Genome-wide association analyses of symptom severity among clozapine-treated patients with schizophrenia spectrum disorders.

Clozapine is the most effective antipsychotic for patients with treatment-resistant schizophrenia. However, response is highly variable and possible genetic underpinnings of this variability remain unknown. Here, we performed polygenic risk score (PRS) analyses to estimate the amount of variance in symptom severity among clozapine-treated patients explained by PRSs (R2) and examined the association between symptom severity and genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activity. Genome-wide association (GWA) analyses were performed to explore loci associated with symptom severity. A multicenter cohort of 804 patients (after quality control N = 684) with schizophrenia spectrum disorder treated with clozapine were cross-sectionally assessed using the Positive and Negative Syndrome Scale and/or the Clinical Global Impression-Severity (CGI-S) scale. GWA and PRS regression analyses were conducted. Genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activities were calculated. Schizophrenia-PRS was most significantly and positively associated with low symptom severity (p = 1.03 × 10-3; R2 = 1.85). Cross-disorder-PRS was also positively associated with lower CGI-S score (p = 0.01; R2 = 0.81). Compared to the lowest tertile, patients in the highest schizophrenia-PRS tertile had 1.94 times (p = 6.84×10-4) increased probability of low symptom severity. Higher genotype-predicted CYP2C19 enzyme activity was independently associated with lower symptom severity (p = 8.44×10-3). While no locus surpassed the genome-wide significance threshold, rs1923778 within NFIB showed a suggestive association (p = 3.78×10-7) with symptom severity. We show that high schizophrenia-PRS and genotype-predicted CYP2C19 enzyme activity are independently associated with lower symptom severity among individuals treated with clozapine. Our findings open avenues for future pharmacogenomic projects investigating the potential of PRS and genotype-predicted CYP-activity in schizophrenia.

Genome-wide association study of antisocial personality disorder.

The pathophysiology of antisocial personality disorder (ASPD) remains unclear. Although the most consistent biological finding is reduced grey matter volume in the frontal cortex, about 50% of the total liability to developing ASPD has been attributed to genetic factors. The contributing genes remain largely unknown. Therefore, we sought to study the genetic background of ASPD. We conducted a genome-wide association study (GWAS) and a replication analysis of Finnish criminal offenders fulfilling DSM-IV criteria for ASPD (N=370, N=5850 for controls, GWAS; N=173, N=3766 for controls and replication sample). The GWAS resulted in suggestive associations of two clusters of single-nucleotide polymorphisms at 6p21.2 and at 6p21.32 at the human leukocyte antigen (HLA) region. Imputation of HLA alleles revealed an independent association with DRB1*01:01 (odds ratio (OR)=2.19 (1.53-3.14), P=1.9 × 10(-5)). Two polymorphisms at 6p21.2 LINC00951-LRFN2 gene region were replicated in a separate data set, and rs4714329 reached genome-wide significance (OR=1.59 (1.37-1.85), P=1.6 × 10(-9)) in the meta-analysis. The risk allele also associated with antisocial features in the general population conditioned for severe problems in childhood family (ß=0.68, P=0.012). Functional analysis in brain tissue in open access GTEx and Braineac databases revealed eQTL associations of rs4714329 with LINC00951 and LRFN2 in cerebellum. In humans, LINC00951 and LRFN2 are both expressed in the brain, especially in the frontal cortex, which is intriguing considering the role of the frontal cortex in behavior and the neuroanatomical findings of reduced gray matter volume in ASPD. To our knowledge, this is the first study showing genome-wide significant and replicable findings on genetic variants associated with any personality disorder.

Genetic background of extreme violent behavior.

