Mutation of Celsr1 disrupts planar polarity of inner ear hair cells and causes severe neural tube defects in the mouse.

We identified two novel mouse mutants with abnormal head-shaking behavior and neural tube defects during the course of independent ENU mutagenesis experiments. The heterozygous and homozygous mutants exhibit defects in the orientation of sensory hair cells in the organ of Corti, indicating a defect in planar cell polarity. The homozygous mutants exhibit severe neural tube defects as a result of failure to initiate neural tube closure. We show that these mutants, spin cycle and crash, carry independent missense mutations within the coding region of Celsr1, encoding a large protocadherin molecule [1]. Celsr1 is one of three mammalian homologs of Drosophila flamingo/starry night, which is essential for the planar cell polarity pathway in Drosophila together with frizzled, dishevelled, prickle, strabismus/van gogh, and rhoA. The identification of mouse mutants of Celsr1 provides the first evidence for the function of the Celsr family in planar cell polarity in mammals and further supports the involvement of a planar cell polarity pathway in vertebrate neurulation.

A mutation in Af4 is predicted to cause cerebellar ataxia and cataracts in the robotic mouse.

The robotic mouse is an autosomal dominant mutant that arose from a large-scale chemical mutagenesis program. It has a jerky, ataxic gait and develops adult-onset Purkinje cell loss in the cerebellum in a striking region-specific pattern, as well as cataracts. Genetic and physical mapping of the disease locus led to the identification of a missense mutation in a highly conserved region of Af4, a putative transcription factor that has been previously implicated in leukemogenesis. We demonstrate that Af4 is specifically expressed in Purkinje cells, and we hypothesize that the expression of mutant Af4 leads to neurodegeneration. This function was not identified through knock-out studies, highlighting the power of phenotype-driven mutagenesis in the mouse to identify new pathways involved in neurological disease.

Characterization of common genetic variants in cathepsin K and testing for association with bone mineral density in a large cohort of perimenopausal women from Scotland.

UNLABELLED: BMD values in approximately 3000 perimenopausal Scottish women were adjusted by regression to identify and account for nongenetic factors. Adjusted BMD values were not associated with simple tandem repeat (STR) markers or single nucleotide polymorphisms (SNPs) at the Cathepsin K (CTSK) locus. We present a thorough analysis of common CTSK polymorphisms and genetic relatedness among CTSK haplotypes. INTRODUCTION: CTSK is a cysteine protease of the papain family and is thought to play a critical role in osteoclast-mediated bone degradation. Rare, inactivating mutations in CTSK cause pychodysostosis, an autosomal recessive osteochondrodysplasia characterized by osteosclerosis and short stature. However, there have been no studies of common genetic variants in CTSK and their possible association with bone density in the general population. MATERIALS AND METHODS: To identify common single nucleotide polymorphisms (SNPs) and simple tandem repeat (STR) polymorphisms in and around CTSK, we screened all CTSK exons, intron A, all intron-exon boundaries, and the putative CTSK promoter region in 130 random whites using both high-performance liquid chromatography (HPLC) and DNA sequencing. CTSK markers were genotyped in approximately 3000 perimenopausal Scottish women whose hip and spine bone mineral density (BMD) had been measured by DXA. We performed linear regression analysis to identify and adjust for nongenetic predictors of BMD, and adjusted BMD values (regression residuals) were tested for association with individual CTSK markers and haplotypes by ANOVA and the composite haplotype method of Zaykin et al. RESULTS AND CONCLUSIONS: We discovered two intronic SNPs (8% and 9% frequency), but no common exonic SNPs (> 1% frequency), and found that three STRs at the immediate 5' end of the CTSK locus are highly polymorphic. The population frequencies of haplotypes defined by these five polymorphisms were estimated, and a cladogram was derived showing proximity of relationship and likely descent of the 30 most common CTSK haplotypes. Regression analyses revealed that approximately 39% of spine and 19% of hip rate of change in BMD was accounted for by nongenetic factors. For baseline BMD values in premenopausal women, nongenetic predictors explained 11% of the variance at the spine and 13% at the hip. Adjusted BMD values showed no statistically significant association with any of the individual CTSK polymorphisms or CTSK haplotypes.

Silicon analogues of the nonpeptidic GnRH antagonist AG-045572: syntheses, crystal structure analyses, and pharmacological characterization.

AG-045572 (CMPD1, 1 a) is a nonpeptidic gonadotropin-releasing hormone (GnRH) antagonist that has been investigated for the treatment of sex hormone-related diseases. In the context of systematic studies on sila-substituted drugs, the silicon analogue disila-AG-045572 (1 b) and its derivative 2 were prepared in multi-step syntheses and characterized by elemental analyses (C, H, N), NMR spectroscopic studies (1H, 13C, 29Si), and single-crystal X-ray diffraction. The pharmacological properties of compounds 1 a, 1 b, and 2 were compared in terms of their in vitro potency at cloned human and rat GnRH receptors. Compounds 1 a and 2 were also examined in regard to their pharmacokinetics and in vivo efficacy in both castrated rat (luteinizing hormone (LH) suppression) and intact rat (testosterone suppression) models. The efficacy and pharmacokinetic profiles of 1 a and its silicon-containing analogue 2 appear similar, indicating that replacement of the 5,6,7,8-tetrahydronaphthalene ring system by the 1,3-disilaindane skeleton led to retention of efficacy. Therefore, the silicon compound 2 represents a novel drug prototype for the design of potent, orally available GnRH antagonists suitable for once-daily dosing.

CCR2 and coronary artery disease: a woscops substudy.

