Biology subjects

Nafisi, M.

Publications and source records attributed to Nafisi, M..

3 recordsLinked to original sources

bioRxiv2026

Single-molecule spatial genomics reveals the multi-scale organization and plasticity of extrachromosomal DNA in glioblastoma

Extrachromosomal DNA (ecDNA) is a major driver of intratumoral heterogeneity and is associated with poor clinical outcomes across cancers, yet how individual ecDNA molecules are organized and regulated within intact tumors remains unknown. Here, we leveraged single-molecule, multi-modal spatial genomics to resolve the three-dimensional chromatin organization and transcriptional activity of individual EGFR-containing ecDNA molecules in glioblastoma (GBM) cells in vitro, in orthotopic xenografts, and in patient-derived GBM tissue. At the larger scale, we find that distinct GBM molecular and functional states emerge depending on the local cellular environment. EGFR expression was markedly different between GBM subpopulations, and perturbations of EGFR dosage shifted GBM cellular states. ecDNA expression was modulated by multiple mechanisms, including variation in copy number, chromatin organization, DNA sequence, and chromosomal reintegration, which were simultaneously measured within the same cells. At the single-molecule scale, ecDNA adopts a physically expanded chromatin configuration with larger ecDNA molecules having higher transcriptional activity and interaction with active transcriptional machinery. ecDNA regulation was coordinated within cells and across GBM states, and ecDNA copy number, structure, and transcription were spatially organized across the tumor architecture. Co-culturing GBM cells with neurons recapitulated key features of infiltrative regions, including lower EGFR expression, reduced ecDNA copy number, and increased chromosomal reintegration, suggesting a causal role for the microenvironment in shaping ecDNA regulation. Collectively, these findings support a model in which GBM states and ecDNA are linked, plastic, and influenced by microenvironmental contexts, revealing a previously inaccessible layer of genome organization underlying tumor heterogeneity and malignant cell behavior.

genomics↗

bioRxiv2025

Multiscale Spatial Transcriptomic Atlas of Human Basal Ganglia Cell-Type and Cellular Community Organization

We generated a multi-region, subcellular-resolution spatial transcriptomic atlas of the human basal ganglia by integrating MERFISH+ and Stereo-seq across four neurotypical donors. These datasets profiled [~]7 million cells spanning the caudate, putamen, nucleus accumbens, and globus pallidus, resolving 60 transcriptionally distinct cell types. We show region-selective, molecular and spatial diversification of medium-spiny-neuron cell types and multiple non-neuronal populations with distinct molecular identities and spatial localizations. Subcellular RNA localization captures somatic size and projection-inferred signatures that reflect direct and indirect pathway topology. Cellular community analyses reveal the enrichment of sub-clusters of astrocytes and oligodendrocytes at striosome-matrix borders, while primate-expanded interneurons are confined to matrix territories. Cross-species mapping uncovers orthologous striosome-matrix organization and conserved dorsolateral-ventromedial gene expression gradients. This atlas provides a foundational molecular and spatial framework for studying human basal ganglia architecture, offering a multi-centimeter scale resource that links cell types, spatial architecture, and subcellular transcript topography across multiple nuclei. HighlightsO_LIOur multi-centimeter scale spatial taxonomy identifies the precise locations of 60 neuronal and glial cell types of human basal ganglia. C_LIO_LIMERFISH+ and Stereo-seq platforms map consistent spatial modules that align with classical neuroanatomical nuclei. C_LIO_LID1D2 hybrid MSNs and primate-expanded interneurons show regional and domain specific organization C_LIO_LISubcellular RNA localization reports soma morphology and projection-inferred signatures. C_LI

neuroscience↗

bioRxiv2023

Mapping Human Tissues with Highly Multiplexed RNA in situ Hybridization

In situ transcriptomic techniques promise a holistic view of tissue organization and cell-cell interactions. Recently there has been a surge of multiplexed RNA in situ techniques but their application to human tissues and clinical biopsies has been limited due to their large size, general lower tissue quality and high background autofluorescence. Here we report DART-FISH, a versatile padlock probe-based technology capable of profiling hundreds to thousands of genes in centimeter-sized human tissue sections at cellular resolution. We introduced an omni-cell type cytoplasmic stain, dubbed RiboSoma that substantially improves the segmentation of cell bodies. We developed a computational decoding-by-deconvolution workflow to extract gene spots even in the presence of optical crowding. Our enzyme-free isothermal decoding procedure allowed us to image 121 genes in a large section from the human neocortex in less than 10 hours, where we successfully recapitulated the cytoarchitecture of 20 neuronal and non-neuronal subclasses. Additionally, we demonstrated the detection of transcripts as short as 461 nucleotides, including neuropeptides and discovered new cortical layer markers. We further performed in situ mapping of 300 genes on a diseased human kidney, profiled >20 healthy and pathological cell states, and identified diseased niches enriched in transcriptionally altered epithelial cells and myofibroblasts.

genomics↗