In developed countries, the majority of all violent crime is committed by a small group of antisocial recidivistic offenders, but no genes have been shown to contribute to recidivistic violent offending or severe violent behavior, such as homicide. Our results, from two independent cohorts of Finnish prisoners, revealed that a monoamine oxidase A (MAOA) low-activity genotype (contributing to low dopamine turnover rate) as well as the CDH13 gene (coding for neuronal membrane adhesion protein) are associated with extremely violent behavior (at least 10 committed homicides, attempted homicides or batteries). No substantial signal was observed for either MAOA or CDH13 among non-violent offenders, indicating that findings were specific for violent offending, and not largely attributable to substance abuse or antisocial personality disorder. These results indicate both low monoamine metabolism and neuronal membrane dysfunction as plausible factors in the etiology of extreme criminal violent behavior, and imply that at least about 5-10% of all severe violent crime in Finland is attributable to the aforementioned MAOA and CDH13 genotypes.

Reduced serotonin transporter binding in binge eating women.

RATIONALE: There is evidence that abnormalities in brain dopamine, norepinephrine and serotonin metabolism may play an important role in binge eating. Serotonin-active antidepressant drugs have also been found to decrease binge eating. OBJECTIVE: We investigated serotonin transporter binding in obese binge-eating women. Eleven obese binge-eating and seven obese control women participated in the study. The subjects were not taking any medication known to affect serotonin (5-HT) transporters. METHODS: We used single-photon emission tomography (SPECT) with the radioligand 123I-labelled nor-beta-CIT, which specifically labels 5-HT transporters. RESULTS: Obese binge-eating women showed significantly decreased 5-HT transporter binding in the mid-brain compared with obese controls (2.1 +/- 0.5 versus 2.9 +/- 0.5, respectively). CONCLUSIONS: SPECT imaging with a ligand specific for 5-HT transporters can be used to assess altered serotonin transporter binding in the living human brain. The results tentatively suggest that 5-HT transporter binding is decreased in binge-eating women.

Accumulation of a form of p27(Kip1) not associated with Cdk-cyclin complexes in transforming growth factor-beta-arrested Mv1Lu cells.

The p27(Kip1) cyclin-dependent kinase inhibitor translocates in response to transforming growth factor-beta to a Cdk2-cyclin E complex inhibiting its catalytic activity, but the p27(Kip1) protein levels are unaffected [1]. We show here that transforming growth factor-beta induces the accumulation of a form of p27(Kip1) representing a subpopulation of total p27(Kip1) in growth-arrested Mv1Lu epithelial cells. The inducible p27(Kip1) is detectable only by a specific p27(Kip1) monoclonal antibody recognizing a native form of p27(Kip1). The increase in this subset of p27(Kip1) correlates with G(1) arrest and withdrawal of the cells from the cycle induced by transforming growth factor-beta, serum starvation, or contact inhibition. In contrast to the majority of p27(Kip1) in the cells, the transforming growth factor-beta-inducible p27(Kip1) is devoid of cyclin-dependent kinase/cyclin interactions. The results indicate that growth arresting treatments induce the accumulation of non-cyclin-dependent kinase-bound p27(Kip1), which may function as a reservoir for inhibition of Cdk2-cyclin E activities.

Hepatocyte growth factor releases mink epithelial cells from transforming growth factor beta1-induced growth arrest by restoring Cdk6 expression and cyclin E-associated Cdk2 activity.

