Figure 7.

Induction of a reactive phenotype exacerbates disease-associated phenotypes in patient-specific cell lines

Astrocytes were differentiated from hPSC lines carrying mutations associated with either glaucoma OPTN(E50K), Alzheimer’s disease (PSEN1-N141I), or ALS (SOD1-N139K).

(A–L) Upon induction of reactivity, astrocytes from all backgrounds developed a hypertrophic profile (A–F) and increased accumulation of C3 (G–L). Among astrocytes with the glaucoma OPTN-E50K mutation (M–O), reactivity led to a significant increase in the number of branches, along with a significant decrease in longest branch length as well as morphological complexity by Sholl analysis.

(P) Induction of reactivity also exacerbated disease-related phenotypes such as a significant increase in autophagy proteins P62 and the LC3-II/I ratio.

(Q–S) Similarly, among astrocytes with the Alzheimer’s PSEN1-N141I mutation, reactivity led to a significant increase in the number of branches along with a significant decrease in longest branch length, although no significant differences were observed in overall morphological complexity.

(T–U) Astrocyte reactivity led to a decreased capacity for amyloid beta uptake compared to homeostatic PSEN1 astrocytes.

(V–X) ALS SOD1-N139K astrocytes induced to reactivity exhibited an increased number of branches along with a significant decrease in the longest branch length, although no differences were observed in overall morphological complexity.

(Y and Z) Reactive SOD1-N139K astrocytes exhibited more prominent aggregates of SOD1 protein and had significantly increased intracellular levels of SOD1. Data represent mean values ±SEM, two-tailed paired Student’s t test, ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 vs. respective control astrocytes. Scale bar: 30 μm.