Biology subjects

Farsi, Z.

Publications and source records attributed to Farsi, Z..

12 recordsLinked to original sources

bioRxiv2025

Spatially resolved translational dysregulation in Grin2a+/- mouse model of schizophrenia

Loss-of-function (LoF) mutations of GRIN2A, encoding the GluN2A subunit of N-methyl-D-aspartate receptor (NMDAR), confer a high risk for schizophrenia (SCZ)1-3, yet how they affect diverse brain cell types remains poorly understood. Here, we combined subcellular-resolution spatial omics technologies, STARmap4 and RIBOmap5, to jointly resolve single-cell transcriptomes and translatomes for 3,447 genes in the brains of Grin2a+/- mice and their wild-type littermates across 538,188 cells. Translational dysregulation was markedly more prominent than transcriptional changes in neurons. Across neuronal subtypes, a set of genes including Camk2a, Arc, Egr1, Egr3, Chmp2b, and Pja2 exhibited translational reduction in a Grin2a gene dose-dependent fashion, suggesting a connection between NMDAR hypofunction and reduced protein synthesis of downstream synaptic plasticity effectors. In interneurons (particularly parvalbumin interneurons), a strong reduction of Gad2 translation implies loss of inhibitory function in cortical microcircuits, which has long been hypothesized for SCZ pathophysiology. Non-neuronal cell types including astrocytes, oligodendrocytes, and vascular cells also exhibited region-specific translational changes in neurotransmitter transport, lipid synthesis, myelination, and stress response pathways, some of which co-varied with regional neuron state. Together, our study reveals brain-wide translation dysregulation as a critical mechanism underlying SCZ pathophysiology.

neuroscience↗

bioRxiv2025

Altered striatal dopamine dynamics and behavior in Grin2a mutant mice, a genetic mouse model of schizophrenia

Schizophrenia (SCZ), a complex psychiatric disorder with a strong genetic basis, is thought to involve, at least in part, dopamine dysregulation in the striatum. Recent large-scale exome sequencing has identified multiple SCZ risk genes, including GRIN2A (encoding an NMDA (N-methyl-D-aspartate) receptor subunit) and AKAP11 (encoding a protein kinase A binding protein), which is also a risk gene for bipolar disorder (BD). However, the mechanisms by which these genetic risk factors perturb dopamine circuits and cause psychotic symptoms remain poorly understood. We asked how behavior, dorsomedial striatal dopamine (DA) dynamics and the activity of D1-/D2-spiny projection neurons (SPNs) were altered in Grin2a and Akap11 mutants. In the open field, Grin2a knockout mice display hyperlocomotion and an abnormal organization of naturalistic behaviors. They also displayed heightened behavioral responses to objects and auditory stimuli. Grin2a heterozygous animals mostly showed intermediate phenotypes, suggesting a dose-dependent effect of Grin2a loss. Further, Grin2a knockout mutants exhibited aberrant dopamine events, altered coupling of dopamine with locomotor features, and exaggerated stimuli-evoked dopamine responses. Notably, heterozygous animals also showed altered striatal SPN events in the open field reflecting dysregulated neural activity in both dSPNs and iSPNs. Compared to Grin2a mutants, Akap11 mutants displayed opposite phenotypes, showing reduced locomotion with a shift from high- to low-velocity movement and distinct alterations in striatal neural activity. Together, GRIN2A (SCZ risk) and AKAP11 (BD/SCZ risk) mutations induce different, often opposite, effects on striatal dopamine signaling and behavior, suggesting that these two risk genes act through distinct mechanisms.

neuroscience↗

bioRxiv2025

Meta-analysis of the brain transcriptomes of multiple genetic mouse models of schizophrenia highlights dysregulation in striatum and thalamus

Schizophrenia is a severe mental illness with high heritability, but its underlying mechanisms are poorly understood. We meta-analyzed large-scale brain transcriptomic data from mice harboring individual loss-of-function mutations in seven schizophrenia risk genes (Akap11, Dagla, Gria3, Grin2a, Sp4, Srrm2, Zmym2). While all studied brain regions were affected, the striatum and the thalamus emerged as key brain regions of convergence. Striatum showed downregulation of synapse-and oxidative phosphorylation-related gene sets in all models. In the thalamus, mutants separated into two groups based on transcriptomic phenotype: synapse-related gene sets were upregulated in mutants with only schizophrenia and bipolar association, and were downregulated in mutants that are associated with developmental delay/intellectual disability in addition to schizophrenia. Overall, our meta-analysis reveals convergence and divergence in brain transcriptomic phenotype in these schizophrenia genetic models, supports the involvement of striatal disturbance and synapse dysfunction in schizophrenia, and points to a key role of the thalamus.