Transforming growth factor beta (TGF-beta) potently suppresses Mv1Lu mink epithelial cell growth, whereas hepatocyte growth factor (HGF) counteracts TGF-beta-mediated growth inhibition and induces Mv1Lu cell proliferation (J. Taipale and J. Keski-Oja, J. Biol. Chem. 271:4342-4348, 1996). By addressing the cell cycle regulatory mechanisms involved in HGF-mediated release of Mv1Lu cells from TGF-beta inhibition, we show that increased DNA replication is accompanied by phosphorylation of the retinoblastoma protein and alternative regulation of cyclin-Cdk-inhibitor complexes. While TGF-beta treatment decreased the expression of Cdk6, this effect was counteracted by HGF, followed by partial restoration of cyclin D2-associated kinase activity. Notably, HGF failed to prevent TGF-beta induction of p15 and its association with Cdk6. However, HGF reversed the TGF-beta-mediated decrease in Cdk6-associated p27 and cyclin D2-associated Cdk6, suggesting that HGF modifies the TGF-beta response at the level of G1 cyclin complex formation. Counteraction of TGF-beta regulation of Cdk6 by HGF may in turn affect the association of p27 with Cdk2-cyclin E complexes. Though HGF did not differentially regulate the total levels of p27 in TGF-beta-treated cells, p27 immunodepletion experiments suggested that upon treatment with both growth factors, less p27 is associated with Cdk2-cyclin E complexes, in parallel with restoration of the active form of Cdk2 and the associated kinase activity. The results demonstrate that HGF intercepts TGF-beta cell cycle regulation at multiple points, affecting both G1 and G1-S cyclin kinase activities.

Cloning and characterization of p10, an alternatively spliced form of p15 cyclin-dependent kinase inhibitor.

We have cloned an alternatively spliced form of cyclin-dependent kinase (CDK) inhibitor p15 from human placenta. The alternative splice arises from an alternative 5' donor site in intron 1. An in-frame stop codon within the new exon, called exon 1beta, leads to translation of a Mr 10,000 protein identical to the NH2 terminus of p15 but contains a novel, basic COOH terminus. The alternatively spliced form, termed here as p10, is ubiquitously expressed in normal and tumor cell lines as shown by Northern hybridization and reverse transcription-PCR. Transforming growth factor beta1 induces the expression of p10 similarly to p15 in human HaCaT keratinocytes. Expression and analysis of p15 and epitope-tagged p10 in cells by immunohistochemistry showed similar localization of both to the cytoplasm and nucleus in mink epithelial cells and cytoplasmic localization in mouse fibroblasts. Analysis of the effects of p10 and p15 on cell growth indicated that both were transiently growth inhibitory in Mv1Lu and NIH 3T3 cells, but their stable expression did not significantly reduce the number of cell colonies. In contrast to p15, CDK4 and CDK6 did not coimmunoprecipitate p10 in transient expression assays in COS-7 cells. Furthermore, overexpression of p10 together with p15 in COS-7 cells did not interfere with the complex formation of p15 with CDK4 or CDK6. Thus, in the absence of detectable CDK binding, p10 is transiently able to restrain cell cycling, indicating that the alternative splicing of the CDK inhibitors presents further complexity in their regulation and functions.

p21ras-mediated decrease of the retinoblastoma protein in fibroblasts occurs through growth factor-dependent mechanisms.

Stable coexpression of the human retinoblastoma protein (pRB) cDNA and EJ c-Ha-ras oncogene in murine fibroblasts leads to loss of pRB expression with concomitant transformation of the cells (1). We show here that conditional expression of p21ras in mouse fibroblasts expressing human pRB leads to a rapid decrease of pRB expression at both protein and mRNA levels. The decrease of pRB mRNA is blocked by cycloheximide, suggesting the requirement of ongoing protein synthesis. p21ras expression leads also to decreases of c-myc and tissue metalloproteinase inhibitor-2 mRNAs, whereas cyclin-dependent kinase 4, cyclin D1, E2F-1, and ornithine decarboxylase are unaffected. The decrease in pRB is accompanied by progressive morphological transformation of the cells. The effect of p21ras on pRB expression was serum and growth factor dependent. A shift of the cells to low serum (0.2% FCS) abolished the effects of p21ras on pRB, but this effect was reconstituted by the addition of growth factors epidermal growth factor, fibroblast growth factor-2, transforming growth factor beta 1, and platelet-derived growth factor to the cells. The results suggest a complex interaction between p21ras, pRB, and growth factors in the control of cell growth. p21ras appears to drive the cell cycle by deregulation of key cell cycle regulators, the functions of which in low serum become redundant or require the presence of growth factors positively driving the cell cycle.