BICC1 expression is elevated in depressed subjects and contributes to depressive behavior in rodents

Potential Risk Factors of Susceptibility to Recurrent Depression

BACKGROUND

Major depressive disorder (MDD) is a highly prevalent and recurrent neuropsychiatric disorder associated with alterations in the BicC family RNA binding protein 1 (BICC1). However, the potential risk factors that regulate BICC1 and affect susceptibility to recurrent depression remain unclear.

METHODS

Herein, we firstly tested the heat shock protein 90 (HSP90), hypoxia-inducible factor 1-alpha (HIF1α), and BICC1 in the serum of the patients that were in first-episode or recurrent depression, as well as their controls. Then, through re-exposure to chronic unpredictable mild stress (CUMS) in mice, an animal model of recurrent depression was assessed. And the expression of HSP90, HIF1α, and BICC1 in the prefrontal cortex (PFC) were analyzed.

RESULTS

We found that HSP90, HIF1α, and BICC1 were significantly increased in the serum of depressed patients, especially in those with recurrent depression, indicating that these molecules may serve as specific pathogenetic risk factors for depression, especially depression recurrence. In addition, the recurrent depression mice model was found to be accompanied by a significant increase in expression of HSP90, HIF1α and BICC1 in the prefrontal cortex (PFC).

CONCLUSIONS

The current study identified HSP90, HIF1α, and BICC1 as novel potential risk factors that affect susceptibility to recurrent depression.

Genetic Landscape of Major Depressive Disorder: Assessment of Potential Diagnostic and Antidepressant Response Markers

BACKGROUND

The clinical heterogeneity in major depressive disorder (MDD), variable treatment response, and conflicting findings limit the ability of genomics toward the discovery of evidence-based diagnosis and treatment regimen. This study attempts to curate all genetic association findings to evaluate potential variants for clinical translation.

METHODS

We systematically reviewed all candidates and genome-wide association studies for both MDD susceptibility and antidepressant response, independently, using MEDLINE, particularly to identify replicated findings. These variants were evaluated for functional consequences using different in silico tools and further estimated their diagnostic predictability by calculating positive predictive values.

RESULTS

A total of 217 significantly associated studies comprising 1200 variants across 545 genes and 128 studies including 921 variants across 412 genes were included with MDD susceptibility and antidepressant response, respectively. Although the majority of associations were confirmed by a single study, we identified 31 and 18 replicated variants (in at least 2 studies) for MDD and antidepressant response. Functional annotation of these 31 variants predicted 20% coding variants as deleterious/damaging and 80.6% variants with regulatory effect. Similarly, the response-related 18 variants revealed 25% coding variant as damaging and 88.2% with substantial regulatory potential. Finally, we could calculate the diagnostic predictability of 19 and 5 variants whose positive predictive values ranges from 0.49 to 0.66 for MDD and 0.36 to 0.66 for response.

CONCLUSIONS

The replicated variants presented in our data are promising for disease diagnosis and improved response outcomes. Although these quantitative assessment measures are solely directive of available observational evidence, robust homogenous validation studies are required to strengthen these variants for molecular diagnostic application.

Predicting the diagnosis of various mental disorders in a mixed cohort using blood-based multi-protein model: a machine learning approach

The lack of objective diagnostic methods for mental disorders challenges the reliability of diagnosis. The study aimed to develop an easily accessible and useable objective method for diagnosing major depressive disorder (MDD), schizophrenia (SZ), bipolar disorder (BPD), and panic disorder (PD) using serum multi-protein. Serum levels of brain-derived neurotrophic factor (BDNF), VGF (non-acronymic), bicaudal C homolog 1 (BICC1), C-reactive protein (CRP), and cortisol, which are generally recognized to be involved in different pathogenesis of various mental disorders, were measured in patients with MDD (n = 50), SZ (n = 50), BPD (n = 55), and PD along with 50 healthy controls (HC). Linear discriminant analysis (LDA) was employed to construct a multi-classification model to classify these mental disorders. Both leave-one-out cross-validation (LOOCV) and fivefold cross-validation were applied to validate the accuracy and stability of the LDA model. All five serum proteins were included in the LDA model, and it was found to display a high overall accuracy of 96.9% when classifying MDD, SZ, BPD, PD, and HC groups. Multi-classification accuracy of the LDA model for LOOCV and fivefold cross-validation (within-study replication) reached 96.9 and 96.5%, respectively, demonstrating the feasibility of the blood-based multi-protein LDA model for classifying common mental disorders in a mixed cohort. The results suggest that combining multiple proteins associated with different pathogeneses of mental disorders using LDA may be a novel and relatively objective method for classifying mental disorders. Clinicians should consider combining multiple serum proteins to diagnose mental disorders objectively.

