Biology subjects

Bhattacharya, R.

Publications and source records attributed to Bhattacharya, R..

At least 19 recordsLinked to original sources

bioRxiv2026

Biomechanical effects of load-carrying in adolescent idiopathic scoliosis: a subject-specific musculoskeletal modelling study

Load carrying is a common activity during adolescence, yet its biomechanical consequences for the structurally asymmetric spine in adolescent idiopathic scoliosis (AIS) remain poorly understood. This study investigated how load magnitude, carrying height, and side of application influence spinal loading and paraspinal muscle forces in AIS. A subject-specific musculoskeletal model of a 16-year-old female with a 59{degrees} right-convex thoracic curve was used to simulate bilateral and unilateral load carrying at the hand, chest, and above-shoulder levels, with loads corresponding to 5%, 10%, and 15% of body weight. Intervertebral compressive and lateral forces and erector spinae (ES) and multifidus (MF) muscle forces were evaluated. Spinal loading increased progressively with load magnitude and carrying height. At 15% body weight, compressive forces at the curve apex increased from 511-566 N at hand level to 721-831 N above the shoulder. Unilateral carrying produced distinct side-dependent responses: convex-side carrying generated greater compressive forces, whereas concave-side carrying generated greater lateral forces, which were concentrated around the curve apex. Paraspinal muscles also exhibited muscle-specific responses. ES forces primarily reflected the imposed external asymmetry, with unilateral carrying eliciting predominantly contralateral recruitment, whereas MF maintained a characteristic convex-side dominance concentrated around the curve apex. These findings demonstrate that load carrying in AIS produces a coupled biomechanical response governed by both the external loading configuration and the pre-existing structural asymmetry of the spine, highlighting the importance of considering loading direction and muscular adaptation alongside load magnitude when evaluating everyday carrying activities in AIS.

bioengineering↗

bioRxiv2026

Influence of trunk posture on spinal loading and paraspinal muscle forces in adolescent idiopathic scoliosis: a subject-specific musculoskeletal modelling study

Adolescent idiopathic scoliosis (AIS) alters spinal geometry and may influence the biomechanical response of the spine during functional postures. However, posture-dependent changes in spinal loading and paraspinal muscle forces in AIS remain poorly understood. This study investigated the effects of trunk posture on intervertebral loading and paraspinal muscle forces using a subject-specific musculoskeletal model of an adolescent with AIS. The spinal deformity was reconstructed from biplanar radiographs and incorporated into a full-body musculoskeletal model. Flexion, extension, lateral bending, and axial rotation were simulated at three incremental magnitudes, with motion distributed across the thoracolumbar spine. Intervertebral compressive and lateral forces around the curve apex and forces in the erector spinae (ES) and multifidus (MF) muscles were evaluated. Trunk flexion produced the greatest compressive loading, reaching 337 N at the curve apex and 372 N two levels below the apex at 30{degrees} flexion. Lateral bending produced pronounced direction-dependent loading: concave-side bending increased lateral forces, whereas convex-side bending increased compressive forces. Axial rotation produced similar but smaller direction-dependent changes. Paraspinal muscle forces were consistently asymmetric, with concave-side dominance of the ES and convex-side dominance of the MF. Flexion and convex-sided movements generally produced greater muscle imbalance, while increasing posture magnitude amplified spinal loading and muscle forces. These findings demonstrate that trunk posture, movement direction, and magnitude substantially influence the biomechanical environment of the scoliotic spine and should be considered when evaluating spinal mechanics in AIS.

