我国6个地方绵羊品种微卫星DNA多态性研究

利用聚丙烯酰胺凝胶电泳技术研究了我国蒙古羊、乌珠穆沁羊、哈萨克羊、阿勒泰羊、滩羊和藏绵羊 6个地方绵羊品种 17个微卫星标记的多态性 ,以探讨其遗传多样性、起源分化及群体间的遗传亲缘关系。结果表明微卫星标记不同位点间遗传多样性差异极显著 (P <0 0 1) ,群体间多态信息含量 (PIC)、近交程度 (Fis)和观察杂合度 (Obs .Het)差异不显著 ,但基因多样性 (genediversity)和期望杂合度 (Exp .Het)差异显著 (P <0 0 5 )。所研究的我国 6个地方绵羊品种与欧洲品种具有相似的遗传多样性 ,但具有较高的近交系数。个体和群体的聚类分析结果提示我国地方绵羊品种可能起源于两类祖先。群体间的聚类分析结果还表明 ,蒙古羊与乌珠穆沁羊分化不明显且具有较近的遗传亲缘关系 ,蒙古羊与藏绵羊间分化明显且具有较远的遗传亲缘关系。滩羊、阿勒泰羊以及藏绵羊间也具有较近的遗传亲缘关系。所研究的我国 6个地方绵羊品种的遗传分化 (Fst)与西班牙绵羊品种接近 ,但明显小于欧洲其他绵羊品种     

SLC1A2 Variant Is Associated with Essential Tremor in Taiwanese Population

Essential tremor (ET), which is one of the most common movement disorders, may lead to severe interference in quality of life. The first genome-wide association study (GWAS) has identified an association of the LINGO1 variant (rs9652490) with ET in Americans and Europeans. Recently, a second GWAS that was performed in a European population has discovered a new variant (rs3794087) of the main glial glutamate transporter (SLC1A2) that increases the risk of ET with an odds ratio of about 1.4. SLC1A2 encodes for the major glial high-affinity glutamate reuptake transporter in the brain and is a potential ET susceptibility gene. Because replication in a different ethnic population is important for validating a finding, we conducted a case-control study to investigate the SLC1A2 variant in an Asian cohort with ET in Taiwan. A total of 542 subjects (273 ET patients and 269 controls) were included. The results showed that rs3794087 was associated with ET among the Taiwanese. The odds ratio was 1.37. Our results were similar to those of the second GWAS of ET in Europeans, and this confirms that SLC1A2 may be a good functional candidate gene for ET. A replication study in another independent population is of importance to validate this association.     

Regulation of SLC11A3 by inflammation

Acute and chronic inflammatory states are characterized by changes in body iron metabolism. These changes include a drop in serum iron, an increase in the rate of plasma iron disappearance, a decline in the rate of plasma iron turnover, reticuloendothelial system (RES) cell iron sequestration and a decline in intestinal iron absorption. This response is elicited by a variety of metabolic conditions and acute bacterial infections, especially gram-negative bacteria, and by experimental mediators of inflammation such as endotoxin and turpentine. These changes in iron metabolism contribute to the development of the anemia of chronic diseases. SLC11A3 (aka MTP1, ferroportin 1, IREG1) is a metal transporter that exports iron from the cytosol of cells and was initially identified as the duodenal epithelial basolateral iron transporter. Recent identification of a MTP1 mutation leading to hemochromatosis in man adds further weight to the hypothesis that MTP1 is involved in iron homeostasis. RES cells are responsible for the recycling of iron from the breakdown of heme from senescent erythrocytes and MTP1 has been hypothesized to be the key iron exporter in these cells. Supporting this hypothesis is the observation that MTP1 is expressed in the RES macrophages of the spleen, Kupffer cells, bone marrow and lymph node histiocytes, mesangial cells, brain microglial cells. In a mouse (C57/Bl6) model of lipopolysaccharide (LPS) induced acute inflammation, MTP1 expression in the cells of the RES is regulated by acute inflammation. Immunohistochemical staining of tissues, using an anti-MTP1 antibody, of mice given parenteral injections of LPS demonstrated down-regulation of MTP1 expression in the RES cells of the spleen and liver and also in the duodenal epithelial cells compared to control animals. Western blotting of total liver and spleen lysates confirmed the decline in MTP1 protein expression induced by LPS. In addition, RT-PCR analysis showed that LPS treatment also resulted in a decline in MTP1 mRNA in spleen, liver and duodenum compared to controls. One clue to the molecular signaling mechanism for MTP1 down-regulation by LPS comes from the study of the C3H/HeJ mouse, which lacks a functional LPS receptor, toll-like receptor 4 (TLR4). C3H/HeJ mice are resistant to the toxic and hypoferraemic effects of LPS. Similarly, a down-regulation of MTP1 in response to LPS in the C3H/HeJ mice was not observed. This finding indicates that the down-regulation of MTP1 by LPS requires signaling through TLR4. Despite resistance to LPS, treatment of C3H/HeJ mice with turpentine, an inducer of sterile inflammation, for a period of 24 hours resulted in down-regulation of MTP1 expression in the spleen. These data indicate that LPS mediated down-regulation of MTP1 requires a functional TLR4, but that there are non-TLR4 dependent mechanisms for the down-regulation of MTP1 by inflammatory stimuli. In vitro treatment of mouse adherent splenocytes with 5 ug ml of LPS also resulted in down-regulation of MTP1 mRNA. This in vitro down-regulation was not abrogated by co-treatment of cells with pyrrolidinedithiocarbamate (PDTC), a well-characterized inhibitor of NF-KB activation or anti-tumor necrosis factor-a antibodies. In addition, in vitro treatment of mouse splenocytes with recombinant TNF- did not result in down-regulation of MTP1 mRNA. The lack of antagonism between LPS and PDTC and the lack of an effect of TNF- in vitro indicates that NF-B activation may not be required for MTP1 mRNA down-regulation. This inflammation-mediated down-regulation of MTP1 expression in the RES may be a component responsible for iron sequestration in the RES in both acute and chronic inflammatory states.     

