Biology subjects

Sharma, S.

Publications and source records attributed to Sharma, S..

At least 235 records · Page 13Linked to original sources

bioRxiv2024

Nanoligomers targeting NF-κB and NLRP3 reduce neuroinflammation and improve cognitive function with aging and tauopathy

Neuroinflammation contributes to impaired cognitive function in brain aging and neurodegenerative disorders like Alzheimers disease, which is characterized by the aggregation of pathological tau. One major driver of both age- and tau-associated neuroinflammation is the NF-{kappa}B and NLRP3 signaling axis. However, current treatments targeting NF-{kappa}B or NLRP3 may have adverse/systemic effects, and most have not been clinically translatable. In this study, we tested the efficacy of a novel, nucleic acid therapeutic (Nanoligomer) cocktail specifically targeting both NF-{kappa}B and NLRP3 in the brain for reducing neuroinflammation and improving cognitive function in old (aged 19 months) wildtype mice, and in rTg4510 tau pathology mice (aged 2 months). We found that 4 weeks of NF-{kappa}B/NLRP3-targeting Nanoligomer treatment strongly reduced neuro-inflammatory cytokine profiles in the brain and improved cognitive-behavioral function in both old and rTg4510 mice. These effects of NF-{kappa}B/NLRP3-targeting Nanoligomers were also associated with reduced glial cell activation and pathology, favorable changes in transcriptome signatures of glia-associated inflammation (reduced) and neuronal health (increased), and positive systemic effects. Collectively, our results provide a basis for future translational studies targeting both NF-{kappa}B and NLRP3 in the brain, perhaps using Nanoligomers, to inhibit neuroinflammation and improve cognitive function with aging and neurodegeneration.

physiology↗

bioRxiv2024

Crebinostat Facilitates Memory Formation

ObjectivesProtein modifications importantly contribute to memory formation. Protein acetylation is a posttranslational modification of proteins that regulates memory formation. Acetylation level is determined by the relative activities of acetylases and deacetylases. Crebinostat is a histone deacetylase inhibitor. In this study, our aim was to examine whether Crebinostat affects memory formation in object recognition task. Further, we aimed to understand regulation of plasticity-related proteins by Crebinostat. MethodsObject recognition task was used to examine the effect of Crebinostat on memory formation. The effect of Crebinostat on plasticity-related proteins was examined using Western blot experiments. ResultsWe show that Crebinostat facilitates memory formation by a weak training in object recognition task. Further, this compound enhances acetylation of -tubulin, and reduces the level of histone deacetylase 6, an -tubulin deacetylase. ConclusionsThe results suggest that enhanced acetylation of -tubulin by Crebinostat contributes to its facilitatory effect on memory formation. AbstractProtein modifications importantly contribute to memory formation. Protein acetylation is a posttranslational modification of proteins that regulates memory formation. Acetylation level is determined by the relative activities of acetylases and deacetylases. Crebinostat is a histone deacetylase inhibitor. Here we show that in object recognition task, Crebinostat facilitates memory formation by a weak training. Further, this compound enhances acetylation of -tubulin, and reduces the level of histone deacetylase 6, an -tubulin deacetylase. The results suggest that enhanced acetylation of -tubulin by Crebinostat contributes to its facilitatory effect on memory formation.

neuroscience↗

bioRxiv2024

Molecular basis of ligand promiscuity, structural mimicry, and atypical dimerization in the chemokine receptors

