Biology subjects

Kelley, S.

Publications and source records attributed to Kelley, S..

13 recordsLinked to original sources

bioRxiv2026

Communication as a Two-Person Neural Process: fNIRS Hyperscanning in Adults with and without Post-Stroke Aphasia

Communication is inherently interactive, yet most neuroimaging studies examine individuals in isolation. Here, we used functional near-infrared spectroscopy (fNIRS) hyperscanning to investigate interbrain synchrony (IBS) during naturalistic communication. In Study 1, 13 healthy familiar dyads completed Joint Singing, Joint Reading, and Picture Guessing tasks. IBS was quantified using wavelet transform coherence across bilateral frontal and temporoparietal regions. Joint Singing produced higher IBS than the other tasks in several regions, including the dorsolateral prefrontal cortex and temporoparietal junction, and selected effects were greater in true than pseudo-dyads. In Study 2, we applied the same paradigm to five individuals with chronic post-stroke aphasia interacting with trained speech-language pathologists. IBS could be estimated in all dyads after lesion-informed channel exclusion, although regional coverage varied with lesion location. These findings demonstrate that fNIRS hyperscanning can capture task-dependent interpersonal neural coupling during spoken interaction and can be extended to communication involving individuals with aphasia. This approach provides a foundation for studying how neural coordination between communication partners relates to functional communication and partner-supported interaction.

neuroscience↗

bioRxiv2025

Novel Role of Copper Transporter CTR1 and Therapeutic Potential of Copper Chelators in Retinal Ischemia-Reperfusion Injury

BackgroundRetinal ischemia contributes to vision loss in ischemic and diabetic retinopathies through oxidative stress, neurovascular injury, and inflammation. Copper (Cu), while essential, can be toxic in excess and is regulated by Cu transporters such as CTR1. However, the role of CTR1 in ischemic retinopathy remains unclear. Methods and ResultsRetinal ischemia-reperfusion (IR) injury was induced by elevating intraocular pressure to 110 mmHg for 40 minutes in the right eye of Ctr1 heterozygous (Ctr1/-) and wild-type (WT) mice. In WT mice, IR triggered rapid CTR1 upregulation and increased retinal Cu levels (measured by ICP-MS). IR injury caused retinal ganglion cell loss, inner retinal thinning, vascular degeneration, and apoptosis, all of which were significantly attenuated in Ctr1/- mice. Ctr1/- mice also exhibited reduced microglial (Iba1) and glial cells (GFAP) activation and preserved visual function, as assessed by electroretinography. Mechanistically, IR-induced reactive oxygen species (O2-) production (DHE staining), upregulation of NADPH oxidase components (NOX2, p47phox), and NF-{kappa}B activation were markedly suppressed in Ctr1/- mice. Treatment with the Cu chelator tetrathiomolybdate (TTM) similarly reduced retinal thinning, neurovascular damage, apoptosis, gliosis, and oxidative stress after IR injury. ConclusionsCTR1 plays a central role in mediating Cu-dependent oxidative stress, neurovascular degeneration, and inflammation following retinal IR injury. Targeting the CTR1- Cu axis may represent a novel therapeutic strategy for ischemic retinopathy.

cell biology↗

bioRxiv2025

Endothelial Cu Uptake Transporter CTR1 Senses Disturbed Flow to Promote Atherosclerosis through Cuproptosis

Endothelial cells (ECs) lining blood vessels sense disturbed blood flow (D-flow), which drives mitochondrial dysfunction and atherosclerosis. Copper (Cu) is an essential micronutrient, and its disruption of homeostasis has been implicated in atherosclerosis. Cellular Cu levels are tightly controlled by Cu transport proteins including the Cu importer CTR1. Cuproptosis is a recently discovered form of regulated cell death triggered by mitochondrial Cu accumulation, but its endogenous stimulants and role in atherosclerosis remain unknown. Using EC-specific CTR1-deficient mice and cultured ECs, we show that endothelial CTR1 responds to D-flow by increasing mitochondrial Cu levels through its interaction with the mitochondrial Cu transporter SLC25A3 at caveolae/lipid rafts. This leads to the aggregation of lipoylated mitochondrial proteins, mitochondrial dysfunction, and cuproptosis, thereby exacerbating atherosclerosis. Importantly, mitochondria-targeted Cu-chelating nanoparticles effectively mitigate D-flow-induced cuproptosis and atherosclerosis, highlighting the endothelial CTR1-SLC25A3-mitochondrial Cu axis as a potential therapeutic target.

