Selected Grantee Publications
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- Rodent Models
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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.
Intestinal Epithelial Adaptations to Vertical Sleeve Gastrectomy Defined at Single-Cell Resolution
Koch-Laskowski et al., Genomics. 2024.
https://pubmed.ncbi.nlm.nih.gov/38309446/
Perturbations in the intestinal epithelium have been linked to the pathogenesis of metabolic disease. Bariatric procedures, such as vertical sleeve gastrectomy (VSG), cause gut adaptations that induce robust metabolic improvements. Using a male mouse model, the authors assessed the effects of VSG on different cell lineages of the small intestinal epithelium. They show that Paneth cells display increased expression of the gut peptide Reg3g after VSG. Additionally, VSG restores pathways pertaining to mitochondrial respiration and cellular metabolism, especially within crypt-based cells. Overall, this work demonstrates how adaptations among specific cell types can affect gut epithelial homeostasis; these findings can help researchers develop targeted, less invasive treatment strategies for metabolic disease. Supported by ORIP (F30OD031914), NCI, and NIDDK.
The Power of the Heterogeneous Stock Rat Founder Strains in Modeling Metabolic Disease
Wagner et al., Endocrinology. 2023.
https://pubmed.ncbi.nlm.nih.gov/37882530/
Metabolic diseases are a host of complex conditions, including obesity, diabetes mellitus, and metabolic syndrome. Endocrine control systems (e.g., adrenals, thyroid, gonads) are causally linked to metabolic health outcomes. In this study, investigators determined novel metabolic and endocrine health characteristics in both sexes of six available substrains similar to the N/NIH Heterogeneous Stock (HS) rat founders. This deep-phenotyping protocol provides new insight into the exceptional potential of the HS rat population to model complex metabolic health states. The following hypothesis was tested: The genetic diversity in the HS rat founder strains represents a range of endocrine health conditions contributing to the diversity of cardiometabolic disease risks exhibited in the HS rat population. Supported by ORIP (R24OD024617), NHLBI, NIGMS and NIDDK.
A Germ-Free Humanized Mouse Model Shows the Contribution of Resident Microbiota to Human-Specific Pathogen Infection
Wahl et al., Nature Biotechnology. 2023.
https://www.nature.com/articles/s41587-023-01906-5
Germ-free (GF) mice are of limited value in the study of human-specific pathogens because they do not support their replication. In this report, investigators developed a GF humanized mouse model using the bone marrow–liver–thymus platform to provide a robust and flexible in vivo model that can be used to study the role of resident microbiota in human health and disease. They demonstrated that resident microbiota promote viral acquisition and pathogenesis by using two human-specific pathogens, Epstein–Barr virus and HIV. Supported by ORIP (P40OD010995), FIC, NIAID, NCI, and NIDDK.
Simultaneous Evaluation of Treatment Efficacy and Toxicity for Bispecific T-Cell Engager Therapeutics in a Humanized Mouse Model
Yang et al., The FASEB Journal. 2023.
https://faseb.onlinelibrary.wiley.com/doi/10.1096/fj.202300040R
Immuno-oncology–based therapies are an evolving powerful treatment strategy that targets the immune system and harnesses it to kill tumor cells directly. Investigators describe the novel application of a humanized mouse model that can simultaneously evaluate the efficacy of bispecific T cell engagers to control tumor burden and the development of cytokine release syndrome. The model also captures variability in responses for individual patients. Supported by ORIP (R24OD026440), NIAID, NCI, and NIDDK.
A Class of Anti-Inflammatory Lipids Decrease with Aging in the Central Nervous System
Tan et al., Nature Chemical Biology. 2023.
https://doi.org/10.1038/s41589-022-01165-6
Impaired lipid metabolism in the brain has been implicated in neurological disorders of aging, yet analyses of lipid pathway changes with age have been lacking. The researchers examined the brain lipidome of mice of both sexes across the lifespan using untargeted lipidomics. They found that 3-sulfogalactosyl diacylglycerols (SGDGs) are structural components of myelin and decline with age in the central nervous system. The researchers discovered that SGDGs also are present in male human and rhesus macaque brains, demonstrating their evolutionary conservation in mammals. The investigators showed that SGDGs possess anti-inflammatory activity, suggesting a potential role for this lipid class in age-related neurodegenerative diseases. Supported by ORIP (P51OD011092), NIA, NCI, NIDDK, and NINDS.
Human Hematopoietic Stem Cell Engrafted IL-15 Transgenic NSG Mice Support Robust NK Cell Responses and Sustained HIV-1 Infection
Abeynaike et al., Viruses. 2023.
https://www.mdpi.com/1999-4915/15/2/365
A major obstacle to human natural killer (NK) cell reconstitution is the lack of human interleukin‑15 (IL-15) signaling, as murine IL-15 is a poor stimulator of the human IL-15 receptor. Researchers show that immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice expressing a transgene encoding human IL-15 (NSG-Tg(IL-15)) have physiological levels of human IL-15 and support long-term engraftment of human NK cells when transplanted with human umbilical cord blood–derived hematopoietic stem cells (HSCs). These mice demonstrate robust and long-term reconstitution with human immune cells but do not develop graft-versus-host disease, allowing long-term studies of human NK cells. The HSC-engrafted mice can sustain HIV-1 infection, resulting in human NK cell responses. This work provides a robust novel model to study NK cell responses to HIV-1. Supported by ORIP (R24OD026440), NIAID, NCI, and NIDDK.
Gut Microbiome Dysbiosis in Antibiotic-Treated COVID-19 Patients Is Associated with Microbial Translocation and Bacteremia
Bernard-Raichon et al., Nature Communications. 2022.
https://www.doi.org/10.1038/s41467-022-33395-6
The investigators demonstrated that SARS-CoV-2 infection induced gut microbiome dysbiosis in male mice. Samples collected from human COVID-19 patients of both sexes also revealed substantial gut microbiome dysbiosis. Analysis of blood culture results testing for secondary microbial bloodstream infections with paired microbiome data indicated that bacteria might translocate from the gut into the systemic circulation of COVID-19 patients. These results were consistent with a direct role for gut microbiome dysbiosis in enabling dangerous secondary infections during COVID-19. Supported by ORIP (S10OD021747), NCI, NHLBI, NIAID, and NIDDK.
Rapid Joule Heating Improves Vitrification Based Cryopreservation
Zhan et al., Nature Communications. 2022.
https://www.doi.org/10.1038/s41467-022-33546-9
Cryopreservation by vitrification is an effective approach for long-term preservation of biosystems, but effective vitrification often requires high concentrations of cryoprotective agent (CPA), which can be toxic. The investigators described a joule heating–based platform technology for rapid rewarming of biosystems, which allows the use of low concentrations of CPA. They demonstrated the success of this platform in cryopreservation of three model systems: adherent cells, Drosophila melanogaster embryos, and rat kidney slices with low CPA concentrations. This work provides a general solution to cryopreserve a broad spectrum of cells, tissues, organs, and organisms. Supported by ORIP (R21OD028758), NIDDK, NHLBI, and NIGMS.