Bicaudal-C Post-transcriptional regulator of cell fates and functions

Bicaudal-C (Bicc1) is an evolutionarily conserved RNA binding protein that functions in a regulatory capacity in a variety of contexts. It was originally identified as a genetic locus in Drosophila that when disrupted resulted in radical changes in early development. In the most extreme phenotypes embryos carrying mutations developed with mirror image duplications of posterior structures and it was this striking phenotype that was responsible for the name Bicaudal. These seminal studies established Bicc1 as an important regulator of Drosophila development. What was not anticipated from the early work, but was revealed subsequently in many different organisms was the broad fundamental impact that Bicc1 proteins have on developmental biology; from regulating cell fates in vertebrate embryos to defects associated with several human disease states. In the following review we present a perspective of Bicc1 focusing primarily on the molecular aspects of its RNA metabolism functions in vertebrate embryos.

Bicaudal-C protein, a potential antidepressant target

Bicaudal-C protein is a highly conserved RNA binding protein, which contains K homology domains and sterile alpha motif domain. Genome-wide association study identified that Bicaudal-C protein was associated with depression. The expression of Bicaudal-C increased in depression patients, also increased expression of Bicaudal-C induces the behavior of depression. The decrease of synaptic plasticity plays a part in depression. Bicaudal-C protein reduces the synaptic plasticity of neurons via TrkB/mTOR/AMPA/pGluA1 pathways, Wnt pathway, or influencing some proteins related to synaptic plasticity. The decreased expression of Bicaudal-C plays an important role in the action of several antidepressants, such as ketamine, biperiden, and scopolamine. Therefore, Bicaudal-C protein may be a potential antidepressant target. Clarifying the relationship between Bicaudal-C protein and depression may help us to find new antidepressants. This review focuses on the research advances of the relationship between Bicaudal-C protein and depression.

Genetics of resilience: Implications from genome-wide association studies and candidate genes of the stress response system in posttraumatic stress disorder and depression

Resilience is the ability to cope with critical situations through the use of personal and socially mediated resources. Since a lack of resilience increases the risk of developing stress-related psychiatric disorders such as posttraumatic stress disorder (PTSD) and major depressive disorder (MDD), a better understanding of the biological background is of great value to provide better prevention and treatment options. Resilience is undeniably influenced by genetic factors, but very little is known about the exact underlying mechanisms. A recently published genome-wide association study (GWAS) on resilience has identified three new susceptibility loci, DCLK2, KLHL36, and SLC15A5. Further interesting results can be found in association analyses of gene variants of the stress response system, which is closely related to resilience, and PTSD and MDD. Several promising genes, such as the COMT (catechol-O-methyltransferase) gene, the serotonin transporter gene (SLC6A4), and neuropeptide Y (NPY) suggest gene × environment interaction between genetic variants, childhood adversity, and the occurrence of PTSD and MDD, indicating an impact of these genes on resilience. GWAS on PTSD and MDD provide another approach to identifying new disease-associated loci and, although the functional significance for disease development for most of these risk genes is still unknown, they are potential candidates due to the overlap of stress-related psychiatric disorders and resilience. In the future, it will be important for genetic studies to focus more on resilience than on pathological phenotypes, to develop reasonable concepts for measuring resilience, and to establish international cooperations to generate sufficiently large samples.

