Claus-Jürgen Scholz

Expression of microRNA‐221 is progressively reduced in aggressive prostate cancer and metastasis and predicts clinical recurrence

Emerging evidence shows that microRNAs (miR) are involved in the pathogenesis of a variety of cancers, including prostate carcinoma (PCa). Little information is available regarding miR expression levels in lymph node metastasis of prostate cancer or the potential of miRs as prognostic markers in this disease. Therefore, we analyzed the global expression of miRs in benign, hyperplastic prostate tissue (BPH), primary PCa of a high risk group of PCa patients, and corresponding metastatic tissues by microarray analysis. Consistent with the proposal that some miRs are oncomirs, we found aberrant expression of several miRs, including the downregulation of miR‐221, in PCa metastasis. Downregulation of miR‐221 was negatively correlated with the expression of the proto‐oncogen c‐kit in primary carcinoma. In a large study cohort, the prostate‐specific oncomir miR‐221 was progressively downregulated in aggressive forms of PCa. Downregulation of miR‐221 was associated with clinicopathological parameters, including the Gleason score and the clinical recurrence during follow up. Kaplan–Meier estimates and Cox proportional hazard models showed that miR‐221 downregulation was linked to tumor progression and recurrence in a high risk prostate cancer cohort. Our results showed that progressive miR‐221 downregulation hallmarks metastasis and presents a novel prognostic marker in high risk PCa. This suggests that miR‐221 has potential as a diagnostic marker and therapeutic target in PCa.

Differential effects of prenatal stress in 5-Htt deficient mice: towards molecular mechanisms of gene × environment interactions.

Prenatal stress (PS) has been shown to influence the development of the fetal brain and to increase the risk for the development of psychiatric disorders in later life. Furthermore, the variation of human serotonin transporter (5-HTT, SLC6A4) gene was suggested to exert a modulating effect on the association between early life stress and the risk for depression. In the present study, we used a 5-Htt×PS paradigm to investigate whether the effects of PS are dependent on the 5-Htt genotype. For this purpose, the effects of PS on cognition, anxiety- and depression-related behavior were examined using a maternal restraint stress paradigm of PS in C57BL6 wild-type (WT) and heterozygous 5-Htt deficient (5-Htt +/−) mice. Additionally, in female offspring, a genome-wide hippocampal gene expression profiling was performed using the Affymetrix GeneChip® Mouse Genome 430 2.0 Array. 5-Htt +/− offspring showed enhanced memory performance and signs of reduced anxiety as compared to WT offspring. In contrast, exposure of 5-Htt +/− mice to PS was associated with increased depressive-like behavior, an effect that tended to be more pronounced in female offspring. Further, 5-Htt genotype, PS and their interaction differentially affected the expression of numerous genes and related pathways within the female hippocampus. Specifically, MAPK and neurotrophin signaling were regulated by both the 5-Htt +/− genotype and PS exposure, whereas cytokine and Wnt signaling were affected in a 5-Htt genotype×PS manner, indicating a gene×environment interaction at the molecular level. In conclusion, our data suggest that although the 5-Htt +/− genotype shows clear adaptive capacity, 5-Htt +/− mice –particularly females– at the same time appear to be more vulnerable to developmental stress exposure when compared to WT offspring. Moreover, hippocampal gene expression profiles suggest that distinct molecular mechanisms mediate the behavioral effects of the 5-Htt genotype, PS exposure, and their interaction.

