Dishevelled-1 Research Articles

Abstract 3091: Functional screening of genes involved in carcinogenesis using a cDNA expression library of ovarian clear cell carcinoma cells

Abstract Background: Ovarian clear cell carcinoma (OCCC) is one of the 4 major histological types of ovarian carcinoma (OVC) and is frequently arising from ovarian endometriotic cysts. OCCC is rare in the United States and western countries, but it is more frequent in Japan and may be seen in almost 25% of OVC. OCCC commonly shows chemo-resistance which makes difficult to treat OCCC. In order to develop the new therapeutics for OCCC, genetic abnormalities that lead to the development of OCCC need to be elucidated in detail. The comprehensive analysis using next-generation sequencing has rapidly revealed the accumulation of genetic abnormalities in many cancers. However, the significance of each abnormality has not been elucidated. Therefore, functional screening using a cDNA expression library was performed in order to identify genes involved in the pathogenesis of OCCC. Methods: The mRNA was extracted from an OCCC cell line, RMG-1, and a cDNA library was established using a retroviral vector. This cDNA library was transfected into mouse NIH3T3 cells, and then the transformed foci which formed multilayered growth were picked up and the inserted DNAs of those foci were detected by sequencing. The mRNA and protein expression and the transforming ability of the identified genes were confirmed by immunohistochemistry and focus-formation assay. Result: Seven genes were isolated; Dishevelled 1(DVL1), beta subunit of Sec61 (SEC61B), K-specific demethylase 4A (KDM4A), chromosome 1 open reading frame 38 (C1ORF38), splicing factor 1 (SF1), ribosomal protein S2 (RPS2), and ribosomal protein S3A (RPS3A). Of these genes, RT-PCR and immunostaining revealed that the expression of SEC61B and C1ORF38 was stronger than that in other histological types of ovarian cancer. A mutational analysis of the DVL1 c-terminal region detected 3 point-mutations in RMG1 cells, whereas no mutation was found in 24 cases of OCCC. Focus formation was confirmed by the transfection of SEC61B, C1ORF38, and DVL1 into NIH3T3 cells. Conclusion: These results suggest that SEC61B, C1ORF38, and DVL1 may be involved in the pathogenesis of OCCC. Citation Format: Tsutomu Miyamoto, Yasushi Yamada, Koichi Ida, Ryoichi Asaka, Hisanori Kobara, Hirofumi Ando, Hiroyasu Kashima, Akihisa Suzuki, Tanri Shiozawa. Functional screening of genes involved in carcinogenesis using a cDNA expression library of ovarian clear cell carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3091.

Dishevelled 1, a pivotal positive regulator of the Wnt signalling pathway, mediates 5-fluorouracil resistance in HepG2 cells

Acquired resistance to 5-fluorouracil (5-FU) frequently occurs in patients with hepatocellular carcinoma (HCC), the underlying molecular mechanisms of which are poorly understood. The aim of this study was to identify candidate genes and associated signalling pathways that may play a role in developing drug resistance following repeated 5-FU treatments. In this work, we established 5-FU-resistant cells (HepG2/5-FU) using stepwise increasing concentrations of 5-FU in parental HepG2 cells. Using transcriptome sequencing, we found that the expressions of the Wnt signalling genes, including negative regulators (DKK1, DKK3, ZNRF3, RNF43 and APC2) and positive regulators (FZD10 and DVL1), were significantly downregulated and upregulated in HepG2/5-FU cells, respectively, resulting in increased Wnt signalling. Dishevelled-1 (DVL1) is an essential Wnt signalling pathway component that stabilizes β-catenin and mediates the Wnt pathway. Silencing DVL1 using siDVL1 or other small molecular inhibitors in HepG2/5-FU cells could restore 5-FU responsiveness via reduced cell proliferation and migration, and increased apoptosis. Moreover, DVL1 was found to be upregulated in BEL-7402/5-FU cells when compared to the parental BEL-7402 cells. Collectively, our results provide the first clue towards understanding the contribution of DVL1-mediated acquired resistance to 5-FU in HepG2/5-FU cells, suggesting a promising therapeutic strategy for liver cancer resistant to 5-FU.

