Biology subjects

Nath, S.

Publications and source records attributed to Nath, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Gut bacterium of Leishmania donovani-non-transmitting sand fly induces IL-23~Th17 axis to protect hosts from drug-resistant visceral leishmaniasis

Background: Visceral leishmaniasis (VL) is caused by Leishmania donovani and differentiates under the influence of biotope-specific gut bacteria in the Leishmania donovani-transmitting sand fly vector, Phlebotomus argentipes, which coexists with the Leishmania donovani-non-transmitting Sergentomyia species in the Indian subcontinent. Hypothesis: Sergentomyia are primarily herpetophilic. Interestingly, we identified a specific population of anthropophilic Sergentomyia babu babu, a proven naturally non-competent vector for transmitting Leishmania donovani, with high abundance and human-bite incidences in VL-non-endemic regions, compared with VL-endemic regions of India. Thus, the possibility of egesting gut bacteria to humans from VL-non-transmitting Sergentomyia and inducing downstream immune cascades remains undeniable. Innovation: We characterized gut bacteria from anthropophilic Sergentomyia babu babu in both VL-endemic and VL-non-endemic regions of India and found that a heat-inactivated formulation of Heyndrickxia sporothermodurans [NCBI Sequence Read Archive (SRA): PRJNA1403236], isolated from anthropophilic Sergentomyia babu babu from a VL-non-endemic region, prevented and cured L. donovani infection by inducing IL-23~Th17. More importantly, it also prevented the initial parasite establishment by inducing phagocytosis, ROS, and TNF- in circulatory Ly6G-CD11b+Ly6Chi monocytes. To the best of our knowledge, this is the first report confirming that the gut bacteria of VL-non-transmitting sand flies are critical and need to be investigated in depth for developing therapeutics and/or prophylactics against visceral leishmaniasis (VL), and suggests that possible bite-transfer of gut bacteria from disease-non-transmitting vectors to hosts may restrict disease pathogenicity. Further clinical trials are needed to warrant (Indian patent: 202511041013, April 28, 2025).

immunology↗

bioRxiv2026

Mechanochemical cues control the coupling of metabolic and migratory patterns in cancer

Confined migration is essential for metastasis, yet how cells adapt their migratory and metabolic programs across stiffness-varying microenvironments remains unclear. We uncover a stiffness-dependent mechano-metabolic switch governing migration. In stiff microchannels, cells utilize the osmotic engine model (OEM), relying on NHE1 activity, front-polarization, and glycolysis. In soft microchannels, migration is OEM-independent and requires pyruvate-fueled oxidative phosphorylation (OxPHOS). This OxPHOS-driven motility depends on Arp3, {beta}1-integrin and integrin-linked kinase, which increase membrane tension in confinement that in turn triggers TRPM7-mediated calcium influx and RhoA-/myosin-II contractility. Activating and polarizing NHE1, via overexpression, hypoxia or elevated viscosity, restore OEM- and glycolysis-dependent migration in soft microchannels, bypassing the need for actin polymerization in vitro and in chick embryos. Mitochondria addition reinstates Arp3 polarization and enhances migration in NHE1-overexpressing cells, enabling engagement of both mechanisms in vitro and in zebrafish. These findings uncover a previously unrecognized mechano-metabolic link, revealing that intracellular rewiring overrides stiffness-dependent metabolic demands.

cell biology↗

bioRxiv2026

Organoid-T cell co-cultures functionally stratify tumor-reactive T cells and their responses to immune checkpoint inhibitors

Tumor-reactive T cells (TRTs) are critical for anti-tumor immunity but are incompletely captured by current assays, which fail to reproduce tumor-specific antigen diversity. Here, we show that multiplex functional profiling of patient-derived tumor organoid-T cell co-cultures (PDOTs) enables robust identification of TRTs across CD8, CD4, and double-negative (DN) T cell populations. Single activation markers underestimated TRT responses, whereas integrated analysis revealed broader functional repertoire. MHCI blockade abrogated CD8 and DN TRT responses while preserving CD4 reactivity, supporting antigen-dependent recognition across T cell lineages. Tumor PDO expressed MHCI and MHCII, and PDOTs enabled generation and detection of TRTs from peripheral blood. PD1 blockade induced heterogeneous responses, enhancing CD8 and DN activity and unexpectedly augmenting CD4 reactivity. PDOTs further identified additional inhibitory pathways whose therapeutic targeting in combination with PD1 blockade increased TRT responses. These findings establish PDOTs as a platform to identify TRTs and functionally stratify patient-specific tumor-T cell responses to checkpoint immunotherapy.