Selectivity of natural agonists for their cognate receptors is one of the hallmarks of the members of GPCR family, and it is crucial for the specificity of downstream signal-transduction. However, this selectivity often breaks down in the chemokine receptor subfamily, wherein a high degree of promiscuity is observed with one receptor recognizing multiple chemokines and one chemokine binding to multiple receptors. The molecular determinants of such a striking promiscuity for natural ligands in the chemokine-chemokine receptor system remain mostly elusive and represent an important knowledge gap in our current understanding. Here, we carry out a comprehensive transducer-coupling analysis, testing all known C-X-C chemokines on every C-X-C type chemokine receptor, to generate a global fingerprint of the selectivity and promiscuity encoded within this system. Taking lead from our finding, we determined cryo-EM structures of the most promiscuous receptor, CXCR2, in complex with every interacting chemokine, and deciphered the conserved molecular signatures and distinct binding modalities. While most chemokines position themselves on the receptor as a dimer, CXCL6 exhibits a monomeric binding pose induced by a previously unanticipated reorientation of its carboxyl-terminal -helix, leading to disruption of the dimer interface. Surprisingly, one of the chemokines, CXCL5, induces a ligand-swapped dimer of CXCR2, the first of its kind observed in class A GPCRs, wherein each protomer of the ligand engages its own receptor without any discernible receptor-receptor interface. These unique observations provide a possible structural mechanism for inherent functional specialization encoded in chemokines despite their convergence to a common receptor. Furthermore, we also determined cryo-EM structures of CXCR3 in complex with G-protein-biased and {beta}-arrestin-biased small molecule agonists that elucidate distinct allosteric modulations in the receptor driving their divergent transducer-coupling bias. Guided by structural analysis and experimental validation, we discover that in contrast to previously held notion, small molecule agonists of CXCR3 display robust agonism at CXCR7, an intrinsically biased, {beta}-arrestin-coupled receptor, making them first-in-class dual agonists for chemokine receptors with exclusive {beta}arr-bias at CXCR7. Taken together, our study provides molecular insights into ligand promiscuity and signaling bias at the chemokine receptors, and also demonstrates a proof of principle that naturally encoded structural mimicry can be recapitulated using synthetic pharmacophores with potential implications for developing novel therapeutics.

biochemistry↗

bioRxiv2024

A genetic and physiological model of renal dysfunction in Lowe syndrome

Lowe syndrome (LS) is an X-linked recessive genetic disorder characterized by renal dysfunction, neurodevelopmental defects, and cataract. The affected gene, OCRL encodes for a polyphosphoinositide 5-phosphatase. OCRL is localized to multiple sub-cellular locations in the endolysosomal system and defects in these organelles have been described in human cells depleted of OCRL. However, the relationship of the endolysosomal defects in OCRL depleted cells to the altered physiology of kidney cells of LS patients has not been completely determined. Here we model the kidney phenotypes of LS using a Drosophila nephrocyte model. Using this model system, we demonstrate that OCRL plays a cell-autonomous role in nephrocyte function. Deletion of the only OCRL ortholog in Drosophila (dOCRL) leads to cell-autonomous defects in larval nephrocyte structure and function. Null mutants of dOCRL (dOCRLKO) show defects in the endolysosomal system of larval nephrocytes that are associated with physiological defects in nephrocyte function. These defects could be rescued by reconstitution with a human OCRL transgene but not with a phosphatase dead version or a human LS patient derived mutation. Overall, this work provides a model system to understand the mechanisms by which the sub-cellular changes from loss of OCRL leads to defects in kidney function in human patients.

cell biology↗

bioRxiv2024

GEMCAT - A new algorithm for gene expression-based prediction of metabolic alterations

The conclusive interpretation of multi-omics datasets obtained from high throughput approaches is an important prerequisite to understand disease-related physiological changes and to predict biomarkers in body fluids. We here present a Gene Expression-based Metabolite Centrality Analysis Tool, GEMCAT, a new genome scale metabolic modelling algorithm. GEMCAT enables integration of transcriptomics or proteomics data to predict changes in metabolite concentrations which can be verified by targeted metabolomics. In addition, GEMCAT allows to trace measured and predicted metabolic changes back to the underlying alterations in gene expression or proteomics and thus enables functional interpretation and integration of multi-omics data. We demonstrate the predictive capacity of GEMCAT on two datasets, one using RNA sequencing data and metabolomics from an engineered human cell line with a functional deletion of the mitochondrial NAD-transporter and another using proteomics and metabolomics measurements from patients with inflammatory bowel disease.

bioinformatics↗

bioRxiv2024

Targeted-Neuroinflammation Mitigation Using Inflammasome-Inhibiting Nanoligomers is Therapeutic in Experimental Autoimmune Encephalomyelitis (EAE) Mouse Model

