The cellular pathology of schizophrenia and the potential of antipsychotics to target underlying neuronal dysfunctions are still largely unknown. We employed glutamatergic neurons derived from induced pluripotent stem cells (iPSC) obtained from schizophrenia patients with known histories of response to clozapine and healthy controls to decipher the mechanisms of action of clozapine, spanning from molecular (transcriptomic profiling) and cellular (electrophysiology) levels to observed clinical effects in living patients. Glutamatergic neurons derived from schizophrenia patients exhibited deficits in intrinsic electrophysiological properties, synaptic function and network activity. Deficits in K+ and Na+ currents, network behavior, and glutamatergic synaptic signaling were restored by clozapine treatment, but only in neurons from clozapine-responsive patients. Moreover, neurons from clozapine-responsive patients exhibited a reciprocal dysregulation of gene expression, particularly related to glutamatergic and downstream signaling, which was reversed by clozapine treatment. Only neurons from clozapine responders showed return to normal function and transcriptomic profile. Our results underscore the importance of K+ and Na+ channels and glutamatergic synaptic signaling in the pathogenesis of schizophrenia and demonstrate that clozapine might act by normalizing perturbances in this signaling pathway. To our knowledge this is the first study to demonstrate that schizophrenia iPSC-derived neurons exhibit a response phenotype correlated with clinical response to an antipsychotic. This opens a new avenue in the search for an effective treatment agent tailored to the needs of individual patients.

• Publication type
• Journal Article MeSH

Astrocytes are the most abundant cell type in the human brain and are important regulators of several critical cellular functions, including synaptic transmission. Although astrocytes are known to play a central role in the etiology and pathophysiology of schizophrenia, little is known about their potential involvement in clinical response to the antipsychotic clozapine. Moreover, astrocytes display a remarkable degree of morphological diversity, but the potential contribution of astrocytic subtypes to disease biology and drug response has received little attention. Here, we used state-of-the-art human induced pluripotent stem cell (hiPSC) technology to derive a morphological subtype of astrocytes from healthy individuals and individuals with schizophrenia, including responders and nonresponders to clozapine. Using functional assays and transcriptional profiling, we identified a distinct gene expression signature highly specific to schizophrenia as shown by disease association analysis of more than 10 000 diseases. We further found reduced levels of both glutamate and the NMDA receptor coagonist d-serine in subtype astrocytes derived from schizophrenia patients, and that exposure to clozapine only rescued this deficiency in cells from clozapine responders, providing further evidence that d-serine in particular, and NMDA receptor-mediated glutamatergic neurotransmission in general, could play an important role in disease pathophysiology and clozapine action. Our study represents a first attempt to explore the potential contribution of astrocyte diversity to schizophrenia pathophysiology using a human cellular model. Our findings suggest that specialized subtypes of astrocytes could be important modulators of disease pathophysiology and clinical drug response, and warrant further investigations.

• MeSH
• Antipsychotic Agents pharmacology   MeSH
• Astrocytes metabolism   MeSH
• Adult MeSH
• Induced Pluripotent Stem Cells MeSH
• Clozapine pharmacology   MeSH
• Glutamic Acid metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Schizophrenia drug therapy   metabolism   MeSH
• Serine metabolism   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Neural rosette formation is a critical morphogenetic process during neural development, whereby neural stem cells are enclosed in rosette niches to equipoise proliferation and differentiation. How neural rosettes form and provide a regulatory micro-environment remains to be elucidated. We employed the human embryonic stem cell-based neural rosette system to investigate the structural development and function of neural rosettes. Our study shows that neural rosette formation consists of five types of morphological change: intercalation, constriction, polarization, elongation and lumen formation. Ca2+ signaling plays a pivotal role in the five steps by regulating the actions of the cytoskeletal complexes, actin, myosin II and tubulin during intercalation, constriction and elongation. These, in turn, control the polarizing elements, ZO-1, PARD3 and β-catenin during polarization and lumen production for neural rosette formation. We further demonstrate that the dismantlement of neural rosettes, mediated by the destruction of cytoskeletal elements, promotes neurogenesis and astrogenesis prematurely, indicating that an intact rosette structure is essential for orderly neural development.