immunology↗

bioRxiv2026

α-Synuclein Triggers Intercellular Nanotubes Formation to Prevent Apoptosis in Astroglia by Promoting Stemness

Astrocytes play a significant role in neuroprotection by internalizing neurodegenerative aggregates and facilitating their degradation. Recent studies indicate that -Synuclein (-SYN) protofibrils promote the transfer of pathogenic aggregates and dysfunctional mitochondria between astroglia via tunneling nanotubes (TNTs), which enhances cell survival and resistance to apoptosis. However, the underlying mechanism of TNT-driven apoptosis resistance remains unclear. We find that -SYN protofibrils induce aberrant mitochondria with decreased membrane potential ({Psi}m) and promote dynamic actin remodeling by relocating phosphorylated focal adhesion kinase (pFAK) to the nucleus, which triggers TNT formation in human astrocytoma cell lines and primary murine astrocytes. The important novel finding of this study is that pFAK in the nucleus co-localizes with Nanog, a crucial transcription factor for preserving stemness, and the interaction between pFAK and Nanog is critical for promoting p53 degradation via Mdm2-mediated ubiquitination and upregulating autophagy, thereby supporting the survival of astroglia exposed to toxic -SYN protofibrils. ROCK inhibitor y-27632 also drives TNT-formation via pFAK translocation to the nucleus, colocalizes with Nanog, and enhances stemness-related gene expression. Inhibiting TNT with the actin depolymerizing agent cytochalasin-D prevents pFAK co-localization with Nanog in the nucleus and fails to protect cells from -SYN-induced apoptosis. Nanog knockdown does not degrade p53 and hinders cell rescue from apoptosis. Furthermore, these transient TNTs transfer mitochondria to adjacent cells, potentially helping maintain metabolic stability. This study reveals that the TNT formation pathway promotes pFAK-Nanog interaction in the nucleus, leading to p53 degradation, which protects astroglia against -SYN proteotoxicity and prevents apoptosis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/727344v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@18d8675org.highwire.dtl.DTLVardef@76a383org.highwire.dtl.DTLVardef@e92202org.highwire.dtl.DTLVardef@1b7ee4b_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2026

Mechanical Signaling Drives Tunneling Nanotubes to Preserve Cytoskeleton Tension and Lamin Integrity Against α-Synuclein-Induced Senescence in Astroglia

Astroglia can counteract the harmful effects of -synuclein (-SYN) protofibrils and reverse premature cellular senescence by promoting tunneling nanotubes (TNTs). However, the mechanism behind this recovery is unknown. This study is the first to examine TNT-mediated mechanical stability in senescent astroglial recovery. We demonstrate that disruption of Lamin A/C in -SYN-protofibrils-treated senescent cells reduces actin-cytoskeleton stress, as measured by nucleus flatness index and isometric scale factor from quantitative microscopy. ROCK (Rho-associated kinase) inhibition, which is crucial for reducing actin-cytoskeleton tension, promotes TNTs. Small molecules like Cytochalasin-D, Nocodazole, and Jasplakinolide, which inhibit TNTs by altering actin tension other than ROCK pathway, cannot reverse senescence. RNA-sequence heatmaps reveal changes in senescence-, integrin-, and ROCK-pathway genes; STRING links these to the Hippo pathway. Experimental results show that cytosolic YAP translocation, a key regulator of Hippo pathway, is vital for TNT formation and actin-based stability in U87-MG astrocytoma and primary astrocytes. Interestingly, TNTs form between two cells with different actin tensions: one exhibits low actin tension with Hippo signaling on, while the other has higher actin tension with Hippo signaling off. The most notable observation is the high abundance of YAP inside the TNTs, along with actin. The study shows that TNTs maintain mechanical stability through Lamin A/C integrity and actin tension in -SYN-induced senescent astroglia, thereby protecting the cells, reversing senescence. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/711517v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@192307dorg.highwire.dtl.DTLVardef@ad8b75org.highwire.dtl.DTLVardef@19ece78org.highwire.dtl.DTLVardef@1056395_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

NTX250: A Modular mRNA-Based Immunotherapy Platform for HPV-Associated Cancers with Broad Applicability.