Multiple Sclerosis (MS) is a debilitating autoimmune disease that impacts millions of patients worldwide, disproportionately impacting women (4:1), and often presenting at highly productive stages of life. This disease affects the spinal cord and brain, and is characterized by severe neuroinflammation, demyelination, and subsequent neuronal damage, resulting in symptoms like loss of mobility. While untargeted and pan-immunosuppressive therapies have proven to be disease-modifying and manage (or prolong the time between) symptoms in many patients, a significant fraction are unable to achieve remission. Recent work has suggested more targeted neuroinflammation mitigation through selective inflammasome-inhibition can offer relief to patients, while preserving key components of immune function. Here we show a screening of potential therapeutic targets using inflammasome-inhibiting Nanoligomers (NF-{kappa}B1, TNFR1, TNF-, IL-6), that meet or far-exceed commercially available small-molecule counterparts like Ruxolitinib, MCC950, and Deucravacitinib. Using the human brain organoid model, top Nanoligomer combinations (NF-{kappa}B1+TNFR1: NI111, and NF-{kappa}B1+NLRP3: NI112) were shown to significantly reduce neuroinflammation, without any observable negative impact on organoid function. Further testing of these top Nanoligomer combinations in an aggressive Experimental Autoimmune Encephalomyelitis (EAE) mouse model for MS using intraperitoneal (IP) injections showed that NF-{kappa}B1and NLRP3 targeting Nanoligomer combination NI112 rescues mice without observable loss of mobility or disability, minimal inflammation in brain and spinal cord histology, and minimal to no immune cell infiltration of the spinal cord and no demyelination, similar to or at par with mice that received no EAE injections (negative control). Mice receiving NI111 (NF-{kappa}B1+TNFR1) also showed reduced neuroinflammation compared to saline (sham) treated EAE mice and at par/similar to other inflammasome-inhibiting small molecule treatments, although it was significantly higher than NI112 leading to subsequent worsening clinical outcomes. Furthermore, treatment with an oral formulation of NI112 at lower doses showed a significant reduction in EAE severity, albeit with higher variance owing to administration and formulation/fill-and-finish variability. Overall, these results point to the potential of further development and testing these inflammasome targeting Nanoliogmers as an effective neuroinflammation treatment for multiple neurodegenerative diseases, and potentially benefit several patients suffering from such debilitating autoimmune diseases like MS.

neuroscience↗

bioRxiv2023

Large pan-cancer cell screen coupled to (phospho-) proteomics underscores high-dose vitamin C as a potent anti-cancer agent

Increasing preclinical and clinical evidence has positioned high-dose vitamin C as a promising anti-cancer treatment that merits more clinical attention. Multiple cytotoxicity mechanisms have been described, including pro-oxidant effects. To contribute to the preclinical understanding of the broad pan-cancer effects of high-dose vitamin C in a global manner, we determined the IC50 of a large panel of cancer cell lines (n=51) representing 7 solid tumour types and generated proteome data. The majority of cell lines were highly sensitive (IC50 range 0.036-10mM, mean 1.7 {+/-} 0.4 mM), well below a clinically achievable dose. The proteome data (>5000 proteins per sample), showed that high sensitivity is associated with proliferation, as indicated by functional enrichment of cell cycle, RNA splicing and chromatin organization, while lower sensitivity is linked to extracellular vesicles, glycolysis, fatty acid metabolism and mitochondria. Moreover, (phospho-)proteome analysis of on-treatment vitamin C effects on four pancreatic ductal adenocarcinoma (PDAC) cells dosed at a range of IC50 values (Hs766 T, 2 mM; Capan-2, 0.6 mM; PANC-1, 0.14 mM and Suit-2, 0.1 mM) revealed, next to cell line specific effects, down-modulation of AKT-MTOR signalling and immune suppressive signalling, while IFN- response was enhanced upon vitamin C. Altogether, our comprehensive pharmacological and (phospho-)proteome analysis is the first to assess cancer vulnerabilities and effects of vitamin C on a large cancer cell line panel and underscores the potential of high-dose vitamin C as an anti-cancer agent.

cancer biology↗

bioRxiv2023

Haplo-pheno association for OsNRT1.1 paralog in rice reveals superior haplogroup with high nitrate uptake efficiency

