Darcie L. Moore, PhD – Slide of the Week

Darcie L. Moore, PhD - Slide of the Week

Title: Specific Autofluorescent Signals in Neural Stem Cells Reporting on Cellular Metabolism Can Predict Their Cell State

Legend: Neural stem cells (NSCs) in the adult brain are primarily quiescent. When they receive signals, they can activate, re-entering into the cell cycle. Technologies capable of detecting a quiescent from an activated NSC in live cells are limited. Here we use specific excitation and emission parameters to detect endogenous autofluorescence in mouse NSCs purified directly from the brain, and then send them for single cell sequencing. Previously published data from other groups (Lllorens-Bobadilla et al, 2015) used single cell sequencing to show that subventricular zone-derived NSCs could be separated into qNSC1 (dark purple), qNSC2 (green), aNSC1 (light purple), and aNSC2 (orange), showing different stages of the most dormant quiescence (qNSC1) going to the most activated (aNSC2). Here we compared our sequencing to data to theirs, showing clustering of our cells (plus sign) with theirs (circles). When we pseudocolor our cells by their autofluorescence intensity on this UMAP, we find that the most dormant qNSCs (qNSC1; dark purple) also have the highest autofluorescence, whereas the lowest autofluorescent NSCs align with the most activated NSCs (aNSC2; orange), confirming all of our findings in vitro.

Citation: Autofluorescence is a biomarker of neural stem cell activation state. Morrow, C.S., Tweed, K., Arndt, Z.P., Walsh, A.J., Peng, B., Risgaard, R.D., Klosa, P.C., Chi, M.M., Wallace, E.P., Jones, M.V., Roopra, A., Skala, M.C., Moore, D.L. bioRxiv 2022.12.14.520430; doi: https://doi.org/10.1101/2022.12.14.520430

Abstract: Neural stem cells (NSCs) in the adult brain are primarily quiescent but can activate and enter the cell cycle to produce newborn neurons. NSC quiescence can be regulated by disease, injury, and age, however our understanding of NSC quiescence is limited by technical limitations imposed by the bias of markers used to isolate each population of NSCs and the lack of live-cell labeling strategies. Fluorescence lifetime imaging (FLIM) of autofluorescent metabolic cofactors has previously been used in other cell types to study shifts in cell states driven by metabolic remodeling that change the optical properties of these endogenous fluorophores. Here we asked whether autofluorescence could be used to discriminate NSC activation state. We found that quiescent NSCs (qNSCs) and activated NSCs (aNSCs) each have unique autofluorescence intensity and fluorescence lifetime profiles. Additionally, qNSCs specifically display an enrichment of a specific autofluorescent signal localizing to lysosomes that is highly predictive of cell state. These signals can be used as a graded marker of NSC quiescence to predict cell behavior and track the dynamics of quiescence exit at single cell resolution in vitro and in vivo. Through coupling autofluorescence imaging with single-cell RNA sequencing in vitro and in vivo, we provide a high-resolution resource revealing transcriptional features linked to rapid NSC activation and deep quiescence. Taken together, we describe a single-cell resolution, non-destructive, live-cell, label-free strategy for measuring NSC activation state in vitro and in vivo and use this tool to expand our understanding of adult neurogenesis.

About the Lab: The Moore Lab is interested in understanding the mechanisms that neural stem cells (NSCs) utilize to stay active during aging. More specifically, the Moore Lab is interested in understanding how NSCs utilize asymmetric cell division to maintain a pristine proteome and preserve cellular function.

Investigator: Darcie L. Moore, PhD

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