cell biology↗

bioRxiv2024

The O-Fucosyltransferase SPINDLY Attenuates Auxin-Induced Fruit Growth by Inhibiting ARF6 and ARF8 binding to Coactivator Mediator Complex in Arabidopsis

The phytohormone auxin plays a pivotal role in promoting fruit initiation and growth upon fertilization in flowering plants. Upregulation of auxin signaling by genetic mutations or exogenous auxin treatment can induce seedless fruit formation from unpollinated ovaries, termed parthenocarpy. Recent studies suggested that the class A AUXIN RESPONSE FACTOR6 (ARF6) and ARF8 in Arabidopsis play dual functions by first inhibiting fruit initiation when complexed with unidentified corepressor IAA protein(s) before pollination, and later promoting fruit growth after fertilization as ARF dimers. However, whether and how posttranslational modification(s) regulate ARF6- and ARF8-mediated fruit growth were unknown. In this study, we reveal that both ARF6 and ARF8 are O-fucosylated in their middle region (MR) by SPINDLY (SPY), a novel nucleocytoplasmic protein O-fucosyltransferase, which catalyzes the addition of a fucose moiety to specific Ser/Thr residues of target proteins. Epistasis, biochemical and transcriptome analyses indicated that ARF6 and ARF8 are downstream of SPY, but ARF8 plays a more predominant role in parthenocarpic fruit growth. Intriguingly, two ARF6/8-interacting proteins, the co-repressor IAA9 and MED8, a subunit of the coactivator Mediator complex, were also O-fucosylated by SPY. Biochemical assays demonstrated that SPY-mediated O-fucosylation of these proteins reduced ARF-MED8 interaction, which led to enhanced transcription repression activity of the ARF6/8-IAA9 complex but impaired transactivation activities of ARF6/8. Our study unveils the role of protein O-fucosylation by SPY in attenuating auxin-triggered fruit growth through modulation of activities of key transcription factors, a co-repressor and the coactivator MED complex.

plant biology↗

bioRxiv2024

Endothelial Drp1 Couples VEGF-induced Redox Signaling with Glycolysis Through Cysteine Oxidation to Drive Angiogenesis

Angiogenesis plays a vital role for postnatal development and tissue repair following ischemia. Reactive oxygen species (ROS) generated by NADPH oxidases (NOXes) and mitochondria act as signaling molecules that promote angiogenesis in endothelial cells (ECs) which mainly relies on aerobic glycolysis for ATP production. However, the connections linking redox signaling with glycolysis are not well understood. The GTPase Drp1 is a member of the dynamin superfamily that moves from cytosol to mitochondria through posttranslational modifications to induce mitochondrial fission. The role of Drp1 in ROS-dependent VEGF signaling and angiogenesis in ECs has not been previously described. Here, we identify an unexpected function of endothelial Drp1 as a redox sensor, transmitting VEGF-induced H2O2 signals to enhance glycolysis and angiogenesis. Loss of Drp1 expression in ECs inhibited VEGF-induced angiogenic responses. Mechanistically, VEGF rapidly induced the NOX4-dependent sulfenylation (CysOH) of Drp1 on Cys644, promoting disulfide bond formation with the metabolic kinase AMPK and subsequent sulfenylation of AMPK at Cys299/304 via the mitochondrial fission-mitoROS axis. This cysteine oxidation of AMPK, in turn, enhanced glycolysis and angiogenesis. In vivo, mice with EC-specific Drp1 deficiency or CRISPR/Cas9-engineered "redox-dead" (Cys to Ala) Drp1 knock-in mutations exhibited impaired retinal angiogenesis and post-ischemic neovascularization. Our findings uncover a novel role for endothelial Drp1 in linking VEGF-induced mitochondrial redox signaling to glycolysis through a cysteine oxidation-mediated Drp1-AMPK redox relay, driving both developmental and reparative angiogenesis.