Haplotype-based breeding approaches hold promise for enhancing crop improvement strategies, allowing for targeted selection of superior genetic combinations to develop high-yielding and resilient varieties. The current study aimed at identification of NRT1.1 nitrate transporter haplotype that could serve as "donors" in haplotype-based breeding. We phenotyped 272 rice accessions in hydroponics with sufficient and low nitrogen (N) for nitrate uptake efficiency. By employing principal component and hierarchical cluster analysis, the accessions were grouped into N efficient, intermediate, and inefficient clusters. Haplotype analysis unveiled the presence of two haplogroups for OsNRT1.1A, three for OsNRT1.1B, and five for OsNRT1.1C. Through haplo-pheno association, the comparison of mean trait values revealed H2 and H3 as the superior haplotypes (SH) for OsNRT1.1A and OsNRT1.1B, respectively. In the case of OsNRT1.1C, H3 and H1 emerged as SH within the N-efficient cluster. Conversely, the inferior haplotypes (IH) consisted of H1 in OsNRT1.1A, H3 in OsNRT1.1B, and H3 and H2 in OsNRT1.1C within the N-inefficient cluster. However, relative expression of OsNRT1.1 (with specific paralogs) in contrasting rice accessions revealed that a few of the inferior accession exhibited higher expression levels in the root but lower in the shoot, which might have contributed to their N-inefficiency. Furthermore, amino acid change at position 403 (Isoleucine to Valine) in inferior accessions influences the active site OsNRT1.1C protein causing N-inefficiency. Ours is the first report on haplotype analysis of NRT1.1 gene demonstrating its genetic diversity, as well as its association with phenotype will have potential implications for improving nitrate uptake efficiency.

plant biology↗

bioRxiv2023

Drosophila Wg and Evi/Wntless dissociation occurs post apical internalization in the late endosomes

Signaling pathways activated by secreted Wnt ligands play an essential role in tissue development and the progression of diseases, like cancer. Secretion of the lipid-modified Wnt proteins is tightly regulated by a repertoire of intracellular factors. For instance, a membrane protein, Evi/Wntless, interacts with the Wnt ligand in the ER, and it is essential for its further trafficking and release in the extracellular space. After dissociating from the Wnt, the Wnt-unbound Evi is recycled back to the ER via Golgi. However, where in this trafficking path Wnt proteins dissociate from Evi remains unclear. Here, we have used the Drosophila wing epithelium to trace the route of the Evi-Wg (Wnt homolog) complex leading up to their separation. In these polarized cells, Wg is first trafficked to the apical surface, however, the secretion of Wg is believed to occur post-internalization via recycling. Our results show that the Evi-Wg complex is internalized from the apical surface. Furthermore, using antibodies that specifically label the Wnt-unbound Evi, we show that Evi and Wg separation occurs post-internalization in the acidic endosomes. These results refine our understanding of the polarized trafficking of Wg and highlight the importance of Wg endocytosis in its secondary secretion.

cell biology↗

bioRxiv2023

DeePNAP: A deep learning method to predict protein-nucleic acids binding affinity from sequence

Predicting the protein-nucleic acid (PNA) binding affinity solely from their sequences is of paramount importance for the experimental design and analysis of PNA interactions (PNAIs). A large number of currently developed models for binding affinity prediction are limited to specific PNAIs, while also relying on both sequence and structural information of the PNA complexes for both train/test and also as inputs. As PNA complex structures available are scarce, this significantly limits the diversity and generalizability due to a small training dataset. Additionally, a majority of the tools predict a single parameter such as binding affinity or free energy changes upon mutations, rendering a model less versatile for usage. Hence, we propose DeePNAP, a machine learning-based model trained on a vast and heterogeneous dataset with 14,401 entries (from both eukaryotes and prokaryotes) of ProNAB database, consisting of wild-type and mutant PNA complex binding parameters. Our model precisely predicts the binding affinity and free energy changes due to the mutation(s) of PNAIs exclusively from the sequences. While other similar tools extract features from both sequence and structure information, DeePNAP employs sequence-based features to yield high correlation coefficients between the predicted and experimental values with low root mean squared errors for PNA complexes in predicting the KD and {Delta}{Delta}G implying the generalizability of DeePNAP. Additionally, we have also developed a web interface hosting DeePNAP that can serve as a powerful tool to rapidly predict binding affinities for a myriad of PNAIs with high precision toward developing a deeper understanding of their implications in various biological systems. Web interface: http://14.139.174.41:8080/

biophysics↗

bioRxiv2023

High-capacity flexible hippocampal associative and episodic memory enabled by prestructured ''spatial'' representations