Cripto-1 contributes to stemness in hepatocellular carcinoma by stabilizing Dishevelled-3 and activating Wnt/\u03b2-catenin pathway

Identification and characterization of functional molecular targets conferring stemness properties in hepatocellular carcinoma (HCC) offers crucial insights to overcome the major hurdles of tumor recurrence, metastasis and chemoresistance in clinical management. In the current study, we investigated the significance of Cripto-1 in contributing to HCC stemness. Cripto-1 was upregulated in the sorafenib-resistant clones derived from HCC cell lines and patient-derived xenograft that we previously developed, suggesting an association between Cripto-1 and stemness. By in vitro experiments, Cripto-1 fostered cell proliferation, migration, and invasion. It also enhanced self-renewal ability and conferred chemoresistance of HCC cells. Consistently, silencing of Cripto-1 suppressed in vivo tumorigenicity on serial transplantation. On the downstream signaling mechanism, expression of major components of Wnt/β-catenin pathway β-catenin, AXIN2, and C-MYC, accompanied by β-catenin activity was reduced upon Cripto-1 knockdown. The suppressive effects on stemness properties with Cripto-1 knockdown in vitro and in vivo were partially rescued by forced expression of constitutively active β-catenin. Further elucidation revealed the binding of Cripto-1 to Frizzled-7 (FZD7), low-density lipoprotein receptor-related protein 6 (LRP6) and Dishevelled-3 (DVL3) of the Wnt/β-catenin pathway and stabilized DVL3 protein. Analyses with clinical samples validated Cripto-1 overexpression in HCC tissues, as well as a positive correlation between Cripto-1 and AXIN2 expressions. High Cripto-1 level in tumor was associated with poorer disease-free survival of HCC patients. Taken together, Cripto-1 binds to FZD7/LRP6 and DVL3, stabilizes DVL3 expression and activates the Wnt/β-catenin signaling cascade to confer stemness in HCC. Our study findings substantiated the role of Cripto-1 in determining stemness phenotypes of HCC and mechanistically in modulating the Wnt/β-catenin signaling cascade, one of the most frequently deregulated pathways in liver cancer.

Abstract A46: Wnt5a signals through DVL1 to repress ribosomal DNA transcription by RNA polymerase I

Abstract Ribosome biogenesis is essential for cell growth and proliferation and is commonly elevated in cancer. Accordingly, numerous oncogene and tumor suppressor signaling pathways target rRNA synthesis. In breast cancer, non-canonical Wnt signaling by Wnt5a has been reported to antagonize tumor growth. Here, we show that Wnt5a rapidly represses rDNA gene transcription in breast cancer cells and generates a chromatin state with reduced transcription of rDNA by RNA polymerase I (Pol I). These effects were specifically dependent on Dishevelled1 (DVL1), which accumulates in nucleolar organizer regions (NORs) and binds to rDNA regions of the chromosome. Upon DVL1 binding, the Pol I transcription activator and deacetylase Sirtuin 7 (SIRT7) releases from rDNA loci, concomitant with disassembly of Pol I transcription machinery at the rDNA promoter. These findings reveal that Wnt5a signals through DVL1 to suppress rRNA transcription. This provides a novel mechanism for how Wnt5a exerts tumor suppressive effects and why disruption of Wnt5a signaling enhances mammary tumor growth in vivo. Note: This abstract was not presented at the conference. Citation Format: Randall Dass, Aishe Sarshad, Brittany Carson, Jennifer Feenstra, Amanpreet Kaur, Ales Obrdlik, Matthew Parks, Varsha Prakash, Damon Love, Kristian Pietras, Rosa Serra, Scott Blanchard, Piergiorgio Percipalle, Anthony Brown, Clara Theresa Vincent. Wnt5a signals through DVL1 to repress ribosomal DNA transcription by RNA polymerase I. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A46.