bioengineering↗

bioRxiv2026

Cancer Evolvability Determines Therapy Outcomes

Cancer progression following treatment failure is an evolutionary process in which therapy acts as a selection pressure driving Darwinian selection on heritable variation to favor resistant clones. This ability to generate variation, i.e., the cancers evolvability, is a key determinant of how rapidly tumors adapt to therapy. Here, we present an evolutionary game-theoretic model to evaluate how evolvability shapes resistance dynamics under two treatment modalities: targeted therapy and chemotherapy. We first compare cancer populations with fixed evolvabilities: low or high. Targeted therapy imposes a steep selection gradient, enabling rapid resistance evolution, while chemotherapy exerts a flatter gradient but drives tumors toward more extreme resistance strategies. We show that targeted therapy works better in low-evolvability cancers, whereas chemotherapy better controls high-evolvability populations. We then extend the model to incorporate facultative evolvability in which cancer cells dynamically adjust their evolvability in response to therapy-induced stress in which cells fine-tune the trade-off between acquiring higher resistance and limiting the costs of resistance and evolvability. The latter strategy sustains a higher tumor burden than fixed-evolvability populations. To address the challenges of facultative evolvability for therapy efficacy, we develop and simulate an evolutionary double bind using sequential cycles of chemotherapy and targeted therapy. With an appropriate sequence and timing, this strategy can drive cancer cells with facultative evolvability to extinction. Our results highlight the importance of evolvability in shaping treatment response and underscore the need to incorporate evolutionary principles into therapy design.

cancer biology↗

bioRxiv2026

Modeling VEGF and GLUT1 Expression as Coadapted Foraging Strategies in Cancer

Natural selection acting on cancer cells within their tumor microenvironment should favor cells with fast or efficient nutrient uptake strategies. Here, we develop and analyze a game-theoretic model focusing on the coadaptation between two foraging traits: vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT1). Studies show that VEGF and GLUT1 are often co-expressed and are associated with more aggressive tumor phenotypes and poor clinical prognosis. VEGF is a diffusible paracrine factor that recruits blood vessels towards neighborhoods of cancer cells (angiogenesis). GLUT1 is a cell-surface transporter that enables the uptake of nutrients, especially glucose. We model these strategies operating at different scales: VEGF influences resource availability at the neighborhood level, while GLUT1 determines resource uptake at the cellular level. For VEGF, we introduce a resource-sharing continuum. With no resource sharing, cells access resources in proportion to their VEGF contribution. With uniform sharing, cells have equal access to resources, regardless of their VEGF contribution. The former leads to a tragedy of the commons and overproduction of VEGF. The latter yields a public goods game with moderate VEGF expression matching a group optimum. GLUT1 expression mediates uptake of resources recruited by VEGF and is largely independent of the degree of resource sharing. Therapeutically, both VEGF and GLUT1 inhibitors are more effective in high resource-sharing neighborhoods and less so as resource sharing declines. Overall, inhibition of GLUT1-mediated uptake emerges as more effective. The model, perhaps the first to consider VEGF and GLUT1 as coadaptations, emphasizes the need to consider cancer cell traits jointly.

cancer biology↗

bioRxiv2026

DOT1L-AF10-mediated H3K79me3 promotes NF-kB p65-dependent inflammatory activation in endothelial cells

DOT1L-catalyzed H3K79 methylation is a hallmark of actively transcribed genes and has been extensively studied in developmental and disease contexts. While DOT1L inhibition has emerged as a promising therapeutic strategy in cancer, its role in pro-atherogenic endothelial inflammation remains unclear. To investigate this, we utilized an in vivo partial carotid artery ligation model and observed increased DOT1L expression and H3K79me3 level. Consistently, in vitro studies employing a 3D-printed human coronary artery model and TNF- stimulation corroborated these results, showing elevated DOT1L expression and H3K79me3 deposition, while levels of H3K79me and me2 remained unchanged. Further analyses identified key DOT1L-containing complex (DotCom) components, AF10 and AF9 (upregulated) and AF17 (downregulated), as contributors to the enhanced H3K79me3 landscape. CUT&RUN sequencing showed prominent H3K79me3 enrichment at the RELA (NF-{kappa}B p65) promoter, corresponding with increased NF-{kappa}B p65 expression and activation. Notably, inhibition/knockdown of the methyltransferase DOT1L or overexpression of the demethylase FBXL10 significantly reduced H3K79me3 levels, thereby suppressing NF-{kappa}B p65 expression and attenuating endothelial inflammation, independent of canonical NF-{kappa}B p65 activation. These findings establish DOT1L-mediated H3K79me3 as a crucial epigenetic regulator of endothelial inflammation, highlighting a potential therapeutic avenue for mitigating NF-{kappa}B p65-driven pro-atherogenic endothelial dysfunction.

