Single-Cell Analysis for Glycogen Localization and Metabolism in Cultured Astrocytes

Yuanyuan Zhu,Ze Fan,Yan Li,Rui Wang,Haifeng Zhang,Tangna Sun,Rougang Xie,Shengxi Wu,Haiyun Guo,Baolin Guo,Ming Zhang,Lixia Zhuo

doi:10.1007/s10571-019-00775-4

Abstract

Cerebral glycogen is principally localized in astrocytes rather than in neurons. Glycogen metabolism has been implicated in higher brain functions, including learning and memory, yet the distribution patterns of glycogen in different types of astrocytes have not been fully described. Here, we applied a method based on the incorporation of 2-NBDG, a d-glucose fluorescent derivative that can trace glycogen, to investigate glycogen’s distribution in the brain. We identified two types of astrocytes, namely, 2-NBDGI (glycogen-deficient) and 2-NBDGII (glycogen-rich) cells. Whole-cell patch-clamp and fluorescence-activated cell sorting (FACS) were used to separate 2-NBDGII astrocytes from 2-NBDGI astrocytes. The expression levels of glycogen metabolic enzymes were analyzed in 2-NBDGI and 2-NBDGII astrocytes. We found unique glycogen metabolic patterns between 2-NBDGI and 2-NBDGII astrocytes. We also observed that 2-NBDGII astrocytes were mainly identified as fibrous astrocytes but not protoplasmic astrocytes. Our data reveal cell type-dependent glycogen distribution and metabolism patterns, suggesting diverse functions of these different astrocytes.

Highlights

Glial cells are the main type of neural cell and exist throughout the central nervous system (CNS) (Gallo and Deneen 2014; Brosius Lutz and Barres 2014; Walsh et al 2014)
To explore whether glycogen metabolism patterns are associated with the diversity of astrocytes, we developed a multidisciplinary approach to investigate the expression levels of glycogen metabolic key enzymes in single astrocytes
We found that the distribution of glycogen was not homogeneous among astrocytes under transmission electron microscopy

Summary

Introduction

Glial cells are the main type of neural cell and exist throughout the central nervous system (CNS) (Gallo and Deneen 2014; Brosius Lutz and Barres 2014; Walsh et al 2014). Estimates regarding the ratio of glial cells to neurons vary. Brain glycogen is principally localized in astrocytes rather than in neurons (Magistretti and Allaman 2018; Gotoh et al 2017). The brain glycogen stored in astrocytes was reported to activate the neuronal system, and the level of astrocytic glycogen increased during anesthesia and sleep (Brown and Ransom 2015; Zhang et al 2016). Astrocytes are strongly heterogeneous, including their morphology and function

Methods

Results

Conclusion