Biology subjects

Sutphin, G. L.

Publications and source records attributed to Sutphin, G. L..

7 recordsLinked to original sources

bioRxiv2026

Kynurenine Metabolism Mediates Tumor Progression in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is characterized by dysregulation of the kynurenine pathway (KP), which converts tryptophan to NAD+ while generating immunomodulatory metabolites. Therapeutic efforts have focused on inhibiting IDO1 at the pathway entry point, but the functional consequences of targeting downstream KP enzymes remain poorly characterized. We used CRISPR/Cas9 to generate knockouts of three KP enzymes in the RENCA murine RCC model--kynurenine 3-monooxygenase (KMO), quinolinic acid phosphoribosyltransferase (QPRT), and 3-hydroxyanthranilic acid dioxygenase (HAAO)--and evaluated effects on cell migration, colony formation, tumor burden, metastasis, and survival. KMO and QPRT knockouts consistently reduced migratory capacity and colony size in vitro. However, in vivo effects were distinct: while QPRT knockout reduced tumor burden, KMO knockout did not. Notably, we did not detect metastasis in female mice receiving KMO knockout RENCA cells. HAAO knockout produced divergent effects, increasing migration and colony size in vitro, but reducing tumor burden and metastasis in vivo. Mice challenged orthotopically with all three knockout cell lines had significantly extended survival compared to mice receiving wild type cells. These results indicate that individual KP enzymes exert distinct, context-dependent effects on RCC progression. The enhanced in vitro aggressiveness coupled with reduced in vivo tumorigenicity observed in HAAO knockout RENCA cells illustrates that cell culture phenotypes do not reliably predict tumor behavior, particularly when perturbing metabolic pathways with pleiotropic effects. Our findings suggest that targeting specific KP enzymes warrants further investigation as a therapeutic strategy in RCC.

cancer biology↗

bioRxiv2024

Experimental variables that impact outcomes in Caenorhabditis elegans aging stress response

Cellular stress is a fundamental component of age-associated disease. Cells encounter various forms of stress - oxidative stress, protein misfolding, DNA damage, etc. - and respond by activating specific, well-defined stress response pathways. As we age, the burden of stress and resulting damage increases while our cells ability to deal with the consequences becomes diminished due to dysregulation of cellular stress response pathways. Many interventions that extend lifespan activate one or more stress response pathways or allow cells to maintain normal stress response later in life. The nematode Caenorhabditis elegans is a commonly used model for both aging and stress response research. As such, stress response experiments are regularly conducted as part of studies focused on mechanisms of aging in C. elegans. However, experimental design across experiments in the field are highly variable, including stressor dose, age at exposure, culture type (liquid vs. solid), bacterial strain used as a food source, and environmental temperature. These differences can result in different experimental outcomes, making comparison of results between studies challenging. Here we evaluate several experimental variables that are variable in the published literature and find that each can meaningfully alter experimental outcomes for multiple stressors. Our goal is to raise awareness of the issue of experimental variability within the field and suggest a standardized experimental design to serve as a set of guidelines for future experiments. By adopting these guidelines as a starting point, and explicitly noting differences in specific experiments, we aim to promote rigor and reproducibility, ultimately fostering more interpretable and translatable outcomes in geroscience research.

molecular biology↗

bioRxiv2024

The Emerging Role of 3-Hydroxyanthranilic Acid on C. elegans Aging Immune Function

3-hydroxyanthranilic acid (3HAA) is considered to be a fleeting metabolic intermediate along tryptophan catabolism through the kynurenine pathway. 3HAA and the rest of the kynurenine pathway have been linked to immune response in mammals yet whether it is detrimental or advantageous is a point of contention. Recently we have shown that accumulation of this metabolite, either through supplementation or prevention of its degradation, extends healthy lifespan in C. elegans and mice, while the mechanism remained unknown. Utilizing C. elegans as a model we investigate how 3HAA and haao-1 inhibition impact the host and the potential pathogens. What we find is that 3HAA improves host immune function with aging and serves as an antimicrobial against gram-negative bacteria. Regulation of 3HAAs antimicrobial activity is accomplished via tissue separation. 3HAA is synthesized in the C. elegans hypodermal tissue, localized to the site of pathogen interaction within the gut granules, and degraded in the neuronal cells. This tissue separation creates a new possible function for 3HAA that may give insight to a larger evolutionarily conserved function within the immune response. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/574394v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@3d74d1org.highwire.dtl.DTLVardef@c079c7org.highwire.dtl.DTLVardef@7b1f2eorg.highwire.dtl.DTLVardef@13c3eb3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

SICKO: Systematic Imaging of Caenorhabtidis Killing Organisms

Caenorhabditis elegans are an important model system for research on host-microbe interaction. Their rapid life cycle, short lifespan, and transparent body structure allow simple quantification of microbial load and the influence of microbial exposure on host survival. C. elegans host-microbe interaction studies typically examine group survival and infection severity at fixed timepoints. Here we present an imaging pipeline, Systematic Imaging of Caenorhabditis Killing Organisms (SICKO), that allows longitudinal characterization of microbes colonizing isolated C. elegans, enabling dynamic tracking of tissue colonization and host survival in the same animals. Using SICKO, we show that Escherichia coli or Pseudomonas aeruginosa gut colonization dramatically shortens C. elegans lifespan and that immunodeficient animals lacking pmk-1 are more susceptible to colonization but display similar colony growth relative to wild type. SICKO opens new avenues for detailed research into bacterial pathogenesis, the benefits of probiotics, and the role of the microbiome in host health.

immunology↗

bioRxiv2023

Inhibition of haao-1 enhances oxidative stress response by activating hormetic redox signaling in C. elegans.

