Biology subjects

Andersen, R. E.

Publications and source records attributed to Andersen, R. E..

5 recordsLinked to original sources

bioRxiv2026

Creation of a High-Resolution, Continually Evolvable Lineage Tracer

Cellular diversity is required for the proper function of many tissues, including the retina, with its ~130 cell types.1-3 Previous lineage studies suggested that retinal progenitor cells (RPCs) generate cell diversity through biased cell divisions.4-9 However, the extent to which each progenitor cell contributes to diversity, and the overarching rules governing the lineages of the collection of progenitor cells, are unknown. While classic lineage tracing approaches including retroviral labeling4,6,10, dye injection11,12, and time-lapse microscopy13,14 were used to make the foundational insights regarding retinal lineages, they cannot be used to interrogate multigenerational lineages at scale. Here we describe the creation of an evolvable lineage tracing tool, "SCRIBBLE" for Sequential Combinatorial Recorder for Iterative Barcode-Based Lineage Evolution. SCRIBBLE uses prime editor to iteratively edit a barcode sequence while preserving the order of genesis of clonally related progeny. Through a series of rationally designed high-throughput screens and design optimizations, we identified novel sequences that support a high level of barcode editing and information content. Evaluation of SCRIBBLE in embryonic mouse retina recapitulated known lineages in retinal development, demonstrating that SCRIBBLE is capable of high-resolution lineage tracing in a complex tissue.

developmental biology↗

bioRxiv2026

Pannexin-1 channel activity regulates neurogenesis and cell survival in the developing cortex

Mutations in genes encoding a range of ion-conducting proteins disrupt development of the cerebral cortex in humans, often causing polymicrogyria (PMG); yet how ion conduction guides the development of cortical architecture is not clear. Here, we describe three individuals with brain malformations including PMG and microcephaly in whom de novo, missense mutations were identified in PANX1--encoding an ATP and ion conducting channel. We show that these PMG-associated PANX1 mutations (p.D14H, p.M37R, and p.N338T) disrupt normal glycosylation and confer gain-of-function with respect to ATP release and channel conductance. In vivo modeling of mutant PANX1 in cortical progenitor cells demonstrated disrupted cell migration and excess cell death in both mice and ferret models. In vitro modeling of the p.N338T allele in human induced pluripotent stem cell (hiPSC)-derived neurons further revealed changes in neuronal morphology and increased excitability, and dysregulation of key transcription factors critical for neurogenesis and cell fate. In addition, p.N338T iPSC-derived neural progenitor cells displayed increased PANX1 activation. Our results show that normal PANX1 function contributes to cortical structure through regulation of ion conductance and ATP release and provides insight into how these processes influence corticogenesis and cytoarchitecture more broadly.

neuroscience↗

bioRxiv2025

Structural basis for the function of long noncoding RNA Pnky in neural stem cells

LncRNA Pnky is a trans-acting regulator of neural stem cell (NSC) differentiation, but the molecular mechanisms by which Pnky regulates neurogenesis is unknown. A fundamental step towards mechanistic understanding is to determine whether a lncRNA has folded structure that underlies biological function. Using chemical probing and high-throughput analysis, we determined the secondary structure of Pnky folded in vitro and in cellulo. Pnky adopts a compact structure in vitro with distinct modules and evidence of tertiary interactions. In cellulo, Pnky structure is remarkably similar to the in vitro conformation. We used locked nucleic acid oligonucleotides to interrogate the entire Pnky transcript for function in NSCs and identified regions that when targeted increased neurogenesis - phenocopying Pnky knockdown - without decreasing transcript abundance. Our findings provide a structural basis for the role of Pnky in neurogenesis and, more broadly, illustrate how structural maps combined with phenotypic data can advance fundamental understanding of lncRNA mechanism. HIGHLIGHTSPnky folds into highly structured conformation in vitro with distinct modules. Pnky is a compact lncRNA with evidence of tertiary interactions. Pnky structure in neural stem cells is similar to its in vitro conformation. LNA ASO perturbations identify structured regions of Pnky involved in neuronal differentiation.

molecular biology↗

bioRxiv2024

Spatial Single-cell Analysis Decodes Cortical Layer and Area Specification

The human cerebral cortex, pivotal for advanced cognitive functions, is composed of six distinct layers and dozens of functionally specialized areas1,2. The layers and areas are distinguished both molecularly, by diverse neuronal and glial cell subtypes, and structurally, through intricate spatial organization3,4. While single-cell transcriptomics studies have advanced molecular characterization of human cortical development, a critical gap exists due to the loss of spatial context during cell dissociation5,6,7,8. Here, we utilized multiplexed error-robust fluorescence in situ hybridization (MERFISH)9, augmented with deep-learning-based cell segmentation, to examine the molecular, cellular, and cytoarchitectural development of human fetal cortex with spatially resolved single-cell resolution. Our extensive spatial atlas, encompassing 16 million single cells, spans eight cortical areas across four time points in the second and third trimesters. We uncovered an early establishment of the six-layer structure, identifiable in the laminar distribution of excitatory neuronal subtypes by mid-gestation, long before the emergence of cytoarchitectural layers. Notably, while anterior-posterior gradients of neuronal subtypes were generally observed in most cortical areas, a striking exception was the sharp molecular border between primary (V1) and secondary visual cortices (V2) at gestational week 20. Here we discovered an abrupt binary shift in neuronal subtype specification at the earliest stages, challenging the notion that continuous morphogen gradients dictate mid-gestation cortical arealization6,10. Moreover, integrating single-nuclei RNA-sequencing and in situ whole transcriptomics revealed an early upregulation of synaptogenesis in V1-specific Layer 4 neurons, suggesting a role of synaptogenesis in this discrete border formation. Collectively, our findings underscore the crucial role of spatial relationships in determining the molecular specification of cortical layers and areas. This work not only provides a valuable resource for the field, but also establishes a spatially resolved single-cell analysis paradigm that paves the way for a comprehensive developmental atlas of the human brain.

neuroscience↗

bioRxiv2023

Sex-specific role for the long noncoding RNA Pnky in mouse behavior

The human brain expresses thousands of different long noncoding RNAs (lncRNAs), and aberrant expression of specific lncRNAs has been associated with cognitive and psychiatric disorders. While a growing number of lncRNAs are now known to regulate neural cell development and function, relatively few have been shown to underlie animal behavior, particularly with genetic strategies that establish lncRNA function in trans. Pnky is an evolutionarily conserved, neural lncRNA that regulates brain development. Using mouse genetic strategies, we show that Pnky has sex-specific roles in mouse behavior and that this lncRNA underlies specific behavior by functioning in trans. Male Pnky-knockout (KO) mice have deficits in cued fear recall, a type of Pavlovian associative memory. In female Pnky-KO mice, the acoustic startle response (ASR) is increased and accompanied by a decrease in prepulse inhibition (PPI), both of which are behaviors altered in affective disorders. Remarkably, expression of Pnky from a bacterial artificial chromosome (BAC) transgene reverses the ASR phenotype of female Pnky-KO mice, demonstrating that Pnky underlies specific animal behavior by functioning in trans. More broadly, these data provide genetic evidence that a lncRNA gene and its function in trans can play a key role in the behavior of adult mammals, contributing fundamental knowledge to our growing understanding of the association between specific lncRNAs and disorders of cognition and mood.

neuroscience↗