Infection with high-risk human papillomavirus (HPV) is a key driver of multiple HPV-associated malignancies, including cervical intraepithelial neoplasia (CIN), oropharyngeal, head and neck, and anogenital cancers. Despite the high efficacy of prophylactic HPV vaccines, a substantial population remains at ongoing risk due to issues related to vaccine accessibility, awareness, or personal choice. Current treatments, such as the loop electrosurgical excision procedure (LEEP), address lesions but do not eliminate persistent HPV infection and are associated with potential complications. Moreover, individuals treated for HPV-related disease are at increased risk for subsequent HPV-associated malignancies. These factors underscore an urgent need for effective, non-invasive therapeutic strategies capable of targeting and eradicating persistent HPV infections. Here we introduce NTX250, an innovative mRNA-based therapeutic platform designed to deliver HPV type 16 (HPV16) E6-E7 antigens, combined with immunomodulators human interleukin-12 (IL-12) p70 and engineered human LIGHT (LIGHT). The mRNAs are co-delivered via lipid and ionizable peptoid nanoparticles referred to as Nutshell formulation for intralesional administration. Our preclinical evaluation demonstrates that localized delivery of NTX250 in HPV16-transformed tumor-bearing models results in complete tumor regression and the induction of durable, antigen-specific immune memory. Moreover, this modular mRNA nanoparticle approach combining tumor-specific antigens and immunomodulators is adaptable beyond HPV, with potential applications targeting neoepitopes or other tumor-associated antigens, thus offering a versatile platform for immunotherapy across a broad range of indications. These findings highlight the potential of this strategy as a broadly applicable, non-surgical immunotherapeutic capable of inducing robust and specific anti-tumor responses.

immunology↗

bioRxiv2025

The sociobiome-oral microbiome pathway in dental caries among Indigenous Australians

Indigenous Australians experience disproportionately high rates of dental caries, yet the biological pathways linking socioeconomic disadvantage to oral health remain unclear. This study examined how individual- and neighbourhood-level socioeconomic status (SES) shape the oral microbiome and mediate dental caries risk in Indigenous adults. A cross-sectional study of 100 Indigenous Australians ([≥]18 years) collected demographic, SES, and oral health behaviour data, followed by dental examinations for dental caries assessment, followed by collection of saliva and plaque samples. The microbiome was profiled using 16S rRNA sequencing, with analyses of microbial diversity, composition, differential abundance, and mediation of SES-caries associations. Saliva exhibited greater observed and Shannon diversity than plaque (both p < 0.01), with significant compositional differences (adonis p < 0.001). In saliva, alpha diversity was reduced with age, secondary education, low income, ownership of a healthcare card, and caries presence (all p < 0.05). SES explained greater variation in saliva than plaque composition, with associations for income (R{superscript 2}=3.8%, p<0.01), education (R{superscript 2}=2.0%, p<0.01), and caries (R{superscript 2}=2.2%, p<0.01). Differentially abundant taxa in low-income and caries groups included Rikenellaceae RC9 gut group, F0058, Filifactor, and Treponema. Mediation analyses showed 75.6% of the income effect on caries was mediated by microbiome shifts (ME=0.28, SE=0.32), compared with 21% for education (ME=0.03, SE=0.02). Socioeconomic disadvantage has a significant impact on the oral microbiome, influencing caries risk through income-related microbial dysbiosis. Saliva emerges as a sensitive biomarker of SES gradients. Addressing oral health inequities requires both structural policies targeting income inequality and microbiome-informed interventions. IMPORTANCEThis research provides novel biological insights into how socioeconomic disadvantage contributes to the higher burden of dental caries among Indigenous Australians. Although social determinants of health are well recognised, the pathways connecting these determinants to oral disease remain unclear. By demonstrating that low income and education affect oral microbiome diversity and composition, and that a significant part of income-related caries risk is mediated through microbiome changes, this study highlights an important mechanism behind oral health inequalities. Identifying saliva as particularly responsive to socioeconomic differences makes it a useful, non-invasive biomarker for tracking risk in vulnerable populations. These findings emphasise the need for two approaches: structural interventions to reduce social and income gaps, and microbiome-based strategies to address microbial imbalance and disease risk. Together, they strengthen the evidence for more effective, culturally sensitive efforts to promote oral health equity.

microbiology↗

bioRxiv2025

Defects in lamin A-Prohibitin crosstalk leads to ROS elevation and OxPhos imbalance in laminocardiomyopathy

