Selected Grantee Publications
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- 14 results found
- S10 [SIG, BIG, HEI]
- Microscopy
A Murine Model of Trypanosoma brucei-Induced Myocarditis and Cardiac Dysfunction
Crilly et al., Microbiology Spectrum. 2025.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11792545
Trypanosoma brucei is a protozoan parasite that causes human and animal African trypanosomiases, HAT and AAT, respectively. Cardiac symptoms are commonly reported in HAT patients, and intracardiac parasites with accompanying myocarditis have been observed in both natural hosts and animal models for T. brucei infection. A clinically relevant, reproducible murine model for T. brucei–associated cardiomyopathy is currently unavailable. The researchers developed a 7- to 10-week-old C57Bl/6J male and female mouse model for T. brucei infection that demonstrates myocarditis, elevated serum levels of NT-proBNP, and electrocardiographic abnormalities, recapitulating the clinical features of infection. The results demonstrate the importance of interstitial space in T. brucei colonization and provide a relevant, reproducible murine model to investigate the pathogenesis and potential therapeutics of T. brucei-mediated heart damage. Supported by ORIP (T32OD011089, S10OD026859), NCI, and NIA.
Functional Differences Between Rodent and Human PD-1 Linked to Evolutionary Divergence
Masubuchi et al., Science Immunology. 2025.
https://pubmed.ncbi.nlm.nih.gov/39752535/
Programmed cell death protein 1 (PD-1), an immune checkpoint receptor, regulates immunity against cancer. Rodent models (e.g., mice) do not exhibit the same response rates and immune-related adverse effects to PD-1 blocking drugs as patients with cancer. Only 59.6% amino acid sequence identity is conserved in human PD-1 (hu PD-1) and mouse PD-1 (mo PD-1). Researchers used mouse tumor models, coculture assays, and biophysical assays to determine key functional and biochemical differences between hu PD-1 and mo PD-1. HuPD-1 demonstrates stronger suppressive activity of interleukin-2 secretion and CD69 expression than mo PD-1 because of the ectodomain and intracellular domain, but not the transmembrane domain. Analysis of rodent evolution demonstrated that other inhibitory immunoreceptors were positively selected or had selection intensification over PD-1. Understanding the conservation and divergence of PD-1 signaling at the molecular level in humans compared with mice is needed to properly translate preclinical data to clinical therapeutics. Supported by ORIP (S10OD026929), NCI, and NIA.
Plural Molecular and Cellular Mechanisms of Pore Domain KCNQ2 Encephalopathy
Abreo et al., eLife. 2025.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11703504
This study investigates the cellular and molecular mechanisms underlying KCNQ2 encephalopathy, a severe type of early-onset epilepsy caused by mutations in the KCNQ2 gene. Researchers describe a case study of a child with a specific KCNQ2 gene mutation, G256W, and found that it disrupts normal brain activity, leading to seizures and developmental impairments. Male and female Kcnq2G256W/+ mice have reduced KCNQ2 protein levels, epilepsy, brain hyperactivity, and premature deaths. As seen in the patient study, ezogabine treatment rescued seizures in mice, suggesting a potential treatment avenue. These findings provide important insights into KCNQ2-related epilepsy and highlight possible therapeutic strategies. Supported by ORIP (U54OD020351, S10OD026804, U54OD030187), NCI, NHLBI, NICHD, NIGMS, NIMH, and NINDS.
Engineered Bacteria That Self-Assemble Bioglass Polysilicate Coatings Display Enhanced Light Focusing
Sidor et al., PNAS. 2024.
https://pubmed.ncbi.nlm.nih.gov/39656206
Organisms in nature have evolved to create multifunctional structures with advanced optical properties that can be used to design new optical materials. Researchers created constructs containing the enzyme silicatein, derived from sea sponges, and the outer membrane protein A (OmpA) to engineer Escherichia coli bacteria to express surface-level silicatein enzymes. Using Rhodamine123 staining and transmission electron microscopy, results showed that engineered E. coli expressing OmpA-silicatein displayed polysilicate encapsulation with smooth, nonruffled cell borders compared with wild-type E. coli. Light-scattering analysis demonstrated that engineered E. coli create photonic nanojets that are brighter than wild-type E. coli. This study serves as proof of concept that cells can be engineered for potential utilization as tunable photonic components. Supported by ORIP (S10OD030296) and NIGMS.
Indoleamine-2,3-Dioxygenase Inhibition Improves Immunity and Is Safe for Concurrent Use with cART During Mtb/SIV Coinfection
Singh et al., JCI Insight. 2024.
https://pubmed.ncbi.nlm.nih.gov/39114981/
HIV and tuberculosis (TB) coinfection can lead to TB reactivation that is caused by chronic immune system activation. Researchers explored indoleamine-2,3-dioxygenase (IDO) inhibition as a host-directed therapy (HDT) to mitigate immune suppression and TB reactivation in a rhesus macaque Mycobacterium tuberculosis (Mtb)/simian immunodeficiency virus (SIV) model. The IDO inhibitor D-1-methyl tryptophan improved T-cell immunity, reduced tissue damage, and controlled TB-related inflammation without interfering with the efficacy of combinatorial antiretroviral therapy (cART). These findings support IDO inhibition as a potential HDT in HIV/TB coinfection, providing a strategy to balance immune control while preventing TB reactivation in cART-treated patients. Supported by ORIP (S10OD028732, U42OD010442, S10OD028653) and NIAID.