FGFR2-BICC1: A Subtype Of FGFR2 Oncogenic Fusion Variant In Cholangiocarcinoma And The Response To Sorafenib

Fibroblast growth factor receptor (FGFR) family includes four highly conserved receptor tyrosine kinases. Particularly, FGFR2 has been identified as a potential target for tyrosine kinase inhibitor (TKI) treatment. Except for immunohistochemistry and fluorescence in situ hybridization, next-generation sequencing (NGS) technology represents a novel tool for FGFR2 detection that covers a wide range of fusion genes. In the present work, we present a case of cholangiocarcinoma who had FGFR2-BICC1 rearrangement detected by NGS. A 76-year-old female diagnosed with cholangiocarcinoma underwent four cycles of chemotherapy. The NGS assay showed that the tumor had a FGFR2-BICC1 rearrangement. The patient had a favorable tumor response to sorafenib. Herein, we report the first case with cholangiocarcinoma harboring FGFR2-BICC1 who is sensitive to sorafenib therapy.

Identification of bovine CpG SNPs as potential targets for epigenetic regulation via DNA methylation

Methylation patterns established and maintained at CpG sites may be altered by single nucleotide polymorphisms (SNPs) within these sites and may affect the regulation of nearby genes. Our aims were to: 1) identify and generate a database of SNPs potentially subject to epigenetic control by DNA methylation via their involvement in creating, removing or displacing CpG sites (meSNPs), and; 2) investigate the association of these meSNPs with CpG islands (CGIs), and with methylation profiles of DNA extracted from tissues from cattle with divergent feed efficiencies detected using MIRA-Seq. Using the variant annotation for 56,969,697 SNPs identified in Run5 of the 1000 Bull Genomes Project and the UMD3.1.1 bovine reference genome sequence assembly, we identified and classified 12,836,763 meSNPs according to the nature of variation created at CpGs. The majority of the meSNPs were located in intergenic regions (68%) or introns (26.3%). We found an enrichment (p<0.01) of meSNPs located in CGIs relative to the genome as a whole, and also in differentially methylated sequences in tissues from animals divergent for feed efficiency. Seven meSNPs, located in differentially methylated regions, were fixed for methylation site creating (MSC) or destroying (MSD) alleles in the differentially methylated genomic sequences of animals differing in feed efficiency. These meSNPs may be mechanistically responsible for creating or deleting methylation targets responsible for the differential expression of genes underlying differences in feed efficiency. Our methyl SNP database (dbmeSNP) is useful for identifying potentially functional "epigenetic polymorphisms" underlying variation in bovine phenotypes.

Protein Translation and Psychiatric Disorders

Although historically research has focused on transcription as the central governor of protein expression, protein translation is now increasingly being recognized as a major factor for determining protein levels within cells. The central nervous system relies on efficient updating of the protein landscape. Thus, coordinated regulation of mRNA localization, initiation, or termination of translation is essential for proper brain function. In particular, dendritic protein synthesis plays a key role in synaptic plasticity underlying learning and memory as well as cognitive processes. Increasing evidence suggests that impaired mRNA translation is a common feature found in numerous psychiatric disorders. In this review, we describe how malfunction of translation contributes to development of psychiatric diseases, including schizophrenia, major depression, bipolar disorder, and addiction.

Underlying mechanisms of recombinant adeno-associated virus-mediated bicaudal C homolog 1 overexpression in the medial prefrontal cortex of mice with induced depressive-like behaviors

Bicaudal C homolog 1 gene (BICC1) in the medial prefrontal cortex (mPFC) has been implicated in major depressive disorder (MDD); however, less is known about the mechanisms of BICC1-induced depression. The purpose of the present study was to investigate changes in depressive-like behaviors induced by recombinant adeno-associated virus (rAAV)-mediated overexpression of BICC1 in the mPFC of mice. A viral-mediated genetic approach was employed to explore the BICC1 overexpression-induced depressive-like behavioral and molecular changes in mice. For the first time, we found that BICC1 overexpression significantly induced depressive-like behaviors in mice. Further, the expression of disheveled-2 and the phosphorylation of Ser9 of glycogen synthase kinase 3β (GSK3β), mechanistic target of rapamycin (mTOR) and GluA1, GluA1, brain-derived neurotrophic factor (BDNF), and VGF were markedly down-regulated in BICC1 overexpression-treated animals. Our results demonstrate that the overexpression of BICC1 in the mPFC may induce depressive-like behaviors via GSK3β/mTOR signaling and GluA1 trafficking in the mPFC of mice, indicating that BICC1 may be a potential target for antidepressant treatment.

