Variants in Doublecortin- and Calmodulin Kinase Like 1, a Gene Up-Regulated by BDNF, Are Associated with Memory and General Cognitive Abilities

Human memory and general cognitive abilities are complex functions of high heritability and wide variability in the population. The brain-derived neurotrophic factor (BDNF) plays an important role in mammalian memory formation.Based on the identification of genes markedly up-regulated during BDNF-induced synaptic consolidation in the hippocampus, we selected genetic variants that were tested in three independent samples, from Norway and Scotland, of adult individuals examined for cognitive abilities. In all samples, we show that markers in the doublecortin- and calmodulin kinase like 1 (DCLK1) gene, are significantly associated with general cognition (IQ scores) and verbal memory function, resisting multiple testing. DCLK1 is a complex gene with multiple transcripts which vary in expression and function. We show that the short variants are all up-regulated after BDNF treatment in the rat hippocampus, and that they are expressed in the adult human brain (mostly in cortices and hippocampus). We demonstrate that several of the associated variants are located in potential alternative promoter- and cis-regulatory elements of the gene and that they affect BDNF-mediated expression of short DCLK1 transcripts in a reporter system.These data present DCLK1 as a functionally pertinent gene involved in human memory and cognitive functions

Drug-induced activation of SREBP-controlled lipogenic gene expression in CNS-related cell lines: Marked differences between various antipsychotic drugs

BACKGROUND: The etiology of schizophrenia is unknown, but neurodevelopmental disturbances, myelin- and oligodendrocyte abnormalities and synaptic dysfunction have been suggested as pathophysiological factors in this severe psychiatric disorder. Cholesterol is an essential component of myelin and has proved important for synapse formation. Recently, we demonstrated that the antipsychotic drugs clozapine and haloperidol stimulate lipogenic gene expression in cultured glioma cells through activation of the sterol regulatory element-binding protein (SREBP) transcription factors. We here compare the action of chlorpromazine, haloperidol, clozapine, olanzapine, risperidone and ziprasidone on SREBP activation and SREBP-controlled gene expression (ACAT2, HMGCR, HMGCS1, FDPS, SC5DL, DHCR7, LDLR, FASN and SCD1) in four CNS-relevant human cell lines. RESULTS: There were marked differences in the ability of the antipsychotic drugs to activate the expression of SREBP target genes, with clozapine and chlorpromazine as the most potent stimulators in a context of therapeutically relevant concentrations. Glial-like cells (GaMg glioma and CCF-STTG1 astrocytoma cell lines) displayed more pronounced drug-induced SREBP activation compared to the response in HCN2 human cortical neurons and SH-SY5Y neuroblastoma cells, indicating that antipsychotic-induced activation of lipogenesis is most prominent in glial cells. CONCLUSION: Our present data show a marked variation in the ability of different antipsychotics to induce SREBP-controlled transcriptional activation of lipogenesis in cultured human CNS-relevant cells. We propose that this effect could be relevant for the therapeutic efficacy of some antipsychotic drugs

LOC689986, a unique gene showing specific expression in restricted areas of the rodent neocortex

Background The neocortex is a highly specialised and complex brain structure, involved in numerous tasks, ranging from processing and interpretation of somatosensory information, to control of motor functions. The normal function linked to distinct neocortical areas might involve control of highly specific gene expression, and in order to identify such regionally enriched genes, we previously analysed the global gene expression in three different cortical regions (frontomedial, temporal and occipital cortex) from the adult rat brain. We identified distinct sets of differentially expressed genes. One of these genes, namely the hypothetical protein LOC689986 (LOC689986), was of particular interest, due to an almost exclusive expression in the temporal cortex. Results Detailed analysis of LOC689986 in the adult rat brain confirmed the expression in confined areas of parieto-temporal cortex, and revealed highly specific expression in layer 4 of the somatosensory cortex, with sharp borders towards the neighbouring motor cortex. In addition, LOC689986 was found to be translated in vivo, and was detected in the somatosensory cortex and in the Purkinje cells of the cerebellar cortex. The protein was present in neuronal dendrites and also in astrocyte cells. Finally, this unique gene is apparently specific for, and highly conserved in, the vertebrate lineage. Conclusions In this study, we have partially characterised the highly conserved LOC689986 gene, which is specific to the vertebrate linage. The gene displays a distinct pattern of expression in layer 4 of the somatosensory cortex, and areas of the parieto-temporal cortex in rodents

