Biology subjects

Poddar, N.

Publications and source records attributed to Poddar, N..

4 recordsLinked to original sources

bioRxiv2026

A CRISPR-Based Humanized Model Reveals Cooperative Role of STAG2 Loss in Familial GATA2-Deficient MDS Progression

Myelodysplastic syndrome (MDS) is a heterogeneous myeloid malignancy driven by hematopoietic stem cell dysfunction, leading to ineffective hematopoiesis and cytopenias. Familial GATA2 deficiency is the most common cause of Myelodysplastic syndrome in adolescents, with progression often accelerated by co-occurring mutations, notably STAG2 loss-of-function. Using CRISPR/Cas9-mediated genome engineering in primary human fetal liver-derived hematopoietic stem cells and xenotransplantation in mice, we modeled GATA2-deficient Myelodysplastic syndrome with acquired STAG2 loss to investigate disease initiation and progression. While GATA2 deficiency alone had minimal short-term impact in our model, combined GATA2 and STAG2 loss increased hematopoietic stem cell maintenance and self-renewal, induced a myeloid-lineage bias, and expanded primitive progenitors. Single-cell transcriptional profiling revealed upregulation of stemness genes and inflammatory pathways. This humanized model faithfully recapitulates high-risk GATA2-deficient Myelodysplastic syndrome, providing mechanistic insight into how cooperative mutations drive stem cell expansion, inflammatory signaling, and myeloid skewing. Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/702879v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@1972beforg.highwire.dtl.DTLVardef@1c57886org.highwire.dtl.DTLVardef@16bd582org.highwire.dtl.DTLVardef@8e728a_HPS_FORMAT_FIGEXP M_FIG C_FIG Key PointsO_LIHumanized model of familial GATA2-deficiency requires the loss of STAG2 for progression to an MDS disease phenotype C_LIO_LIGATA2-ko+STAG2-ko increase HSC self-renewal, induce a myeloid-lineage bias, and trigger an inflammatory transcriptional program C_LI

cancer biology↗

bioRxiv2025

Ontogeny Dictates Oncogenic Potential, Lineage Hierarchy, and Therapy Response in Pediatric Leukemia

Accumulating evidence links pediatric cancers to prenatal transformation events, yet the influence of the developmental stage on oncogenesis remains elusive. We investigated how hematopoietic stem cell developmental stages affect leukemic transformation, disease progression, and therapy response using a novel, humanized model of NUP98::NSD1-driven pediatric acute myeloid leukemia, that is particularly aggressive with WT1 co-mutations. Fetal-derived hematopoietic stem cells readily transform into leukemia, and WT1 mutations further enhance stemness and alter lineage hierarchy. In contrast, stem cells from later developmental stages become progressively resistant to transformation. Single-cell analyses revealed that fetal-origin leukemia stem cells exhibit greater quiescence and reliance on oxidative phosphorylation than their postnatal counterparts. These differences drive distinct therapeutic responses, despite identical oncogenic mutations. In patients, onco-fetal transcriptional programs correlate with worse outcomes. By targeting key vulnerabilities of fetal-origin leukemia cells, we identified combination therapies that significantly reduce aggressiveness, highlighting the critical role of ontogeny in pediatric cancer treatment.

cancer biology↗

bioRxiv2022

Direct conversion of human fibroblasts to pancreatic epithelial cells through transient progenitor states is controlled by temporal activation of defined factors

Cell fate can be reprogrammed by ectopic expression of lineage-specific transcription factors (TF). For example, few specialized cell types like neurons, hepatocytes and cardiomyocytes have been generated from fibroblasts by defined factors (Wang et al, 2021). However, the exact cell state transitions and their control mechanisms during cell fate conversion are still poorly understood. Moreover, the defined TFs for generating vast majority of the human cell types are still elusive. Here, we report a novel protocol for reprogramming human fibroblasts to pancreatic exocrine cells with phenotypic and functional characteristics of ductal epithelial cells using a minimal set of six TFs. We mapped the molecular determinants of lineage dynamics at single-cell resolution using a novel factor-indexing method based on single-nuclei multiome sequencing (FI-snMultiome-seq) that enables dissecting the role of each individual TF and pool of TFs in cell fate conversion. We show that transdifferentiation - although being considered a direct cell fate conversion method - occurs through transient progenitor states orchestrated by stepwise activation of distinct TFs. Specifically, transition from mesenchymal fibroblast identity to epithelial pancreatic exocrine fate involves two deterministic steps: first, an endodermal progenitor state defined by activation of HHEX concurrently with FOXA2 and SOX17, and second, temporal GATA4 activation essential for maintenance of pancreatic cell fate program. Collectively, our data provide a high-resolution temporal map of the epigenome and transcriptome remodeling events that facilitate cell fate conversion, suggesting that direct transdifferentiation process occurs through transient dedifferentiation to progenitor cell states controlled by defined TFs.

cell biology↗

bioRxiv2021

Transfer RNA-derived non-coding RNAs (tncRNAs): Uncovering hidden regulators of transcriptional regulatory circuits in plants

The lateral emergence of distinct classes of non-coding RNAs has led to better insights into the eukaryotic regulatory networks. Among them, the existence of transfer RNA (tRNA)-derived non-coding RNAs (tncRNAs) demands their exploration in the plant kingdom. Here, we have designed a methodology to uncover the bigger picture of tncRNAome in plants. Using this, we have identified diverse tncRNAs of length 14-50 nt in ~2500 small RNA sequencing (sRNA-seq) samples of six major angiosperms, and further studied their various features including length, codon-usage, cleavage pattern, and modified tRNA nucleosides. Codon-dependent generation of tncRNAs indicates that the process is highly specific rather than being mere random tRNA degradation. Analysis for nucleotide composition of tncRNA cleavage positions indicates that they are generated through precise endoribonucleolytic machinery. Certain tRNA nucleoside modifications on tncRNAs were found to be conserved across the plants, and hence may influence tRNA cleavage, as well as tncRNA functions. Pathway enrichment analysis revealed that common tncRNA targets were majorly involved in the metabolic and developmental processes of plants. Also, many tRFs were found to be associated with transposable elements. Distinct tissue-specific tncRNA clusters indicate their role in plant development under normal physiological conditions. Furthermore, the identification of a significant number of differentially expressed tncRNAs under several abiotic and biotic stresses highlights their probable role as gene expression modulators during various stress conditions. Thus, this study will be beneficial to investigate the emerging role of tncRNAs as prospective biomarkers in plant development and stress. HighlightsO_LIComputational pipeline for accurate identification of genuine transfer RNA-derived non-coding RNAs (tncRNAs) using small RNA sequencing (sRNA-seq) datasets. C_LIO_LISix major tncRNA classes of length ranging from 14 to 50 nt were identified in ~2,500 sRNA-seq datasets in six different angiosperms. C_LIO_LItRNA nucleoside modifications may affect tncRNA cleavage in plants. C_LIO_LIConserved tncRNAs target transcripts are involved in plant growth, development, and metabolism. C_LIO_LItncRNAs are expressed in a tissue-dependent, and stress-specific manner in plants. C_LI

bioinformatics↗