neuroscience↗

bioRxiv2025

Epigenetic changes, neuronal dysregulation and metabolomic abnormalities in Zmym2 mutant mice, a genetic model of schizophrenia and neurodevelopmental disorders

Loss-of-function mutations in ZMYM2 are associated with an increased risk of schizophrenia (SCZ) and neurodevelopmental disorders (NDD). ZMYM2 interacts with proteins involved in histone modification and gene regulation, including LSD1 and ADNP; however, its specific roles in the brain remain poorly understood. In this multi-omics study, we demonstrate that heterozygous knockout of Zmym2 in mice results in widespread disturbances in gene expression affecting diverse molecular pathways, including those related to histone modifications and neuronal activity. Proteomic analysis of synapses reveals dysregulation of lipid metabolism and neurofilament-associated pathways, while metabolomic profiling identifies alterations in sphingomyelin and ceramide levels. Furthermore, Zmym2 mutant mice exhibit abnormal brain oscillation patterns on EEG and locomotor hyperactivity in the open field test. Collectively, these findings underscore the critical role of ZMYM2 in brain development and function and highlight Zmym2 mutant mice as a genetic animal model for SCZ and NDD.

neuroscience↗

bioRxiv2024

Brain-region-specific changes and dysregulation of activity regulated genes in Gria3 mutant mice, a genetic animal model of schizophrenia

Protein-truncating variants in GRIA3 (encoding the GluA3/GluR3 subunit of -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors) are associated with substantially increased risk of schizophrenia (SCZ). Here we characterized Gria3 mutant mice carrying a protein-truncating mutation that mimics a SCZ-associated variant. Transcriptomic analysis revealed that activity-regulated genes are downregulated in cortical regions, while immune and glia-related pathways exhibit brain-region-specific changes. The transcriptomic changes in Gria3 mutant mice are remarkably different from those in Grin2a mutant mice, particularly in the prefrontal cortex, even though both encode glutamate receptors and are associated with SCZ risk. Proteomic analysis further demonstrated that loss-of-function of Gria3 profoundly alters the protein composition of synapses. These findings in a genetic mouse model provide potential insights into the pathophysiological mechanisms underlying SCZ.

neuroscience↗

bioRxiv2024

Reduction of SynGAP-γ, disrupted splicing of Agap3, and oligodendrocyte deficits in Srrm2 mice, a genetic model of schizophrenia and neurodevelopmental disorder

Rare loss-of-function variants in SRRM2, which encodes a nuclear speckle scaffold and splicing factor, are associated with schizophrenia and neurodevelopmental disorders. How SRRM2 haploinsufficiency disrupts brain function is unknown. We find that Srrm2+/- mice exhibit (i) large-scale changes in gene expression in neuronal and glial cells, affecting DNA-binding-, synapse-, translation-, mitochondria-related pathways across multiple brain regions; (ii) alterations in splicing and/or abundance of multiple postsynaptic proteins, including reduction of the gamma isoform of SynGAP and elevation of its interactor, Agap3; and (iii) reduced oligodendrocyte proportions, particularly in striatum, accompanied by decreased expression of myelin-related mRNAs and proteins. Human iPSC-derived neurons deficient in SRRM2 display conserved AGAP3 splicing defects. Behaviorally, Srrm2+/- mice have reduced locomotor activity and impaired startle responses, and EEG recordings reveal reduced sleep spindles resembling humans with schizophrenia. Our findings identify specific synaptic changes, splicing dysregulation, and impaired myelination as mechanisms linking SRRM2 haploinsufficiency to neuropsychiatric disease.

neuroscience↗

bioRxiv2024

Muti-omics characterization reveals brain-wide disruption of synapses and region- and age-specific changes in neurons and glia in Sp4 mutant mice, a genetic model of schizophrenia and bipolar disorder