Hippocampal circuits in the brain enable two distinct cognitive functions: the construction of spatial maps for navigation and the storage of sequential episodic memories. This dual role remains an enduring enigma. While there have been advances in modeling spatial representations in the hippocampus, we lack good models of its role in episodic memory. Here we present a neocortical-entorhinal-hippocampal network model that implements a high-capacity general associative memory, spatial memory, and episodic memory by factorizing content storage from the dynamics of generating error-correcting stable states. Unlike existing neural memory models, which exhibit a memory cliff, the circuit (which we call Vector-HaSH, Vector Hippocampal Scaffolded Heteroassociative Memory) exhibits a graceful tradeoff between number of stored items and detail. Next, we show that structured internal scaffold states are essential for constructing episodic memory: they enable high-capacity sequence memorization by abstracting the chaining problem into one of learning low-dimensional transitions. Finally, we show that previously learned spatial sequences in the form of cortico-hippocampal location-landmark associations can in turn be used as larger scaffolds and associated with neocortical inputs for a high-fidelity one-shot memory, providing the first circuit model of the "memory palaces" used in the striking feats of memory athletes.

neuroscience↗

bioRxiv2023

Tick bite-induced Alpha-Gal Syndrome and Immunologic Responses in an Alpha-Gal Deficient Murine Model

IntroductionAlpha-Gal Syndrome (AGS) is a delayed allergic reaction due to specific IgE antibodies targeting galactose--1,3-galactose (-gal), a carbohydrate found in red meat. This condition has gained significant attention globally due to its increasing prevalence, with more than 450,000 cases estimated in the United States alone. Previous research has established a connection between AGS and tick bites, which sensitize individuals to -gal antigens and elevate the levels of -gal specific IgE. However, the precise mechanism by which tick bites influence the hosts immune system and contribute to the development of AGS remains poorly understood. This study investigates various factors related to ticks and the host associated with the development of AGS following a tick bite, using mice with a targeted disruption of alpha-1,3-galactosyltransferase (AGKO) as a model organism. MethodsLone-star tick (Amblyomma americanum) and gulf-coast tick (Amblyomma maculatum) nymphs were used to sensitize AGKO mice, followed by pork meat challenge. Tick bite site biopsies from sensitized and non-sensitized mice were subjected to mRNA gene expression analysis to assess the host immune response. Antibody responses in sensitized mice were also determined. ResultsOur results showed a significant increase in the titer of total IgE, IgG1, and -gal IgG1 antibodies in the lone-star tick-sensitized AGKO mice compared to the gulf-coast tick-sensitized mice. Pork challenge in Am. americanum -sensitized mice led to a decline in body temperature after the meat challenge. Gene expression analysis revealed that Am. americanum bites direct mouse immunity toward Th2 and facilitate host sensitization to the -gal antigen, while Am. maculatum did not. ConclusionThis study supports the hypothesis that specific tick species may increase the risk of developing -gal-specific IgE and hypersensitivity reactions or AGS, thereby providing opportunities for future research on the mechanistic role of tick and host-related factors in AGS development.

immunology↗

bioRxiv2023

Whole Genome Sequencing and Assembly of the House Sparrow, Passer domesticus

The common house sparrow, Passer domesticus is a small bird belonging to the family Passeridae. Here, we provide high-quality whole genome sequence data along with assembly for the house sparrow. The final genome assembly was assembled using a Shovill/SPAdes/MASURCA/BUSCO workflow, consisting of contigs spanning 268193 bases and coalescing around a 922 MB sized reference genome. We employed rigorous statistical thresholds to check the coverage, as the Passer genome showed considerable similarity to Gallus gallus (chicken) and Taeniopygia guttata (Zebra finch) genomes, also providing a functional annotation. This new annotated genome assembly will be a valuable resource as a reference for comparative and population genomic analyses of passerine, avian, and vertebrate evolution. SignificanceAvian evolution has been of great interest in the context of extinction. Annotating the genomes such as passerines would be of significant interest as we could understand the behavior/foraging traits and further explore their evolutionary landscape. In this work, we provide a full genome sequence of Indian house sparrow, viz. Passer domesticus which will serve as a useful resource in understanding the adaptability, evolution, geography, allee effects and circadian rhythms.

