👤 Priyanka Sengupta

Alzheimer's disease (AD) involves progressive neurodegeneration, with abnormal receptor signaling and disrupted cell-cycle activity leading to neuronal loss. Here, we identify a previously unknown mechanism linking β-amyloid (Aβ) exposure to the nuclear translocation of the Insulin-like Growth Factor 1 Receptor (IGF1R) in differentiated SH-SY5Y neuronal cells. The differentiated cholinergic model induced by retinoic acid and BDNF expresses acetylcholinesterase (AChE) and indicates that under amyloidogenic stress, IGF1R may transition from homeostatic membrane and vesicular signaling to a nuclear-centric function. We show that prolonged Aβ treatment causes phosphorylation-dependent nuclear import of IGF1R, confirmed by confocal imaging and biochemical fractionation. IGF1R is conventionally located in the membrane and vesicular membranes; however, under amyloidogenic stress, we show here that it is imported to the nucleus and exerts transcriptional control. The buildup of nuclear IGF1R coincided with increased Cyclin D1 levels and redistribution of neurons into S and G₂ phases, indicating abnormal cell-cycle re-entry. Chromatin immunoprecipitation demonstrated increased IGF1R binding at the CCND1 and JUN promoters after Aβ exposure, suggesting a direct role in gene transcription. Pharmacological blockade of IGF1R phosphorylation by PPP or SUMOylation by Ginkgolic acid significantly reduced Cyclin D1 elevation, implying that both post-translational modifications are involved in receptor nuclear trafficking. Co-immunoprecipitation and confocal imaging identified Nucleophosmin (NPM1) as a putative IGF1R interacting partner, potentially contributing to its nuclear transport and stabilizing receptor-chromatin complexes. These results establish IGF1R as a signaling-transcription connector linking extracellular amyloid stress to nuclear gene regulation, providing a mechanistic explanation for faulty neuronal cell-cycle re-entry in AD. We suggest that abnormal IGF1R-NPM1 interactions contribute to receptor mislocalization and cell-cycle failure, highlighting new targets for therapeutic intervention aimed at receptor trafficking and neuroprotection in Alzheimer's disease. Show less

Epithelial-to-mesenchymal transition (EMT) is essential for normal development and cancer progression. However, how nuclear Lamins regulate EMT is unclear. Here, we show that Lamin A/C modulates the epithelial-mesenchymal (E-M) plasticity of cells through its interaction with the chromatin organizer, EZH2. The overexpression of Lamin A reinforces an epithelial identity, while its depletion promotes a mesenchymal phenotype. This positions Lamin A/C as a crucial modulator of Epithelial-Mesenchymal plasticity. Furthermore, CDK1-mediated phosphorylation of Lamin A/C (Ser22) and EZH2 (Thr345) disrupts Lamin A/C-EZH2 interaction, destabilizing EZH2, with a concomitant decrease in the occupancy of the heterochromatin mark (H3K27me3) on the SNAI1, TWIST1, and ZEB1 promoters, thereby facilitating a transition towards mesenchymal transcriptional programs. Conversely, phosphodeficient Lamin A/C (S22A) and EZH2 (T345A) mutants restore epithelial identity, highlighting a regulatory role of the Lamin A/C-EZH2 axis in maintaining epithelial homeostasis. In vivo, xenograft assays in NOD-SCID mice reveal that while phosphorylated Lamin A/C or EZH2 promote tumor growth and metastasis, phospho-deficient mutants markedly suppress it. Lamin A/C-EZH2 interaction regulates the expression of E-M-associated transcription factors, highlighting the role of this interaction in modulating transcriptional plasticity, thereby serving as a potential therapeutic target for regulating metastasis in breast cancers. Show less