Identification of New Therapeutic Targets by Genome-Wide Analysis of Gene Expression in the Ipsilateral Cortex of Aged Rats after Stroke

Background Because most human stroke victims are elderly, studies of experimental stroke in the aged rather than the young rat model may be optimal for identifying clinically relevant cellular responses, as well for pinpointing beneficial interventions. Methodology/Principal Findings We employed the Affymetrix platform to analyze the whole-gene transcriptome following temporary ligation of the middle cerebral artery in aged and young rats. The correspondence, heat map, and dendrogram analyses independently suggest a differential, age-group-specific behaviour of major gene clusters after stroke. Overall, the pattern of gene expression strongly suggests that the response of the aged rat brain is qualitatively rather than quantitatively different from the young, i.e. the total number of regulated genes is comparable in the two age groups, but the aged rats had great difficulty in mounting a timely response to stroke. Our study indicates that four genes related to neuropathic syndrome, stress, anxiety disorders and depression (Acvr1c, Cort, Htr2b and Pnoc) may have impaired response to stroke in aged rats. New therapeutic options in aged rats may also include Calcrl, Cyp11b1, Prcp, Cebpa, Cfd, Gpnmb, Fcgr2b, Fcgr3a, Tnfrsf26, Adam 17 and Mmp14. An unexpected target is the enzyme 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 1 in aged rats, a key enzyme in the cholesterol synthesis pathway. Post-stroke axonal growth was compromised in both age groups. Conclusion/Significance We suggest that a multi-stage, multimodal treatment in aged animals may be more likely to produce positive results. Such a therapeutic approach should be focused on tissue restoration but should also address other aspects of patient post-stroke therapy such as neuropathic syndrome, stress, anxiety disorders, depression, neurotransmission and blood pressure.

Allelic variation in CRHR1 predisposes to panic disorder: evidence for biased fear processing.

Corticotropin-releasing hormone (CRH) is a major regulator of the hypothalamic–pituitary–adrenal axis. Binding to its receptor CRHR1 triggers the downstream release of the stress response-regulating hormone cortisol. Biochemical, behavioral and genetic studies revealed CRHR1 as a possible candidate gene for mood and anxiety disorders. Here we aimed to evaluate CRHR1 as a risk factor for panic disorder (PD). Allelic variation of CRHR1 was captured by 9 single-nucleotide polymorphisms (SNPs), which were genotyped in 531 matched case/control pairs. Four SNPs were found to be associated with PD, in at least one sub-sample. The minor allele of rs17689918 was found to significantly increase risk for PD in females after Bonferroni correction and furthermore decreased CRHR1 mRNA expression in human forebrains and amygdalae. When investigating neural correlates underlying this association in patients with PD using functional magnetic resonance imaging, risk allele carriers of rs17689918 showed aberrant differential conditioning predominantly in the bilateral prefrontal cortex and safety signal processing in the amygdalae, arguing for predominant generalization of fear and hence anxious apprehension. Additionally, the risk allele of rs17689918 led to less flight behavior during fear-provoking situations but rather increased anxious apprehension and went along with increased anxiety sensitivity. Thus reduced gene expression driven by CRHR1 risk allele leads to a phenotype characterized by fear sensitization and hence sustained fear. These results strengthen the role of CRHR1 in PD and clarify the mechanisms by which genetic variation in CRHR1 is linked to this disorder.

The genetic contribution of the NO system at the glutamatergic post-synapse to schizophrenia : further evidence and meta-analysis

NO is a pleiotropic signaling molecule and has an important role in cognition and emotion. In the brain, NO is produced by neuronal nitric oxide synthase (NOS-I, encoded by NOS1) coupled to the NMDA receptor via PDZ interactions; this protein-protein interaction is disrupted upon binding of NOS1 adapter protein (encoded by NOS1AP) to NOS-I. As both NOS1 and NOS1AP were associated with schizophrenia, we here investigated these genes in greater detail by genotyping new samples and conducting a meta-analysis of our own and published data. In doing so, we confirmed association of both genes with schizophrenia and found evidence for their interaction in increasing risk towards disease. Our strongest finding was the NOS1 promoter SNP rs41279104, yielding an odds ratio of 1.29 in the meta-analysis. As findings from heterologous cell systems have suggested that the risk allele decreases gene expression, we studied the effect of the variant on NOS1 expression in human post-mortem brain samples and found that the risk allele significantly decreases expression of NOS1 in the prefrontal cortex. Bioinformatic analyses suggest that this might be due the replacement of six transcription factor binding sites by two new binding sites as a consequence of proxy SNPs. Taken together, our data argue that genetic variance in NOS1 resulting in lower prefrontal brain expression of this gene contributes to schizophrenia liability, and that NOS1 interacts with NOS1AP in doing so. The NOS1-NOS1AP PDZ interface may thus well constitute a novel target for small molecules in at least some forms of schizophrenia.