evolutionary biology↗

bioRxiv2023

DystoGen Compendium: A comprehensive resource of ACMG annotated movement disorder associated genetic variants

PurposeIn recent years, the advent of high throughput sequencing techniques has led to the identification of a number of genetic variants across different genes that are associated with movement disorders. However, the under-appreciation of the variant spectrum in movement disorders and the lack of consolidated and systematic evidence-based annotation of these variants has long undermined the true potential of genomic approaches to expedite precision medicine. MethodsWe manually curated the genetic variants from a panel of 118 genes that have been associated with monogenic causes of movement disorders and systematically annotated them according to ACMG & AMP (American College of Medical Genetics and the Association of Molecular Pathologists) guidelines. ResultsData integration after systematic classification of variants according to ACMG & AMP guidelines showed 5118 pathogenic/likely pathogenic variants accounting for 18.03% of the total unique variants being annotated. This data and annotations are available in a comprehensive online compendium DystoGen. ConclusionTo the best of our knowledge, this is the most comprehensive compendium of genetic variants in movement disorders annotated as per the ACMG & AMP guidelines for pathogenicity. The compendium indexes 28377 variants along with a wide array of information including the geographical origin of the variant, global distribution, and population allele frequency. The resource has been made available in the URL https://clingen.igib.res.in/dystogen/.

bioinformatics↗

bioRxiv2023

Comprehensive single cell aging atlas of mammary tissues reveals shared epigenomic and transcriptomic signatures of aging and cancer

Aging is the greatest risk factor for breast cancer; however, how age-related cellular and molecular events impact cancer initiation is unknown. We investigate how aging rewires transcriptomic and epigenomic programs of mouse mammary glands at single cell resolution, yielding a comprehensive resource for aging and cancer biology. Aged epithelial cells exhibit epigenetic and transcriptional changes in metabolic, pro-inflammatory, or cancer-associated genes. Aged stromal cells downregulate fibroblast marker genes and upregulate markers of senescence and cancer-associated fibroblasts. Among immune cells, distinct T cell subsets (Gzmk+, memory CD4+, {gamma}{delta}) and M2-like macrophages expand with age. Spatial transcriptomics reveal co-localization of aged immune and epithelial cells in situ. Lastly, transcriptional signatures of aging mammary cells are found in human breast tumors, suggesting mechanistic links between aging and cancer. Together, these data uncover that epithelial, immune, and stromal cells shift in proportions and cell identity, potentially impacting cell plasticity, aged microenvironment, and neoplasia risk.

genomics↗

bioRxiv2023

Phytochemical Characterization of Bio-active Compounds in Hydroethanolic Extract of Elaeocarpus ganitrus leaves using HPLC, LC-MS, and HPTLC Analyses

Bioactive compounds have various applications in different industries, including food, pharmaceutical, and cosmetic industries, demonstrating the need to identify the best-standardized technique to screen the phytochemical profile of medicinal plants. This study aimed to characterize the bioactive compounds in the hydroethanolic extracts of Elaeocarpus ganitrus leaves using various analytical techniques: HPLC, LC-MS, and HPTLC. Air-dried leaves of E. ganitrus were extracted with 70% ethanol. The phytochemical composition of crude extracts was analyzed by the High performance liquid chromatography (HPLC) method, and a total of 93 compounds, including 46 flavonoids, 17 phenols, 14 polyphenols, 3 phenolic acid, 3 phenolic glycosides, 2 flavonoid glycosides, 2 glycosides, 2 phenylpropanoid glycoside, 1 hydroxycinnamic acid, 1 lignan, 1 tannin, and 1 terpene glycoside were detected and quantified. The Liquid chromatography mass spectrometry (LC-MS) analyses identified 11 major eleven compounds: quercetin (803.0215 {micro}g/L), gallic acid (726.13 {micro}g/L), ferulic acid (652.34 {micro}g/L), chlorogenic acid (651.021{micro}g/L), pinocembrin (264.11 {micro}g/L), p-aminobenzoic acid (251.021 {micro}g/L), epicatechin (246.02 {micro}g/L), catechin (161.51 {micro}g/L), caffeic acid (123.31 {micro}g/L), syringaldehyde (116.31 {micro}g/L), and naringenin (106.31 {micro}g/L). The chemical fingerprinting was carried out by high performance thin layer chromatography (HPTLC), and HPTLC fingerprint qualitatively revealed a predominant amount of gallic acid (48.64 %), curcumin (15.21 %), caffeic acid (12.19 %) and cinnamic acid (6.50 %). A significant amount of bioactive constituents in a hydroethanolic extract of E. ganitrus leaves indicates the plants therapeutic potential, including antioxidant, anti-inflammatory, antidiabetic, anticancer, neuroprotective, and cardio-protective activities.