Lamins are critical for maintaining nuclear homeostasis, chromosome positioning, and cellular mechanotransduction, which involves the transfer of mechanical signals from the cellular microenvironment to the nucleus. Recent studies have also highlighted the involvement of lamin A in mitochondrial homeostasis and the regulation of reactive oxygen species production. Missense mutations in lamin A are linked to a spectrum of diseases known as laminopathies, which include conditions such as dilated cardiomyopathy (DCM), muscular dystrophy, and progeria. One such mutation, K97E, is associated with DCM, causing severe cardiac complications that can lead to myocardial infarction in extreme cases. Our study reveals a detailed pathogenic cascade in K97E-transfected cells involving disrupted interaction with Prohibitin-2, a key mitochondrial protein. Mitochondria exhibit increased fission, reduced fusion, and fragmentation, due to OPA1 downregulation and DRP1 recruitment driven by actin cytoskeletal remodelling. Impaired Rho-ERK- FAK signalling reduces F-actin assembly, elevating G-actin, which further promotes mitochondrial fission. This feedback loop leads to mitochondrial depolarisation, ATP deficiency, and global metabolic catastrophe, in particular cholesterol metabolism, accompanied by elevated ROS. In cardiomyocytes, such dysfunction may underlie contractile deficits and arrhythmias. Our findings establish PHB2 as a critical node linking nuclear integrity, cytoskeletal architecture, and mitochondrial homeostasis, offering new insights into DCM pathogenesis and therapeutic targets. Our findings elucidate the pivotal role of lamin A in cellular energetics and mechanotransduction, offering novel insights into DCM pathophysiology, which in turn opens avenues for developing targeted therapeutic strategies. TeaserLamin A K97E mutation alters cellular metabolome through disturbed mitochondrial and actin homeostasis in a feedback loop with PHB2 at its hub and causes gross pathogenesis of DCM. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/665267v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@176d89aorg.highwire.dtl.DTLVardef@1868703org.highwire.dtl.DTLVardef@109dff8org.highwire.dtl.DTLVardef@14f469a_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 5C_FLOATNO Gross mitochondrial defects arising from PHB2 and actin perturbations leading to severe metabolic and bioenergetic effects during K97E mutation of lamin A C_FIG

cell biology↗

bioRxiv2025

Lead optimization against drug-resistant Leishmania donovani infection: Semi-synthetic derivatives of ethyl linoleate isolated from Indian edible mushroom Meripilus giganteus.

Visceral leishmaniasis, the most severe form, affects thousands of people annually. Current drugs in practice fail to provide an absolute cure. Globally, treatment relies on a single dose of liposomal amphotericin B, which requires a costly setup and cold chain to maintain. Natural molecules remain the vital sources of therapeutic ingredients in modern medicine. Meripilus giganteus is traditionally consumed by the people of the North-eastern regions of the Himalayas, India. In this study, we planned for the stepwise bioactivity-guided isolation of natural molecules from M. giganteus and to synthesize more potential therapeutic derivatives against the drug-resistant Leishmania infection. HPLC chromatogram of ethyl acetate extract obtained from M. giganteus revealed the presence of ethyl linoleate as the most active anti-leishmanial molecule. Several derivatives of ethyl linoleate were synthesized and evaluated against Leishmania promastigotes. Among them, a single epoxygenated variant of ethyl linoleate, ethyl (Z)-8-(3-(oct-2-en-1-yl) oxiran-2-yl) octanoate (EL3), showed promising anti-leishmanial activity against both drug-sensitive and drug-resistant Leishmania donovani. The lead derivative disrupts the biosynthesis of trypanothione from glutathione and spermidine, making the parasite vulnerable to the oxidative burst inside the host. Interestingly, the lead derivative was found to be more efficient against the drug-resistant L. donovani, in vivo. Besides this, it has almost no toxicity towards host cells. Considering the urgency for new drug development, we propose this novel semi-synthetic derivative as a potent therapeutic lead.

immunology↗

bioRxiv2025

Exercise serum promotes DNA damage repair and upregulates DNA repair gene PNKP in colon cancer cells

