Low levels of taurine introgression in the current Brazilian Nelore and Gir indicine cattle populations.

BACKGROUND: Nelore and Gir are the two most important indicine cattle breeds for production of beef and milk in Brazil. Historical records state that these breeds were introduced in Brazil from the Indian subcontinent, crossed to local taurine cattle in order to quickly increase the population size, and then backcrossed to the original breeds to recover indicine adaptive and productive traits. Previous investigations based on sparse DNA markers detected taurine admixture in these breeds. High-density genome-wide analyses can provide high-resolution information on the genetic composition of current Nelore and Gir populations, estimate more precisely the levels and nature of taurine introgression, and shed light on their history and the strategies that were used to expand these breeds. RESULTS: We used the high-density Illumina BovineHD BeadChip with more than 777 K single nucleotide polymorphisms (SNPs) that were reduced to 697 115 after quality control filtering to investigate the structure of Nelore and Gir populations and seven other worldwide populations for comparison. Multidimensional scaling and model-based ancestry estimation clearly separated the indicine, European taurine and African taurine ancestries. The average level of taurine introgression in the autosomal genome of Nelore and Gir breeds was less than 1% but was 9% for the Brahman breed. Analyses based on the mitochondrial SNPs present in the Illumina BovineHD BeadChip did not clearly differentiate taurine and indicine haplotype groupings. CONCLUSIONS: The low level of taurine ancestry observed for both Nelore and Gir breeds confirms the historical records of crossbreeding and supports a strong directional selection against taurine haplotypes via backcrossing. Random sampling in production herds across the country and subsequent genotyping would be useful for a more complete view of the admixture levels in the commercial Nelore and Gir populations.

The German multi-centre study on smoking-related behavior-description of a population-based case-control study.

Tobacco smoking is a major risk factor for most of the diseases leading in mortality. Nicotine dependence (ND), which sustains regular smoking, is now acknowledged to be under substantial genetic control with some environmental contribution. At present, however, genetic studies on ND are mostly conducted in populations that have been poorly characterized with regard to ND-related phenotypes for the simple reason that the respective populations were not primarily collected to study ND. The German multi-centre study 'Genetics of Nicotine Dependence and Neurobiological Phenotypes', which is funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) as part of the Priority Program (Schwerpunktprogramm) SPP1226: 'Nicotine-Molecular and Physiological Effects in CNS', was intended to overcome some of these inherent problems of current genetic studies of ND. The multi-centre study is a population-based case-control study of smokers and never-smokers (n = 2396). The study was unique worldwide because it was the first large-scale genetic study specifically addressing ND with the collection of a wide range of environmental, psychosocial and neurobiological phenotypes. Study design and major population characteristics with emphasis on risk prediction of smoking status were presented in this paper.

P50 sensory gating and smoking in the general population.

P50 gating is a major functional biomarker in research on schizophrenia and other psychiatric conditions with high smoking prevalence. It is used as endophenotype for studying nicotinic systems genetics and as surrogate endpoint measure for drug development of nicotinic agonists. Surprisingly, little is known about P50 gating in the general population and the relationship to smoking-related characteristics. In this multicenter study at six academic institutions throughout Germany, n=907 never-smokers (NS<20 cigarettes/lifetime), n=463 light smokers (LS) with Fagerström Test for Nicotine Dependence (FTND)≥4 and n=353 heavy smokers (HS, FTND<4) were randomly selected from the general population. As part of a standardized protocol for investigating the genetics of nicotine dependence (ND), an auditory P50 paradigm was applied. The main outcome measure was P50-amplitude difference followed by time-frequency analyses and functional imaging (sLORETA). Reduced P50 gating was found in HS compared to NS with LS taking an intermediate position-correlating with the degree of ND. sLORETA and time-frequency analyses indicate that high-frequency oscillations in frontal brain regions are particularly affected. With growing age, P50 gating increased in (heavy) smokers. This is the first large-scale study (normative sample data) on P50 sensory gating and smoking in the general population. Diminished gating of P50 and associated high-frequency oscillations in the frontal brain region are indications of a deficient inhibitory cortical function in nicotine-dependent smokers. The suitability and application of sensory P50 gating as functional biomarker with regard to genetic and pharmacological studies is discussed.

Feasible and successful: genome-wide interaction analysis involving all 1.9 x 10(11) pair-wise interaction tests.

The Genome-Wide Association Study (GWAS) is the study design of choice for detecting common genetic risk factors for multifactorial diseases. The performance of full Genome-Wide Interaction Analyses (GWIA) has always been considered computationally challenging. Two-stage strategies to reduce the amount of numerical analysis require the detection of single marker effects or prior pathophysiological hypotheses before the analysis of interaction. This prevents the detection of pure epistatic effects. Our case-control study in idiopathic generalized epilepsy demonstrates that a full GWIA is feasible through use of data compression, specific data representation, interleaved data organization, and parallelization of the analysis on a multi-processor system. Following extensive quality control of the genotypes, our final list of top interaction hits contains only pairs of interacting SNPs with negligible marginal effects. The TOP HIT interaction was between a SNP-pair intragenic to gene DNER (chr 2) and gene CTNNA3 (chr 10). Both of these genes are functionally involved in neuronal migration, synaptogenesis, and the formation of neuronal circuits. Our results therefore indicate a possible interaction between these two genes in epileptogenesis. Results from GWAS are beginning to reveal a 'missing heritability' in complex traits and diseases. Systematic, hypothesis-free analysis of epistatic interaction (GWIA) may help to close this increasingly recognized gap in heritability.