Pharmacogenomics of Antidepressant Induced Mania

Identifying clinical and genetic risk factors associated with antidepressant-induced mania (AIM) may improve individualized treatment strategies for bipolar depression. Several small studies have investigated the association of variation in the serotonin transporter gene (SLC6A4) with AIM. Here we extend these studies using a new sample from the Mayo Clinic Bipolar Disorder Biobank, and perform the first genome wide association study (GWAS) of AIM. Bipolar patients, confirmed by structured interview were retrospectively screened for AIM. AIM cases reported a manic/hypomanic episode within 60 days of starting or changing dose of antidepressant, while control had an adequate (≥60 days) exposure to an antidepressant with no associated manic/hypomanic episode. The sample with genome-wide genotyping included 525 Caucasian bipolar patients (174 AIM cases and 351 controls). No genome-wide significant associations were observed in our GWAS of AIM. The SNP with strongest evidence of association (rs10093489; p=5.79E-07) maps to an intron of ZMAT4. Another top signal represents a cluster of SNPs that map to the DVL1 (Dishevelled -1) gene region (top SNP rs307364; P = 1.25E-06). A set of candidate variants selected based on association with treatment response in prior antidepressant pharmacogenomics studies in major depressive disorder did not show evidence of association in the AIM GWAS, suggesting that different variants may contribute to antidepressant response in unipolar and bipolar depression. Ongoing analyses using polygenic methods are being used to further investigate this question. The potential role of DVL1 warrants further investigation, as the gene encodes a cytoplasmic scaffolding protein involved in Wnt signaling, which has been implicated in antidepressant effects in rodents. Further work is encouraged to better delineate the potential role of Wnt signaling in antidepressant response in mood disorders.

DNA methylation patterns associated with oxidative stress in an ageing population.

BackgroundOxidative stress has been related to type 2 diabetes (T2D) and cardiovascular disease (CVD), the leading global cause of death. Contributions of environmental factors such as oxidative stress on complex traits and disease may be partly mediated through changes in epigenetic marks (e.g. DNA methylation). Studies relating differential methylation with intermediate phenotypes and disease endpoints may be useful in identifying additional candidate genes and mechanisms involved in disease.MethodsTo investigate the role of epigenetic variation in oxidative stress marker levels and subsequent development of CVD and T2D, we performed analyses of genome-wide DNA methylation in blood, ten markers of oxidative stress (total glutathione [TGSH], reduced glutathione [GSH], oxidised glutathione [GSSG], GSSG to GSH ratio, homocysteine [HCY], oxidised low-density lipoprotein (oxLDL), antibodies against oxLDL [OLAB], conjugated dienes [CD], baseline conjugated dienes [BCD]-LDL and total antioxidant capacity [TAOC]) and incident disease in up to 966 age-matched individuals.ResultsIn total, we found 66 cytosine-guanine (CpG) sites associated with one or more oxidative stress markers (false discovery rate [FDR] <0.05). These sites were enriched in regulatory regions of the genome. Genes annotated to CpG sites showed enrichment in annotation clusters relating to phospho-metabolism and proteins with pleckstrin domains. We investigated the contribution of oxidative stress-associated CpGs to development of cardiometabolic disease. Methylation variation at CpGs in the 3'-UTR of HIST1H4D (cg08170869; histone cluster 1, H4d) and in the body of DVL1 (cg03465880; dishevelled-1) were associated with incident T2D events during 10 years of follow-up (all permutation p-values <0.01), indicating a role of epigenetic regulation in oxidative stress processes leading to development or progression of diabetes. Methylation QTL (meQTL) analysis showed significant associations with genetic sequence variants in cis at 28 (42%) of oxidative stress phenotype-associated sites (FDR < 0.05). Integrating cis-meQTLs with genotype-phenotype associations indicated that genetic effects on oxidative stress phenotype at one locus (cg07547695; BCL2L11) may be mediated through DNA methylation.ConclusionsIn conclusion, we report novel associations of DNA methylation with oxidative stress, some of which also show evidence of a relation with T2D incidence.Electronic supplementary materialThe online version of this article (doi:10.1186/s12920-016-0235-0) contains supplementary material, which is available to authorized users.