Exercise protects against colon cancer progression, but the underlying biological mechanisms remain incompletely understood. One proposed mechanism is the release of bioactive molecules into the interstitium and systemic circulation during exercise, which may act directly on precancerous or tumour cells to suppress DNA damage, inhibit proliferation, and preserve genomic stability. Here, we evaluated the effects of exercise-conditioned human serum on DNA damage kinetics and transcriptomic signatures in colon cancer cells. Blood samples were collected from 30 participants (age 50-78 years, body mass index [≥]25 kg/m2) before and immediately after a maximal incremental cycling test. LoVo cells were exposed to pre- or post-exercise serum, treated with 2 Gy irradiation, and assessed for {gamma}-H2AX foci over 24 hours. Compared to pre-exercise serum, post-exercise serum significantly reduced {gamma}-H2AX foci at 6 hours (p=0.024) and decreased the area under the curve (AUC, p=0.014), indicating accelerated DNA repair. Post-exercise serum also increased expression of the DNA repair protein PNKP in LoVo cells, both with and without irradiation (p=0.007 and p=0.029, respectively). Transcriptomic analysis revealed upregulation of mitochondrial energy metabolism and downregulation of cell cycle and proteasome-related pathways. These findings suggest that acute exercise elicits systemic responses that enhance DNA repair and shift colon cancer cells towards a less proliferative transcriptomic state under sublethal genotoxic stress, offering a potential mechanistic explanation for the protective effects of exercise against colorectal carcinogenesis.

cancer biology↗

bioRxiv2025

Genome-wide CRISPR screens identify PTGES3 as a novel AR modulator

The androgen receptor (AR) is a critical driver of prostate cancer (PCa). To study regulators of AR protein levels and oncogenic activity, we created the first live cell quantitative endogenous AR fluorescent reporters. Leveraging this novel AR reporter, we performed genome-scale CRISPRi flow cytometry sorting screens to systematically identify genes that modulate AR protein levels. We identified and validated known AR protein regulators including HOXB13 and GATA2 and also unexpected top hits including PTGES3, a poorly characterized gene in PCa. PTGES3 repression resulted in loss of AR protein, cell cycle arrest, and cell death in AR-driven PCa models. PTGES3 is not a commonly essential gene, and our data nominate it as a prime PCa therapeutic target. Clinically, analysis of PCa data demonstrate that PTGES3 expression is associated with AR-directed therapy resistance. Mechanistically, we show PTGES3 binds directly to AR, forms a protein complex with AR in the nucleus, regulates AR protein stability in vitro and in vivo and modulates AR function in the nucleus at AR target genes. PTGES3 represents a novel therapeutic target for overcoming known mechanisms of resistance to existing AR-directed therapies in PCa.

cancer biology↗

bioRxiv2025

Tubulin hyperacetylation drives HMGB1 nuclear exit via the ROS-PARP1 axis leading to rotenone-induced G2/M Arrest

Rotenone, a lipophilic pesticide, is strongly linked to dopaminergic neuronal loss in Parkinsons disease (PD), primarily through mitochondrial complex I inhibition. While rotenone induces G2/M arrest in dividing cells, the underlying molecular events remain unclear. We identify HMGB1 as a key player in this process. HMGB1, known for its roles in genomic integrity and inflammation, exits the nucleus during rotenone-induced G2/M arrest, whereas its nuclear retention protects against mitotic DNA damage. We further reveal that tubulin hyperacetylation precedes HMGB1 nuclear release. Notably, reducing tubulin acetyltransferase lowers mitochondrial ROS (mtROS), preventing HMGB1 nuclear exit and mitotic DNA damage. Additionally, inhibiting PARP1 hyperactivation with PJ34 blocks HMGB1 exit and prevents G2/M arrest. These findings suggest that ROS-induced DNA damage elevates PARP1 activity, promoting HMGB1 nuclear exit and interfering with DNA repair. This tubulin acetylation/mtROS/HMGB1 axis may underlie rotenone-induced neurotoxicity, contributing to dopaminergic neuron vulnerability in PD and offering potential neuroprotective targets.

cell biology↗

bioRxiv2025

p21-activated kinase regulates Rab3a vesicles to repair plasma membrane damage caused by Amyloid-β oligomers

