Table 4 Currently redefined astrocyte subtypes and characteristics
Astrocyte type | Identity | Distribution | Characteristic genes | Defining roles |
|---|---|---|---|---|
AST1 | Mature astrocyte | Dominant subtype in hippocampus and subpial layer, spread throughout cortex | High expression of Gfap and Agt | Synaptogenesis, synaptic plasticity, glutamatergic neurotransmission |
AST2 | Mature astrocyte | Uniformly distributed across cortical layers | High expression of Unc13c, absent expression of Agt | Glutamatergic neurotransmission |
AST3 | Mature astrocyte | Dominant subtype in layer 6 of cortex | Expression of Agt, absent expression of Unc13c and Gfap | GABAergic neurotransmission |
AST4 | Hippocampal neural stem cells/progenitor astrocyte | High levels in dentate gyrus of hippocampus, predominantly found in subgranular layer of hippocampus | High expression of Frzb, Ascl1, Slc1a3, Sirt2, Sept2, and Emp2 | Mitosis and cell cycle control; Transcriptional regulation; Neurogenesis and neuronal differentiation |
AST5 | Intermediate progenitor astrocyte | High in cortical layers 2/3, and 5 Dominant in subpial layer, stratum lacunosum-moleculare and dentate gyrus of hippocampus | High expression of Frzb, Ascl1, Slc1a3, Sirt2, Sept2, and Emp2 | Mitosis and cell cycle control; Glucose metabolism; Energy production; Smallest proportion of astrocyte types (1.4%) |