cell biology↗

bioRxiv2023

Myeloid Drp1 Deficiency Limits Revascularization in Ischemic Muscles via Inflammatory Macrophage Polarization and Metabolic Reprograming

In the preclinical model of peripheral arterial disease (PAD), M2-like anti-inflammatory macrophage polarization and angiogenesis are required for revascularization. The regulation of cell metabolism and inflammation in macrophages is tightly linked to mitochondrial dynamics. Drp1, a mitochondrial fission protein, has shown context-dependent macrophage phenotypes with both pro- and anti-inflammatory characteristics. However, the role of macrophage Drp1 in reparative neovascularization remains unexplored. Here we show that Drp1 expression was significantly increased in F4/80+ macrophages within ischemic muscle at day 3 after hindlimb ischemia (HLI), an animal model of PAD. Myeloid-specific Drp1-/- mice exhibited reduced limb perfusion recovery, angiogenesis and muscle regeneration after HLI. These effects were associated with an increase in pro-inflammatory M1-like macrophages, p-NFkB and TNF, and reduced anti-inflammatory M2-like macrophages and p-AMPK in ischemic muscle of myeloid Drp1-/- mice. In vitro, Drp1-/- macrophages under hypoxia serum starvation (HSS), an in vitro PAD model, demonstrated enhanced glycolysis via reducing p-AMPK as well as mitochondrial dysfunction and excessive mitochondrial ROS, resulting in increased M1-gene and reduced M2-gene expression. Conditioned media from HSS-treated Drp1-/- macrophages exhibited increased secretion of pro-inflammatory cytokines and suppressed angiogenic responses in cultured endothelial cells. Thus, Drp1 deficiency in macrophages under ischemia drives inflammatory metabolic reprogramming and macrophage polarization, thereby limiting revascularization in experimental PAD.

cell biology↗

bioRxiv2021

Genome-wide in vivo screen of circulating tumor cells identifies SLIT2 as a regulator of metastasis

Circulating tumor cells (CTCs) break free from primary tumors and travel through the bloodstream and lymphatic system to seed metastatic tumors, which are the major cause of death from cancer. The identification of the major genetic factors that enhance production and persistence of CTCs in the bloodstream at a whole genome level would enable more comprehensive molecular mechanisms of metastasis to be elucidated and the identification of novel therapeutic targets, but this remains a challenging task due to the heterogeneity and extreme rarity of CTCs. Here, we describe the first in vivo genome-wide CRISPR KO screen using CTCs directly isolated from a mouse xenograft. This screen elucidated SLIT2 - a gene encoding a secreted protein acting as a cellular migration cue - as the most significantly represented gene knockout in the CTC population. SLIT2 knockout cells are highly metastatic with hypermigratory and mesenchymal phenotype. Reduced expression of SLIT2 is observed in human tumors, indicating its role as a negative modulator of tumor progression and metastasis.

cancer biology↗

bioRxiv2020

Reagentless Biomolecular Analysis Using a Nanoscale Molecular Pendulum

The ability to sense biological inputs using self-contained devices unreliant on external reagents or reporters would open countless opportunities to collect information about our health and environment. Currently, a very limited set of molecular inputs can be detected using this type of sensor format. The development of versatile reagentless sensors that could track molecular analytes in biological fluids remains an unmet need. Here, we describe a new universal sensing mechanism that is compatible with the analysis of proteins that are important physiological markers of stress, allergy, cardiovascular health, inflammation and cancer. The sensing mechanism we developed is based on the measurement of field-induced directional diffusion of a nanoscale molecular pendulum tethered to an electrode surface and the sensitivity of electron-transfer reaction kinetics to molecular size. Using time-resolved electrochemical measurements of diffusional motion, the presence of an analyte bound to a sensor complex can be continuously tracked in real time. We show that this sensing approach is compatible with making measurements in blood, saliva, urine, tears and sweat and that the sensors can collect data in situ in living animals. The sensor platform described enables a broad range of applications in personalized health monitoring.

bioengineering↗

bioRxiv2020

Multiplex single-molecule kinetics of nanopore-coupled polymerases

DNA polymerases have revolutionized the biotechnology field due to their ability to precisely replicate stored genetic information. Screening variants of these enzymes for unique properties gives the opportunity to identify polymerases with novel features. We have previously developed a single-molecule DNA sequencing platform by coupling a DNA polymerase to a -hemolysin pore on a nanopore array. Here, we use this approach to demonstrate a single-molecule method that enables rapid screening of polymerase variants in a multiplex manner. In this approach, barcoded DNA strands are complexed with polymerase variants and serve as templates for nanopore sequencing. Nanopore sequencing of the barcoded DNA reveals both the barcode identity and kinetic properties of the polymerase variant associated with the cognate barcode, allowing for multiplexed investigation of many polymerase variants in parallel on a single nanopore array. Further, we develop a robust classification algorithm that discriminates kinetic characteristics of the different polymerase mutants. As a proof of concept, we demonstrate the utility of our approach by screening a library of ~100 polymerases to identify variants for potential applications of biotechnological interest. We anticipate our screening method to be broadly useful for applications that require polymerases with unique or altered physical properties.

synthetic biology↗

bioRxiv2019

Age-related differences in white matter: Comparing fixel based and tensor based analyses

Aging is associated with widespread alterations in cerebral white matter (WM). Most prior studies of age differences in WM have used diffusion tensor imaging (DTI), but typical DTI metrics (e.g., fractional anisotropy; FA) can reflect multiple neurobiological features, making interpretation challenging. Here, we used fixel-based analysis (FBA) to investigate age-related WM differences observed using DTI in a sample of 45 older and 25 younger healthy adults. Age- related FA differences were widespread but were strongly associated with differences in multifiber complexity (CX), suggesting that they reflected differences in crossing fibers in addition to structural differences in individual fiber segments. FBA also revealed a frontolimbic locus of age-related effects and provided insights into distinct microstructural changes underlying them. Specifically, age differences in fiber density were prominent in fornix, bilateral anterior internal capsule, forceps minor, body of the corpus callosum and corticospinal tract, while age differences in fiber cross section were largest in cingulum bundle and forceps minor. These results provide novel insights into specific structural differences underlying major WM differences associated with aging.

neuroscience↗

bioRxiv2018

Exposure to a Healthy Gut Microbiome Protects Against Reproductive and Metabolic Dysregulation in a PCOS Mouse Model

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting approximately 10% of reproductive-aged women worldwide. Diagnosis requires two of the following: hyperandrogenism, oligo/anovulation and polycystic ovaries. In addition to reproductive dysfunction, many women with PCOS display metabolic abnormalities associated with hyperandrogenism. Recent studies have reported that the gut microbiome is altered in women with PCOS and rodent models of the disorder. However, it is unknown whether the gut microbiome plays a causal role in the development and pathology of PCOS. Given its potential role, we hypothesized that exposure to a healthy gut microbiome would protect against development of PCOS. A co-housing study was performed using a letrozole-induced PCOS mouse model that recapitulates many reproductive and metabolic characteristics of PCOS. Since mice are coprophagic, co-housing results in repeated, non-invasive inoculation of gut microbes in co-housed mice via the fecal-oral route. In contrast to letrozole-treated mice housed together, letrozole-treated mice co-housed with placebo mice showed significant improvement in both reproductive and metabolic PCOS phenotypes. Using 16S rRNA gene sequencing, we observed that the gut microbial composition of letrozole-treated mice co-housed with placebo mice differed from letrozole mice housed together. In addition, our analyses identified several bacterial taxa including Coprobacillus, Dorea and Adlercreutzia associated with the improved PCOS phenotype in letrozole-treated mice co-housed with placebo mice. These results indicate that disruption of the gut microbiome may play a causal role in PCOS and that manipulation of the gut microbiome may be a potential treatment option for PCOS.\n\nSignificancePCOS is a common cause of female infertility and ~80% of women with PCOS have metabolic dysregulation that predisposes them to type 2 diabetes and cardiovascular disease. Since treatment options for the metabolic symptoms of PCOS are limited, there is a need to develop novel therapeutic options. The gut microbiome has emerged as an important player in human health and has been shown to play a causal role in obesity. In this study, we found that exposure to a healthy gut microbiome through co-housing protected against the development of reproductive and metabolic dysregulation in a PCOS mouse model. These results suggest that manipulation of the gut microbiome may be a potential treatment option for women with PCOS.