The interaction of amyloid-{beta} (A{beta}) peptides with the plasma membrane (PM) is a potential trigger that initiates the formation of higher-order aggregates, membrane alterations/damage, and progressive neurotoxicity in Alzheimers disease (AD). In a previous study, we showed that oligomers of A{beta}1-42 (oA{beta}1-42) induced PM damage, resulting in PM repair cascade via lysosomal exocytosis coupled with endocytosis, and facilitation of tunneling nanotubes (TNTs)-like membrane protrusions to promote direct cell-to-cell transfer of aggregates. In this study, we demonstrated that PM damage induced by oligomers of the aggregation-prone peptide A{beta}1-42 significantly facilitates PM repair by enhancing phosphorylated p21-activated kinase 1 (pPAK1)-dependent endocytosis and Rab3a-dependent exocytosis in SH-SY5Y and SK-N-SH neuronal cells compared to control and oA{beta}1-40 treated cells. We studied the kinetics of pPAK1-dependent endocytosis and the fusion of EGFP-Rab3a vesicles near the PM using total internal reflection fluorescence (TIRF) microscopy. IPA-3, a selective non-ATP competitive inhibitor of PAK1, inhibits endocytosis of oA{beta} peptides and Rab3a-dependent PM repair. Further, shRNA-mediated knockdown of the Rab3a gene inhibits pPAK1 and disrupts PM repair. Repair of damaged PM is a vital protective mechanism for non-proliferative cells like neurons, as disruption in PM repair leads to gradual neuronal cell death. However, there was no explicit understanding of PM repair in response to A{beta} oligomers. This study revealed the interconnected action of Rab3a and pPAK1 in PM repair in response to oA{beta}-mediated damage, and its potential correlation in AD pathogenesis.

cell biology↗

bioRxiv2024

Building capacity among caregivers for managing children with Type 1 Diabetes Mellitus through a structured Interprofessional training program

BackgroundEffective management of type 1 diabetes mellitus (T1DM) in children necessitates not only medical care but also substantial involvement from caregivers, who often encounter psychological, financial, and emotional challenges. This study aimed to develop and evaluate a structured educational program for caregivers of children with T1DM, facilitated by an interprofessional team. MethodsThis mixed-method study, conducted from May 15 to August 15, 2023, comprised two parts. First, a structured educational module was developed based on a needs assessment from semi-structured interviews with 20 caregivers. The module was created in English, Hindi, and Khortha (the local language of Deoghar, Jharkhand, India) and validated by a panel of 10 experts (CVI = 0.83). It was delivered using audio-visual aids, live demonstrations, posters, and booklets. The programs effectiveness was evaluated through a pre-post-test questionnaire. ResultsThe interviews revealed themes such as misunderstandings of treatment plans, distress from frequent insulin administration, fear of glucose monitoring, financial burdens, and psychological stress. Data from 68 of the 75 caregivers who participated in the educational program were analyzed. The Wilcoxon signed-rank test indicated a significant improvement in caregiver knowledge and management practices (P < 0.001), with a large effect size (Cohens d = 3.2). ConclusionThis study demonstrates that structured educational interventions can significantly enhance caregivers knowledge and practices in managing T1DM. Multidisciplinary education and support are crucial for addressing the emotional and financial burdens caregivers face, ultimately improving the well-being of both caregivers and children.

scientific communication and education↗

bioRxiv2024

Structural and functional insights into nuclear role of Parkinson's Disease-associated α-Synuclein

-Synuclein (Syn) plays a critical role in the pathogenesis of Synucleinopathies. Although increased nuclear Syn localization induces neurotoxicity, its definitive physiological role remains elusive. Previous studies on nuclear Syn are limited to its interactions with individual histones and dsDNA, leaving a significant gap in understanding its interactions with assembled histone H2a-H2b dimer and (H3-H4)2 tetramer, as well as its role in chromatin regulation. Here, we demonstrated that Syn binds specifically to both H2a-H2b and (H3-H4)2 with high affinity. Truncation studies revealed that Syn(1-103) region interacts with (H3-H4)2, while the acidic (121-140) C-terminal end is crucial for H2a-H2b binding. Sequence analysis suggests Syn-dimer binding region contains a conserved DEF/YxP motif present in other dimer-binding histone chaperones. High-resolution structure of Syn- dimer binding region with H2a-H2b complex reveals that Syn adopts two binding modes (BM1 and BM2). In BM-1, Syn utilizes nucleosomal DNA-binding surface, while in BM-2, it engages with both DNA- and the H3-interaction interface. Additionally, dimer recognition by Syn overlaps with other dimer-binding histone chaperones, suggesting Syns potential role in the nucleosome assembly/disassembly process.