DCLK1 Variants Are Associated across Schizophrenia and Attention Deficit/Hyperactivity Disorder

Doublecortin and calmodulin like kinase 1 (DCLK1) is implicated in synaptic plasticity and neurodevelopment. Genetic variants in DCLK1 are associated with cognitive traits, specifically verbal memory and general cognition. We investigated the role of DCLK1 variants in three psychiatric disorders that have neuro-cognitive dysfunctions: schizophrenia (SCZ), bipolar affective disorder (BP) and attention deficit/hyperactivity disorder (ADHD). We mined six genome wide association studies (GWASs) that were available publically or through collaboration; three for BP, two for SCZ and one for ADHD. We also genotyped the DCLK1 region in additional samples of cases with SCZ, BP or ADHD and controls that had not been whole-genome typed. In total, 9895 subjects were analysed, including 5308 normal controls and 4,587 patients (1,125 with SCZ, 2,496 with BP and 966 with ADHD). Several DCLK1 variants were associated with disease phenotypes in the different samples. The main effect was observed for rs7989807 in intron 3, which was strongly associated with SCZ alone and even more so when cases with SCZ and ADHD were combined (P-value = 4×10−5 and 4×10−6, respectively). Associations were also observed with additional markers in intron 3 (combination of SCZ, ADHD and BP), intron 19 (SCZ+BP) and the 3′UTR (SCZ+BP). Our results suggest that genetic variants in DCLK1 are associated with SCZ and, to a lesser extent, with ADHD and BP. Interestingly the association is strongest when SCZ and ADHD are considered together, suggesting common genetic susceptibility. Given that DCLK1 variants were previously found to be associated with cognitive traits, these results are consistent with the role of DCLK1 in neurodevelopment and synaptic plasticity

Implication of NOTCH1 Gene in Susceptibility to Anxiety and Depression among Sexual Abuse Victims

Sexual abuse contributes to the development of multiple forms of psychopathology, including anxiety and depression, but the extent to which genetics contributes to these disorders among sexual abuse victims remains unclear. In this translational study, we first examined gene expression in the brains of rodents exposed to different early-life conditions (long, brief or no maternal separation). Hypothesizing that genes revealing changes in expression may have relevance for psychiatric symptoms later in life, we examined possible association of those genes with symptoms of anxiety and depression in a human sample of sexual abuse victims. Changes in rodent brain gene expression were evaluated by means of correspondence and significance analyses of microarrays by comparing brains of rodents exposed to different early-life conditions. Tag single-nucleotide polymorphisms (SNPs) of resulting candidate genes were genotyped and tested for their association with symptoms of anxiety and depression (Hospital Anxiety and Depression Scale) in a sample of 361 sexual abuse victims, using multinomial logistic regression. False discovery rate was applied to account for multiple testing in the genetic association study, with q-value of 0.05 accepted as significant. We identified four genes showing differential expression among animals subjected to different early-life conditions as well as having potential relevance to neural development or disorders: Notch1, Gabrr1, Plk5 and Zfp644. In the human sample, significant associations were observed for two NOTCH1 tag SNPs: rs11145770 (OR=2.21, q=0.043) and rs3013302 (OR=2.15, q=0.043). Our overall findings provide preliminary evidence that NOTCH1 may be implicated in the susceptibility to anxiety and depression among sexual abuse victims. The study also underscores the potential importance of animal models for future studies on the health consequences of early-life stress and the mechanisms underlying increased risk for psychiatric disorders

Neuropsychological Deficits in Mice Depleted of the Schizophrenia Susceptibility Gene <i>CSMD1</i>

