Biology subjects

Ledo, J. H.

Publications and source records attributed to Ledo, J. H..

5 recordsLinked to original sources

bioRxiv2026

Efficacy of glucocorticoid modulator PT150 as a weight loss strategy

Obesity affects millions of people worldwide and has serious complications such as cardiovascular disease and diabetes. Current treatments for obesity target proteins such as the receptors for glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP) and/or glucagon (GCG). These interventions have revolutionized the treatment of obesity and represent first-line pharmacotherapeutic strategies. One major weakness to these strategies is that once drug treatment stops, most patients are unable to maintain the new body weight setpoint, often gaining weight back rapidly. Thus, the identification of new therapies that focus on the ability to maintain homeostatic setpoint are necessary. The glucocorticoid receptor (GR) has been implicated in several pathways including reward-seeking, inflammation, stress and energy balance. Here, we investigated the effects of 30 days treatment with PT150 (40 mg/kg), a novel GR antagonist, alone and in combination with semaglutide (30 nmol/kg) on food intake, glucose homeostasis, body weight and setpoint maintenance using a C57Bl/6 diet-induced obesity (DIO) mouse model. We monitored food intake and body weight throughout treatment and after drug washout for 20 days to evaluate defended body weight maintenance (body weight setpoint). Our results indicate that treatment with PT150 alone does not significantly alter body weight but in combination with semaglutide it shows the most promising effects in body weight reduction and homeostatic setpoint maintenance. Together, these data suggest that PT150, a GR modulator, may be effective as a homeostatic setpoint modulator when combined with semaglutide.

physiology↗

bioRxiv2026

Functional border-associated macrophages limit Alzheimer's Disease progression

Brain-resident macrophages are known to play numerous roles in the progression of Alzheimers Disease (AD). However, the relative contribution of microglia and border-associated macrophages (BAM) to AD pathogenesis has been difficult to disentangle. We recently identified Maf, a newly described AD GWAS gene, as essential for BAM, but not microglial, survival. By crossing BAM depleted mice with the 5xFAD AD model, we found stark evidence of cerebral amyloid angiopathy (CAA), increased overall {beta}-amyloid burden, accelerated markers of neurodegeneration, and early memory deficits. In the healthy brain, BAM take up more {beta}-amyloid per cell than microglia. However, as disease progresses, both in human AD patient samples and model AD mice, BAM number is reduced, and the remaining BAMs display impaired endocytic capacity, and show signs of metabolic exhaustion at an earlier age than microglia. Thus, strategies to preserve or restore BAM function represents a novel therapeutic avenue for AD and CAA.

immunology↗

bioRxiv2026

Wasf1 deletion attenuates tau hyperphosphorylation, microglial state transition, and cognitive deficits in P301S tau mice

We previously reported that WAVE1, a major activator of Arp2/3 complex-mediated actin polymerization, is downregulated in postmortem brains of Alzheimers disease (AD) and that WAVE1 regulates amyloid precursor protein trafficking and amyloid-{beta} production. However, its role in tau pathology remains unknown. Here, we demonstrate that WAVE1 activity is suppressed in P301S tau mice through elevated inhibitory phosphorylation. Strikingly, WAVE1 gene (Wasf1) knockout in P301S tau mice significantly reduces tau hyperphosphorylation and improves cognition, suggesting a compensatory role for WAVE1 suppression in tau pathogenesis. Single-nucleus RNA sequencing reveals that Wasf1 deletion in P301S tau mice reverses microglial state transitions, with minimal impact on other brain cell types. Wasf1 mRNA is highly translated in microglia in non-Tg mice, while its expression is downregulated in P301S tau mice. Wasf1 knockdown in BV2 microglia cells enhances the degradation of engulfed tau fibrils, indicating WAVE1 as an endogenous regulator of microglial function. Additionally, CellChat analysis indicates that Wasf1 deletion alters microglial autocrine signaling and their interactions with other cell types in P301S tau mice. These findings, taken together, suggest that Wasf1 deletion restores homeostatic microglial function, mitigates tau pathology, and alleviates cognitive deficits, highlighting WAVE1 as a potential therapeutic target for tauopathy-related dementias.

neuroscience↗

bioRxiv2021

Molecular and cellular adaptations in hippocampal parvalbumin neurons mediate behavioral responses to chronic social stress

Parvalbumin-expressing interneurons (PV neurons) maintain inhibitory control of local circuits implicated in behavioral responses to environmental stressors. However, the roles of molecular and cellular adaptations in PV neurons in stress susceptibility or resilience have not been clearly established. Here, we show behavioral outcomes of chronic social defeat stress (CSDS) are mediated by differential neuronal activity and gene expression in hippocampal PV neurons in mice. Using in vivo electrophysiology and chemogenetics, we find increased PV neuronal activity in the ventral dentate gyrus is required and sufficient for behavioral susceptibility to CSDS. PV neuron-selective translational profiling indicates mitochondrial oxidative phosphorylation is the most significantly altered pathway in stress-susceptible versus resilient mice. Among differentially expressed genes associated with stress-susceptibility and resilience, we find Ahnak, an endogenous regulator of L-type calcium channels which are implicated in the regulation of mitochondrial function and gene expression. Notably, Ahnak deletion in PV neurons impedes behavioral susceptibility to CSDS. Altogether, these findings indicate behavioral effects of chronic stress can be controlled by selective modulation of PV neuronal activity or a regulator of L-type calcium signaling in PV neurons.

neuroscience↗

bioRxiv2021

A Developmental Role for Microglial Presenilin 1 in Memory

Microglia, the macrophages of the brain, are increasingly recognized to play a key role in synaptic plasticity and function; however, the underlying mechanisms remain elusive. Presenilin 1 (PS1) is an essential protein involved in learning and memory, through neuronal mechanisms. Loss of Presenilin function in neurons impairs synapse plasticity and causes cognitive deficits in mice. Surprisingly, here we show memory enhancement in mice by deleting PS1 selectively in microglia. We further demonstrate increased synapse transmission and in vivo neuronal activity in mice by depleting PS1 during microglial development, but not after microglial maturation. Remarkably, conditional deletion of PS1 in microglia during development increased memory retention in adulthood and was dependent on the NMDA receptor subunit GluN2B. In vivo calcium imaging of freely behaving mice revealed increased amplitude of neuronal Ca2+ transients in the CA1 hippocampus of PS1 cKO mice compared to control mice, suggesting a greater CA1 engagement during novel object exploration. Finally, loss of PS1 in microglia mitigated synaptic and cognitive deficits in a mouse model of Alzheimers disease. Together our results reveal a novel mechanism and function of PS1 in microglia in which modulation can enhance neuronal activity, learning and memory in mice.

neuroscience↗