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Introduction: The main finding of a large-scale collaborative study (Rees et al. Nat Neurosci 2020;23(2) 179-184), which focused on  de novo  mutations in schizophrenia, was the discovery of an enrichment of these mutations in the  SLC6A1  gene. This gene encodes the gamma-aminobutyric acid (GABA) transporter GAT1, thereby encouraging further research into novel schizophrenia targets within the GABA pathway. However, the gene was not highlighted in recent schizophrenia genetic studies, while typically pathogenic  SLC6A1  mutations result in epilepsy, motor dysfunction, autistic spectrum disorder (ASD) and developmental delay. The absence of genetic replication for  SLC6A1 's involvement in schizophrenia and the differing clinical spectrum for  SLC6A1  mutations led us to study in depth one of the only three original probands from the Rees et al. 2020 study. Objectives: In our comprehensive case study, we delved deep into the relationship between the SLC6A1 mutation and schizophrenia. Methods: Our subject, a patient who first presented with acute mania symptoms at age 15 and was later diagnosed with schizophrenia, carried the SLC6A1 Arg211Cys mutation. Over a detailed 25-year follow-up, we conducted an array of assessments and tests, including cognitive testing, personality assessments, EEG, and 1H-MRS. Results: Notably, we discovered abnormal GABA levels, potentially indicating a dysfunction in GABA reuptake, adding a new layer of complexity to our understanding. Further analysis revealed a significant correlation between the patient's clinical picture and a polygenic background, rather than the SLC6A1 mutation. Despite having a high polygenic risk score for bipolar disorder, the dominant features of his condition were more representative of schizophrenia. Interestingly, neither the patient nor his father, who also showed a higher BP PRS, had a diagnosis of bipolar disorder. The pathogenic significance of the mutation warrants investigation in cells of neuronal origin. We generated induced pluripotent stem cells (iPSC) from the patient and his parents. This approach provides us with a platform for future investigations into the pathogenic significance of the mutation in neuronal cells. The Human Pluripotent Stem Cell Registry accession numbers of those cells are MHRCCGi001-A (patient), MHRCCGi005-A (mother) and MHRCCGi004-A (father). Conclusions: In the presented case the clinical picture is rather explained by the polygenic background than by the SLC6A1 Arg211Cys mutation. The study is supported by Russian Science Foundation, grant 21-15-00124 (https://rscf.ru/project/21-15-00124) Disclosure of Interest: None Declared [ABSTRACT FROM AUTHOR]

Introduction: ASCL1 (Achaete-scute homolog 1) is a neuron-specific transcription factor involved in CNS maturation in the mammalian brain. It has been shown to be associated with schizophrenia (SZ), Parkinson's disease, and the development of brain tumors. ASCL1 is expressed in the neuroblastoma cell line SH-SY5Y, which is a widely used model for the study of neurodevelopmental diseases, including SZ. Objectives: The aim of this work was to study the effect of functional ASCL1 knockout on the transcriptional landscape of SH-SY5Y cells in undifferentiated and neuron-like phenotypes. Methods: For ASCL1 deletion, SH-SY5Y was sequentially transduced with two lentiviral vectors. One pLV-rtTA-Cas9-(nls)-pCMV-eGFP-PuroR-T2A-rTetR (derived from pCW-Cas9 and pEGFP-Puro) construct encoded Cas9. Stably transduced lines were selected for 3-5 days on puromycin (2 g/L). The inducibility of Cas9 expression was checked after adding the inducer oxytetracycline to the culture medium. The second construct (based on pLK05-tagRFP) encoded, a pair of guide RNAs targeting the start and end of the ASCL1 gene. The sgRNA construct was transduced into the SH-SY5Y-Cas9 cell line in parallel with a nontemplate control (NTC gRNA) as a negative control. Cas9 expression was induced with oxytetracycline for 2 days. Individual clones were obtained by serial dilutions. ASCL1 partial deletion in the clones was confirmed by PCR followed by Sanger sequencing. Disruption of ASCL1 protein synthesis was confirmed by western blot analysis. SH-SY5Y differentiation was induced by retinoic acid (RA). The transcriptomes of mutant clones and NTC controls before and after RA-induced differentiation were sequenced using Illumina technology. Results: RNAseq data show that a wide range of genes are differentially expressed between control NTC gRNA and wild-type SH-SY5Y. This can be explained by insertional mutagenesis of lentiviral vectors and/or cellular response to the presence of lentiviral constructs. Therefore, we compared the transcriptomes of the ASCL1-del line with NTC control. Differentially expressed genes (DEGs) are predominantly associated with the pathogenesis of SZ, bipolar and depressive disorders. DEGs in ASCL1-del are involved in cell mitosis, neuronal projection, neuropeptide signaling, and formation of intercellular contacts including the synapse. During RA-induced differentiation, ASCL1 activity is restricted to the regulation of a small subset of genes involved in neuroplasticity. Conclusions: We have established a valid cellular model to study ASCL1-mediated mechanisms associated with SZ. ASCL1 dysfunction promotes SZ development predominantly before neuronal differentiation begins, slowing cell proliferation and preventing the formation of neuronal signatures. Disclosure of Interest: None Declared [ABSTRACT FROM AUTHOR]

