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Alzheimer's disease (AD) is characterized by tau pathology, leading to neurodegeneration. Astrocytes regulate central nervous system homeostasis and influence AD progression. The APOE3‐Christchurch (APOE3‐Ch) variant is linked to AD resilience, but its protective mechanisms remain unclear. Human induced pluripotent stem cell–derived astrocytes (APOE3‐Ch and wild type) were used to assess tau uptake, clearance, lipid metabolism, and transcriptomic adaptations. Fluorescently labeled 2N4R‐P301L tau oligomers were tracked, and pathway‐specific inhibitors dissected tau clearance mechanisms. Lipidomic and transcriptomic analyses were performed to identify genotype‐specific adaptations. APOE3‐Ch astrocytes exhibited enhanced tau uptake via heparan sulfate proteoglycan‐ and lipoprotein receptor‐related protein 1‐mediated pathways and superior clearance through lysosomal and proteasomal degradation. They exported less tau, limiting propagation. Transcriptomic analyses revealed upregulation of genes involved in cell projection assembly and endocytosis. Lipidomic profiling showed reduced ceramides and gamma‐linolenic acid, linked to decreased neuroinflammation and ferroptosis. APOE3‐Ch astrocytes promote tau clearance and metabolic adaptations, providing insights into genetic resilience in AD and potential therapeutic targets. APOE3‐Christchurch (APOE3‐Ch) astrocytes exhibit significantly increased tau internalization compared to wild‐type astrocytes, facilitated by upregulated heparan sulfate proteoglycan and low‐density lipoprotein receptor‐related protein 1 pathways. APOE3‐Ch astrocytes demonstrate more efficient tau degradation via both lysosomal and proteasomal pathways, while exporting significantly less tau, potentially reducing tau propagation in the central nervous system. APOE3‐Ch astrocytes show upregulation of genes involved in cell projection assembly and endocytosis, suggesting structural and functional modifications that enhance tau processing. Lipidomic profiling reveals reduced ceramide levels and gamma‐linolenic acid downregulation in APOE3‐Ch astrocytes, alterations linked to reduced neuroinflammatory and ferroptotic activity, contributing to the protective phenotype.

Bipolar disorder (BD) is a complex psychiatric condition usually requiring long-term treatment. Lithium (Li) remains the most effective mood stabilizer for BD, yet it benefits only a subset of patients, and its precise mechanism of action remains elusive. Exome sequencing has identified AKAP11 (A-kinase anchoring protein 11) as a shared risk gene for BD and schizophrenia (SCZ). Given that both the AKAP11-Protein Kinase A (PKA) complex and Li target and inhibit Glycogen Synthase Kinase-3 beta (GSK3β), we hypothesize that Li may partially normalize the transcriptomic and/or epigenomic alterations observed in heterozygous AKAP11-knockout (Het-AKAP11-KO) iPSC-derived neurons. In this study, we employed genome-wide approaches to assess the effects of Li on the transcriptome and epigenome of human iPSC-derived Het-AKAP11-KO neuronal culture. We show that chronic Li treatment in this cellular model upregulates key pathways that were initially downregulated by Het-AKAP11-KO, several of which have also been reported as downregulated in synapses of BD and SCZ post-mortem brain tissues. Moreover, we demonstrated that Li treatment partially rescues certain transcriptomic alterations resulting from Het-AKAP11-KO, bringing them closer to the WT state. We suggest two possible mechanisms underlying these transcriptomic effects: (1) Li modulates histone H3K27ac levels at intergenic and intronic enhancers, influencing enhancer activity and transcription factor binding, and (2) Li enhances GSK3β serine 9 phosphorylation, impacting WNT/β-catenin signaling and downstream transcription. These findings underscore Li’s potential as a therapeutic agent for BD and SCZ patients carrying AKAP11 loss-of-function variants or exhibiting similar pathway alterations to those observed in Het-AKAP11-KO models.

CACNA1A encodes the pore-forming α 1A subunit of the Ca V 2.1 calcium channel, whose altered function is associated with various neurological disorders, including forms of ataxia, epilepsy, and migraine. In this study, we generated isogenic iPSC-derived neural cultures carrying CACNA1A loss-of-function mutations differently affecting Ca V 2.1 splice isoforms. Morphological, molecular, and functional analyses revealed an essential role of CACNA1A in neurodevelopmental processes. We found that different CACNA1A loss-of-function mutations produce distinct neurodevelopmental deficits. The F1491S mutation, which is located in a constitutive domain of the channel and therefore causes a complete loss-of-function, impaired neural induction at very early stages, as demonstrated by changes in single-cell transcriptomic signatures of neural progenitors, and by defective polarization of neurons. By contrast, cells carrying the Y1854X mutation, which selectively impacts the synaptically-expressed Ca V 2.1[EFa] isoform, behaved normally in terms of neural induction but showed altered neuronal network composition and lack of synchronized activity. Our findings reveal previously unrecognized roles of CACNA1A in the mechanisms underlying neural induction and neural network dynamics and highlight the differential contribution of the divergent variants Ca V 2.1[EFa] and Ca V 2.1[EFb] in the development of human neuronal cells. The online version contains supplementary material available at 10.1007/s00018-025-05740-7.