3-hydroxyanthranilate 3,4-dioxygenase (HAAO) is an intermediate enzyme in the conversion from tryptophan (TRP) to nicotinamide adenine dinucleotide (NAD+) via the kynurenine pathway. The kynurenine pathway is the sole de novo NAD+ biosynthetic pathway from ingested tryptophan. Inhibition of several enzymatic steps in the kynurenine pathway increases lifespan in Drosophila melanogaster, Saccharomyces cerevisiae, and Caenorhabditis elegans. Knockout or knockdown of haao-1, the C. elegans gene encoding HAAO, or supplementation of its substrate metabolite 3-hydroxyanthranilic acid (3HAA), has been shown to promote healthy lifespan extension; however, the underlying mechanism remains unknown. In the present study, we report that haao-1 knockdown induces oxidative stress resistance against several reactive oxygen species (ROS) inducing agents by activating the Nrf2/SKN-1 oxidative stress response pathway. An examination of the redox state of animals with reduced haao-1 suggests that activation of the Nrf2/SKN-1 pathway is mediated by shifting the balance toward generation of ROS, generating a hormetic effect. Our results identify a novel mechanism for an endogenous metabolite (3HAA) that activates the oxidative stress response. These results provide a conceptual basis by which modulation of the kynurenine pathway can promote healthy aging and enhanced stress resistance. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/528568v1_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@1563682org.highwire.dtl.DTLVardef@114917dorg.highwire.dtl.DTLVardef@15bc7f2org.highwire.dtl.DTLVardef@a42023_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIKnockdown of haao-1 promotes oxidative stress resistance. C_LIO_LIKnockdown of haao-1 activates the Nrf2/SKN-1 oxidative stress response. C_LIO_LIThe shift in redox balance in haao-1 knockout animals suggests a hormetic mechanism for oxidative stress resistance. C_LI

molecular biology↗

bioRxiv2021

3-hydroxyanthranilic acid - a new metabolite for healthy lifespan extension

The metabolism of tryptophan to nicotinamide adenine dinucleotide (NAD+) through the kynurenine pathway is increasingly linked to aging and age-associated disease. Kynurenine pathway enzymes and metabolites influence a range of molecular processes critical to healthy aging, including regulation of inflammatory and immune responses, cellular redox homeostasis, and energy production. Aberrant kynurenine metabolism is observed during normal aging and has been implicated in a range of age-associated pathologies, including chronic inflammation, atherosclerosis, neurodegeneration, and cancer. In previous work, we and others identified three genes--kynu-1, tdo-2, and acsd-1--encoding kynurenine pathway enzymes for which decreasing expression extends lifespan in invertebrate models. Here we report that knockdown of haao-1, a fourth kynurenine pathway gene encoding the enzyme 3-hydroxyanthranilic acid dioxygenase (HAAO), extends lifespan by ~30% and delays age-associated decline in health in Caenorhabditis elegans. This lifespan extension is mediated by increased physiological levels of the HAAO substrate 3-hydroxyanthranilic acid (3HAA). 3HAA increases resistance to oxidative stress during aging by directly degrading hydrogen peroxide and activating the Nrf2/SKN-1 oxidative stress response. Aging mice fed a diet supplemented with 3HAA are similarly long-lived. Our results identify HAAO and 3HAA as novel therapeutic targets for age-associated disease. This works provides a foundation for more detailed examination of the molecular mechanisms underlying the benefits of 3HAA, and how these mechanisms interact with other interventions both within and beyond the kynurenine pathway. We anticipate that these findings will bolster growing interest in developing pharmacological strategies to target tryptophan metabolism to improve health aging.

molecular biology↗

bioRxiv2018

Integration of heterogeneous functional genomics data in gerontology research identifies genes and pathway underlying aging across species

Understanding the biological mechanisms behind aging, lifespan and healthspan is becoming increasingly important as the proportion of the world's population over the age of 65 grows, along with the cost and complexity of their care. BigData oriented approaches and analysis methods for integrative functional genomics enable current and future bio-gerontologists to synthesize, distill and interpret vast, heterogeneous data. GeneWeaver is an analysis system for integration of data that allows investigators to store, search, and analyze immense amounts of data including user-submitted experimental data, data from primary publications, and data in other databases. Aging related genome-wide gene sets from primary publications were curated into this system in concert with data from other model-organism and aging-specific databases, and used in several application using GeneWeavers analysis tools. For example, we identified Cd63 as a frequently represented gene among aging-related genome-wide results. To evaluate the role of Cd63 in aging, we performed RNAi knockdown of the C. elegans ortholog, tsp-7, demonstrating that this manipulation is capable of extending lifespan. The tools in GeneWeaver enable aging researchers to make new discoveries into the associations between the genes, normal biological processes, and diseases that affect aging, healthspan, and lifespan.

bioinformatics↗