Biology subjects

Jati, S.

Publications and source records attributed to Jati, S..

9 recordsLinked to original sources

bioRxiv2026

Ketone body beta-hydroxybutyrate restores neuronal Tau proteostasis via ketolysis-independent mechanism

Metabolic interventions that induce ketosis, including ketogenic diets, caloric restriction, intermittent fasting, and exercise, show promise in the treatment of Alzheimers disease (AD) and related tauopathies. {beta}-hydroxybutyrate ({beta}HB), the primary ketone body produced during ketosis, reproduces key features of these metabolic interventions, but the molecular mechanism underlying its neuroprotective properties is not fully understood. Here, we demonstrate that a {beta}HB precursor diet is sufficient to ameliorate Tau pathophysiology in a tauopathy mouse model. Furthermore, across in vitro, ex vivo, and in vivo models, we find that {beta}HB enhances neuronal Tau proteostasis and reduces Tau aggregation and secretion. Importantly, these effects are independent of {beta}HBs oxidation for ATP production, as its ketolysis-resistant enantiomer reproduces these benefits, indicating that ketolysis is dispensable for these effects. Overall, these data position {beta}HB as a novel therapeutic avenue for AD and tauopathy and elucidate a novel mechanism of action of metabolic interventions in neurodegenerative disease.

neuroscience↗

bioRxiv2026

Catestatin ameliorates tauopathy and amyloidogenesis via adrenergic inhibition

Neurodegenerative disorders like Alzheimers disease (AD), Corticobasal Degeneration (CBD), and Progressive Supranuclear Palsy (PSP) are characterized by Tau aggregation, synaptic dysfunction, neuroinflammation, and progressive cognitive decline. Although metabolic dysregulation and neuropeptide imbalance have been linked to these disorders, the functional consequences of such imbalance and its potential for therapeutic reversal remain poorly understood. Our previous work identified chromogranin A (CgA), which encodes a pro-hormone for several metabolic peptides, as a key regulator of Tau pathology. Here, we investigate Catestatin (CST), a CgA-derived peptide that is a potent inhibitor of catecholamine release and has been shown to increase insulin sensitivity and lower peripheral blood pressure. We report significant reductions in CST levels in the hippocampus and cortex of AD brains, as well as in the frontal cortex of CBD and the basal ganglia of PSP. Supplementing CST in cortical neuronal cultures and organotypic slice cultures (OTSC) decreased Tau phosphorylation and aggregation. In vivo, CST administration in PS19 Tauopathy mice reduced pathological Tau species, attenuated gliosis, and improved cognitive function. CST treatment also lowered amyloid plaque burden and neuroinflammation in 5xFAD mice. Mechanistically, CST decreased epinephrine (EPI) levels in both PS19 and 5xFAD mice and suppressed downstream protein kinase A (PKA) hyperactivation in PS19 and OTSC. These findings reveal a previously unrecognized neuropeptidergic mechanism linking CST deficiency to elevated adrenergic receptor (ADR)-EPI-PKA stress signaling and Tauopathy-driven neurodegeneration, suggesting CST replacement as a promising therapeutic approach.

neuroscience↗

bioRxiv2025

Catestatin suppresses melanoma progression and drug resistance through multitargeted modulation of signaling pathways

BackgroundDespite advances in targeted and immune-based therapies, melanoma remains one of the most aggressive and treatment-resistant cancers. Resistance to small-molecule inhibitors and immune checkpoint blockade highlights the need for new mechanistically distinct interventions. Catestatin (CST), a Chromogranin A (CgA)- derived peptide with immunomodulatory and reparative properties, has been implicated in tissue protection, but its role in melanoma remains unknown. MethodsCST expression was analyzed across melanoma stages and correlated with disease progression. Functional effects of CST were assessed in patient-derived and established melanoma cell lines, as well as in B16-F10 melanoma-bearing mice. RNA sequencing and pathway analyses were performed to delineate CST-regulated molecular networks. Vemurafenib-resistant A375 cells were used to examine CSTs effects on drug resistance mechanisms. ResultsCST expression declined with advancing tumor stage. CST treatment inhibited proliferation, migration, and invasion, while inducing apoptosis in melanoma cells but not in normal fibroblasts. In vivo, systemic CST administration significantly reduced tumor volume and mass. Transcriptomic profiling revealed coordinated downregulation of hypoxia-inducible, epithelial-mesenchymal transition (EMT), and collagen-remodeling pathways, alongside suppression of oxidative stress-adaptive signaling. In Vemurafenib-resistant A375 cells, CST restored apoptotic sensitivity and repressed multiple MAPK and PI3K-AKT-linked resistance genes. ConclusionsCST acts as a mechanistically distinct peptide modulator that reprograms oncogenic signaling through inhibition of hypoxia, EMT, and survival pathways. These findings identify CST as a promising therapeutic prototype for mitigating melanoma progression and overcoming resistance to targeted therapy.