biophysics↗

bioRxiv2024

Cardiomyopathic mutations of lamin A perturb mutual interactions of lamin, nuclear membrane, and chromatin leading to LLPS

Lamins are nuclear intermediate filaments constituting the nuclear lamina which maintains the structural integrity of the nucleus and play a key role in the spatial organisation of the genome. Mutations in the lamin protein have been associated with diverse diseases collectively known as laminopathies. In this study, we focused on two lamin A mutants - E161K and K97E - associated with dilated cardiomyopathy (DCM). Through confocal imaging, we established that these mutations cause large scale disruption of the peripheral lamin and consequent heterochromatin organisation, along with the formation of lamin aggregates inside the nucleoplasm. Using coarse-grained polymer simulations, we uncovered the role of lamin-lamin, lamin-membrane and lamin-chromatin interactions in maintaining wild-type lamin and chromatin organisation and showed that disruptions in these interactions can reproduce the experimental observations in the lamin mutants. These predictions were verified using 3D-FISH experiments to quantify the reorganisation of chromosome territories in these mutants. Using advanced imaging methods, we characterised the dynamical properties of the lamin aggregates in the mutants to show for the first time a liquid-like state of the lamin aggregates through a liquid-liquid phase separation. The altered lamin and chromatin interactions in the mutants thus manifest as liquid-like aggregates in the nucleoplasm leading to disruption of the spatial organisation of the genome in these laminopathy-associated mutants.

biophysics↗

bioRxiv2024

Estrogen receptor alpha (ERα) driven trans-regulation of mitotic checkpoint complex (MCC) components affects the clinical outcome of breast cancer

Hormone receptors (HR), namely estrogen receptor (ER) and progesterone receptor (PR), are prevalent in most malignant tumors. Although previous literature provided clues for ER in regulating mitosis and ploidy status in breast cancer (BC) cells, reports on the mitotic regulators being the targets of HR are sparse. To delve deeper into ERs impact on mitotic execution, our study focuses on examining its transcriptional activity on the core mitotic checkpoint complex (MCC) components, which are involved in ploidy maintenance. The expression of the core MCC components (Bub3, Mad2, and BubR1) was analyzed by quantitative-PCR and immunohistochemistry in breast tumors and adjacent normal tissues from the cancer genome atlas-breast invasive carcinoma collection (TCGA BRCA) dataset and in a prospective cohort of Eastern Indian breast cancer affected individuals. The preliminary data from these cohorts indicated an influence of ER on the two MCC components, namely Mad2 and BubR1. Subsequently, luciferase reporter assays and chromatin immunoprecipitation were performed which revealed that ER promotes transcriptional activation of MAD2 and BUB1B through direct recruitment on these promoters, showing affects in mitotic outcome. Interestingly, the ectopic introduction of ER, in an HR-ve breast cancer line, MDA-MB-231, significantly reduced the percent aneuploidy. Moreover, we found that overexpression of MAD2 and BUB1B is associated with poorer survival in HR-positive (HR+ve) patients in both cohorts. Our findings provide insights into the specific role of ER-mediated transcriptional regulation of mitosis and ploidy outcome. Targeting the deregulated MCC components thus offers translational potential for the therapeutic management of breast cancer.

cancer biology↗

bioRxiv2024

Loss of FBXO31-mediated γH2AX foci formation impairs initiation of NHEJ and HR repair pathways, and sensitizes breast cancer to therapy

In response to genotoxic stress, cell initiates complex signalling cascades to combat genomic insults through simultaneous initiation of growth arrest and DNA damage repair process. {gamma}H2AX functions as a crucial initiator in DNA double strand damage repair process. Therefore, {gamma}H2AX foci formation onto the damage sites is essential to initiate the recruitment of repair proteins involved in NHEJ (Non-homologous DNA-end joining) or HR (Homologous recombination) repair process. However, molecular events associated with {gamma}H2AX foci formation onto the DNA damage sites are poorly understood. Here, we show that FBXO31, the first ubiquitin ligase, mediated Lys-63-linked ubiquitination of {gamma}H2AX is essential for its foci formation onto the DNA damage sites to initiate recruitment of proteins involved in NHEJ and HR-mediated DNA damage repair. Therefore, tumors with FBXO31 deficiency show enhanced growth suppression following chemotherapeutic drug treatment because of synthetic lethality, indicating that FBXO31 could be used as a marker for predicting the outcome of chemotherapy treatment.

cancer biology↗