Biology subjects

Bronson, R.

Publications and source records attributed to Bronson, R..

8 recordsLinked to original sources

bioRxiv2026

Sequential vaccination matures VRC01-class HIV-1 neutralizing antibodies in humans

Inducing a broadly neutralizing antibody (bnAb) response is a key goal of HIV-1 vaccine development. Despite significant progress, it is unknown whether vaccine-primed B cells can be reactivated and matured to secrete bona fide bnAbs. In the IAVI C107/C110 single-arm, open-label human trial, VRC01-class memory B cells previously primed by the GT1.1 germline-targeting envelope glycoprotein (Env) trimer were reactivated by a BG505 SOSIP.664 trimer boost. Somatic hypermutation in the activated B cells drove higher antibody affinity for the CD4-binding site on fully glycosylated, heterologous Env trimers. Three VRC01-class monoclonal antibodies derived from independent B cell lineages neutralized 18-31% of 119 viruses in a globally diverse panel. This work advances the HIV-1 germline-targeting vaccination concept from proof-of-priming towards proof-of-breadth and defines a benchmark for bnAb induction.

immunology↗

bioRxiv2026

Inter-organ communication shapes human metabolic tissue states and resolves anti-diabetic drug response modes in a six-tissue microphysiological system

Systemic glucose regulation depends on coordinated signaling among metabolically specialized tissues, yet most human in vitro models capture only limited portions of this network. Here, we developed and benchmarked a perfused human six-tissue MPS by combining AnthroHive, a recirculating perfusion platform, with MOTIVE-6, a six-compartment Multiorgan Tissue Interaction Vessel, to culture human gut epithelium, pancreatic islets, liver organoids, adipocytes, skeletal muscle, and midbrain-patterned brain organoids in a microphysiological system. Shared perfusion redirected engineered tissue states toward tissue-aligned metabolic, endocrine, absorptive, contractile, and neural-associated programs while reducing selected isolation-associated stress and remodeling signatures. Under High nutrient conditions, however, multi-tissue interaction shifted liver and islet responses toward inflammatory and nutrient-stress-associated gene expression, indicating context-dependent effects of cross-compartment signaling. Graded nutrient exposure resolved a staged circuit trajectory: Low nutrient conditions supported maintenance-associated programs, Mid nutrient exposure induced compensatory endocrine and anabolic remodeling with declining net glucose depletion, and High nutrient exposure shifted the system toward stress-associated metabolic dysfunction. Under High conditions, metformin and semaglutide produced distinct response modes. Metformin preserved circuit-level glucose handling without increasing insulin or C-peptide accumulation, while semaglutide remodeled gut, brain organoid, islet, and liver organoid transcriptional programs linked to nutrient sensing, epithelial maintenance, endocrine signaling, and neurometabolic state. Together, this study establishes a benchmarked human six-tissue MPS resource, paired with tissue-resolved transcriptomic, shared-media metabolomic, functional, endocrine, and inflammatory datasets, for investigating how tissue interaction, nutrient availability, and metabolic therapies reshape glucose-regulatory networks. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/726943v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@181cdfforg.highwire.dtl.DTLVardef@fb211eorg.highwire.dtl.DTLVardef@13b7284org.highwire.dtl.DTLVardef@1db7543_HPS_FORMAT_FIGEXP M_FIG C_FIG Created in BioRender. Trapecar, M. (2026) https://BioRender.com/a4tl7nv

bioengineering↗

bioRxiv2026

RUNX1-deficiency drives immune-active ER+ mammary tumorigenesis through activation of interferon signaling

AbstractRecurrent loss-of-function mutations in RUNX1 occur in estrogen receptor-positive (ER+) breast cancers, yet how RUNX1-loss contributes to breast tumorigenesis remains unclear. Here we used genetically engineered mouse models with luminal mammary epithelial cell (MEC)-restricted gene disruption to investigate its role in breast cancer initiation. Loss of RUNX1 alone, or together with RB1, was insufficient to drive tumor formation. In contrast, combined loss of RUNX1 and p53 induced mammary tumors with full penetrance. These tumors contained ER+ cancer cells and exhibited extensive T cell and macrophage infiltration, indicative of an immune hot microenvironment. Mechanistically, RUNX1-deficiency activated interferon signaling in luminal MECs, associated with derepression of RUNX1 target STAT1 and enhanced inflammatory responses. Consistent with these findings, human ER+ breast cancers with low RUNX1 expression displayed elevated immune signatures and poorer patient survival. Together, our results identify RUNX1-loss as a driver of an immune-active subtype of ER+ breast cancer.

cancer biology↗

bioRxiv2025

Olfactory Bulb Pinprick Induction of Cortical Spreading Depolarizations

Cortical spreading depolarization (CSD) is a wave of cellular depolarization followed by prolonged depression of neuronal activity and is associated with a broad array of neurological diseases, including migraine with aura, traumatic brain injury, and stroke. Traditional CSD induction methods for animal studies have included pinprick, concentrated potassium chloride (KCl) application, and electrical stimulation. These methods are invasive and can cause injury to the cortex. Recently, a non-invasive approach using optogenetics has become available, but requires the use of transgenic mice or transfection of an optogene, which limits its wide adoption. Here, we describe a novel approach using olfactory bulb needle insertion in rodents to induce CSD. We also included KCl-induced CSDs as a comparator in the same mice. Olfactory bulb pinprick resulted in CSDs on every attempt (n = 18/18) as confirmed with optical intrinsic signal imaging. Histological analysis revealed that needle disruption in the caudal olfactory bulb, which is continuous with the cerebral cortex, may account for the propagation of CSD from the olfactory bulb to the cortex. Olfactory bulb pinprick reliably induces CSD and is non-invasive with respect to cortex. The approach may prove to be useful in rodent studies where maintenance of cortical integrity is important.