Tspan-1 is a tetraspanin preferentially expressed by mucinous and endometrioid subtypes of human ovarian carcinomas

In many human cancers, tumor progression was found to be associated with an altered expression of tetraspanins, a group of transmembrane adaptor proteins that are implicated in fundamental cellular processes. Although recognized as a characteristic of malignant cells of various origins, Tspan-1 has not yet been characterized in detail due to lack of specific antibodies. We describe the generation of Tspan-1-specific antibodies and immunohistochemical staining of different subtypes of ovarian carcinomas (n=72) that revealed significant differences in Tspan-1 expression that was pronounced in mucinous and endometrioid tumors. The observation that immunoreactivity was focused in intracellular vesicles often concentrated at the luminal sides of glandular structures further supported the assumption that Tspan-1 is involved in secretory pathways. In the group of serous ovarian carcinomas, pronounced expression of Tspan-1 was observed in FIGO stage III C-classified tumors of advanced stages. In summary, our results show that Tspan-1 is an important characteristic of malignant ovarian cancer cells and a potential therapeutic target.

Prenatal stress-induced programming of genome-wide promoter DNA methylation in 5-HTT-deficient mice

The serotonin transporter gene (5-HTT/SLC6A4)-linked polymorphic region has been suggested to have a modulatory role in mediating effects of early-life stress exposure on psychopathology rendering carriers of the low-expression short (s)-variant more vulnerable to environmental adversity in later life. The underlying molecular mechanisms of this gene-by-environment interaction are not well understood, but epigenetic regulation including differential DNA methylation has been postulated to have a critical role. Recently, we used a maternal restraint stress paradigm of prenatal stress (PS) in 5-HTT-deficient mice and showed that the effects on behavior and gene expression were particularly marked in the hippocampus of female 5-Htt+/− offspring. Here, we examined to which extent these effects are mediated by differential methylation of DNA. For this purpose, we performed a genome-wide hippocampal DNA methylation screening using methylated-DNA immunoprecipitation (MeDIP) on Affymetrix GeneChip Mouse Promoter 1.0 R arrays. Using hippocampal DNA from the same mice as assessed before enabled us to correlate gene-specific DNA methylation, mRNA expression and behavior. We found that 5-Htt genotype, PS and their interaction differentially affected the DNA methylation signature of numerous genes, a subset of which showed overlap with the expression profiles of the corresponding transcripts. For example, a differentially methylated region in the gene encoding myelin basic protein (Mbp) was associated with its expression in a 5-Htt-, PS- and 5-Htt × PS-dependent manner. Subsequent fine-mapping of this Mbp locus linked the methylation status of two specific CpG sites to Mbp expression and anxiety-related behavior. In conclusion, hippocampal DNA methylation patterns and expression profiles of female prenatally stressed 5-Htt+/− mice suggest that distinct molecular mechanisms, some of which are promoter methylation-dependent, contribute to the behavioral effects of the 5-Htt genotype, PS exposure and their interaction.

KCNIP4 as a candidate gene for personality disorders and adult ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder in children with striking persistence into adulthood and a high co-morbidity with other psychiatric disorders, including personality disorders (PD). The 4p15.31 region was shown to be associated with ADHD in several genome wide association studies (GWAS). In the present study we also report association of the 4p15.31 locus with Cluster B and Cluster C PD as identified by a pooled genome-wide association study in 400 individuals suffering from PD. The gene coding for the Kv channel-interacting protein 4 (KCNIP4) is located in this region. KCNIP4 is an interaction partner of presenilin and plays a role in a negative feedback loop in the Wnt/β-catenin pathway. Thus, we reasoned it to be a promising candidate gene for ADHD as well as for PD. To clarify the role of KCNIP4 in those disorders, we conducted candidate gene based association studies in 594 patients suffering from adult ADHD and 630 PD patients as compared to 974 healthy control individuals. In the adult ADHD sample, six single markers and one haplotype block revealed to be associated with disease (p values from 0.0079 to 0.049). Seven markers within the KCNIP4 gene showed an association with PD (p values from 0.0043 to 0.0437). The results of these studies suggest a role of KCNIP4 in the etiology of ADHD, PD and other co-morbid disorders.