biochemistry↗

bioRxiv2023

Telomeres control regulation of the human Telomerase (hTERT) gene through non-telomeric TRF2 and independent of Telomere looping

The function of the human telomerase reverse transcriptase (hTERT) in the synthesis and maintenance of chromosome ends, or telomeres, is widely understood. Whether and how telomeres, on the other hand, influence hTERT regulation is relatively less studied. We found hTERT was transcriptionally altered depending on telomere length (TL). This resulted from TL-dependent binding of TRF2 between telomeres and the hTERT promoter. hTERT promoter-bound TRF2 was non-telomeric and did not involve the looping of telomeres to the hTERT promoter. Cell lines from different tissue types (fibrosarcoma (HT1080), colon cancer (HCT116), and breast cancer (MDA-MB-231), engineered for either telomere elongation/shortening gave increase/decrease in hTERT, respectively. Mechanistically, we show hTERT promoter-bound non-telomeric TRF2 recruits the canonical PRC2-complex inducing repressor histone H3K27-trimethylation in a TL-dependent fashion. This was further supported by TL-dependent promoter activity from an exogenously inserted hTERT reporter. Increase in TL over days followed by gradual decline, resulted in activation followed by repression of hTERT in a concerted manner, further implicating TL as a key factor for hTERT regulation. Notably on reprogramming primary fibroblasts to induced pluripotent stem cells (iPSCs), TRF2 loss from the hTERT promoter was evident along with telomere elongation and hTERT upregulation. Conversely, on telomere shortening in iPSCs, hTERT promoter-bound TRF2 was restored with marked reduction in hTERT further supporting the causal role of TL in hTERT transcription. Mechanisms of tight control of hTERT by TL shown here are likely to have major implications in telomere-related physiologies, particularly, cancer, ageing and pluripotency. TeaserTelomere length controls hTERT expression by modulating TRF2 distribution and PRC2-mediated repression, highlighting a self-regulatory mechanism in cancer.

cancer biology↗

bioRxiv2023

Neuroprotective Effects of Naltrexone in a Mouse Model of Post-Traumatic Epilepsy

Traumatic Brain Injury (TBI) induces neuroinflammatory responses that can initiate epileptogenesis, which develops into epilepsy. Recently, we identified the anti-convulsive effects of naltrexone, a mu-opioid receptor (MOR) antagonist. While blocking opioid receptors can reduce inflammation, it is unclear if post-TBI epileptogenesis can be prevented by blocking MORs. Here, we tested if naltrexone prevents neuroinflammation and epileptogenesis post-TBI. TBI was induced by a modified Marmarau Weight-Drop (WD) method applied to four-week-old C57BL/6J male mice. Mice were given the pro-convulsant pentylenetetrazol (PTZ) on day two post-injury while telemetry-monitored mice received PTZ on day five. Naltrexone/vehicle treatment started two hours after PTZ. Integrated EEG-video (vEEG) recorded interictal events and spontaneous seizures for three months. Molecular, histological and neuroimaging techniques were used to evaluate neuroinflammation and neurodegeneration both acutely and chronically. Peripheral immune responses were assessed through serum chemokine/cytokine measurements. We observed increases in MOR expression, nitro-oxidative stress, mRNA expression of inflammatory cytokines, microgliosis, neurodegeneration, and white matter damage in the neocortex of TBI mice. vEEG revealed increased interictal events in TBI mice, with 71% developing epilepsy. Naltrexone ameliorated neuroinflammation and neurodegeneration, reduced interictal events and prevented epilepsy, illustrating that naltrexone is a promising drug to prevent TBI-associated neuroinflammation and epileptogenesis in post-traumatic epilepsy.

neuroscience↗