Introduction: Understanding the relations between genetic (G) and environmental (E) factors in the development of schizophrenia is important for psychosis prevention. These relations may vary from G x E correlations to G x E interactions and independent additive effects of genetic load and environment. The G x E interactions mean that genetic variants associated with schizophrenia make an individual vulnerable to specific environmental exposures thus enhancing the risk of disease manifestation in those who possess such genetic variants. In the case of independent effects, environmental exposure might serve as the main cause or an additional to genetic load external trigger which is needed for the illness development. Thus, the rate of independent environmental risk factors is expected to be higher in patients with a lower genetic liability to schizophrenia. Objectives: The study aimed to confirm this hypothesis by comparing schizophrenia patients with higher and lower polygenic risk scores for schizophrenia (SZ-PRS) on the rate of urbanicity, winter birth and obstetric complications (OC), as previous data suggested their independence from the genetic burden of the disease. Methods: SZ-PRS were calculated for 861 patients with schizophrenia spectrum diagnoses (ICD-10, F2), predominantly of Slavic decent, based on the latest GWAS. For patients comprising the highest and lowest SZ-PRS deciles, information on the environmental risk factors was extracted from medical records. Each environmental factor was coded as present/absent. The presence were defined as being born in the most urban environment (a city's population > 5 million), in winter months and having at least one OC from a predefined list (Alfimova et al. Int J Mol Sci 2022; 23: 12629). In addition, hypoxia/asphyxia, and low birth weight were analyzed separately. Polyenvirommental risk scores (PERS) aggregating the three factors were calculated using natural logarithms of the odds ratios (OR) from an umbrella review (Radua et al. World Psychiatry 2018; 17: 49-66). Logistic regression adjusted for ancestry-related principal components, demographic, and technical variables was applied to compare the SZ-PRS deciles on each factor and PERS. Results: None of the factors alone or PERS predicted SZ-PRS decile membership. Conclusions: The results did not support the hypothesis. Future research needs reliable data on the frequency of the studied factors in the general population where the patients come from.The study was supported by the Russian Science Foundation, grant no. 21-15-00124. Disclosure of Interest: None Declared [ABSTRACT FROM AUTHOR]

Introduction: Schizophrenia (SZ) is a common psychiatric neurodevelopmental disorder with a complex genetic architecture. Genomic association studies indicate the involvement of transcription factors in the pathogenesis of SZ. A recent GWAS showed a significant association of ZNF536 with SZ. To date, the molecular functions of ZNF536 are poorly understood and its possible role in the pathogenesis of SZ is unclear. Objectives: The aim of this work was to develop a model cell line for study ZNF536-mediated pathogenic mechanisms associated with SZ. Methods: To assess the spatial interaction of ZNF536 with SZ risk loci, we used the Capture-C method. For ZNF536 deletion, SH-SY5Y was sequentially transduced with two lentiviral vectors. The first expressed Cas9 under the control of a tetracycline regulated promoter and the second expressed a pair of sgRNAs for ZNF536 deletion. Puromycin was used to select transduced cells. Stably transduced cells were then treated with oxytetracycline to induce Cas9 expression. In parallel, SH-SY5Y were transduced with lentiviral constructs of Cas9 and sgRNA carrying a spacer lacking targets in the human genome to obtain a negative control. Individual clones were obtained by the limiting dilution method. The ZNF536 deletion was confirmed by PCR and Sanger sequencing. Results: A spatial interaction of ZNF536 with SZ risk loci was found, suggesting its involvement in SZ pathogenesis. Using the CRISPR/Cas9 system, we obtained several clones with heterozygous deletion of ZNF536. We observed that their growth and proliferation were significantly slowed down. In addition, the mutant clones spontaneously differentiate into a neuron-like phenotype in low-serum medium. Conclusions: We established a cellular model to study ZNF536-mediated mechanisms associated with SZ. Disclosure of Interest: None Declared [ABSTRACT FROM AUTHOR]

Introduction: Negative symptoms (NS) are an important clinical characteristic of schizophrenia. In recent years, clinical research on NS has focused on their clinical heterogeneity. Based on two-factor analysis, it has been proposed to divide NS into abulia-apathy (AA) and expressive deficit (ED) domains. A number of studies have shown that these domains have different effects on the clinical features of schizophrenia, which suggests different pathophysiological mechanisms of their development. Neurobiological differences between AA and DE have been identified in neuroimaging and immunological studies but there is less research on the genetic background of NS. Objectives: To search for an association between the rs1344706 polymorphism of the zinc finger protein gene (ZNF804A) and the AA and ED subdomains. The rs1344706 polymorphism is one of the best-supported risk variants for schizophrenia. The risk genotype AA has been shown to be associated with clinical presentations of the disease. Methods: The study included 1116 (741 (66.3% women) patients with schizophrenia. The diagnosis was made according to ICD-10 criteria (item F20). The average age of the patients was 38.4 (13.6) years, age at disease onset was 26.1 (10.6) years. NS were assessed with the PANSS. The PANSS-derived AA domain consisted of Emotional withdrawal (PANSS item N2), Apathetic social withdrawal (N4), Active social avoidance (G16). The DE domain included Blunted affect (N1), Poor rapport (N3), Lack of spontaneity (N6), Mannerism and posturing (G5), Motor retardation (G7), Disturbance of volition (G13). Genotyping of the ZNF804A rs1344706 polymorphism was carried out using HRM-PCR. ANOVA with genotype and sex as independent variables, and age at the time of disease manifestation and its duration as covariates was used. Post hoc tests were performed using Bonferroni correction. Results: A significant effect of the rs1344706 polymorphism on the severity of symptoms in the AA domain was revealed (F=5.88, df=2, p=0.002). In carriers of the CC genotype, the severity of symptoms was significantly lower than in carriers of the AA genotype and the AC genotype (8.4(3.5), 9.4(7.4) and 8.8(3.5) points, respectively). This effect was independent of sex and was not mediated by age at onset or duration of disease. There was no effect of the rs1344706 polymorphism on the severity of symptoms in the ED domain. Conclusions: The association of the ZNF804A rs1344706 (A/C) polymorphism with NS of schizophrenia has not been reported so far though some studies have found the effect of this polymorphism on  PANSS positive symptoms and PANSS total score. The finding of the association with NS can be explained by the fact that the NS heterogeneity was taken into account in the present study. Disclosure of Interest: None Declared [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stromal cells (MSCs) are recognized for their potential in regenerative medicine, attributed to their multipotent differentiation capabilities and immunomodulatory properties. Despite this potential, the classification and detailed characterization of MSCs, especially those derived from specific tissues like the pancreas, remains challenging leading to a proliferation of terminology in the literature. This study aims to address these challenges by providing a thorough characterization of human pancreatic islets-derived mesenchymal stromal cells (hPD-MSCs)., Methods: hPD-MSCs were isolated from donor islets using enzymatic digestion, immortalized through lentiviral transduction of human telomerase reverse transcriptase (hTERT). Cells were characterized by immunostaining, flow cytometry and multilineage differentiation potential into adipogenic and osteogenic lineages. Further a transcriptomic analysis was done to compare the gene expression profiles of hPD-MSCs with other mesenchymal cells., Results: We show that hPD-MSCs express the classical MSC features, including morphological characteristics, surface markers expression (CD90, CD73, CD105, CD44, and CD106) and the ability to differentiate into both adipogenic and osteogenic lineages. Furthermore, transcriptomic analysis revealed distinct gene expression profiles, showing notable similarities between hPD-MSCs and pancreatic stellate cells (PSCs). The study also identified specific genes that distinguish hPD-MSCs from MSCs of other origins, including genes associated with pancreatic function (e.g., ISL1) and neural development (e.g., NPTX1, ZNF804A). A novel gene with an unknown function (ENSG00000286190) was also discovered., Conclusions: This study enhances the understanding of hPD-MSCs, demonstrating their unique characteristics and potential applications in therapeutic strategies. The identification of specific gene expression profiles differentiates hPD-MSCs from other mesenchymal cells and opens new avenues for research into their role in pancreatic function and neural development., (© 2024. The Author(s).)

Objective: To evaluate the association of polymorphisms in the TAAR1-9 gene cluster on chromosome 6 with cognitive functions in patients with schizophrenia spectrum disorders and healthy controls., Material and Methods: Patients with schizophrenia spectrum disorders ( n =216) and healthy people without a family history of mental disorders ( n =240) completed a battery of cognitive tests, from which individual indices of cognitive functioning were derived. Associations of the cognitive index with 22 polymorphisms in the TAAR genes were assessed using ANCOVA controlling for sex, age, genetic structure of the sample, and polygenic risk scores of schizophrenia and intelligence., Results: An interaction effect between group and genotype on the cognitive index was found at the rs3813355 site in the TAAR5 gene (F=6.68; p =0.010; η 2 p =0.02). A post hoc analysis revealed genotype-related differences in the patient group. Homozygotes for the common A allele had a milder cognitive deficit than carriers of the minor G allele ( t =2.75; p =0.032; Cohen's d=0.38). The effect of genotype on cognitive index remained significant after the inclusion of disease duration and negative symptoms in the model (F=7.99; p =0.005; η 2 p =0.04). Of the individual cognitive indicators, associations with genotype were found for working memory and attention (F=8.25; p =0.005; η 2 p=0.05), cognitive flexibility (F=5.82; p =0.017; η 2 p =0.05) and verbal episodic memory (F=6.75; p =0.011; η 2 p =0.05)., Conclusion: The results are consistent with the assumption of the role of the TAAR5 genetic polymorphism in the variability of cognitive deficits in patients with schizophrenia.