Functional variants of TSPAN8 are associated with bipolar disorder and schizophrenia.

Tetraspanins affect protein trafficking and are known to influence a wide variety of physiologic processes. Recently, single nucleotide polymorphisms (SNPs) of the tetraspanin gene TSPAN8 were found among the best ranked markers of genome wide association studies on bipolar disorder (BPD) (rs1705236) and type‐2 diabetes, but functional consequences remained largely unknown. In the present study, we examined 13 tagging SNPs covering the TSPAN8 gene, the intronic TSPAN8 SNP rs1705236 as well as two non‐synonymous (ns) SNPs in schizophrenia (SCZ) and BPD samples. In our analysis setting, we were not able to replicate the association of rs1705236 with BPD, nor did we find an association with SCZ. In the TSPAN8 upstream transcriptional control region however, we found rs4500567 to be associated with BPD. In contrast, in SCZ the nsSNP rs3763978 was associated with disease. The significance of both associations withstood conservative Bonferroni correction. In an attempt to link the polymorphisms to functional consequences, we performed an allele‐specific in silico mapping of transcription factor binding sites around rs4500567 and predicted the tolerance of the Gly73Ala exchange caused by rs3763978. The results argue for a differential promoter activity specific for the variant associated with BPD, but impaired protein functionality in SCZ. This suggests that TSPAN8 contributes to both diseases, yet with different underlying mechanisms: regulatory versus structural. Similar phenomena might also occur in other risk genes for both BPD and SCZ, providing a molecular basis for the genetic overlap of both entities.

Activation of myenteric glia during acute inflammation in vitro and in vivo

Background Enteric glial cells (EGCs) are the main constituent of the enteric nervous system and share similarities with astrocytes from the central nervous system including their reactivity to an inflammatory microenvironment. Previous studies on EGC pathophysiology have specifically focused on mucosal glia activation and its contribution to mucosal inflammatory processes observed in the gut of inflammatory bowel disease (IBD) patients. In contrast knowledge is scarce on intestinal inflammation not locally restricted to the mucosa but systemically affecting the intestine and its effect on the overall EGC network. Methods and Results In this study, we analyzed the biological effects of a systemic LPS-induced hyperinflammatory insult on overall EGCs in a rat model in vivo, mimicking the clinical situation of systemic inflammation response syndrome (SIRS). Tissues from small and large intestine were removed 4 hours after systemic LPS-injection and analyzed on transcript and protein level. Laser capture microdissection was performed to study plexus-specific gene expression alterations. Upon systemic LPS-injection in vivo we observed a rapid and dramatic activation of Glial Fibrillary Acidic Protein (GFAP)-expressing glia on mRNA level, locally restricted to the myenteric plexus. To study the specific role of the GFAP subpopulation, we established flow cytometry-purified primary glial cell cultures from GFAP promotor-driven EGFP reporter mice. After LPS stimulation, we analyzed cytokine secretion and global gene expression profiles, which were finally implemented in a bioinformatic comparative transcriptome analysis. Enriched GFAP+ glial cells cultured as gliospheres secreted increased levels of prominent inflammatory cytokines upon LPS stimulation. Additionally, a shift in myenteric glial gene expression profile was induced that predominantly affected genes associated with immune response. Conclusion and Significance Our findings identify the myenteric GFAP-expressing glial subpopulation as particularly susceptible and responsive to acute systemic inflammation of the gut wall and complement knowledge on glial involvement in mucosal inflammation of the intestine.