Purification and Characterization of Progenitor and Mature Human Astrocytes Reveals Transcriptional and Functional Differences with Mouse

Abstract

Summary The functional and molecular similarities and distinctions between human and murine astrocytes are poorly understood. Here we report the development of an immunopanning method to acutely purify astrocytes from fetal, juvenile, and adult human brains, and to maintain these cells in serum-free cultures. We found that human astrocytes have similar abilities to murine astrocytes in promoting neuronal survival, inducing functional synapse formation, and engulfing synaptosomes. In contrast to existing observations in mice, we found that mature human astrocytes respond robustly to glutamate. We next performed RNA-sequencing of healthy human astrocytes along with astrocytes from epileptic and tumor foci, and compared these to human neurons, oligodendrocytes, microglia, and endothelial cells. With these profiles, we identified novel human-specific astrocyte genes, and discovered a transcriptome-wide transformation between astrocyte precursor cells and mature post-mitotic astrocytes. These data represent some of the first cell type-specific molecular profiles of the healthy and diseased human brain.

Astrocytic neuroligins control astrocyte morphogenesis and synaptogenesis

“…Next, we mined gene expression databases 12-14 to identify astrocytic cell adhesion molecules (CAMs) known to interact with neuronal and synaptic proteins. Intriguingly, astrocytes express three members of the NL family, NL1, NL2, and NL3, at levels comparable to, or higher than, neurons (Extended Data Fig.…”

“…b , Average FPKM values of cell-type specific transcripts from P7 neurons and astrocytes (Aldh1L1 = astrocyte, Eno2 = neuron, MOG = oligodendrocyte all data from 13 ). c , Average FPKM values of NL mRNAs from 25yr-old human neurons (black), 18-18.5gw (gestational week) fetal astrocytes (red), and 8-63yr-old human mature astrocytes (yellow, all data from 14 . d , Average FPKM values of cell-type specific transcripts from specimens listed in c (all data from 14 ).…”

“…c , Average FPKM values of NL mRNAs from 25yr-old human neurons (black), 18-18.5gw (gestational week) fetal astrocytes (red), and 8-63yr-old human mature astrocytes (yellow, all data from 14 . d , Average FPKM values of cell-type specific transcripts from specimens listed in c (all data from 14 ). e , Average FPKM values of NL mRNAs that are engaged with translating ribosomes from P80 mouse astrocytes (red) and total input (black) using the Aldh1L1-creER T2 /Ribo-tag mice (all data from 12 ).…”

The human-specificCASP4gene product contributes to Alzheimer-related synaptic and behavioural deficits

“…This analysis also suggested that the transcription factor IRF8, Spi1, Cebpb, Stat3 and Pbx1, are regulators significantly associated with these modules (Supplementary Material, Table S2). We focused on IRF8 and Spi1 for functional analysis of the CASP4 gene promoter, as they are selectively expressed in microglia (43,44) and play an important role in microglial development (13). Our in silico promoter analysis identified a conserved GGAA motif among different species of CASP4 as well as human CASP5 (Fig.…”

Seducing astrocytes to the dark side

“…To begin dissecting and understanding the diversity, regulation and functions of reactive astrocyte responses, several studies have employed quantitative genomic analyses to characterize astrocyte gene expression profiles in various CNS disorders. The results of these studies highlights the existence of molecularly diverse subtypes of reactive astrocytes that may serve a multitude of beneficial or deleterious roles [3][4][5]. Nevertheless, the identity of key cellular and molecular mechanisms driving such diverse responses, and the functional implications of different forms of astrocyte reactivity for CNS disorders, remain central questions in the study of the neurobiology of disease.…”