Wnt5a Signals through DVL1 to Repress Ribosomal DNA Transcription by RNA Polymerase I.

Ribosome biogenesis is essential for cell growth and proliferation and is commonly elevated in cancer. Accordingly, numerous oncogene and tumor suppressor signaling pathways target rRNA synthesis. In breast cancer, non-canonical Wnt signaling by Wnt5a has been reported to antagonize tumor growth. Here, we show that Wnt5a rapidly represses rDNA gene transcription in breast cancer cells and generates a chromatin state with reduced transcription of rDNA by RNA polymerase I (Pol I). These effects were specifically dependent on Dishevelled1 (DVL1), which accumulates in nucleolar organizer regions (NORs) and binds to rDNA regions of the chromosome. Upon DVL1 binding, the Pol I transcription activator and deacetylase Sirtuin 7 (SIRT7) releases from rDNA loci, concomitant with disassembly of Pol I transcription machinery at the rDNA promoter. These findings reveal that Wnt5a signals through DVL1 to suppress rRNA transcription. This provides a novel mechanism for how Wnt5a exerts tumor suppressive effects and why disruption of Wnt5a signaling enhances mammary tumor growth in vivo.

AIMP2 Controls Intestinal Stem Cell Compartments and Tumorigenesis by Modulating Wnt/β-Catenin Signaling.

Wnt/β-catenin (CTNNB1) signaling is crucial for the proliferation and maintenance of intestinal stem cells (ISC), but excessive activation leads to ISC expansion and eventually colorectal cancer. Thus, negative regulators are required to maintain optimal levels of Wnt/β-catenin signaling. Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMP) function in protein synthesis, but have also been implicated in signaling cascades affecting angiogenesis, immunity, and apoptosis. In this study, we investigated the relationship between AIMP2 and Wnt/β-catenin signaling in a murine model of intestinal homeostasis and tumorigenesis. Hemizygous deletion of Aimp2 resulted in enhanced Wnt/β-catenin signaling, increased proliferation of cryptic epithelial cells, and expansion of ISC compartments. In an Apc(Min/+) background, Aimp2 hemizygosity increased adenoma formation. Mechanistically, AIMP2 disrupted the interaction between AXIN and Dishevelled-1 (DVL1) to inhibit Wnt/β-catenin signaling by competing with AXIN. Furthermore, AIMP2 inhibited intestinal organoid formation and growth by suppressing Wnt/β-catenin signaling in an Aimp2 gene dosage-dependent manner. Collectively, our results showed that AIMP2 acts as a haploinsufficient tumor suppressor that fine-tunes Wnt/β-catenin signaling in the intestine, illuminating the regulation of ISC abundance and activity. Cancer Res; 76(15); 4559-68. ©2016 AACR.

0048 : Frizzled7 controls postnatal vascular formation through Wnt/β-catenin canonical signaling in a Dll4/Notch dependent and independent way