CIN85 associates with multiple effectors controlling intracellular trafficking of epidermal growth factor receptors.

CIN85 is a multidomain adaptor protein involved in Cbl-mediated down-regulation of epidermal growth factor (EGF) receptors. CIN85 src homology 3 domains specifically bind to a proline-arginine (PxxxPR) motif in Cbl, and this association seems to be important for EGF receptor endocytosis. Here, we report identification of novel CIN85 effectors, all containing one or more PxxxPR motifs, that are indispensable for their mutual interactions. These effectors include phosphatidyl-inositol phosphatases SHIP-1 and synaptojanin 2B1, Arf GTPase-activating proteins ASAP1 and ARAP3, adaptor proteins Hip1R and STAP1, and a Rho exchange factor, p115Rho GEF. Acting as a molecular scaffold, CIN85 clusters its effectors and recruits them to high-molecular-weight complexes in cytosolic extracts of cells. Further characterization of CIN85 binding to ASAP1 revealed that formation of the complex is independent on cell stimulation. Overexpression of ASAP1 increased EGF receptor recycling, whereas ASAP1 containing mutated PxxxPR motif failed to promote this event. We propose that CIN85 functions as a scaffold molecule that binds to numerous endocytic accessory proteins, thus controlling distinct steps in trafficking of EGF receptors along the endocytic and recycling pathways.

Receptor endocytosis via ubiquitin-dependent and -independent pathways.

The controlled termination of signaling pathways after their ligand-induced activation is an important mechanism to ensure appropriate signal intensity and the consequent cellular response. Most cell surface receptors are downregulated by receptor endocytosis and subsequent lysosomal degradation, processes accompanied by attachment of ubiquitin (Ub) molecules to activated receptors and associated proteins. A significant body of evidence supports the view that mono-Ub functions as an important internalization and degradation signal conserved from yeast to mammals. Yet, the mechanisms underlying ligand-dependent receptor endocytosis seem to be divergent and more complex in mammalian cells. This is not only a consequence of evolution-based expansion of endocytic proteins and protein-interaction domains, but is also caused by enhanced formation of networks and multi-molecular complexes linked to activated receptors in higher eukaryotes. Here, we discuss the current view on the role of Ub-dependent and -independent pathways in receptor internalization and endocytosis in mammalian cells.

Active influx transport is mediated by members of the organic anion transporting polypeptide family in human epidermal keratinocytes.

Normal human epidermal keratinocytes have been shown to express a cell-type-specific pattern of extrahepatic cytochrome P450 enzymes and efflux transport proteins showing that these cells metabolize and excrete a variety of xenobiotics. Recently transport proteins involved in the uptake of xenobiotics have been detected and here we analyzed the mRNA and protein expression profiles and functional activities of these proteins in human keratinocytes in comparison to primary liver cells. The transporters studied included the subtypes A, B, C, D, and E of the organic anion transporting polypeptide (OATP) family, which are responsible for the uptake of various anionic and neutral molecules and especially organic cations - including drugs. Constitutive expression of OATP-B, OATP-D, and OATP-E was shown for the first time in normal human epidermal keratinocytes on a molecular level using reverse transcription polymerase chain reaction and northern blot analysis, as well as in human skin tissue shown by tissue blot hybridization and immunohistochemistry. Expression of OATP-A and OATP-C was not detected in any of the keratinocyte samples. In contrast, liver tissue showed a significant expression of OATP-A and OATP-B as well as OATP-C, a weak expression of OATP-D, and no expression of OATP-E. These data revealed that normal human epidermal keratinocytes express a specific profile of transporters involved in drug influx. Using a newly developed uptake-transport assay, uptake of known and well-characterized OATP substrates like estradiol-17beta-glucuronide and estrone sulfate was inhibited in normal human epidermal keratinocytes by specific inhibitors such as taurocholate, verifying the functional capacity of the expressed OATPs. Human dermal fibroblasts seem to have a lower influx transport activity for estradiol-17beta-glucuronide, which correlates with the immunohistologic data. Even though the substrate specificity of the OATP isoforms is only partially known until now, our findings support the concept that uptake of large organic cations like drugs in keratinocytes is an active transport process mediated by members of the OATP family.

Phenotype diversity in familial cylindromatosis: a frameshift mutation in the tumor suppressor gene CYLD underlies different tumors of skin appendages.

Familial cylindromatosis (turban tumor syndrome; Brooke-Spiegler syndrome) (OMIM numbers 123850, 132700, 313100, and 605041) is a rare autosomal dominantly inherited tumor syndrome. The disorder can present with cutaneous adnexal tumors such as cylindromas, trichoepitheliomas, and spiradenomas, and tumors preferably develop in hairy areas of the body such as head and neck. In affected families, mutations have been demonstrated in the CYLD gene located on chromosome 16q12-13 and reveal the characteristic attributes of a tumor suppressor. Here, we studied familial cylindromatosis in a multigeneration family of German origin. Clinically, some individuals only revealed discrete small skin-colored tumors localized in the nasolabial region whereas one family member showed expansion of multiple big tumors on the trunk and in a turban-like fashion on the scalp. Histologically, cylindromas as well as epithelioma adenoides cysticum were found. We detected a frameshift mutation in the CYLD gene, designated 2253delG, underlying the disorder and were able to show that a single mutation can result in distinct clinical and histologic expression in familial cylindromatosis. The reasons for different expression patterns of the same genetic defect in this disease remain elusive, however. Identification of mutations in the CYLD gene enable us to rapidly confirm putative diagnoses on the genetic level and to provide affected families with genetic counseling.