physiology↗

bioRxiv2018

Benchmarking university medical centres for responsible metrics. A cross sectional study on timely results dissemination across 36 German centres

ObjectiveTimely and comprehensive reporting of clinical trial results build the backbone of evidence-based medicine and responsible research. The proportion of timely disseminated trial results can inform alternative national and international benchmarking of university medical centers (UMCs).\n\nStudy Design and SettingFor all German UMCs we tracked all registered trials completed between 2009 and 2013. The results and an interactive website benchmark German UMCs regarding their performance in results dissemination.\n\nResultsWe identified and tracked 2,132 clinical trials. For 1,509 trials, one of the German UMCs took the academic lead. Of these 1,509 \"lead trials\", 39% published their results (mostly via journal publications) in a timely manner (<24 months after completion). More than six years after study completion, 26% of all eligible lead trials still had not disseminated results.\n\nConclusionDespite substantial attention from many stakeholders to the topic, there is still a strong delay or even absence of results dissemination for many trials. German UMCs have several opportunities to improve this situation. Further research should evaluate whether and how a transparent benchmarking of UMC performance in results dissemination helps to increase value and reduce waste in medical research.

scientific communication and education↗

bioRxiv2018

Michigan Neural Distinctiveness (MiND) project: Investigating the scope, causes, and consequences of age-related neural dedifferentiation

BackgroundAging is often associated with behavioral impairments, but some people age more gracefully than others. Why? One factor that may play a role is individual differences in the distinctiveness of neural representations. Previous research has found that neural activation patterns in visual cortex in response to different visual stimuli are often more similar (i.e., less distinctive) in older vs. young participants, a phenomenon referred to as age-related neural dedifferentiation. Furthermore, older people whose neural representations are less distinctive tend to perform worse on a wide range of behavioral tasks. The Michigan Neural Distinctiveness (MiND) project aims to investigate the scope of neural dedifferentiation (e.g., does it also occur in auditory, motor, and somatosensory cortex?), one potential cause (age-related reductions in the inhibitory neurotransmitter gamma-aminobutyric acid (GABA)), and the behavioral consequences of neural dedifferentiation. This protocol paper describes the study rationale and methods being used in complete detail, but not the results (data collection is currently underway).\n\nMethods/DesignThe MiND project consists of two studies: the main study and a drug study. In the main study, we are recruiting 60 young and 100 older adults to perform behavioral tasks that measure sensory and cognitive function. They also participate in functional MRI (fMRI), MR spectroscopy (MRS), and diffusion weighted imaging (DWI) sessions, providing data on neural distinctiveness and GABA concentrations. In the drug study, we are recruiting 25 young and 25 older adults to compare neural distinctiveness, measured with fMRI, after participants take (1) a benzodiazepine (lorazepam) that should increase GABA activity or (2) a placebo.\n\nDiscussionBy collecting multimodal imaging measures (fMRI, MRS, DWI) along with extensive behavioral measures from the same subjects, we are linking individual differences in neurochemistry, neural representation, and behavioral performance, rather than focusing solely on group differences between young and old participants. Our findings have the potential to inform new interventions for age-related declines.

neuroscience↗