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Srividya, K.

Publications and source records attributed to Srividya, K..

4 recordsLinked to original sources

T13F2.2 of C. elegans is Critical for Chromatin Organization, Autophagy, and Longevity

Intricately modulated by a spectrum of proteins, Chromatin structure governs gene expression and cellular homeostasis. In Caenorhabditis elegans, critical components like the TATA-binding protein tbp-1 play pivotal roles in orchestrating chromatin dynamics. While the function of many of the interacting partners of tbp-1 is well-understood, our study brings into focus a lesser-known entity, T13F2.2, an unexplored tbp-1 interacting protein and a putative RNA polymerase II transcriptional coactivator. Employing reverse genetics, we found that RNAi-induced depletion of T13F2.2 resulted in pronounced disruptions to nuclear architecture, evidenced by nuclear staining and transmission electron microscopy. Accompanying these structural anomalies, we observed increased autophagy, pointing to cellular stress and a hyperacetylation of the core histones, suggesting potential chromatin decompaction. Notably, multifaceted functional alterations, upon the partial knockdown of the T13F2.2, culminated in a substantial reduction in the worms lifespan. Intriguingly, interventions such as administering ROS scavengers and autophagy modulators offered a reprieve from this life-shortening effect. Transcriptomic analysis upon T13F2.2 knockdown revealed upregulation of genes related to autophagy and chromatin remodelling, alongside downregulation of genes involved in longevity pathways and oxidative stress response. This study, thus, not only puts forward the functional implication of an uncharacterized gene in C. elegans biology, but also further emphasizes the role of chromatin organization in aging at the organismal level.

genetics↗

Changes in microglia chromatin accessibility in aged female mice.

Aged female microglia display a more inflammatory and disease-associated phenotype compared to age-matched males. Epigenetic mechanisms, such as chromatin accessibility, are key drivers of microglial plasticity and phenotypes necessary for development, priming, and immune activation. Therefore, alterations in chromatin accessibility patterns can potentially regulate the neuroimmune responses and phenotypes observed in female microglia with aging, but to date have not been assessed. In this study, hippocampal microglia chromatin accessibility in young (4-5 months) and old (23-24 months) female mice was interrogated by Assay for Transposable Accessible Chromatin using Sequencing (ATAC-Seq). Cx3cr1-cre/ERT2+: NuTRAP mice were used to tag microglia and enable INTACT (isolation of nuclei tagged in specific cell types) collection of microglia-specific nuclei. With aging, loci specific gains and losses in chromatin accessibility were observed. Notably, changes in chromatin accessibility were skewed, with aged female microglia having more regions gaining accessibility than loosing accessibility. These changes were under-represented in the proximal promoter region ([≤]1kb) of genes but were enriched in intergenic regions. Regions that gained accessibility were more concentrated around genes responsible for myeloid cell differentiation and the regulation of immune and inflammatory responses. In contrast, regions that became less accessible were closest to genes involved in neuronal and synaptic function. In addition, X Chromosome accessibility changes were less common compared to autosomal changes, which argues against increased X Chromosome escape from inactivation with aging in female microglia. Overall, our data demonstrate age-related chromatin accessibility changes in female microglia, which may be regulated within enhancers and distal regulatory elements, and that these changes have potential downstream implications for the inflammatory phenotype of microglia in aging female mice.

molecular biology↗

Penetratin inhibits α-synuclein fibrillation and improves locomotor functions in mice model of Parkinsons disease

Parkinsons disease (PD) is the second most common neurodegenerative disease. The presence of lewy bodies, primarily consisting of -synuclein (-syn) aggregates is one of the common features seen in the substantia nigra region of the brain in PD patients. The disease remains incurable and only symptomatic relief is available. We screened various cell-penetrating peptides and reveal that penetratin is a potent inhibitor of -syn aggregation in-vitro, and significantly improved locomotor coordination in mice models of PD in-vivo. The peptide inhibits -syn aggregation in vitro as well as in yeast, and C.elegans models. We further made a cyclic derivative of penetratin by disulfide coupling of N- and C-terminal cysteine residues. Both penetratin and its cyclized derivative interact with -syn. NMR studies show that both linear as well as cyclic derivative interact at the acidic C-terminal tail of the protein. Similar to penetratin, its cyclic derivative inhibited -syn aggregation in the C.elegans model of Parkinsons disease, and also improved worm motility. Molecular Dynamics studies show that penetratin interacts with -synuclein and prevents its conformational transition from disordered into {beta}-sheet rich structure. The therapeutic efficacy of penetratin was further confirmed in a transgenic mice model of the disease, wherein penetratin treatment over a period of 90 days improved locomotor coordination, and halted disease progression. Overall, the present work provides a potent therapeutic agent that could be further explored in the management of PD.

neuroscience↗

Studies on C. elegans probed with estradiol, elucidate the critical role of Na+/H+ exchanger, nhx-2 in reproductive senescence and neuronal health

Setting in of reproductive senescence (RS) gives rise to several changes, making aged individuals susceptible to multiple disorders including neurodegenerative diseases, cardiovascular ailments and bone disorders amongst others. The present study, employing transgenic C. elegans that expresses human alpha synuclein, endeavors to decipher the association of reproductive senescence with age-associated neurodegenerative diseases and behavioral ageing, under normal conditions and after being probed with estradiol. We carried out RNAi induced silencing of a subset of 22 genes that are known to delay RS, followed by studies on alpha-Synuclein aggregation and associated effects. These studies led us to functional characterization of the Na+/H+ exchanger; nhx-2, expressed exclusively in gut. We found that RNAi of nhx-2 not only ameliorates the effects associated with alpha-Synuclein aggregation, but it also attunes effects related to behavioral aging including that of reproductive health-span and neuroprotection via mimicking dietary restriction, as it alters food absorption from the gut. We further elucidated that these effects are Sir-2.1 driven as nhx-2 knock out did not delay reproductive senescence in knock down condition of sir-2.1. To substantiate our findings, we performed whole transcriptome analysis in nhx-2 mutant strain. Our data revealed differential expression of 61 out of 62 hallmark genes of CR described by GenDR, in knock out condition of nhx-2. As estradiol plays a central role in both reproductive health as well as neuronal health, we subjected worms to exogenous estradiol treatment and observed that it led to elevated levels of nhx-2. Studies on structural binding analysis demonstrated significant binding potential of estradiol receptor NHR-14 with nhx-2 gene and ChIP analysis revealed that estradiol treatment gives rise to enhanced NHX-2 levels through inducing the promoter specific histone H3 acetylation (H3K9) and lysine methylation (H3K4me3). These studies identify nhx-2 as an important modulator that extends reproductive longevity and ameliorates effects associated with alpha synuclein aggregation in C elegans. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/229344v2_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@917377org.highwire.dtl.DTLVardef@133a07dorg.highwire.dtl.DTLVardef@6d6f28org.highwire.dtl.DTLVardef@9cde9a_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LISilencing of sodium proton antiporter nhx-2 affords neuroprotection and ameliorates effects associated with alpha-Synuclein aggregation via mimicking dietary restriction in C. elegans. C_LIO_LIExogenous 17-{beta}-Estradiol treatment induces the expression of nhx-2, through inducing the promoter specific histone H3 acetylation (H3K9) and lysine methylation (H3K4me3). C_LIO_LIEffects associated with nhx-2, including prolonged reproductive span and neuroprotective effects, are SIR-2.1 driven. C_LIO_LInhx-2 silencing decreases alpha-Synuclein aggregation, however; estradiol mediated overexpression above the endogenous levels, does not amend the aggregation any further. C_LI

neuroscience↗