Biology subjects

Nathanson, A.

Publications and source records attributed to Nathanson, A..

4 recordsLinked to original sources

bioRxiv2026

Aberrant chromatin remodeling influences human neural cell fate change in Trisomy 21

Correct neural progenitor cell (NPC) fate specification is essential to produce the full complement of neurons and glia needed for proper brain structure and function. Neurodevelopmental disorders, including the autosomal aneuploidy Down syndrome (DS), or Trisomy 21 (T21), are frequently associated with impaired cell fate decisions which ultimately drive differences in overall brain size and cell type composition through unknown mechanisms. To uncover mechanisms driving altered NPC fate in T21, we leverage paired single-nuclei transcriptomic and epigenomic analyses of human induced pluripotent stem cell (iPSC)-derived NPCs and their differentiated progeny coupled with in depth clonal cell fate, cell cycle, and proteomic analyses. Here we show that T21 NPCs fail to activate an orchestrated neurogenic program during the earliest stages of fate specification, instead maintaining a repressive chromatin structure over neurogenic loci, leading to reduced neurogenesis and continued NPC proliferation. We identify novel enrichment of the repressive histone mark H3K27me3 at fate instructive genes dysregulated across diverse cell and tissue types in T21, with corresponding genome-wide changes in H3K27me3 binding in T21 NPCs. Moreover, pharmacological treatment with an inhibitor of the Polycomb repressive complex 2 (PRC2) which catalyzes H3K27 methylation, is sufficient to partially restore neurogenesis in T21 cells. Collectively, our analyses reveal a chromatin mechanism influencing neurogenic defects in T21.

neuroscience↗

bioRxiv2022

Robust induction of functional astrocytes using NGN2 expression in human pluripotent stem cells

Astrocytes play essential roles in normal brain function, with dysfunction implicated in diverse developmental and degenerative disease processes. Emerging evidence of profound species divergent features of astrocytes coupled with the relative inaccessibility of human brain tissue underscore the utility of human pluripotent stem cell (hPSC) technologies for the generation and study of human astrocytes. However, existing approaches for hPSC-astrocyte generation are typically lengthy, incompletely characterized, or require intermediate purification steps, limiting their utility for multi-cell line, adequately powered functional studies. Here, we establish a rapid and highly scalable method for generating functional human induced astrocytes (hiAs) based upon transient Neurogenin 2 (NGN2) induction of neural progenitor-like cells followed by maturation in astrocyte media, which demonstrate remarkable homogeneity within the population and across 11 independent cell lines in the absence of additional purification steps. These hiAs express canonical astrocyte markers, respond to pro-inflammatory stimuli, exhibit ATP-induced calcium transients and support neuronal maturation in vitro. Moreover, single-cell transcriptomic analyses reveal the generation of highly reproducible cell populations across individual donors, most closely resembling human fetal astrocytes, and highly similar to hPSC-derived astrocytes generated using more complex approaches. Finally, the hiAs capture key molecular hallmarks in a trisomy 21 disease model. Thus, hiAs provide a valuable and practical resource well-suited for study of basic human astrocyte function and dysfunction in disease.

neuroscience↗

bioRxiv2022

An automated high-content synaptic phenotyping platform in human neurons and astrocytes reveals a role for BET proteins in synapse assembly

Resolving fundamental molecular and functional processes underlying human synaptic development is crucial for understanding normal brain function as well as dysfunction in disease. Based upon increasing evidence of species divergent features of brain cell types, coupled with emerging studies of complex human disease genetics, we developed the first automated and quantitative high-content synaptic phenotyping platform using human neurons and astrocytes. To establish the robustness of our platform, we screened the effects of 376 small molecules on presynaptic density, neurite outgrowth and cell viability, validating six small molecules which specifically enhanced human presynaptic density in vitro. Astrocytes were essential for mediating the effects of all six small molecules, underscoring the relevance of non-cell autonomous factors in synapse assembly and their importance in synaptic screening applications. Bromodomain and extraterminal (BET) inhibitors emerged as the most prominent hit class and global transcriptional analyses using multiple BET inhibitors confirmed upregulation of synaptic gene expression programs. Through these analyses, we demonstrate the robustness of our automated screening platform for identifying potent synaptic modulators, which can be further leveraged for scaled analyses of human synaptic mechanisms and drug discovery efforts.

neuroscience↗

bioRxiv2019

Sample preparation protocol enabling nano-to-mesoscopic mapping of cellular connectomes and their habitats in human tissues and organs

Multibeam scanning electron microscopy (multiSEM) provides a technical platform for seamless nano-to-mesoscale mapping of cells in human tissues and organs, which is a major new initiative of the U.S. National Institutes of Health. Developed for rapid throughput imaging of minute defects on semiconductor wafers, multiSEM has recently been adapted for imaging of human organs, their constituent tissues, and their respective cellular inhabitants. Through integration of geospatial approaches, statistical and network modelling, advances in computing and the management of immense datasets, as well as recent developments in machine learning that enable the automation of big data analyses, multiSEM and other cross-cutting imaging technologies have the potential to exert a profound impact on elucidation of disease mechanisms, translating to improvements in human health. Here we provide a protocol for acquisition and preparation of sample specimen sizes of diagnostic relevance for human anatomy and physiology. We discuss challenges and opportunities to integrate this approach with multibeam scanning electron microscopy work flows as well as multiple imaging modalities for mapping of organ and tissue structure and function.

systems biology↗