Impaired Axon Initial Segment Structure and Function in a Model of ARHGEF9 Developmental and Epileptic Encephalopathy
Wang et al., PNAS. 2024.
https://www.pnas.org/doi/10.1073/pnas.2400709121
Researchers developed a mouse model carrying the G55A missense variant identified in ARHGEF9 patients with severe epilepsy and neurodevelopmental phenotypes. Using male Arhgef9G55A mice, this study examined behavioral, molecular, and electrophysiological phenotypes in the Arhgef9G55A model of developmental and epileptic encephalopathies (DEE). Researchers found that the G55A variant causes disruption of inhibitory postsynaptic organization and axon initial segment (AIS) architecture, leading to impairment of both synaptic transmission and action potential generation. The effects of Arhgef9G55A on neuronal function affect both intrinsic and synaptic excitability and preferentially impair AIS. These findings indicate a novel pathological mechanism of DEE and represent a unique example of a neuropathological condition converging from AIS dysfunctions. Supported by ORIP (U54OD020351, U54OD030187, U54OD020351, S10OD026974) and NINDS.
Obesity Causes Mitochondrial Fragmentation and Dysfunction in White Adipocytes Due to RalA Activation
Xia et al., Nature Metabolism. 2024.
https://pubmed.ncbi.nlm.nih.gov/38286821/
This study presents a molecular mechanism for mitochondrial dysfunction as a characteristic trait of obesity. Chronic activation of the small GTPase RalA in inguinal white adipocytes (iWAT), in male mice fed a high-fat diet (HFD) represses energy expenditure by shifting mitochondrial dynamics toward excessive fission, contributing to weight gain and metabolic dysfunction. Targeted deletion of RalA in iWAT attenuated HFD-induced obesity due to increased energy expenditure and mitochondrial oxidative phosphorylation. Mechanistically, RalA dephosphorylates inhibitory Serine637 on fission protein Drp1, leading to excessive fission in adipocytes and mitochondrial fragmentation. Expression of a human homolog of Drp1—DNM1L—in adipose tissue is positively correlated with obesity and insulin resistance. These findings open avenues to investigate RalA-Drp1 axis in energy homeostasis. Supported by ORIP (S10OD023527), NCI, NHLBI, and NIDDK.
Tumor Explants Elucidate a Cascade of Paracrine SHH, WNT, and VEGF Signals Driving Pancreatic Cancer Angiosuppression
Hasselluhn et al., Cancer Discovery. 2024.
https://pubmed.ncbi.nlm.nih.gov/37966260/
This study presents a key mechanism that prevents pancreatic ductal adenocarcinoma (PDAC) from undergoing neoangiogenesis, which affects its development, pathophysiology, metabolism, and treatment response. Using human and murine PDAC explants, which effectively retain the complex cellular interactions of native tumor tissues, and single-cell regulatory network analysis, the study identified a cascade of three paracrine pathways bridging between multiple cell types and acting sequentially, Hedgehog to WNT to VEGF, as a key suppressor of angiogenesis in KRAS-mutant PDAC cells. This study provides an experimental paradigm for dissecting higher-order cellular interactions in tissues and has implications for PDAC treatment strategies. Supported by ORIP (S10OD012351, S10OD021764), NCI, and NIDDK.
Molecular Basis of Human Trace Amine-Associated Receptor 1 Activation
Zilberg et al., Nature Communications. 2024.
https://www.nature.com/articles/s41467-023-44601-4
The authors reported the cryogenic electron microscopy structure of human trace amine-associated receptor 1 (hTAAR1, hTA1) signaling complex, a key modulator in monoaminergic neurotransmission, as well as its similarities and differences with other TAAR members and rodent TA1 receptors. This discovery has elucidated hTA1’s molecular mechanisms underlining the strongly divergent pharmacological properties of human and rodent TA1 and therefore will boost the translation of preclinical studies to clinical applications in treating disorders of dopaminergic dysfunction, metabolic disorders, cognitive impairment, and sleep-related dysfunction. Supported by ORIP (S10OD019994, S10OD026880, and S10OD030463), NIDA, NIGMS, NIMH, and NCATS.
An E1–E2 Fusion Protein Primes Antiviral Immune Signaling in Bacteria
Ledvina et al., Nature. 2023.
https://www.nature.com/articles/s41586-022-05647-4
Investigators show that the cGAS/DncV–like nucleotidyltransferase (CD‑NTase)–associated protein 2 (Cap2) primes bacterial CD-NTases for activation through a ubiquitin transferase–like mechanism. A cryo-electron microscopy structure of the Cap2-CD-NTase complex reveals Cap2 as an all-in-one ubiquitin transferase–like protein, with distinct domains resembling eukaryotic E1 and E2 proteins. The structure captures a reactive-intermediate state with the CD-NTase C terminus positioned in the Cap2 E1 active site and conjugated to AMP. Cap2 conjugates the CD-NTase C terminus to a target molecule that primes the CD-NTase for increased cGAMP production. The investigators further demonstrate bacteria control immune signaling using an ancient, minimized ubiquitin transferase–like system and provide insight into the evolution of the E1 and E2 machinery across domains of life. Supported by ORIP (S10OD023498, S10OD021527, S10OD025267) and NIGMS.