Serum BICC1 levels are significantly different in various mood disorders

PURPOSE

Mood disorders are recurrent chronic disorders with fluctuating mood states and energy, and misdiagnosis is common when based solely on clinical interviews because of overlapping symptoms. Because misdiagnosis may lead to inappropriate treatment and poor prognosis, finding an easily implemented objective tool for the discrimination of different mood disorders is very necessary and urgent. However, there has been no accepted objective tool until now. Recently, BICC1 has been identified as a candidate gene relating to major depressive disorder (MDD). Therefore, the aim of this study is to evaluate the ability of serum BICC1 to discriminate between various mood disorders, including MDD and the manic and depressive phases of bipolar disorder, namely bipolar mania (BM) and bipolar depression (BD).

PATIENTS AND METHODS

Serum BICC1 levels in drug-free patients with MDD (n=30), BM (n=30), and BD (n=13), and well-matched healthy controls (HC, n=30) were measured with ELISA kits. Pearson correlation analyses were used to analyze the correlations between serum BICC1 levels and clinical information. Receiver operating characteristic (ROC) curve analysis was used to analyze the differential discriminative potential of BICC1 for different mood disorders.

RESULTS

One-way ANOVA indicated that serum BICC1 levels were significantly increased in all patient groups compared with the HC group and significantly different between each pair of patient groups. Correlation analyses found no relationship between serum BICC1 levels and any clinical variables in any study group. ROC curve analysis showed that serum BICC1 could discriminate among all three mood disorders from each other accurately with fair-to-excellent discriminatory capacity (area under the ROC curve from 0.787 to 1.0).

CONCLUSION

The findings of this preliminary study indicated significant differences in serum BICC1 levels in patients with different mood disorders. This study provides preliminary evidence that serum BICC1 may be regarded as a promising, objective, easy-to-use tool for diagnosing different mood disorders.

Essential roles of neuropeptide VGF regulated TrkB/mTOR/BICC1 signaling and phosphorylation of AMPA receptor subunit GluA1 in the rapid antidepressant-like actions of ketamine in mice

Previous studies have suggested that rapid reductions in depression-like behaviors are observed in response to sub-anesthetic-doses of ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist. Neuropeptide VGF (non-acronymic) is a critical effector of depression-like behaviors and is thought to be involved in the antidepressant actions of ketamine that have been demonstrated. However, the mechanism underlying the involvement of VGF in the anti-depressant action of ketamine remains unclear. We found that single dose ketamine treatment reversed CSDS-induced depression-like behaviors and decrease of VGF in the PFC of mice. To investigate the involvement of VGF in the antidepressant-like effects of ketamine, a lentivirus vector for VGF was constructed to knockdown the expression of VGF in the prefrontal cortex (PFC) of mice. The biochemical and behavioral effects of this VGF knockdown were examined, using the open field, forced swim, and sucrose preference tests. Our results show that knockdown of VGF increased the immobility time and decreased the sucrose preference in mice. These effects were not improved by ketamine administration. In addition, we found that knockdown of VGF significantly decreased the expression of phosphorylation of tropomyosin receptor kinase B (TrkB), mammalian target of rapamycin (mTOR), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA1 Ser845 and increased the expression of bicaudal C homolog 1 (BICC1) in the mouse PFC, and blocked the regulation of TrkB/mTOR/BICC1 signaling and GluA1 phosphorylation by ketamine. Our results indicate that the rapid onset antidepressant-like actions of ketamine require VGF to regulate TrkB/mTOR/BICC1 signaling and AMPA receptor GluA1 phosphorylation.