Dendritic cell (DC) dysfunction is known to exacerbate intestinal pathologies, but the mechanisms compromising DC-mediated immune regulation in this context remain unclear. Here, we show that intestinal dendritic cells from a mouse model of experimental colitis exhibit significant levels of noncanonical NF-κB signaling, which activates the RelB:p52 heterodimer. Genetic inactivation of this pathway in DCs alleviates intestinal pathologies in mice suffering from colitis. Deficiency of RelB:p52 diminishes transcription of Axin1, a critical component of the β-catenin destruction complex, reinforcing β-catenin-dependent expression of Raldh2, which imparts tolerogenic DC attributes by promoting retinoic acid synthesis. DC-specific impairment of noncanonical NF-κB signaling leads to increased colonic numbers of Tregs and IgA+ B cells, which promote luminal IgA production and foster eubiosis. Experimentally introduced β-catenin haploinsufficiency in DCs with deficient noncanonical NF-κB signaling moderates Raldh2 activity, reinstating colitogenic sensitivity in mice. Finally, inflammatory bowel-disease patients also display a deleterious noncanonical NF-κB signaling signature in intestinal DCs. In sum, we establish how noncanonical NF-κB signaling in dendritic cells can subvert retinoic acid synthesis to fuel intestinal inflammation. Show less

The endothelium of blood vessels is a vital organ that reacts differently to subtle changes in stiffness and mechanical forces exerted on its environment (extracellular matrix (ECM)). Upon alteration of these biomechanical cues, endothelial cells initiate signaling pathways that govern vascular remodeling. The emerging organs-on-chip technologies allow the mimicking of complex microvasculature networks, identifying the combined or singular effects of these biomechanical or biochemical stimuli. Here, we present a microvasculature-on-chip model to investigate the singular effect of ECM stiffness and mechanical cyclic stretch on vascular development. Following two different approaches for vascular growth, the effect of ECM stiffness on sprouting angiogenesis and the effect of cyclic stretch on endothelial vasculogenesis are studied. Our results indicate that ECM hydrogel stiffness controls the size of the patterned vasculature and the density of sprouting angiogenesis. RNA sequencing shows that the cellular response to stretching is characterized by the upregulation of certain genes such as ANGPTL4+5, PDE1A, and PLEC. Show less

Immune-checkpoint blockade has revolutionized cancer treatment, but some cancers, such as acute myeloid leukemia (AML), do not respond or develop resistance. A potential mode of resistance is immune evasion of T cell immunity involving aberrant major histocompatibility complex class I (MHC-I) antigen presentation (AP). To map such mechanisms of resistance, we identified key MHC-I regulators using specific peptide-MHC-I-guided CRISPR-Cas9 screens in AML. The top-ranked negative regulators were surface protein sushi domain containing 6 (SUSD6), transmembrane protein 127 (TMEM127), and the E3 ubiquitin ligase WWP2. SUSD6 is abundantly expressed in AML and multiple solid cancers, and its ablation enhanced MHC-I AP and reduced tumor growth in a CD8 Show less

Deregulated epithelial-to-mesenchymal transition constitutes one of the major aspects of cancer progression. In this study, to identify key molecular principles of EMT pathway in prostate carcinogenesis, an elaborate gene expression profiling was conducted by qRT-PCR and Western blot analyses. A preponderance of mesenchymal trait was observed in the pathological samples of prostate cancer. To simulate an appropriate in vitro model, PC3 cell line was subjected to hypoxic stress, which resulted in elevated expression of vimentin along with EMT-mediating transcription factors Zeb1 and Slug. To conciliate this mesenchymal behavior of PC3 cells, hsa-miR-200c was deliberately overexpressed which led to a marked reduction of cell motility and expression of vimentin, N-cadherin, Zeb1 and Slug with concurrent increase in level of β-catenin. hsa-miR-200c was demonstrated to appease hypoxia-aggravated changes in cellular morphology by coordinated repression of vimentin, Zeb1 and Slug. Mode of action for hsa-miR-200c was mediated through transcriptional repression of Zeb1 and Slug interacting with E-box sequences in the vimentin promoter as documented by promoter assay. This ability of hsa-miR-200c to reclaim epithelial traits leads to the anticipation that molecular reprogramming of Zeb1-Slug/vimentin axis may relieve aggressiveness of prostate cancer. Show less