cell biology↗

bioRxiv2026

Proteomic Remodeling of the Cochlea During Chronic Suppurative Otitis Media Reveals Immune-Driven Injury Pathways

Chronic suppurative otitis media (CSOM) is a persistent middle ear infection in which chronic inflammation drives irreversible sensorineural hearing loss (SNHL), yet the molecular mechanisms linking middle ear chronic infection to cochlear injury remain poorly defined. Using a murine model of CSOM induced by Pseudomonas aeruginosa (PA) persisters, a quantitative proteomic profiling of cochlear tissue was performed at seven days post-infection. Mass spectrometry revealed over 250 proteins that were significantly altered, indicating broad immune activation, oxidative stress, and disruption of ion homeostasis. Among the top candidates, HSPA5, MPO, and ATP2A2 were strongly associated with inflammatory stress and cellular injury pathways. These findings identify immunometabolic remodeling and macrophage-driven inflammation as central mechanisms linking chronic middle ear infection to cochlear injury.

immunology↗

bioRxiv2025

Cystathionine Beta-Synthase Promotes Anoikis Resistance and Transcoelomic Metastasis in Ovarian Cancer via the SP1-ITGB1 axis

Anoikis resistance is crucial for ovarian cancer (OvCa) transcoelomic metastasis, during which exfoliated OvCa cells survive as spheroids before invading the omentum. Here, we demonstrate that cystathionine {beta}-synthase (CBS), an H2S-producing transsulfuration pathway enzyme, is a key determinant of OvCa spheroidal viability and metastatic potential. Analysis of publicly available patient datasets, as well as an in-house tissue microarray, revealed that high CBS expression positively correlates with both poor progression-free survival and clinically observed peritoneal/omental metastasis. Integrated functional and proteomic analyses indicated that CBS silencing induces apoptosis in 2D monolayers. Consistent with this, CBS silencing in spheroids caused apoptosis and disrupted spheroid architecture. Mechanistically, this phenotype was associated with downregulation of oncogenic stemness and epithelial-mesenchymal transition. Further, through proteomic and bioinformatic analyses, we identified ITGB1 to be the hub protein in OvCa spheroidogenesis. Interestingly, knockdown of CBS led to abrogation of the ITGB1-mediated downstream pathway. Moreover, by proteomic and network analyses, we identified SP1 as a key transcriptional regulator of CBS-induced pro-spheroidal transcriptional programs of stemness and invasiveness. Stabilization of SP1 through persulfidation by H2S supplementation restored spheroidal viability and underlying protein signaling. Further, our results reveal that loss of CBS, through ITGB1 repression, disrupts spheroid architecture, leading to reduced metastatic docking on the murine omental surface in vivo. Collectively, these findings identify CBS as a central regulator of anoikis resistance and OvCa transcoelomic metastasis, highlighting the therapeutic potential of targeting CBS-dependent SP1-ITGB1 regulation to control metastatic spread.

cancer biology↗

bioRxiv2025

Splicing factor proline- and glutamine-rich (SFPQ) protein causes transcriptional repression of SNAIL to counteract TGF-β signaling

TGF-{beta} is known to regulate several embryonic and adult signaling pathways. Moreover, this signaling pathway regulates several cellular functions including differentiation, cell division, angiogenesis, hematopoiesis, and cell migration. However, studies suggest that an uncontrolled activation of TGF-{beta} signaling may contribute to many human diseases. Therefore, counter-regulatory mechanism(s) to restrain abrupt TGF-{beta} activation during cellular homeostasis is necessary to maintain an adequate balance of TGF-{beta} downstream signaling. TGF-{beta} through Smad complex activation causes transcriptional regulation of many transcription factors including Snail which act as an immediate-early response gene in TGF-{beta} signaling. Herein, for the first time, we report that Splicing factor proline- and glutamine-rich (SFPQ), an RNA binding paraspeckles-associated protein works as a transcriptional repressor of Snail. We first confirmed a significant reduction in the expression level of SFPQ in the kidney glomeruli of rats that underwent subtotal nephrectomy. Endothelial cells (EC) treated with TGF-{beta} exhibited loss of SFPQ protein level without altering its transcript level. Inhibition of proteasomal or autophagosome-lysosome pathway revealed ubiquitination-dependent proteasomal degradation of SFPQ upon TGF-{beta} challenge. Prior to degradation, TGF-{beta} treatment resulted in the cytosolic export of SFPQ thereby diminishing nuclear SFPQ level. Knockdown of SFPQ augmented TGF-{beta}-dependent increase in Snail level while overexpression of SFPQ reversed TGF-{beta} induced Snail expression. Although SFPQ exhibited association with many transcription factors including Smad2/3, Smad4, and N1-ICD which regulate Snail gene expression, TGF-{beta} failed to alter the association of SFPQ with these transcription factors. Instead, through ChIP-qPCR analysis, we confirmed the enrichment of SFPQ in E-box promoter region and coding region proximal to TSS of the Snail gene. This study is the first to report SFPQ as a transcriptional repressor of Snail thereby regulating TGF-{beta} signaling during cellular homeostasis.