Schizophrenia and bipolar disorder are highly heritable mental illnesses with unclear pathophysiology. Heterozygous loss-of-function mutations of Sp4, a zinc-finger transcription factor, greatly increase risk of schizophrenia and bipolar disorder. To investigate the molecular functions of Sp4 in an unbiased manner in vivo, we performed multi-omics analyses of Sp4 mutant mice. Bulk and single nucleus RNA-seq data showed prominent gene expression changes in all brain regions and most cell types, including neuronal and non-neuronal cells. Gene set enrichment analysis of transcriptomic changes revealed alterations in many molecular pathways, including synapse, oxidative phosphorylation, and ribosome. Synapse proteomics of Sp4 mutants pointed to impaired glutamatergic signaling and altered presynaptic function. In Sp4 heterozygous mutant mice, prefrontal cortex and striatum exhibited downregulation of synapse pathways and neuronal hypoactivity at 1 month, associated with reduced sterol biosynthesis in astrocytes, whereas at 3 months, there was a shift to neuronal hyperactivity, concurrent with suppressed immune pathways in the striatal microglia. Furthermore, our study found that much of the transcriptomic changes might be accounted for by a set of transcription regulators (Nr3c1, Creb1, and Kdm5b) under the control of Sp4. Overall, this study provides cellular and molecular features resulting from Sp4 LoF that may explain the pathophysiology of SCZ-BD psychotic disorder spectrum.

neuroscience↗

bioRxiv2024

Elevated synaptic PKA activity and abnormal striatal dopamine signaling in Akap11 mutant mice, a genetic model of schizophrenia and bipolar disorder

AbstractLoss-of-function mutations in AKAP11 (a protein kinase A (PKA)-binding protein) greatly increase the risk of bipolar disorder and schizophrenia. To determine the neurobiological functions of AKAP11, we conduct multi-omic and neurobiological analyses of Akap11 mutant mouse brains. We find that AKAP11 is a key regulator of PKA proteostasis in the brain whose loss leads to dramatically increased levels of PKA subunits and phosphorylated PKA substrates, especially in synapses. Akap11 mutant mice show extensive transcriptomic changes throughout the brain, including prominent decreases in synapse-related genes sets. Gene expression is highly impacted in spiny projection neurons of the striatum, a brain region implicated in motivation, cognition and psychotic disorders. Real-time measurements of PKA activity reveal elevated basal PKA activity in the striatum of Akap11-/- mice, with exaggerated additional response to dopamine receptor antagonists. Behaviorally, Akap11 mutant mice show abnormally prolonged locomotor response to amphetamine, deficits in associative learning and contextual discrimination, as well as depression-like behaviors. Our study connects molecular changes to circuit dysfunction and behavioral disturbance in a genetically valid animal model of psychotic disorder.

neuroscience↗

bioRxiv2023

Functional Analysis of Human GRIN2A Mutations Associated with Schizophrenia and Neurodevelopmental Disorders Reveals Distinct Pathological Mechanism

Human genetic studies have revealed rare missense and protein-truncating variants in GRIN2A, encoding for the GluN2A subunit of the NMDA receptors, that confer significant risk for schizophrenia (SCZ). Mutations in GRIN2A are also associated with epilepsy and developmental delay/intellectual disability (DD/ID). However, it remains enigmatic how alterations to the same protein can result in diverse clinical phenotypes. Here, we performed functional characterization of human GluN1/GluN2A heteromeric NMDA receptors that contain SCZ-linked GluN2A variants, and compared them to NMDA receptors with GluN2A variants associated with epilepsy or DD/ID. Our findings demonstrate that SCZ-associated GRIN2A variants were predominantly loss-of-function (LoF), whereas epilepsy and DD/ID-associated variants resulted in both gain- and loss-of-function phenotypes. We additionally show that M653I and S809R, LoF GRIN2A variants associated with DD/ID, exert a dominant-negative effect when co-expressed with a wild-type GluN2A, whereas E58Ter and Y698C, SCZ-linked LoF variants, and A727T, an epilepsy-linked LoF variant, do not. These data offer a potential mechanism by which SCZ/epilepsy and DD/ID-linked variants can cause different effects on receptor function and therefore result in divergent pathological outcomes.

neuroscience↗

bioRxiv2023

miR-7 controls glutamatergic transmission and neuronal connectivity in a Cdr1as-dependent manner

