageal carcinogenesis. Our findings provide the first functional investigation of the relationship between EoE and esophageal cancer and suggest that esophageal epithelial remodeling events occurring in response to EoE inflammation may limit act to esophageal carcinogenesis which may have future implications for leveraging allergic inflammation-associated alterations in epithelial biology to prevent and/or treat esophageal cancer.

cell biology↗

bioRxiv2020

Identification of Retinal Ganglion Cell Types and Brain Nuclei expressing the transcription factor Brn3c/Pou4f3 using a Cre recombinase knock-in allele.

Members of the POU4F/Brn3 transcription factor family have an established role in the development of retinal ganglion cell types (RGCs), the projection sensory neuron conveying visual information from the mammalian eye to the brain. Our previous work using sparse random recombination of a conditional knock-in reporter allele expressing Alkaline Phosphatase (AP) and intersectional genetics had identified three types of Pou4f3/Brn3c positive (Brn3c+) RGCs. Here, we describe a novel Brn3cCre mouse allele generated by serial Dre to Cre recombination. We use this allele to explore the expression overlap of Brn3c with Brn3a and Brn3b and the dendritic arbor morphologies and visual stimulus properties of Brn3c+ RGC types. Furthermore, we explore Brn3c-expressing brain nuclei. Our analysis reveals a much larger number of Brn3c+ RGCs and more diverse set of RGC types than previously reported. The majority of RGCs having expressed Brn3c during development are still Brn3c positive in the adult, and all of them express Brn3a while only about half express Brn3b. Intersection of Brn3b and Brn3c expression highlights an area of increased RGC density, similar to an area centralis, corresponding to part of the binocular field of view of the mouse. Brn3c+ neurons and projections are present in multiple brain nuclei. Brn3c+ RGC projections can be detected in the Lateral Geniculate Nucleus (LGN), Pretectal Area (PTA) and Superior Colliculus (SC) but also in the thalamic reticular nucleus (TRN), a visual circuit station that was not previously described to receive retinal input. Most Brn3c+ neurons of the brain are confined to the pretectum and the dorsal midbrain. Amongst theses we identify a previously unknown Brn3c+ subdivision of the deep mesencephalic nucleus (DpMe). Thus, our newly generated allele provides novel biological insights into RGC type classification, brain connectivity and midbrain cytoarchitectonic, and opens the avenue for specific characterization and manipulation of these structures.

neuroscience↗