biochemistry↗

bioRxiv2025

Live-Exudation Assisted Phytobiome Cultromics System (LEAP-CS): A High-Throughput Cultromics System for Studying Plant-Microbiome Interactions through Non-Contact Metabolic Exchange.

This study introduces an innovative methodology for co-cultivating plants and microbes, employing a membrane-based structure to facilitate their physical separation. The Live-Exudation Assisted Phytobiome Cultromics System (LEAP-CS) has the capability to investigate the complex interaction of plant and soil microbiome under in vitro conditions, offering potential benefits. Subsequent validation and testing can be performed through pot, greenhouse, and field trials. The system can efficiently function as a high-throughput screening tool for assessing plant-microbiome interactions and their associated metabolic signatures. Our phytobiome culturing technique harnesses root exudation from live plants, capitalizing on the membranes selective separation to prevent direct physical interaction between plant and microbiome components. Consequently, the interaction is solely through chemical-mediated signalling. By employing this method, we can intricately dissect complex plant-microbiome interactions while faithfully maintaining and emulating the contact independent inherent associations prevalent within these phytobiomes. In conclusion, this user-friendly and reproducible in-vitro model holds immense potential for shedding light on the intricate community and metabolic exchange dynamics of plant-microbiome interactions, thus significantly advancing our understanding in this area.

plant biology↗

bioRxiv2025

A cell-free bacterial signal orchestrates trans-kingdom fitness tradeoff to enhance sulfur deficiency tolerance in plants

Plant-associated microorganisms interact with each other and host plants via intricate chemical signals, offering multiple benefits, including plant nutrition. We report such a mechanism through which the rhizosphere microbiome improves plant growth under sulfur (S) deficiency. Disruption of plant S homeostasis resulted in a coordinated shift in composition and S-metabolism of the rhizosphere microbiome. Using this insight, we developed an 18-membered synthetic rhizosphere bacterial community (SynCom) that rescued growth of Arabidopsis and a leafy Brassicaceae vegetable under S-deficiency. This beneficial trait is taxonomically widespread among SynCom members, with bacterial pairs predominantly providing synergistic benefits to host plants. Notably, stronger competitive interactions among SynCom members conferred greater fitness benefits to the host, suggesting a trans-kingdom fitness tradeoff. Finally, guided chemical screening, deletion knockout mutant, and targeted metabolomics identified and validated microbially released glutathione (GSH) as the necessary bioactive signal that orchestrates plant-microbe (trans-kingdom) fitness tradeoff and improves plant growth under sulfur limitation. HighlightsO_LIAlteration in plant sulfur (S) homeostasis leads to coordinated shifts in the composition and S-metabolism of the rhizosphere microbiome. C_LIO_LITaxonomically divergent bacterial members within the rhizosphere microbiome improve plant growth under S-deficiency. C_LIO_LIStronger competitive interactions within rhizosphere bacterial members provide greater fitness benefit to the host plant under S-deficiency, suggesting a trans-kingdom fitness tradeoff. C_LIO_LIMicrobially released glutathione (GSH) is a necessary bioactive signal that improves plant growth under sulfur limitation and orchestrates plant-microbe (trans-kingdom) fitness tradeoff. C_LI

