Biology subjects

Eastman, A. E.

Publications and source records attributed to Eastman, A. E..

7 recordsLinked to original sources

bioRxiv2026

Isolation of postnatal human neural stem cells

While it was once thought that neurogenesis is complete by birth, it is now apparent that the human brain continues to generate new neurons postnatally, at least into childhood. While much attention has been focused on postnatally-born neurons, their presumed progenitor - the postnatal neural stem cell (NSC) - remains poorly characterized. Using index sorting, we identify and prospectively isolate two subsets of NSCs from the postnatal human brain, and describe their differentiation dynamics using clonal barcoding and in vivo xenotransplantation. We demonstrate an A2B5+EGFR+ population biased towards interneuron and oligodendrocyte fates (NINO), and an A2B5-EGFRhi population biased towards an astrocyte fate (NAC). Profiling of human brains across lifespan shows that the frequency of NSCs declined exponentially across the first two decades of life, but stabilized thereafter, still present in the brains of donors as old as 90 years. Our study provides a framework for the functional study of postnatal human NSCs and their potential roles in development, aging, and disease.

neuroscience↗

bioRxiv2025

Beyond polyA: scalable single-cell total RNA-seq unifies coding and non-coding transcriptomics

Non-coding RNAs represent a widespread and diverse layer of post-transcriptional regulation across cell types and states, yet much of their diversity remains uncharted at single-cell resolution. This gap stems from the limitations of widely used single-cell RNA-sequencing protocols, which focus on polyadenylated transcripts and miss many short or non-polyadenylated RNAs. Here, we adapted single-cell RNA-sequencing on the 10x Genomics platform to capture a broad complement of coding and non-coding RNAs--including miRNAs, tRNAs, lncRNAs, histone RNAs, and non-adenylated viral transcripts. This approach enabled the discovery of rich, dynamic non-coding RNA programs across immune cells, virally infected hepatocytes, and the developing human brain. In dengue virus-infected hepatocytes, we detect non-adenylated viral transcripts and distinguish active from transcriptionally quiescent infected states, each with distinct host regulatory signatures. In brain tissue, we identify biotype-specific, cell-type- restricted non-coding RNAs, including miRNAs whose expression anticorrelates with predicted targets, consistent with post-transcriptional regulatory relationships. We show that MIR137, one of the strongest GWAS loci associated with schizophrenia and intellectual disability, is expressed specifically in Cajal-Retzius cells, an early-born but transient population that guides subsequent cortical neuron migration. These findings demonstrate the importance of non-coding RNAs in defining cell identity and state, and show how expanded transcriptome coverage can reveal additional layers of gene control--now accessible through practical and scalable single-cell profiling.

genomics↗

bioRxiv2024

Modeling Glioma Intratumoral Heterogeneity with Primary Human Neural Stem and Progenitor Cells

Glioblastoma multiforme (GBM) is a deadly form of glioma notable for its significant intratumoral heterogeneity, which is believed to drive therapy resistance. GBM has been observed to mimic a neural stem cell hierarchy reminiscent of normal brain development. However, it is still unclear how cell-of-origin shapes intratumoral heterogeneity. Here, we develop a model of glioma initiation using neural stem and progenitor cells (NSPCs) purified from fetal human brain tissue. We previously described a method to prospectively isolate and culture tripotent neural stem cells (NSCs), bipotent glial progenitor cells (GPCs), and unipotent oligodendrocyte precursor cells (OPCs). We transduced these isogenic lines with dominant-negative TP53R175H and NF1 knockdown, a commonly-used genetic model of GBM in mice. These reprogrammed lines robustly engrafted when transplanted into the brains of immunodeficient mice, and showed significant expansion over time. Engrafted cells were reextracted from the mouse brain for single cell RNA sequencing (scRNA-seq), in order to quantify how the cell-of-origin modulates the cellular subtypes found in the resulting tumor. This result revealed the strong influence the cell-of-origin plays in glioma heterogeneity. Our platform is highly adaptable and allows for modular and systematic interrogation of how cell-of-origin shape the tumor landscape.

cancer biology↗

bioRxiv2020

The Erythropoietin Receptor Stimulates Rapid Cycling and Formation of Larger Red Cells During Mouse and Human Erythropoiesis