BACKGROUND: Several lines of evidence support a role for CCL2 (monocyte chemotactic protein-1) and its receptor CCR2 in the development of atherosclerosis. The aim of the present study was to determine the association of the CCR2 Val64Ile polymorphism with the development of coronary artery disease in the WOSCOPS study sample set. FINDINGS: A total of 443 cases and 1003 controls from the West of Scotland Coronary Prevention Study (WOSCOPS) were genotyped for the Val64Ile polymorphism in the CCR2 gene. Genotype frequencies were compared between cases and controls. The CCR2 Val64Ile polymorphism was found not to be associated with coronary events in this study population (odds ratio 1.15, 95% CI 0.82-1.61, p = 0.41). CONCLUSIONS: This case-control study does not support an association of the CCR2 Val64Ile polymorphism with coronary artery disease in the WOSCOPS sample set and does not confirm a possible protective role for CCR2 Val64Ile in the development of coronary artery disease.

Atypical CTSK transcripts and ARNT transcription read-through into CTSK.

The aryl hydrocarbon receptor nuclear translocator (ARNT) and cathepsin K (CTSK) genes lie in a tandem head-to-tail arrangement on human chromosome 1. The two genes are in extremely close proximity; the usual CTSK transcription start site is less than 1.4 kb downstream of the end of the longest reported ARNT transcript. By generating an RT-PCR product that overlaps both the 3' end of ARNT and the 5' end of CTSK, we show that ARNT transcripts may extend through the ARNT-CTSK intergenic region and progress into the CTSK gene. Furthermore, by using quantitative RT-PCR from several tissues to detect the ARNT expression signature in CTSK introns, we show that ARNT transcripts can read through into CTSK as far as CTSK intron 3, extending approximately 3.7 kb downstream of the end of the longest previously described ARNT mRNA. Given that ARNT and CTSK are expressed in an overlapping range of tissues, ARNT read-through may have a negative impact on CTSK transcript levels by interfering with CTSK expression. We also present evidence for novel CTSK transcripts following sequence analysis of CTSK-derived ESTs and RT-PCR products. These transcripts show alternate 5' splicing and or 5' extension and are sometimes initiated from a cryptic alternative promoter which is upstream of the known CTSK promoter and possibly in the 3' UTR of ARNT.

Three novel pigmentation mutants generated by genome-wide random ENU mutagenesis in the mouse.

Three mutant mice with pigmentation phenotypes were recovered from a genomewide random mouse chemical mutagenesis study. White toes (Whto; MGI:1861986), Belly spot and white toes (Bswt; MGI:2152776) and Dark footpads 2 (Dfp2; MGI:1861991) were identified following visual inspection of progeny from a male exposed to the point mutagen ethylnitrosourea (ENU). In order to rapidly localize the causative mutations, genome-wide linkage scans were performed on pooled DNA samples from backcross animals for each mutant line. Whto was mapped to proximal mouse chromosome (Mmu) 7 between Cen (the centromere) and D7Mit112 (8.0 cM from the centromere), Bswt was mapped to centric Mmul between D1Mit214 (32.1 cM) and D1Mit480 (32.8 cM) and Dfp2 was mapped to proximalMmu4 between Cen and D4Mit18 (5.2 cM). Whto, Bswt and Dfp2 may provide novel starting points in furthering the elucidation of genetic and biochemical pathways relevant to pigmentation and associated biological processes.

Novel phenotypes identified by plasma biochemical screening in the mouse.

We used ENU mutagenesis in the mouse for the rapid generation of novel mutant phenotypes for both gene function studies and use as new animal models of human disease (Nolan et al. 2000b). One focus of the program was the development of a blood biochemistry screen. At 8-12 weeks of age, approximately 300 ml of blood was collected from F1 offspring of ENU mutagenized male mice. This yielded approximately 125 ml of plasma, used to perform a profile of 17 standard biochemical tests on an Olympus analyzer. Cohorts of F1 mice were also aged and then retested to detect late onset phenotypes. In total, 1,961 F1s were screened. Outliers were identified by running means and standard deviations. Of 70 mice showing consistent abnormalities in plasma biochemistry, 29 were entered into inheritance testing. Of these, 9 phenotypes were confirmed as inherited, 10 found not to be inherited, and 10 are still being tested. Inherited mutant phenotypes include abnormal lipid profiles (low total and HDL cholesterol, high triglycerides); abnormalities in bone and liver metabolism (low ALP, high ALP, high ALT, and AST); abnormal plasma electrolyte levels (high sodium and chloride); as well as phenotypes of interest for the study of diabetes (high glucose). The gene loci bearing the mutations are currently being mapped and further characterized. Our results have validated our biochemical screen, which is applicable to other mutagenesis projects, and we have produced a new set of mutants with defined metabolic phenotypes.

Towards a mutant map of the mouse--new models of neurological, behavioural, deafness, bone, renal and blood disorders.

With the completion of the first draft of the human genome sequence, the next major challenge is assigning function to genes. One approach is genome-wide random chemical mutagenesis, followed by screening for mutant phenotypes of interest and subsequent mapping and identification of the mutated genes in question. We (a consortium made up of GlaxoSmithKline, the MRC Mammalian Genetics Unit and Mouse Genome Centre, Harwell, Imperial College, London, and the Royal London Hospital) have used ENU mutagenesis in the mouse for the rapid generation of novel mutant phenotypes for use as animal models of human disease and for gene function assignment (Nolan et al., 2000). As of 2003, 35,000 mice have been produced to date in a genome-wide screen for dominant mutations and screened using a variety of screening protocols. Nearly 200 mutants have been confirmed as heritable and added to the mouse mutant catalogue and, overall, we can extrapolate that we have recovered over 700 mutants from the screening programme. For further information on the project and details of the data, see http://www.mgu.har.mrc.ac.uk/mutabase.