Growing evidence has shown that Wnt/Fzd proteins are expressed in vascular cells and are directly involved in blood vessel development by regulating endothelial cell (EC) properties. In this study, we analyzed the effects of frizzled7 deficiency in EC on vessel formation in the postnatal mouse retina. We generated fzd7F/F mice and crossed them with Pdgfb-iCre mice to generate fzd7iECKO mice. In the fzd7iECKO retinas at P7 dpn, we observed a delay in vascular network formation, a strong increased in tip cells and filopodia numbers and a decrease in proliferation compared to WT. Interestingly, we also analyzed the retinal vascular development in mice KO for Dishevelled1 (DVL1), a partner involved in Wnt/Fzd signaling downstream Fzd receptor. DVL1KO mice showed a similar but mildly vascular phenotype compared with fzd7iECKO mice. Moreover, intraocular injection of siRNA DVL3 in DVL1KO mice increased DVL1KO phenotype and mimics fzd7iECKO mice phenotype showing that Fzd7 may control angiogenesis through DVL1 and 3. To a better understanding of how fzd7 regulates vessels formation in vivo , we analysed the effects of LiCl injection (activator of β-catenin pathway) or Dll4 intraocular injection in fzd7iECKO and WT mice on vascular retinal phenotype. Our results showed that LiCl totally overrules the effects of Fzd7 deficiency in EC whereas Dll4 only partly rescues the phenotype observed in fzd7iECKO mice. The tip cells impairment in fzd7iECKO mice is overruled by Dll4 but not the delay of vascular growth. We then assessed whether fzd7 deletion impaired the expression of partners of β- catenin and Notch pathways by RT-qPCR. In vivo , deletion of fzd7 in EC induces a decrease in both partners of β-catenin and Notch pathways expression compared to control. Moreover this impairment of β-catenin and Notch pathways in vivo is totally rescue by LiCl injection. This study shows that fzd7 plays a crucial role during angiogenesis in postnatal mouse retina. Fzd7 controls vascular growth through a β-catenin signaling in a Notch independent way but also regulates the tip cells selection through a β-catenin signaling in a Notch dependent manner.

Silencing dishevelled-1 sensitizes paclitaxel-resistant human ovarian cancer cells via AKT/GSK-3β/β-catenin signalling.

Expression of dishevelled-1 (DVL1) has recently been linked to cancer progression, however, its role in resistance to cancer therapy is unclear. In this study, we aimed to explore the function of DVL1 in paclitaxel-resistant human ovarian cancer cells. The MTT assay was used to assess effects of DVL1 silencing on sensitivity of cells that were otherwise resistant to paclitaxel (Taxol). Western blotting and immunofluorescence staining were used to examine effects of DVL1 on AKT/GSK-3β/β-catenin signalling. Dishevelled-1 was found to be over-expressed in a paclitaxel-resistant cell line derived from human ovarian cancer cell line A2780 (A2780/Taxol line) as well as parental A2780 cells. Down-regulation of DVL1 (using the inhibitor 3289-8625 or siRNA (siDVL1) against DVL1) sensitized A2780/Taxol cells to paclitaxel. Over-expression of DVL1 in A2780 cells increased protein levels of P-gp, BCRP and Bcl-2, which are known targets of β-catenin. Silencing DVL1 in A2780/Taxol cells also reduced levels of these proteins, and led to accumulation of β-catenin. In addition, DVL1 aberrantly activated AKT/GSK-3β/β-catenin signalling. Inactivation of AKT signalling attenuated DVL1-mediated inhibition of GSK-3β and accumulation of β-catenin, in both A2780 and A2780/Taxol cells. Taken together, these results suggest that silencing DVL1 sensitized A2780/Taxol cells to paclitaxel, by down-regulating AKT/GSK-3β/β-catenin signalling, providing a novel strategy for chemosensitization of ovarian cancer to paclitaxel-induced cytotoxicity.

Brain metastases from lung cancer show increased expression of DVL1, DVL3 and beta-catenin and down-regulation of E-cadherin.

The susceptibility of brain to secondary formation from lung cancer primaries is a well-known phenomenon. In contrast, the molecular basis for invasion and metastasis to the brain is largely unknown. In the present study, 31 brain metastases that originated from primary lung carcinomas were analyzed regarding over expression of Dishevelled-1 (DVL1), Dishevelled-3 (DVL3), E-cadherin (CDH1) and beta-catenin (CTNNB1). Protein expressions and localizations were analyzed by immunohistochemistry. Genetic alterations of E-cadherin were tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH). Heteroduplex was used to investigate mutations in beta-catenin. DVL1 and DVL3 showed over expression in brain metastasis in 87.1% and 90.3% of samples respectively. Nuclear staining was observed in 54.8% of cases for DVL1 and 53.3% for DVL3. The main effector of the Wnt signaling, beta-catenin, was up-regulated in 56%, and transferred to the nucleus in 36% of metastases. When DVL1 and DVL3 were up-regulated the number of cases with nuclear beta-catenin significantly increased (p = 0.0001). Down-regulation of E-cadherin was observed in 80% of samples. Genetic analysis showed 36% of samples with LOH of the CDH1. In comparison to other lung cancer pathologies, the diagnoses adenocarcinoma and small cell lung cancer (SCLC) were significantly associated to CDH1 LOH (p = 0.001). Microsatellite instability was detected in one metastasis from adenocarcinoma. Exon 3 of beta-catenin was not targeted. Altered expression of Dishevelled-1, Dishevelled-3, E-cadherin and beta-catenin were present in brain metastases which indicates that Wnt signaling is important and may contribute to better understanding of genetic profile conditioning lung cancer metastasis to the brain.