microbiology↗

bioRxiv2025

A Novel TRPC6 Mutation Causes Autosomal Dominant FSGS

FSGS is the most common primary glomerular lesion that causes kidney failure in the US. FSGS results from injury or loss of glomerular visceral epithelial cells (i.e. podocytes). Pathogenic variants in TRPC6 can cause FSGS through dysregulated calcium conductance and associated disturbances in podocyte physiology. Here, we describe a 5-generation kindred with FSGS caused by a novel compound C-terminal TRPC6 mutation. Analysis of patient-specific iPSC-derived podocytes and glomerular capillary wall-on-a-chip systems revealed that the compound variants disrupt TRPC6 protein structure, intermolecular interactions, and membrane localization. Combined therapy with Sildenafil and Losartan ameliorated these disturbances compared to conventional immunosuppressive treatment.

genetics↗

bioRxiv2024

Enhancing efficacy of the MEK inhibitor trametinib with paclitaxel in KRAS-mutated colorectal cancer

BackgroundKRAS is frequently mutated in the tumors of patients with metastatic colorectal cancer (mCRC) and thus represents a valid target for therapy. However, the strategies of targeting KRAS directly and targeting the downstream effector mitogen-activated protein kinase kinase (MEK) via monotherapies have shown limited efficacy. Thus, there is a strong need for novel, effective combination therapies to improve MEK-inhibitor efficacy in patients with KRAS-mutated mCRC. ObjectiveOur objective was to identify novel drug combinations that enhance MEK-inhibitor efficacy in patients with KRAS-mutated mCRC. DesignIn this study, we performed unbiased high-throughput screening (HTS) to identify drugs that enhance the efficacy of MEK inhibitors in vitro, and we validated the efficacy of the drugs in vivo. MethodsHTS was performed using 3-dimensional CRC spheroids. Trametinib, the anchor drug, was probed with 2 clinically ready libraries of 252 drugs to identify effective drug combinations. The effects of the drug combinations on CRC cell proliferation and apoptosis were further validated using cell growth assays, flow cytometry, and biochemical assays. Proteomic and immunostaining studies were performed to determine the effects of the drugs on molecular signaling and cell division. The effects of the drug combinations were examined in vivo using CRC patient-derived xenografts. ResultsHTS identified paclitaxel as being synergistic with trametinib. In vitro validation showed that, compared with monotherapies, this drug combination demonstrated strong inhibition of cell growth, reduced colony formation, and enhanced apoptosis in multiple KRAS-mutated CRC cell lines. Mechanistically, combining trametinib with paclitaxel led to alterations in signaling mediators that block cell cycle progression and increases in microtubule stability that resulted in significantly higher defects in the mitosis. Finally, the combination of trametinib with paclitaxel exhibited significant inhibition of tumor growth in several KRAS-mutant patient-derived xenograft mouse models. ConclusionOur data provide evidence supporting clinical trials of trametinib with paclitaxel as a novel therapeutic option for patients with KRAS-mutated, metastatic CRC.

cancer biology↗

bioRxiv2024

Hippo-TOR Signaling Crosstalks Underpin Microtubule Acetylation-linked Carcinogenesis in Drosophila Squamous Epithelia

Protooncogenes, which can also function as tumor suppressors, are termed double agents. The Hippo pathway transcriptional coactivators YAP/TAZ and their Drosophila homolog Yorkie (Yki) are known oncogenes. Paradoxically, in squamous epithelia, they are constitutively active yet non-oncogenic and can even function as tumor suppressors. We previously found that loss of Yki in the Drosophila male accessory gland (MAG) squamous epithelium promotes squamous cell carcinoma (SCC) by upregulating TOR signaling, but the mechanism was unknown. Here, we show that this tumorigenesis stems from TOR-mediated hyperacetylation of -tubulin. This pathway is tissue-specific, as the ovarian follicular epithelium is resistant to Yki loss. A comparison of MAG and follicular epithelia single-cell transcriptomic data revealed their distinct Yki-TOR signaling states, suggesting lineage-specific mechanoconstraints in these two lineages. Our results identify suppression of TOR-driven -tubulin acetylation as the mechanistic basis for Ykis role as a double-agent in select squamous epithelia.