Vesicular glutamate transporter 1 (VGLUT1)-mediated glutamate release and membrane GluA1 activation is involved in the rapid antidepressant-like effects of scopolamine in mice

Emerging data have identified certain drugs such as scopolamine as rapidly acting antidepressants for major depressive disorder (MDD) that increase glutamate release and induce neurotrophic factors through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) activation in rodent models. However, little research has addressed the direct mechanisms of scopolamine on AMPAR activation or vesicular glutamate transporter 1 (VGLUT1)-mediated glutamate release in the prefrontal cortex (PFC) of mice. Herein, using a chronic unpredictable stress (CUS) paradigm, acute treatment with scopolamine rapidly reversed stress-induced depression-like behaviors in mice. Our results showed that CUS-induced depression-like behaviors, accompanied by a decrease in membrane AMPAR subunit 1 (GluA1), phosphorylated GluA1 Ser845 (pGluA1 Ser845), brain-derived neurotrophic factor (BDNF) and VGF (non-acronymic) and an increase in bicaudal C homolog 1 gene (BICC1) in the PFC of mice, and these biochemical and behavioral abnormalities were ameliorated by acute scopolamine treatments. However, pharmacological block of AMPAR by NBQX infusion into the PFC significantly abolished these effects of scopolamine. In addition, knock down of VGLUT1 by lentiviral-mediated RNA interference in the PFC of mice was sufficient to induce depression-like phenotype, to decrease extracellular glutamate accumulation and to cause similar molecular changes with CUS in mice. Remarkably, VGLUT1 knockdown alleviated the rapid antidepressant-like actions of scopolamine and the effects of scopolamine on membrane GluA1-mediated BDNF, VGF and BICC1 changes. Altogether, our findings suggest that VGLUT1-mediated glutamate release and membrane GluA1 activation may play a critical role in the rapid-acting antidepressant-like effects of scopolamine in mice.

The antidepressant-like effects of biperiden may involve BDNF/TrkB signaling-mediated BICC1 expression in the hippocampus and prefrontal cortex of mice

Preclinical and clinical studies suggest that neuronal muscarinic acetylcholine receptor (M-AchR) antagonists have antidepressant-like properties. Despite the recent interest in bicaudal C homolog 1 gene (BICC1) as a target for the treatment of depression, the upstream signaling molecules that regulate BICC1 are unknown, and very few studies have addressed the involvement of BICC1 in the antidepressant-like effects of the selective M1-AchR inhibitor, biperiden. Growing evidence indicates that activation of brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase receptor B (TrkB) signaling may be involved in antidepressant-like activities. In this study, we investigated the role of BDNF/TrkB signaling in the regulation of BICC1 expression in the chronic unpredictable stress (CUS) mouse model of depression. Furthermore, we also examined whether BDNF/TrkB signaling contributes to the antidepressant-like effects of biperiden via down-regulation of BICC1 in the hippocampus and prefrontal cortex of mice. Our current data show that CUS exposure induced significant depression-like behaviors, down-regulation of BDNF/TrkB signaling and up-regulation of BICC1 in the hippocampus and prefrontal cortex of mice. However, biperiden significantly alleviated the CUS-induced abnormalities. Moreover, we found that the effects of biperiden were antagonized by pretreatment with the TrkB antagonist K252a. Our results indicate that BDNF/TrkB signaling may be the major upstream mediator of BICC1 involvement in the antidepressant-like effects of biperiden.

