Garcia-Corral, M. | Search bioRxiv

bioRxiv2025

Altered Protein Phosphorylation in a Novel Midbrain Organoid Model for Bipolar Disorder

Bipolar disorder (BD) is a severe psychiatric condition marked by episodes of mania and depression, with neurotransmitter imbalance in the midbrain believed to play a critical role in its pathophysiology. Despite this, there is currently no validated midbrain model for examining BD-associated molecular changes available. Leveraging recent advances in stem cell technology, we developed a midbrain organoid model using human induced pluripotent stem cells (hiPSCs) from BD patients and healthy controls (CTR). To address issues of variability and enhance the throughput in organoid production, we implemented liquid handling and high-content imaging techniques. Quality control metrics were established to identify organoids unsuitable for further study. Electrophysiological analysis via high-density microelectrode arrays (MEAs) revealed significantly elevated neuronal properties in individual BD organoids, including increased mean amplitude, conduction velocity, and extended axonal and dendritic growth. Transcriptome and proteome analyses indicated significant dysregulation of BD-relevant signaling pathways--such as those involving phosphatidylinositol, glycogen synthase kinase-3 beta, and AKT. Notably, we identified dysregulated casein kinase 2 (CSNK2A1) and calmodulin 3 (CALM3) in BD organoids, which were reversed by lithium treatment, highlighting potential novel targets for therapeutic intervention. This study validates the midbrain organoid model as a valuable tool for exploring the molecular underpinnings of BD and identifying new treatment avenues.

cell biology↗

bioRxiv2022

Iterative transcription factor screening enables rapid generation of microglia-like cells from human iPSC

The ability to differentiate stem cells into human cell types is essential to define basic mechanisms and therapeutics, especially for cell types not routinely accessible by biopsies. But while engineered expression of transcription factors (TFs) identified through TF screens has been found to rapidly and efficiently produce some cell types, generation of other cell types that require complex combinations of TFs has been elusive. Here we develop an iterative, pooled single-cell TF screening method that improves the identification of effective TF combinations using the generation of human microglia-like cells as a testbed: Two iterations identified a combination of SPI1, CEBPA, FLI1, MEF2C, CEBPB, and IRF8 as sufficient to differentiate human iPSC into microglia-like cells in 4 days. Characterization of TF-induced microglia demonstrated molecular and functional similarity to primary microglia. We explore the use of single-cell atlas reference datasets to confirm identified TFs and how combining single-cell TF perturbation and gene expression data can enable the construction of causal gene regulatory networks. We describe what will be needed to fashion these methods into a generalized integrated pipeline, further ideas for enhancement, and possible applications.

bioengineering↗