developmental biology↗

bioRxiv2024

Engineered human iPS cell models reveal altered podocytogenesis and glomerular capillary wall in CHD-associated SMAD2 mutations

Early developmental programming involves extensive cell lineage diversification through shared molecular signaling networks. Clinical observations of congenital heart disease (CHD) patients carrying SMAD2 genetic variants revealed correlations with multi-organ impairments at the developmental and functional levels. For example, many CHD patients present with glomerulosclerosis, periglomerular fibrosis, and albuminuria. Still, it remains largely unknown whether SMAD2 variants associated with CHD can directly alter kidney cell fate, tissue patterning, and organ-level function. To address this question, we engineered human iPS cells (iPSCs) and organ-on-a-chip systems to uncover the role of pathogenic SMAD2 variants in kidney podocytogenesis. Our results show that abrogation of SMAD2 causes altered patterning of the mesoderm and intermediate mesoderm (IM) cell lineages, which give rise to nearly all kidney cell types. Upon further differentiation of IM cells, the mutant podocytes failed to develop arborizations and interdigitations. A reconstituted glomerulus-on-a-chip platform exhibited significant proteinuria as clinically observed in glomerulopathies. This study implicates CHD-associated SMAD2 mutations in kidney tissue malformation and provides opportunities for therapeutic discovery in the future.

bioengineering↗

bioRxiv2024

S-nitrosylation of EZH2 at C329 and C700 interplay with PRC2 complex assembly, methyltransferase activity, and EZH2 stability to regulate endothelial functions

Nitric oxide (NO), a versatile bio-active molecule modulates cellular function through diverse mechanisms including S-nitrosylation of proteins. However, the role of this post-translational modification in regulating epigenetic pathways was very limitedly explored. Herein, we report that NO causes S-nitrosylation of selected cysteine residues of EZH2 in endothelial cells (EC) resulting in SUZ12 dissociation from EZH2 bound PRC2 complex, reduced methyltransferase activity, and diminished nuclear localization eventually hampering its stability. We detected a significant reduction in H3K27me3 upon exposure to NO as contributed by the early dissociation of SUZ12 from the PRC2 complex. Longer exposure to NO donors caused EZH2 cytosolic translocation, its ubiquitination, and further degradation primarily through the autophagosome-lysosome pathway. Through in silico S-nitrosylation prediction analysis and site-directed mutagenesis assay, we identified three cysteine residues namely at locations 260, 329, and 700 in EZH2 and further determined that S-nitrosylation of cysteine 329 induced EZH2 instability while S-nitrosylation of cysteine 700 abrogated EZH2s catalytic activity. A double mutant of EZH2 containing mutations at Cysteine 329 and 700 remained undeterred to NO exposure. Furthermore, reinforcing H3K27me3 in NO exposed EC through the use of an inhibitor of H3K27me3 demethylase, we confirmed a significant contribution of the EZH2-H3K27me3 axis in defining NO-mediated regulation of endothelial gene expression and migration. Molecular dynamics simulation study revealed SUZ12s inability in efficiently binding to the SAL domain of EZH2 upon S-nitrosylation of C329 and C700. Taken together, our study for the first-time reports that S-nitrosylation dependent regulation of EZH2 and its associated PRC2 complex influences endothelial homeostasis.

cell biology↗

bioRxiv2024

Imipridones inhibit tumor growth and improve survival in an orthotopic liver metastasis mouse model of human uveal melanoma

PurposeUveal melanoma (UM) is a highly aggressive disease with very few treatment options. We previously demonstrated that mUM is characterized by high oxidative phosphorylation (OXPHOS). Here we tested the anti-tumor, signaling and metabolic effects of imipridones, CLPP activators which reduce OXPHOS indirectly and have demonstrated safety in patients. Experimental DesignWe assessed CLPP expression in UM patient samples. We tested the effects of imipridones (ONC201, ONC212) on the growth, survival, signaling and metabolism of UM cell lines in vitro, and for therapeutic effects in vivo in UM liver metastasis models. ResultsCLPP expression was confirmed in primary and mUM patient samples. ONC201/212 treatment of UM cell lines in vitro decreased OXPHOS effectors, inhibited cell growth and migration, and induced apoptosis. ONC212 increased metabolic stress and apoptotic pathways, inhibited amino acid metabolism, and induced cell death-related lipids. ONC212 also decreased tumor burden and increased survival in vivo in two UM liver metastasis models. ConclusionImipridones are a promising strategy for further testing and development in mUM.