<div><p>Recent meta-analyses of schizophrenia genome-wide association studies (GWASs) have identified the <i>CUB and SUSHI multiple domains 1</i> (<i>CSMD1</i>) gene as a statistically strong risk factor. CSMD1 is a complement control-related protein suggested to inhibit the classical complement pathway, being expressed in developing neurons. However, expression of <i>CSMD1</i> is largely uncharacterized and relevance for behavioral phenotypes is not previously demonstrated. Here, we assess neuropsychological behaviors of a <i>Csmd1</i> knockout (KO) mouse in a selection of standard behavioral tests. Deregulation of neuropsychological responses were observed in both the open field and the elevated plus maze tests, in which KO mice spent 55% and 33% less time than WT littermate mice in open areas, respectively. Altered behaviors were also observed in tail suspension and to higher acoustic stimuli, for which <i>Csmd1</i> KO mice showed helplessness and moderate increase in startle amplitude, respectively. Furthermore, <i>Csmd1</i> KO mice also displayed increased weight-gain and glucose tolerance, similar to a major phenotype of the metabolic syndrome that also has been associated to the human <i>CSMD1</i> locus. Consistent with a role in the control of behaviors, <i>Csmd1</i> was found highly expressed in the central nervous system (CNS), and with some expression in visceral fat and ovary, under tissue-specific control by a novel promoter-associated lncRNA. In summary, disruption of <i>Csmd1</i> induces behaviors reminiscent of blunted emotional responses, anxiety and depression. These observations suggest an influence of the <i>CSMD1</i> schizophrenia susceptibility gene on psychopathology and endophenotypes of the negative symptom spectra.</p></div

<i>Csmd1</i> RNA and protein expression in <i>Csmd1</i> knock-out and wild-type mice.

<p>(A) Schematic representation of the KO-strategy. A 1 kb genomic region (white lines) of exon1/intron1 was replaced with a selection cassette (grey box). (B) Expression of <i>Csmd1</i> mRNA measured by QPCR in an adult mouse tissue panel. <i>Csmd1</i> is predominantly expressed in brain tissues as compared to peripheral tissues. The highest expression level was identified in areas of the cortex. (C) Depletion of <i>Csmd1</i> mRNA in the cortex was documented by two exon-exon specific QPCR assays. Transcription of exon 1–2 was depleted, while about 20% residual expression could be observed when amplifying exon 32–33. KO mice lacked a protein band of expected size (389 KDa, arrow), as demonstrated by immunoblotting. Signals of lower molecular weight are indicated (a and b). (D) Mapping of RNA-seq reads to the <i>Csmd1</i> locus. RNA sequencing of cortex is shown for 4wild-type (green) and 4 <i>Csmd1</i> KO (red) mice (transcript scale: 0–150 reads). Coverage signals of modified nucleosomes (H3K4me3, H3K4me1 and H3K27Ac) and polymerase-2 binding profiles are shown for the mouse cortex. The 1 kb deleted sequence of <i>Csmd1</i> is highlighted in yellow (upper panel) and blue (lower panel). No RNA reads were mapped to the deleted genomic region in the KO mice. Abbreviations: Cx, cortex; VCx, visual cortex; FCx, frontal cortex; Hipp, hippocampus; Hyp, hypothalamus; Ob, olfactory bulb; Cer, cerebellum; Visc. Fat, visceral fat.</p

Behavior of <i>Csmd1</i> KO and WT mice in the elevated plus maze.

<p>(A) Analysis of total time spent on open arms demonstrate significant less time for KO mice (N = 13) as compared to WT mice (N = 8). (B) Compiled tracks from all mice show that <i>Csmd1</i> KO mice avoid entering open arms, as opposed to WT mice traveling over the entire test arena. Abbreviations: asterisk, statistically significant (<i>P</i>-value<0.05); s, seconds.</p

Behavior of <i>Csmd1</i> KO and WT mice in the open field arena.

<p>(A) Total time spent in the center of the arena is shown for KO and WT mice, respectively. (B) Sequential time bin analysis demonstrates that WT mice adapt to the test arena after the first time bin, while KO mice avoid the center throughout the test period. (C and D) Comparison of total path length and sequential bin analysis of path length demonstrate no statistically significant difference between KO and WT mice. Abbreviations: n.s., not significant; asterisk, statistically significant <i>P</i>-value<0.05; s, seconds.</p

Analysis of object recognition memory in Csmd1 KO and WT mice.

<p>(A and B) Object contacts in the first and second trial of exposure to novel and familiar objects demonstrated increased contact counts for <i>Csmd1</i> KO mice (P-value<0.05). (B and C) Discrimination and preference analysis demonstrated no effect of <i>Csmd1</i> on object recognition. Abbreviation: n.s., not significant; asterisk, statistically significant (<i>P</i>-value<0.05).</p