Transcription Expression and Clinical Significance of Dishevelled-3 mRNA andδ-Catenin mRNA in Pleural Effusions from Patients with Lung Cancer

Objective. To evaluate diagnostic utility of Dishevelled-3 (DVL-3) mRNA and δ-catenin mRNA expression in pleural effusions of patients with lung cancer. Methods. DVL-3 mRNA and δ-catenin mRNA levels were assessed by performing RT-PCR on pleural effusion specimens from patients with lung cancer (n = 75) and with lung benign disease (n = 51). Results. The expressions of DVL-3 mRNA and δ-catenin mRNA were significantly higher in malignant than in benign lung disease (P < 0.01) and were obviously higher than cytology in adenocarcinoma (P < 0.01). In single use, DVL-3 mRNA had the highest specificity (94.1%) and PPV (95.7%), whereas δ-catenin mRNA had the highest sensitivity (92.0%) and NPV (88.5%). When combinations of markers were evaluated together, DVL-3 mRNA and δ-catenin mRNA gave a high-diagnostic performance: sensitivity of 100.0%, NPV of 100.0%, and accuracy of 96.0%, respectively. Conclusion. As molecular markers of detecting pleural micrometastasis, DVL-3 mRNA and δ-catenin mRNA are helpful to diagnose the cancer cells in pleural effusions of patients with lung cancer.

Overexpression of dishevelled-1 attenuates wortmannin-induced hyperphosphorylation of cytoskeletal proteins in N2a cell

To investigate the effect of dishevelled-1 (DVL-1) on wortmannin-induced Alzheimer-like hyperphosphorylation of cytoskeletal proteins in mouse neuroblastoma 2a (N2a) cells. Cultured N2a cells were transitorily transfected with DVL-1 expression plasmid using Lipofectamine 2000. Western blot and immunofluorescence microscopy were used to measure the phosphorylation of neurofilament and tau. Level of phosphorylated neurofilament at SMI31 epitope and phosphorylated tau determined by PHF-1 was increased at 1 h and 3 h and back to normal at 6 h after wortmannin 1 micromol/L treatment. The highest level of phosphorylated neurofilament and phosphorylated tau was seen at 1 h and 3 h after wortmannin treatment, respectively. When DVL-1 protein was overexpressed, the hyperphosphorylation of neurofilament at SMI31 and SMI32 epitopes and tau at PHF-1 (Ser-396/404), M4 (Thr-231/Ser-235), and Tau-1 (Ser-198/199/202) epitopes was attenuated. Overexpression of mouse DVL-1 protein inhibits wortmannin-induced hyperphosphorylation of neurofilament and tau in N2a cells.

KIAA1735 gene on human chromosome 11q23.1 encodes a novel protein with myosine-tail homologous domain and C-terminal DIX domain