Erythroid terminal differentiation entails cell divisions that are coupled to progressive decreases in cell size. EpoR signaling is essential for the survival of erythroid precursors, but it is unclear whether it has other functions in these cells. Here we endowed mouse precursors that lack the EpoR with survival signaling, finding that this was sufficient to support their differentiation into enucleated red cells, but that the process was abnormal. Precursors underwent fewer and slower cell cycles and yet differentiated into smaller red cells. Surprisingly, EpoR further accelerated cycling of early erythroblasts, the fastest cycling cells in the bone marrow, while simultaneously increasing their cell size. EpoR-mediated formation of larger red cells was independent of the established pathway regulating red cell size by iron through Heme-regulated eIF2 kinase (HRI). We confirmed the effect of Epo on red cell size in human volunteers, whose mean corpuscular volume (MCV) increased following Epo administration. This increase persisted after Epo declined and was not the result of increased reticulocytes. Our work reveals a unique effect of EpoR signaling on the interaction between the cell cycle and cell growth. Further, it suggests new diagnostic interpretations for increased red cell volume, as reflecting high Epo and erythropoietic stress.

developmental biology↗

bioRxiv2018

A fluorescent reporter enables instantaneous measurement of cell cycle speed in live cells

Cell proliferation changes concomitantly with fate transitions during reprogramming, differentiation, regeneration, and oncogenesis. Methods to resolve cell cycle length heterogeneity in real-time are currently lacking. Here, we describe a genetically encoded fluorescent reporter that captures live cell cycle speed using a single measurement. This reporter is based on the color-changing Fluorescent Timer (FT) protein, which emits blue fluorescence when newly synthesized before maturing into a red fluorescent protein. We generated a mouse strain expressing an H2B-FT fusion reporter from a universally active locus, and demonstrate that faster-cycling cells can be distinguished from slower-cycling ones based on the intracellular fluorescence ratio between the FTs blue and red states. Using this reporter, we reveal the native cell cycle speed distributions of fresh hematopoietic cells, and demonstrate its utility in analyzing cell proliferation in solid tissues. This system is broadly applicable for dissecting functional heterogeneity associated with cell cycle dynamics in complex tissues.

cell biology↗

bioRxiv2018

MLL-AF9 Initiates Transformation From Fast-Proliferating Myeloid Progenitors

Cancer is a hyper-proliferative clonal disease. Whether the proliferative state originates from the cell-of-origin or emerges later remains elusive. By tracking de novo transformation from normal hematopoietic progenitors expressing an acute myeloid leukemia (AML) oncogene MLL-AF9, we reveal that the cell cycle rate heterogeneity among granulocyte-macrophage progenitors (GMPs) determines their probability of transformation. An intrinsic fast cell cycle kinetics at the time of oncogene expression provide permissiveness for transformation, with the fastest cycling 3% of GMPs ([~]0.006% of bone marrow nucleated cells) acquiring malignancy with nearly 100% efficiency. Molecularly, we propose that MLL-AF9 preserves the gene expression of the cellular states in which it is expressed. As such, when expressed in the naturally-existing, rapidly-cycling myeloid progenitors, this cell state is perpetuated, yielding malignancy. Our work elucidates one of the earliest steps toward malignancy and suggests that modifying the cycling state of the cell-of-origin could be an effective approach to prevent malignancy.

cancer biology↗

bioRxiv2018

Non-cell-autonomous promotion of pluripotency induction mediated by YAP

While Yes-associated protein (YAP) antagonizes pluripotency during early embryogenesis, it has also been shown to promote stemness of multiple stem cell types, including pluripotent stem cells. Whether cellular context underlies these distinct functions of YAP in pluripotency remains unclear. Here, we establish that depending on the specific cells in which it is expressed, YAP exhibits opposing effects on pluripotency induction from somatic cells. Specifically, YAP inhibits pluripotency induction cell-autonomously but promotes it non-cell-autonomously. For its non-cell-autonomous role, YAP alters the expression of many secreted and matricellular proteins including CYR61, which recapitulates the promotional effect when added as a recombinant protein. Thus, we define a unique YAP-driven non-cell-autonomous process that enhances pluripotency induction. Our work highlights the importance of considering the distinct contributions from heterologous cell types in deciphering the mechanism of cell fate control and calls for careful re-examination of the co-existing bystander cells in complex cultures or tissues.

cell biology↗