cancer biology↗

bioRxiv2025

Boolean Network Modeling Identifies Cognitive Resilience in the First Murine Model of Asymptomatic Alzheimer Disease

Alzheimers disease (AD) is a progressive neurodegenerative disorder defined by amyloid beta (A{beta}) plaques and neurofibrillary tangles (NFTs), yet approximately 20-30% of aged individuals exhibit these hallmark lesions without developing cognitive impairment--a clinically silent condition termed asymptomatic AD (AsymAD). The molecular basis of this cognitive resilience remains poorly understood due to a lack of mechanistic models. Here, we integrate systems-level Boolean network modeling with in vivo validation to define the transcriptomic logic of AsymAD and uncover a novel preclinical model. Using Boolean implication networks trained on large-scale human cortical RNA-seq datasets, we identified a robust and invariant AD gene signature that accurately stratifies disease states across independent datasets. Application of this signature to Chromogranin A- deficient PS19 mice (CgA-KO/PS19) revealed a unique resilience phenotype: male mice developed AD-like molecular and neuropathological profiles in the pre-frontal cortex yet retained intact learning and memory. Female CgA-KO/PS19 mice displayed even greater protection, including reduced Tau phosphorylation and preserved synaptic ultrastructure. These findings establish the first validated murine model of AsymAD and identify CgA as a modifiable node linking neuroendocrine signaling, Tauopathy, and cognitive preservation. This work provides a scalable platform to probe sex-specific resilience, uncover early-stage biomarkers, and accelerate preventive therapeutic development in AD.

neuroscience↗

bioRxiv2024

Catestatin improves heart metabolic flexibility by promoting mitochondrial structure and function

Hypertension, a major cause of cardiomyopathy, is one of the most critical risk factors for heart failure and mortality worldwide. Loss of metabolic flexibility of cardiomyocytes is one of the major causes of heart failure. Although Catestatin (CST) treatment is known to be both hypotensive and cardioprotective, its effect on cardiac metabolism is unknown. In this study, we undertook a transcriptomic approach to identify differentially expressed genes that were filtered using Boolean implication relationships to develop a model of gene regulation in saline or CST-supplemented CST knockout (CST-KO) mice. The analysis revealed a set of gene signatures (fibroblast, cardiomyocyte, and macrophage) rescued after CST supplemented CST-KO mice compared to wild-type. Furthermore, we independently validated these gene signature models using publicly available patient datasets. Since the gene signature includes genes related to glucose, fatty acid metabolism, and mitochondrial function, we assessed the glucose and fatty acid uptake after CST treatment. We found that CST treatment can restore the cardiac metabolic inflexibility in CST-KO heart due to the metabolic shift of glucose utilization to fatty acid as energy source. Binding studies after immunoprecipitation and mass spectrometry revealed CST binding with ATP synthase, supported by molecular simulation and computational modeling that predicted CST binding to /{beta} subunit of ATP synthase. Colocalization of CST with mitochondria and increased mitochondrial membrane potential and ATP production upon CST treatment in neonatal cardiomyocytes further exhibit CST as a key regulator of cardiac metabolism and mitochondrial function.

physiology↗

bioRxiv2024

Chromogranin A Deficiency Attenuates Tauopathy by Altering Epinephrine Alpha-Adrenergic Receptor Signaling

Our previous studies have indicated that insulin resistance, hyperglycemia, and hypertension in aged wild-type (WT) mice can be reversed in mice lacking chromogranin-A (CgA-KO mice). These health conditions are associated with a higher risk of Alzheimers disease (AD). CgA, a neuroendocrine secretory protein has been detected in protein aggregates in the brains of AD patients. Here, we determined the role of CgA in tauopathies, including AD (secondary tauopathy) and corticobasal degeneration (CBD, primary tauopathy). We found elevated levels of CgA in both AD and CBD brains, which were positively correlated with increased phosphorylated tau in the frontal cortex. Furthermore, CgA ablation in a human P301S tau (hTau) transgenic mice (CgA-KO/hTau) exhibited reduced tau aggregation, resistance to tau spreading, and an extended lifespan, coupled with improved cognitive function. Transcriptomic analysis of mice cortices highlighted altered levels of alpha-adrenergic receptors (Adra) in hTau mice compared to WT mice, akin to AD patients. Since CgA regulates the release of the Adra ligands epinephrine (EPI) and norepinephrine (NE), we determined their levels and found elevated EPI levels in the cortices of hTau mice, AD and CBD patients. CgA-KO/hTau mice exhibited reversal of EPI levels in the cortex and the expression of several affected genes, including Adra1 and 2, nearly returning them to WT levels. Treatment of hippocampal slice cultures with EPI or an Adra1 agonist intensified, while an Adra1 antagonist inhibited, tau hyperphosphorylation and aggregation. These findings reveal a critical role of CgA in regulation of tau pathogenesis via the EPI-Adra signaling axis.