Dishevelled 1 (DVL1), DVL2 and DVL3 are DIX-domain proteins implicated in the WNT signaling pathway. Here, we searched for a novel DIX-domain protein by using bioinformatics. Uncharacterized human KIAA1735 gene was found encoding a novel DIX-domain protein. Mouse ortholog of human KIAA1735 gene was next identified, and the nucleotide sequence of mouse Kiaa1735 cDNA was determined in silico by assembling nucleotide sequences of ESTs BY753211, BQ931084, CA750490, BQ960056 and a 5'-truncated partial cDNA AK082960. Human KIAA1735 protein (472 aa) and mouse Kiaa1735 protein (474 aa) showed 90.9% total-amino-acid identity. Myosine-tail homologous (MTH) domain and C-terminal DIX domain were conserved between human KIAA1735 and mouse Kiaa1735 proteins. A tyrosine phosphorylation site (Tyr 242) within the MTH domain was conserved between human KIAA1735 and mouse Kiaa1735 proteins. Leucine zipper motif (codon 202-237) and another tyrosine phosphorylation site (Tyr 272) were identified within the MTH domain of human KIAA1735, but not within that of mouse Kiaa1735. Human KIAA1735 mRNA was expressed in brain, subchondral bone, and also in lung cancer. KIAA1735 gene, consisting of 16 exons, was about 45 kb in size. KIAA1735 gene was linked to DLAT gene in tail-to-head manner with an interval less than 4.0 kb. KIAA1735 gene on human chromosome 11q23.1 was located between D11S1391 and D11S1347 loci, the region deleted in sporadic breast cancer. This is the first report on comprehensive characterization of the KIAA1735 gene.

Identification of genomic organisation, sequence variants and analysis of the role of the human dishevelled 1 gene in late onset Alzheimer's disease

Alzheimer's disease (AD) is a disorder characterised by a progressive deterioration in memory and other cognitive functions. Neurofibrillary tangles (NFT) are a major pathological hallmark of AD, these are aggregations of paired helical filaments (PHF) comprised of the hyperphosphorylated microtubule associated protein tau. Several kinases, such as glycogen synthase kinase 3 beta (GSK3beta) and c-Jun N-terminal kinase (JNK), phosphorylate tau at sites that are phosphorylated in PHF. Dishevelled 1 (DVL1) is thought to act as a positive regulator of the wnt signalling pathway, and inhibits GSK3beta activity preventing beta-catenin degradation and thus allowing wnt target gene expression. JNK activation is also regulated by DVL1, however it is unclear if this is via the wnt signalling pathway. These observations suggest a central role for DVL1 in tau phosphorylation and AD and led us to investigate DVL1 as a candidate gene for this disorder. We determined the genomic structure of the DVL1 gene by sequencing and data mining and searched for sequence variations in the coding sequences and flanking introns. The DVL1 gene spans a region of approximately 13.8 kb (not including the 5' untranslated region) and is encoded by 15 exons. Analysis of over 4.3 kb of sequence, including 98% of exonic sequences and introns 2, 3, 6, 7, 9, 10, 11 and 12, revealed there to be six rare (< or =6%) sequence variations. None of these had any association with late onset AD. This would suggest that polymorphic variations in the coding sequences of DVL1 are not important in AD. However further analysis of regulatory regions may lead to the identification of other sequence variations which may be implicated in AD.

Mapping and sequencing rat dishevelled-1: a candidate gene for cerebral ischaemic insult in a rat model of stroke.

A quantitative trait locus on chromosome 5 in the rat is linked to sensitivity to brain ischemia in the stroke-prone spontaneously hypertensive rat (SHRSP). The genes encoding atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) that map to this location have been excluded as candidate genes. We examined dishevelled-1 (DVL-1) as a further candidate gene. DVL-1 had not yet been identified in the rat, but Anp, Bnp, and DVL-1 map to the homologous regions of the rat chromosome 5 quantitative trait locus in both mice and man. Furthermore, DVL-1 is involved in the Notch signalling system, which plays a role in the disorder cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, the symptoms of, which include ischaemic stroke. We show with radiation hybrid mapping that rat DVL-1 indeed maps to chromosome 5, where it is positioned immediately next to microsatellite marker D5Rat49. We sequenced the complete coding sequence and a large part of the intronic genomic sequence for the SHRSP strain and its reference Wistar-Kyoto strain. The DVL-1 sequence in the two strains was identical. Our results essentially exclude the DVL-1 gene as the cause for sensitivity to cerebral ischaemic insult in this rat model of stroke.