• MeSH
• Actins metabolism   MeSH
• Apoptosis drug effects   MeSH
• Cell Lineage drug effects   MeSH
• Cytoskeleton drug effects   metabolism   MeSH
• Humans MeSH
• Human Embryonic Stem Cells cytology   drug effects   metabolism   MeSH
• Myosin Type II metabolism   MeSH
• Neural Stem Cells cytology   drug effects   metabolism   MeSH
• Neurogenesis drug effects   MeSH
• Neurons cytology   drug effects   metabolism   ultrastructure   MeSH
• Cell Polarity drug effects   MeSH
• Zonula Occludens-1 Protein metabolism   MeSH
• Cell Shape * drug effects   MeSH
• Rosette Formation * MeSH
• Calcium pharmacology   MeSH
• Calcium Signaling * drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

This study elucidated the stage-specific roles of FGF2 signaling during neural development using in-vitro human embryonic stem cell-based developmental modeling. We found that the dysregulation of FGF2 signaling prior to the onset of neural induction resulted in the malformation of neural rosettes (a neural tube-like structure), despite cells having undergone neural induction. The aberrant neural rosette formation may be attributed to the misplacement of ZO-1, which is a polarized tight junction protein and shown co-localized with FGF2/FGFR1 in the apical region of neural rosettes, subsequently led to abnormal neurogenesis. Moreover, the FGF2 signaling inhibition at the stage of neural rosettes caused a reduction in cell proliferation, an increase in numbers of cells with cell-cycle exit, and premature neurogenesis. These effects may be mediated by NUMB, to which expression was observed enriched in the apical region of neural rosettes after FGF2 signaling inhibition coinciding with the disappearance of PAX6+/Ki67+ neural stem cells and the emergence of MAP2+ neurons. Moreover, our results suggested that the hESC-based developmental system reserved a similar neural stem cell niche in vivo.

• MeSH
• Cell Differentiation drug effects   MeSH
• Cell Line MeSH
• Time-Lapse Imaging MeSH
• Chromones pharmacology   MeSH
• Fibroblast Growth Factor 2 pharmacology   MeSH
• Immunohistochemistry MeSH
• Humans MeSH
• Human Embryonic Stem Cells cytology   metabolism   MeSH
• RNA, Small Interfering metabolism   MeSH
• Membrane Proteins metabolism   MeSH
• Morpholines pharmacology   MeSH
• Neural Stem Cells cytology   metabolism   MeSH
• Neurogenesis drug effects   MeSH
• Neurons cytology   metabolism   MeSH
• Zonula Occludens-1 Protein antagonists & inhibitors   genetics   metabolism   MeSH
• Microtubule-Associated Proteins metabolism   MeSH
• Nerve Tissue Proteins metabolism   MeSH
• Pyrimidines pharmacology   MeSH
• Receptor, Fibroblast Growth Factor, Type 1 metabolism   MeSH
• RNA Interference MeSH
• Signal Transduction drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

During embryogenesis, the Activin/Nodal pathway promotes the mesendodermal lineage and inhibits neural fate. The molecular mechanisms underlying this role of the Activin/Nodal pathway are not clear. In this study, we report a role for protein tyrosine phosphatase 1B (PTP1B) in Activin-mediated early fate decisions during ESC differentiation and show that PTP1B acts as an effector of the Activin pathway to specify mesendodermal or neural fate. We found that the Activin/ALK4 pathway directly recruits PTP1B and stimulates its release from the endoplasmic reticulum through ALK4-mediated cleavage. Subsequently, PTP1B suppresses p-ERK1/2 signaling to inhibit neural specification and promote mesendodermal commitment. These findings suggest that a noncanonical Activin signaling pathway functions in lineage specification of mouse and human embryonic stem cells.

• MeSH
• Activin Receptors, Type I chemistry   metabolism   MeSH
• Activins metabolism   MeSH
• Benzamides pharmacology   MeSH
• Cell Differentiation * drug effects   MeSH
• Cell Lineage drug effects   MeSH
• Dioxoles pharmacology   MeSH
• Embryonic Stem Cells cytology   drug effects   enzymology   MeSH
• Endoderm cytology   drug effects   metabolism   MeSH
• Extracellular Signal-Regulated MAP Kinases metabolism   MeSH
• Phosphorylation drug effects   MeSH
• Humans MeSH
• MAP Kinase Signaling System drug effects   MeSH
• Mesoderm cytology   drug effects   metabolism   MeSH
• Molecular Sequence Data MeSH
• Mice MeSH
• Neurons cytology   drug effects   metabolism   MeSH
• Pluripotent Stem Cells cytology   drug effects   metabolism   MeSH
• Smad2 Protein metabolism   MeSH
• Amino Acid Sequence MeSH
• Signal Transduction * drug effects   MeSH
• Protein Tyrosine Phosphatase, Non-Receptor Type 1 metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH