Two-step association analyses of the chromosome 18p11.2 region in schizophrenia detect a locus encompassing C18orf1

Impact of gene-by-trauma interaction in MDD-related multimorbidity clusters

BACKGROUND

Major depressive disorder (MDD) is considerably heterogeneous in terms of comorbidities, which may hamper the disentanglement of its biological mechanism. In a previous study, we classified the lifetime trajectories of MDD-related multimorbidities into seven distinct clusters, each characterized by unique genetic and environmental risk-factor profiles. The current objective was to investigate genome-wide gene-by-environment (G × E) interactions with childhood trauma burden, within the context of these clusters.

METHODS

We analyzed 77,519 participants and 6,266,189 single-nucleotide polymorphisms (SNPs) of the UK Biobank database. Childhood trauma burden was assessed using the Childhood Trauma Screener (CTS). For each cluster, Plink 2.0 was used to calculate SNP × CTS interaction effects on the participants' cluster membership probabilities. We especially focused on the effects of 31 candidate genes and associated SNPs selected from previous G × E studies for childhood maltreatment's association with depression.

RESULTS

At SNP-level, only the high-multimorbidity Cluster 6 revealed a genome-wide significant SNP rs145772219. At gene-level, MPST and PRH2 were genome-wide significant for the low-multimorbidity Clusters 1 and 3, respectively. Regarding candidate SNPs for G × E interactions, individual SNP results could be replicated for specific clusters. The candidate genes CREB1, DBH, and MTHFR (Cluster 5) as well as TPH1 (Cluster 6) survived multiple testing correction.

LIMITATIONS

CTS is a short retrospective self-reported measurement. Clusters could be influenced by genetics of individual disorders.

CONCLUSIONS

The first G × E GWAS for MDD-related multimorbidity trajectories successfully replicated findings from previous G × E studies related to depression, and revealed risk clusters for the contribution of childhood trauma.

Novel Peptide DR3penA as a Low-Toxicity Antirenal Fibrosis Agent by Suppressing the TGF-β1/miR-212-5p/Low-Density Lipoprotein Receptor Class a Domain Containing 4/Smad Axis

Renal fibrosis is a complex pathological process that contributes to the development of chronic kidney disease due to various risk factors. Conservative treatment to curb progression without dialysis or renal transplantation is widely applicable, but its effectiveness is limited. Here, the inhibitory effect of the novel peptide DR3penA (DHα-(4-pentenyl)-AlaNPQIR-NH2), which was developed by our group, on renal fibrosis was assessed in cells and mice with established fibrosis and fibrosis triggered by transforming growth factor-β1 (TGF-β1), unilateral ureteral obstruction, and repeated low-dose cisplatin. DR3penA preserved renal function and ameliorated renal fibrosis at a dose approximately 100 times lower than that of captopril, which is currently used in the clinic. DR3penA also significantly reduced existing fibrosis and showed similar efficacy after subcutaneous or intraperitoneal injection. Mechanistically, DR3penA repressed TGF-β1 signaling via miR-212-5p targeting of low-density lipoprotein receptor class a domain containing 4, which interacts with Smad2/3. In addition to having good pharmacological effects, DR3penA could preferentially target injured kidneys and exhibited low toxicity in acute and chronic toxicity experiments. These results unveil the advantages of DR3penA regarding efficacy and toxicity, making it a potential candidate compound for renal fibrosis therapy.

DNA methylation changes in association with trauma-focused psychotherapy efficacy in treatment-resistant depression patients: a prospective longitudinal study

Background: Stressful events increase the risk for treatment-resistant depression (TRD), and trauma-focused psychotherapy can be useful for TRD patients exposed to early life stress (ELS). Epigenetic processes are known to be related to depression and ELS, but there is no evidence of the effects of trauma-focused psychotherapy on methylation alterations.Objective: We performed the first epigenome-wide association study to investigate methylation changes related to trauma-focused psychotherapies effects in TRD patients.Method: Thirty TRD patients assessed for ELS underwent trauma-focused psychotherapy, of those, 12 received trauma-focused cognitive behavioural therapy, and 18 Eye Movement Desensitization and Reprocessing (EMDR). DNA methylation was profiled with Illumina Infinium EPIC array at T0 (baseline), after 8 weeks (T8, end of psychotherapy) and after 12 weeks (T12 - follow-up). We examined differentially methylated CpG sites and regions, as well as pathways analysis in association with the treatment.Results: Main results obtained have shown 110 differentially methylated regions (DMRs) with a significant adjusted p-value area associated with the effects of trauma-focused psychotherapies in the entire cohort. Several annotated genes are related to inflammatory processes and psychiatric disorders, such as LTA, GFI1, ARID5B, TNFSF13, and LST1. Gene enrichment analyses revealed statistically significant processes related to tumour necrosis factor (TNF) receptor and TNF signalling pathway. Stratified analyses by type of trauma-focused psychotherapy showed statistically significant adjusted p-value area in 141 DMRs only for the group of patients receiving EMDR, with annotated genes related to inflammation and psychiatric disorders, including LTA, GFI1, and S100A8. Gene set enrichment analyses in the EMDR group indicated biological processes related to inflammatory response, particularly the TNF signalling pathway.Conclusion: We provide preliminary valuable insights into global DNA methylation changes associated with trauma-focused psychotherapies effects, in particular with EMDR treatment.

Schizophrenia, antipsychotics and diabetes: Genetic aspects

The relatively high comorbidity of type 2 diabetes and schizophrenia may suggest a shared biological susceptibility to these twoconditions. Family studies have demonstrated an increased risk of diabetes in unaffected relatives of patients with schizophrenia, consistent with a heritable susceptibility trait. Linkage analyses have identified several loci that are associated with schizophrenia and some of these, notably those on chromosomes 2p22.1-p13.2 and 6g21-824.1 have also been observed in linkage studies in type 2 diabetes. In addition, the dopamine D5 receptor on chromosome 5 and the tyrosine hydroxylase gene on chromosome 11 have both been suggested as candidate genes in schizophrenia and may also be implicated in susceptibility to poor glycaemic control. In addition, an increased rate of type II diabetes has been observed in some patients treated with antipsychotics. Potential neurochemical substrates of this effect include the histamine H1 receptor, the 5-HT2C serotonin receptor or the β3 adrenoreceptor. However, the search for a genetic basis to the association between diabetes and schizophrenia is still in its infancy, and much further work needs to be performed, including the systematic screening of all confirmed susceptibility loci and quantitative trait locus mapping of glycaemic control.

Low density lipoprotein receptor class A domain containing 4 (LDLRAD4) promotes tumorigenesis of hepatic cancer cells

LDLRAD4 was previously identified and shown to be connected with psychiatric disorders. The structure of LDLRAD4 protein is similar to that of TMEPAI protein, which is overexpressed in many tumors. However, it is still unknown whether LDLRAD4 is involved in tumorigenesis. In this study, the potential role of LDLRAD4 in tumorigenesis was investigated. LDLRAD4 is elevated in hepatic cancer cells and tumor tissues, and expression of LDLRAD4 promotes hepatic cancer cell HepG2 and SMMC-7721 proliferation and migration. LDLRAD4 interacts Nedd4 to promote cell proliferation and migration and negatively regulates the TGF-β signaling. Furthermore, immunofluorescence microscopy analysis indicates that LDLRAD4 is localized to the lysosome and association with Nedd4 is necessary for its intracellular transport to the lysosome. In addition, depletion of LDLRAD4 in HepG2 liver cancer cells inhibited tumorigenesis in nude mice. These results reveal an oncogenic role of LDLRAD4 in tumorigenesis through its association with Nedd4.

C18 ORF1, a novel negative regulator of transforming growth factor-β signaling

Transforming growth factor (TGF)-β signaling is deliberately regulated at multiple steps in its pathway from the extracellular microenvironment to the nucleus. However, how TGF-β signaling is activated or attenuated is not fully understood. We recently identified transmembrane prostate androgen-induced RNA (TMEPAI), which is involved in a negative feedback loop of TGF-β signaling. When we searched for a family molecule(s) for TMEPAI, we found C18ORF1, which, like TMEPAI, possesses two PY motifs and one Smad-interacting motif (SIM) domain. As expected, C18ORF1 could block TGF-β signaling but not bone morphogenetic protein signaling. C18ORF1 bound to Smad2/3 via its SIM and competed with the Smad anchor for receptor activation for Smad2/3 binding to attenuate recruitment of Smad2/3 to the TGF-β type I receptor (also termed activin receptor-like kinase 5 (ALK5)), in a similar fashion to TMEPAI. Knockdown of C18ORF1 prolonged duration of TGF-β-induced Smad2 phosphorylation and concomitantly potentiated the expression of JunB, p21, and TMEPAI mRNAs induced by TGF-β. Consistently, TGF-β-induced cell migration was enhanced by the knockdown of C18ORF1. These results indicate that the inhibitory function of C18ORF1 on TGF-β signaling is similar to that of TMEPAI. However, in contrast to TMEPAI, C18ORF1 was not induced upon TGF-β signaling. Thus, we defined C18ORF1 as a surveillant of steady state TGF-β signaling, whereas TMEPAI might help C18ORF1 to inhibit TGF-β signaling in a coordinated manner when cells are stimulated with high levels of TGF-β.

Sequencing chromosomal abnormalities reveals neurodevelopmental loci that confer risk across diagnostic boundaries

Balanced chromosomal abnormalities (BCAs) represent a relatively untapped reservoir of single-gene disruptions in neurodevelopmental disorders (NDDs). We sequenced BCAs in patients with autism or related NDDs, revealing disruption of 33 loci in four general categories: (1) genes previously associated with abnormal neurodevelopment (e.g., AUTS2, FOXP1, and CDKL5), (2) single-gene contributors to microdeletion syndromes (MBD5, SATB2, EHMT1, and SNURF-SNRPN), (3) novel risk loci (e.g., CHD8, KIRREL3, and ZNF507), and (4) genes associated with later-onset psychiatric disorders (e.g., TCF4, ZNF804A, PDE10A, GRIN2B, and ANK3). We also discovered among neurodevelopmental cases a profoundly increased burden of copy-number variants from these 33 loci and a significant enrichment of polygenic risk alleles from genome-wide association studies of autism and schizophrenia. Our findings suggest a polygenic risk model of autism and reveal that some neurodevelopmental genes are sensitive to perturbation by multiple mutational mechanisms, leading to variable phenotypic outcomes that manifest at different life stages.

Analysis of a t(18;21)(p11.1;p11.1) translocation in a family with schizophrenia

It is suggested that chromosome 18p11 is a susceptibility region for both bipolar disorder and schizophrenia. Aiming to identify susceptibility gene(s), we investigated a family whose members have either schizophrenia or schizophrenia-spectrum psychosis and carried a t(18;21)(p11.1;p11.1) translocation. Fluorescence in situ hybridization showed that the breakpoint on chromosome 21 was localized to a bacterial artificial chromosome (BAC) clone RP11-2503J9, which contained coding sequences for transmembrane phosphatase with tensin homology, although this gene was not disrupted. On chromosome 18p, the break point was narrowed to BAC clone RP11-527H14. In silico sequence analysis of this clone identified possible pseudo genes and gene fragments but no intact genes. RP11-527H14 also showed sites of cross hybridization, including 21p11.1. To test for a position effect on 18p11 sequences translocated to 21p11, we performed quantitative RT-PCR to measure the expression of the candidate gene C18orf1 in translocation carriers, but found no significant differences from controls in lymphoblastoid cells.

Identification of multiple serine racemase (SRR) mRNA isoforms and genetic analyses of SRR and DAO in schizophrenia and D-serine levels

BACKGROUND

We previously reported a reduction in serum levels of D-serine, an endogenous co-agonist of the N-methyl-D-aspartate (NMDA) receptor, in schizophrenia, supporting the hypofunction hypothesis of NMDA neurotransmission in schizophrenia. In this study, we examined the genetic roles of serine racemase (SRR), an enzyme catalyzing the formation of D-serine from L-serine, and D-amino-acid oxidase (DAO) in the susceptibility to schizophrenia and the regulation of serum D-serine levels.

METHODS

We determined the complete cDNA and genomic structures of SRR and performed mutation screening. Single nucleotide polymorphisms (SNPs) in SRR and DAO were tested for their association with schizophrenia in both case-control and family-based designs and for correlation with serum levels of D-serine.

RESULTS

Genomic analyses revealed that human brain SRR transcripts consist of four isoforms with one major species, which were derived from alternative use of various 5' end exons. Genetic association analyses showed no significant association between SRR/DAO and schizophrenia. We replicated the decreased serum D-serine levels in schizophrenia in the sample set, but D-serine levels did not correlate with SRR/DAO genotypes.

CONCLUSIONS

The SRR/DAO are not likely to be major genetic determinants in the development of schizophrenia or control of serum D-serine levels.