The circular RNA (circRNA) Cdr1as is conserved across mammals and highly expressed in neurons, where it directly interacts with microRNA miR-7. However, the biological function of this interaction is unknown. Here, using primary forebrain murine neurons, we demonstrate that stimulating neurons by sustained depolarization rapidly induced two-fold transcriptional up-regulation of Cdr1as and strong post-transcriptional stabilization of miR-7. Cdr1as loss caused doubling of glutamate release from stimulated synapses and increased frequency and duration of local neuronal bursts. Moreover, periodicity of neuronal networks was increased and synchronicity was impaired. Strikingly, these effects were reverted by sustained expression of miR-7 which also cleared Cdr1as molecules from neuronal projections. Consistently, without Cdr1as, transcriptomic changes caused by miR-7 overexpression were stronger (including miR-7-targets down-regulation) and enriched in secretion/synaptic plasticity pathways. Altogether, our results suggest that in forebrain neurons Cdr1as buffers miR-7 activity to control glutamatergic excitatory transmission and neuronal connectivity important for long-lasting synaptic adaptations.

molecular biology↗

bioRxiv2022

Brain region-specific changes in neurons and glia and dysregulation of dopamine signaling in Grin2a mutant mice

Schizophrenia disease mechanisms remain poorly understood, in large part due to a lack of valid animal models. Rare heterozygous loss-of-function mutations in GRIN2A, encoding a subunit of the NMDA (N-methyl-d-aspartate) receptor, greatly increase the risk of schizophrenia. By transcriptomic, proteomic, electroencephalogram (EEG) recording and behavioral analysis, we report that heterozygous Grin2a mutant mice show: (i) large-scale gene expression changes across multiple brain regions and in neuronal (excitatory and inhibitory) and non-neuronal cells (astrocytes, oligodendrocytes); (ii) evidence of reduced activity in prefrontal cortex and increased activity in hippocampus and striatum; (iii) elevated dopamine signaling in striatum; (iv) altered cholesterol biosynthesis in astrocytes; (v) reduction of glutamatergic receptor signalin g proteins in the synapse; (iv) heightened gamma oscillation power in EEG; (vi) aberrant locomotor behavioral pattern opposite of that induced by antipsychotic drugs. These findings reveal potential pathophysiologic mechanisms, provide support for both the "hypo-glutamate" and "hyper-dopamine" hypotheses of schizophrenia, and underscore the utility of Grin2a-deficient mice as a new genetic model of schizophrenia.

neuroscience↗

bioRxiv2022

Mouse mutants in schizophrenia risk genes GRIN2A and AKAP11 show EEG abnormalities in common with schizophrenia patients

BACKGROUNDSchizophrenia is a heterogeneous psychiatric disorder with a strong genetic basis, whose etiology and pathophysiology remain poorly understood. Exome sequencing studies have uncovered rare, loss-of-function variants that greatly increase risk of schizophrenia [1], including loss-of-function mutations in GRIN2A (aka GluN2A or NR2A, encoding the NMDA receptor subunit 2A) and AKAP11 (A-Kinase Anchoring Protein 11). AKAP11 and GRIN2A mutations are also associated with bipolar disorder [2], and epilepsy and developmental delay/intellectual disorder [1, 3, 4], respectively. Accessible in both humans and rodents, electroencephalogram (EEG) recordings offer a window into brain activity and display abnormal features in schizophrenia patients. Does loss of Grin2a or Akap11 in mice also result in EEG abnormalities? METHODSWe monitored EEG in heterozygous and homozygous knockout Grin2a and Akap11 mutant mice compared with their wild-type littermates, at 3- and 6-months of age, across the sleep/wake cycle and during auditory stimulation protocols. RESULTSGrin2a and Akap11 mutants exhibited increased resting gamma power, attenuated 40-50 Hz auditory steady-state responses (ASSR), and reduced responses to unexpected auditory stimuli during mismatch negativity (MMN) tests. Sleep spindle density was reduced in a gene dose-dependent manner in Akap11 mutants, whereas Grin2a mutants showed increased sleep spindle density. CONCLUSIONSThe EEG phenotypes of Grin2a and Akap11 mutant mice show a variety of abnormal features that overlap considerably with human schizophrenia patients, reflecting systems-level changes caused by Grin2a and Akap11 deficiency. These neurophysiologic findings further substantiate Grin2a and Akap11 mutants as genetic models of schizophrenia and identify potential biomarkers for stratification of schizophrenia patients.

neuroscience↗