cancer biology↗

bioRxiv2023

Hippo effector, Yorkie, is a Tumor Suppressor in Select Drosophila Squamous Epithelia

Out-of-context gain of nuclear signaling of mammalian YAP/TAZ or Drosophila Yki--the transcription cofactors of the highly conserved Hippo tumor suppressor pathway--is oncogenic. By contrast, in mechanically strained squamous epithelia (SE), YAP/TAZ/Yki displays developmentally programmed nuclear translocation, leading to its constitutive signaling. How organ homeostasis is maintained in constitutively YAP/TAZ/Yki signaling SE is unclear. Here, we show that Yki signaling negatively regulates the cell growth-promoting PI3K/Akt/TOR signaling in the SEs in the tubular organs of Drosophila. Thus, in the adult male accessory gland (MAG), knockdown of Yki signaling upregulates PI3K/Akt/TOR signaling in its SE-lined lumen, inducing cell hypertrophy, culminating in squamous cell carcinoma (SCC). MAG SCC-bearing adults display early mortality due to cancer cachexia, which is reversed by simultaneous knockdown of a secreted factor, ImpL2--a Drosophila homolog of mammalian IGFBP7--without arresting tumor progression per se. By contrast, a knockdown of PI3K/Akt/TOR signaling suppresses MAG SCC, reversing adult mortality. In the SE-lined lumens in other tubular organs, like the dorsal trunk of larval tracheal airways or adult Malpighian tubules, too, knockdown of Yki signaling triggers PI3K/Akt/TOR-induced cell hypertrophy and loss of epithelial homeostasis, culminating in their tumor-like transformation. Thus, Yki signaling turns tumor suppressive in the SEs of tubular organs in Drosophila by arresting runaway PI3K/Akt/TOR signaling.

cancer biology↗

bioRxiv2023

Regulation of shelterin proteins TERF2IP and TRF2 by H3K4me3-p65 axis drives hyperglycemia dependent endothelial senescence

BackgroundEndothelial senescence has been linked to several cardiovascular diseases. Dysregulation of proteins of the shelterin complex including TRF2 and TERF2IP causes senescence as it hampers DNA repair and cell proliferation. However, whether exposure to hyperglycemia interplays with proteins of the shelterin complex thus further dictates the senescent phenotype of endothelial cells (EC) remain to be explored. Approach and ResultsIn this study, we observed elevated levels of p21 and p53 in endothelial cells upon exposure to intermittent hyperglycemia. We also noted hyperglycemia exposure increased the levels of TERF2IP and TRF2, part of the shelterin complex. No change in the level of TRF1 and TPP1 were detected. Furthermore, a robust induction was detected in p65 level upon intermittent hyperglycemia challenge. ChIP-qPCR analysis revealed enhanced H3K4me3 enrichment in the promoter regions of p65, TERF2IP and TRF2. Inhibition of catalysis of H3K4me3 either by pharmacological inhibitor or siRNA-mediated knockdown of MLL2 attenuated increase in p65, TERF2IP and TRF2 levels including reversal of senescence markers p53 and p21. Interestingly, pharmacological inhibition of NF-{kappa}B signaling also diminished abrupt increase in TERF2IP and TRF2 levels thus further reversed intermittent hyperglycemia-induced p53 and p21 levels. More importantly, co-immunoprecipitation and co-localization analysis revealed an interaction between nuclear p65 and MLL2 in EC stimulated with hyperglycemia. Further knockdown of either TERF2IP or TRF2 impaired intermittent hyperglycemia-induced p53 and p21 expression and associated endothelial senescence. ConclusionOverall, the present study describes an interplay of epigenetics in defining NF-{kappa}B signaling and shelterin proteins expression which further govern the biochemical and functional state of endothelial senescence in hyperglycemic milieu.

biochemistry↗