neuroscience↗

bioRxiv2024

Airway injury induces alveolar epithelial and mesenchymal responses mediated by macrophages

Airway injury activates local progenitors and stimulates cell-cell interactions to restore homeostasis, but it is unknown how distal niches are impacted. We utilized mouse models of airway-specific epithelial injury to examine secondary tissue-wide alveolar and immune responses. Single-cell transcriptomics and in vivo validation of mouse models of airway-specific epithelial injury revealed transient, tissue-wide proliferation of alveolar type 2 (AT2) progenitor cells after club cell-specific injury or ablation. Myeloid cells exhibited altered gene expression after club cell loss and were detectable in the bronchoalveolar lavage fluid. The AT2 cell proliferative response was reliant on alveolar macrophages (AMs) exhibiting an injury-induced gene expression program. Overall, these results demonstrate that acute airway damage can trigger myeloid-mediated lung alveolar responses that may contribute to disease susceptibility or dysfunction.

cell biology↗

bioRxiv2022

Fitm2 is required for ER homeostasis and normal function of murine liver

The ER-resident protein fat-inducing transcript 2 (FIT2) catalyzes acyl-CoA cleavage in vitro and is required for endoplasmic reticulum (ER) homeostasis and normal lipid storage in cells. The gene encoding FIT2 is essential for the viability of mice and worms. Whether FIT2 acts as an acyl-CoA diphosphatase in vivo and how this activity affects liver, where the protein was discovered, are unknown. Here, we report that hepatocyte-specific Fitm2 knockout (FIT2-LKO) mice exhibited elevated acyl-CoA levels, ER stress, and signs of liver injury. FIT2-LKO mice fed a chow diet had more triglycerides in their livers than control littermates due, in part, to impaired secretion of triglyceride-rich lipoproteins and reduced capacity for fatty acid oxidation. Challenging FIT2-LKO mice with a high-fat diet to increase FIT2 acyl-CoA substrates worsened hepatic ER stress and liver injury, but unexpectedly reversed the steatosis phenotype, similar to what is observed in FIT2-deficient cells loaded with fatty acids. Our findings support the model that FIT2 acts as an acyl-CoA diphosphatase in vivo and is crucial for normal hepatocyte function and ER homeostasis in murine liver.

cell biology↗

bioRxiv2021

Chromatin alterations in the aging lung change progenitor cell activity

The lung contains multiple progenitor cell types that respond to damage, but how their responses are choreographed and why they decline with age is poorly understood. We report that histone H3 lysine 9 di-methylation (K9me2), mediated by histone methyltransferase G9a, regulates the dynamics of lung epithelial progenitor cells, and this regulation deteriorates with age. In aged mouse lungs, K9me2 loss coincided with lower frequency and activity of alveolar type 2 (AT2) cell progenitors. In contrast, K9me2 loss resulted in increased frequency and activity of multipotent progenitor cells with bronchiolar and alveolar potential (BASCs) and bronchiolar progenitors. K9me2 depletion in young mice through deletion or inhibition of G9a decreased AT2 progenitor activity and impaired alveolar injury regeneration. Conversely, K9me2 depletion increased chromatin accessibility of bronchiolar cell genes, increased BASC frequency and accelerated bronchiolar repair. K9me2 depletion also resulted in increased bronchiolar cell expression of the SARS-CoV2 receptor Ace2 in aged lungs. These data point to K9me2 and G9a as a critical regulator of the balance of lung progenitor cell regenerative responses and prevention of susceptibility to age-related lung diseases. These findings indicate that epigenetic regulation coordinates progenitor cell populations to expedite regeneration in the most efficient manner and disruption of this regulation presents significant challenges to lung health.

molecular biology↗

bioRxiv2021

Pyruvate kinase M1 suppresses development and progression of prostate adenocarcinoma

Most cancers, including prostate cancers, express the M2 splice isoform of pyruvate kinase (Pkm2). This isoform can promote anabolic metabolism to support cell proliferation; however, Pkm2 expression is dispensable for many cancers in vivo. Pyruvate kinase M1 (Pkm1) isoform expression is restricted to relatively few tissues and has been reported to promote growth of select tumors, but the role of PKM1 in cancer has been less studied. Pkm1 is expressed in normal prostate tissue; thus, to test how differential pyruvate kinase isoform expression affects cancer initiation and progression we generated mice harboring a conditional allele of Pkm1 and crossed this allele, as well as a Pkm2 conditional allele, to a Pten loss-driven prostate cancer model. We found that Pkm1 loss leads to Pkm2 expression and accelerates prostate cancer, while deletion of Pkm2 leads to increased Pkm1 expression and suppresses cancer. Consistent with these data, a small molecule pyruvate kinase activator that mimics a PKM1-like state suppresses progression of established prostate tumors. PKM2 expression is retained in most human prostate cancers, arguing that pharmacological PKM2 activation may be beneficial for some prostate cancer patients.

cancer biology↗