FIGURE 1.

Characteristics of astrocyte senescence. Senescent astrocytes that have undergone cell cycle arrest and have enlarged sharply. The expression of GFAP increased, whereas the expression of glutamate transporters (GLAST and GS) and SR-B1 and LRP1 decreased. The lysosomal content has increased, and the lysosomes have high β-galactosidase activity and dysfunctional mitochondria that produce high levels of ROS and release mtDNA. They have DNA damage and SAHFs, and their nuclear integrity is compromised due to the loss of laminB1. The elevated ROS activates the NF-κB pathway and promotes SASP production. The secretion of neurotrophic factors is decreased. GFAP, glial fibrillary acidic protein; GLAST, glutamate aspartate transporter; GLT-1, glutamate transporter-1; GS, glutamine synthetase; iNOS, inducible nitric oxide synthase; LRP1, lipoprotein receptor–related protein 1; NOX, NADPH oxidase; ROS, reactive oxygen species; SAHFs, senescence-associated heterochromatic foci; SASP, senescence-associated secretory phenotype; SR-B1, scavenger receptor B1.