neuroscience↗

bioRxiv2022

Wnt5A Signaling Regulates Gut Bacterial Survival and T cell Homeostasis

In light of the demonstrated antagonism of Wnt5A signaling toward the growth of several bacterial pathogens, it was important to study the influence of Wnt5A on gut resident bacteria, and its outcome. Here we demonstrate that in contrast to inhibiting the survival of the established gut pathogen Salmonella enterica, Wnt5A clearly promotes the survival of the common gut commensals Enterococcus faecalis and Lactobacillus rhamnosus within macrophages through a self-perpetuating Wnt5A-Actin axis. A Wnt5A - Actin axis furthermore regulates the subsistence of the natural bacterial population of the Peyers patches, as is evident from the diminution in the countable bacterial colony forming units therein through the application of Wnt5A signaling and actin assembly inhibitors. Wnt5A dependency of the gut resident bacterial population is also manifested in the notable difference between the bacterial diversities associated with the feces and Peyers patches of Wnt5A heterozygous mice, which lack a functional copy of the Wnt5A gene, and the wild type counterparts. Alterations in gut commensal bacterial population resulting from either the lack of a copy of the Wnt5A gene or inhibitor mediated attenuation of Wnt5A signaling correlate with significantly different ratios of regulatory vs. activated CD4 T cells associated with the Peyers patches. Taken together, our study reveals the importance of Wnt5A signaling in shaping the gut commensal bacterial population and the T cell repertoire linked to it, thus unveiling a crucial control device for the maintenance of gut bacterial diversity and T cell homeostasis. Significance StatementGut commensal bacterial diversity and T cell homeostasis are crucial entities of the host innate immune network. Yet molecular details of host directed signaling pathways that sustain the steady state of gut bacterial colonization and T cell activation remain unclear. Here we describe the protective role of a Wnt5A-Actin axis in the survival of several gut bacterial commensals, and its importance in shaping gut bacterial colonization and the associated T cell repertoire. This study opens up new avenues of investigation into the role of the Wnt5A-Actin axis in protection of the gut from dysbiosis related inflammatory disorders.

immunology↗

bioRxiv2021

Chromogranin A plays a crucial role in the age-related development of insulin resistance and hypertension

Aging is associated with the development of metabolic disorders, including insulin resistance and hypertension. Young mice that are negative for the neuroendocrine prohormone Chromogranin A (CgA knockout, CgA-KO) display two opposite aging phenotypes: hypertension but heightened insulin sensitivity. We determined these phenotypes in aging CgA mice. In comparison, aging wild-type (WT) mice gradually lost glucose tolerance and insulin sensitivity. Moreover, while aging WT mice had increased inflammation with higher plasma TNF-, IFN-{gamma} and CCL2 and increased mitochondrial fission, these phenotypes were the opposite in aging CgA-KO mice. CgA-KO mice also showed increased expression of mitochondrial and nuclear-encoded complex I genes, implying that they were healthier than WT mice. Most intriguingly, the hypertension in CgA-KO mice was spontaneously reversed with aging. Supplementation of CgA-KO mice with pancreastatin, a hyperglycemic peptide produced from CgA by proteolysis, increased both blood glucose levels and blood pressure, implicating hyperglycemia, and hypertension. We conclude that age-related insulin resistance and hypertension are caused by CgA.

physiology↗

bioRxiv2020

Host Response to Bacterial Pathogens and Non-Pathogens is Determined by Wnt5A Mediated Actin Organization

Wnt5A signaling facilitates the killing of numerous bacterial pathogens but not non-pathogens. The basis of such distinction in killing remains unclear. Accordingly, we analyzed the influence of Wnt5A signaling on pathogenic E.coli K1 in relation to non-pathogenic E.coli K12-MG1655 and E.coli DH5. We found that bacterial killing by macrophages is dictated by the effect of Wnt5A aided actin assembly on the incumbent bacteria. Actin assembly mediated by Wnt5A signaling antagonized the disruptive influence of internalized E.coli K1 on cytoskeletal actin facilitating its eradication. However, internalized E.coli K12-MG1655 and E.coli DH5, which stabilize the actin cytoskleton remained unaffected by Wnt5A. Interestingly, actin assembly inhibitors altered bacterial phagosome compositions, supporting survival of K1, yet promoting killing of both K12-MG1655 and DH5, in Wnt5A activated macrophages. Taken together, our study reveals the importance of Wnt5A signaling dependent assembly of cytoskeletal actin in determining the outcome of host response to bacterial pathogens and non-pathogens.

immunology↗