To interrogate enriched prostate cancer cells and autologous non-malignant prostate epithelial cells from men with localized prostate cancer, in order to identify early oncogenic pathways. We collected malignant and matched non-malignant prostatectomy samples from men with adenocarcinoma involving two or more contiguous areas in only one lobe of the prostate. Tissue samples from both lobes were subjected to digestion and single-cell suspensions were prepared. Epithelial cell adhesion molecule-positive cells from cancerous and contralateral non-malignant (control) samples were isolated using magnetic beads, ensuring uniform populations were obtained for each donor. Unbiased RNA sequencing analysis was used to measure gene expression and for detection of transcribed mutations or splice variants that were over- or under-represented in malignant prostate epithelial cells relative to autologous control prostate epithelial cells. From five patient samples we identified 17 genes that were altered in prostate cancer epithelial cells, with 82% of genes being downregulated. Three genes, TDRD1, ANGTL4, and CLDN3, were consistently upregulated in malignant tissue. Malignant cells from three of the five patients showed evidence of upregulated ERG signalling, however, only one of these contained a TMPRSS2-ERG rearrangement. We did not identify mutations, gene rearrangements, or splice variants that were consistent amongst the patients. Events occurring early in prostate cancer oncogenesis in these samples were characterized by a predominant downregulation of gene expression along with upregulation of TDRD1, ANGTL4 and CLDN3. No consistent mutations or splice variants were observed, but upregulation of ERG signalling was seen both in the presence and absence of the classic TMPRSS2-ERG rearrangement. Show less

Gene environment interactions leading to epigenetic alterations play pivotal role in the pathogenesis of Coronary Artery Disease (CAD). Altered DNA methylation is one such epigenetic factor that could lead to altered disease etiology. In this study, we comprehensively identified methylation sites in several genes that have been previously associated with young CAD patients. The study population consisted of 42 healthy controls and 33 young CAD patients (age group <50 years). We performed targeted bisulfite sequencing of promoter as well as gene body regions of several genes in various pathways like cholesterol synthesis and metabolism, endothelial dysfunction, apoptosis, which are implicated in the development of CAD. We observed that the genes like GALNT2, HMGCR were hypermethylated in the promoter whereas LDLR gene promoter was hypomethylated indicating that intracellular LDL uptake was higher in CAD patients. Although APOA1 did not show significant change in methylation but APOC3 and APOA5 showed variation in methylation in promoter and exonic regions. Glucokinase (GCK) and endothelial nitric oxide synthase 3 (NOS3) were hyper methylated in the promoter. Genes involved in apoptosis (BAX/BCL2/AKT2) and inflammation (PHACTR1/LCK) also showed differential methylation between controls and CAD patients. A combined analysis of the methylated CpG sites using machine learning tool revealed 14 CpGs in 11 genes that could discriminate CAD cases from controls with over 93% accuracy. This study is unique because it highlights important gene methylation alterations which might predict the risk of young CAD in Indian population. Large scale studies in different populations would be important for validating our findings and understanding the epigenetic events associated with CAD. Show less

Coronary artery disease (CAD) is one of the largest causes of death worldwide yet the traditional risk factors, although useful in identifying people at high risk, lack the desired predictive accuracy. Techniques like quantitative plasma proteomics holds immense potential to identify newer markers and this study (conducted in three phases) was aimed to identify differentially expressed proteins in stable CAD patients. In the first (discovery) phase, plasma from CAD cases (angiographically proven) and controls were subjected to iTRAQ based proteomic analysis. Proteins found to be differentially expressed were then validated in the second and third (verification and validation) phases in larger number of (n = 546) samples. After multivariate logistic regression adjusting for confounding factors (age, diet, etc.), four proteins involved in the reverse cholesterol pathway (Apo A1, ApoA4, Apo C1 and albumin) along with diabetes and hypertension were found to be significantly associated with CAD and could account for approximately 88% of the cases as revealed by ROC analysis. The maximum odds ratio was found to be 6.70 for albumin (p < 0.0001), followed by Apo AI (5.07, p < 0.0001), Apo CI (4.03, p = 0.001), and Apo AIV (2.63, p = 0.003). Down-regulation of apolipoproteins and albumin implicates the impairment of reverse cholesterol pathway in CAD. Show less