Biology subjects

Kal, S.

Publications and source records attributed to Kal, S..

5 recordsLinked to original sources

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↗

bioRxiv2021

Wnt/β-catenin signaling and p68 conjointly regulate CHIP in colorectal cancer

The differential expression pattern of Carboxy terminus of Hsc70 Interacting Protein (CHIP, alias STIP1 Homology and U-box Containing Protein 1 or STUB1) in cancers is associated with ubiquitination mediated degradation of its client proteins. Emerging evidences suggest its abundant expression of CHIP in colorectal cancer compared to normal tissues, but the mechanistic detail of this augmented expression pattern is unclear. The signature driver of canonical Wnt pathway, {beta}-catenin, and its co-activator RNA helicase p68, are also overexpressed in colorectal cancer. In this study, we describe a novel mechanism of Wnt/{beta}-catenin and p68 mediated transcriptional activation of CHIP gene leading to enhanced proliferation of colorectal cancer cells. Wnt3A treatment and pharmacological activation of canonical Wnt signaling pathway resulted in increased nuclear translocation of {beta}-catenin and elevated expression of CHIP. Likewise, overexpression and knockdown of {beta}-catenin and p68 upregulated and downregulated CHIP expression, respectively, at both mRNA and protein levels. After cloning CHIP promoter, the increased and decreased promoter activities of CHIP induced by overexpression and knockdown of either {beta}-catenin or p68 further confirmed transcriptional regulation of CHIP gene by Wnt/{beta}-catenin signaling cascade. p68 along with {beta}-catenin were found to occupy Transcription Factor 4 (TCF4) binding sites on endogenous CHIP promoter and regulate its transcription. Finally, enhanced cellular propagation and migration of colorectal cancer cells induced by Wnt/{beta}-catenin-p68-CHIP axis established the significance of this pathway in oncogenesis. To the best of our knowledge, this is the first report elucidating the mechanistic details of transcriptional regulation of CHIP (STUB1) gene expression.

cancer biology↗