Molecular and Cellular Mechanisms of Rapid-Acting Antidepressants Ketamine and Scopolamine

Major depressive disorder (MDD) is a prevalent neuropsychiatric disease that causes profound social and economic burdens. The impact of MDD is compounded by the limited therapeutic efficacy and delay of weeks to months of currently available medications. These issues highlight the need for more efficacious and faster-acting treatments to alleviate the burdens of MDD. Recent breakthroughs demonstrate that certain drugs, including ketamine and scopolamine, produce rapid and long-lasting antidepressant effects in MDD patients. Moreover, preclinical work has shown that the antidepressant actions of ketamine and scopolamine in rodent models are caused by an increase of extracellular glutamate, elevated BDNF, activation of the mammalian target of rapamycin complex 1 (mTORC1) cascade, and increased number and function of spine synapses in the prefrontal cortex (PFC). Here we review studies showing that both ketamine and scopolamine elicit rapid antidepressant effects through converging molecular and cellular mechanisms in the PFC. In addition, we discuss evidence that selective antagonists of NMDA and muscarinic acetylcholine (mACh) receptor subtypes (i.e., NR2B and M1-AChR) in the PFC produce comparable antidepressant responses. Furthermore, we discuss evidence that ketamine and scopolamine antagonize inhibitory interneurons in the PFC leading to disinhibition of pyramidal neurons and increased extracellular glutamate that promotes the rapid antidepressant responses to these agents. Collectively, these studies indicate that specific NMDA and mACh receptor subtypes on GABAergic interneurons are promising targets for novel rapid-acting antidepressant therapies.

The identification of metabolic disturbances in the prefrontal cortex of the chronic restraint stress rat model of depression

Major depressive disorder, with serious impairment in cognitive and social functioning, is a complex psychiatric disorder characterized by pervasive and persistent low mood and a loss of interest or pleasure. However, the underlying molecular mechanisms of depression remain largely unknown. In this study, we used a non-targeted metabolomics approach based on gas chromatography-mass spectrometry of the prefrontal cortex in chronic restraint stress (CRS)-treated rats. CRS was induced in the stress group by restraining rats in a plastic restrainer for 6h every day. This stress paradigm continued for 21 days. Body weight measurement and behavior tests were applied, including the sucrose preference test for anhedonia, the forced swimming test for despair-like behavior, and open field test and the elevated plus-maze to test for anxiety-like behaviors in rats after CRS. Differentially expressed metabolites associated with CRS-treated rats were identified by combining multivariate and univariate statistical analysis and corrected for multiple testing using the Benjamini-Hochberg procedure. A heat map of differential metabolites was constructed using Matlab. Ingenuity Pathways Analysis was applied to identify the predicted pathways and biological functions relevant to the bio-molecules of interest. Our findings showed that CRS induces depression-like behaviors and not anxiety-like behaviors. Thirty-six metabolites were identified as potential depression biomarkers involved in amino acid metabolism, energy metabolism and lipid metabolism, as well as a disturbance in neurotransmitters. Consequently, this study provides useful insights into the molecular mechanisms of depression.

GWAS-identified risk variants for major depressive disorder: Preliminary support for an association with late-life depressive symptoms and brain structural alterations

A number of genome-wide association studies (GWAS) have investigated risk factors for major depressive disorder (MDD), however there has been little attempt to replicate these findings in population-based studies of depressive symptoms. Variants within three genes, BICC1, PCLO and GRM7 were selected for replication in our study based on the following criteria: they were identified in a prior MDD GWAS study; a subsequent study found evidence that they influenced depression risk; and there is a solid biological basis for a role in depression. We firstly investigated whether these variants were associated with depressive symptoms in our population-based cohort of 929 elderly (238 with clinical depressive symptoms and 691 controls), and secondly to investigate associations with structural brain alterations. A number of nominally significant associations were identified, but none reached Bonferroni-corrected significance levels. Common SNPs in BICC1 and PCLO were associated with a 50% and 30% decreased risk of depression, respectively. PCLO rs2522833 was also associated with the volume of grey matter (p=1.6×10(-3)), and to a lesser extent with hippocampal volume and white matter lesions. Among depressed individuals rs9870680 (GRM7) was associated with the volume of grey and white matter (p=10(-4) and 8.3×10(-3), respectively). Our results provide some support for the involvement of BICC1 and PCLO in late-life depressive disorders and preliminary evidence that these genetic variants may also influence brain structural volumes. However effect sizes remain modest and associations did not reach corrected significance levels. Further large imaging studies are needed to confirm our findings.