A model of Salmonella colitis with features of diarrhea in SLC11A1 wild-type mice

BACKGROUND: Mice do not get diarrhea when orally infected with S. enterica, but pre-treatment with oral aminoglycosides makes them susceptible to Salmonella colitis. However, genetically susceptible ItyS mice (Nramp1(G169D) allele) die from systemic infection before they develop diarrhea, so a new model is needed to study the pathogenesis of diarrhea. We pretreated ItyR mice (Nramp1(G169)) with oral kanamycin prior to infecting them with virulent S. Typhimurium strain 14028s in order to study Salmonella-induced diarrhea. We used both a visual scoring system and the measurement of fecal water content to measure diarrhea. BALB/c.D2(Nramp1) congenic started losing weight 5 days post-infection and they began to die from colitis 10-14 days after infection. A SPI-1 (invA) mutant caused cecal, but not colonic inflammation and did not cause diarrhea. A phoP- mutant did not cause manifestations of diarrhea in either normal or NADPH-deficient (gp91(phox)) mice. However, strain 14028s caused severe colitis and diarrhea in gp91(phox)-deficient mice on an ItyR background. pmr A and F mutants, which are less virulent in orally infected BALB/c mice, were fully virulent in this model of colitis. CONCLUSIONS: S. enterica must be able to invade the colonic epithelium and to persist in the colon in order to cause colitis with manifestations of diarrhea. The NADPH oxidase is not required for diarrhea in Salmonella colitis. Furthermore, a Salmonella phoP mutant can be cleared from the colon by non-oxidative host defenses.     

Molecular Characterization of Natural Hybrids Formed between Five Related Indigenous Clade 6 Phytophthora Species

Most Phytophthora hybrids characterized to date have emerged from nurseries and managed landscapes, most likely generated as a consequence of biological invasions associated with the movement of living plants and germplasm for ornamental, horticultural and agricultural purposes. Presented here is evidence for natural hybridization among a group of five closely related indigenous clade 6 Phytophthora species isolated from waterways and riparian ecosystems in Western Australia. Molecular characterization of hybrids consisted of cloning and sequencing two nuclear genes (ITS and ASF), sequencing of two further nuclear loci (BT and HSP) and of two mitochondrial loci (COI and NADH). Additionally, phenotypic traits including morphology of sporangia and optima and maxima temperatures for growth were also determined. In most cases the nuclear genes were biparentally and in all cases the mtDNA were uniparentally inherited, indicating hybrid formation through sexual crosses. Some isolates bear the molecular signature of three parents suggesting additional hybrid events, although it cannot be determined from the data if these were sequential or simultaneous. These species and their hybrids co-exist in riparian ecosystems and waterways where their ability for rapid asexual proliferation would enable them to rapidly colonize green plant litter. The apparent ease of hybridization could eventually lead to the merging of species through introgression. However, at this point in time, species integrity has been maintained and a more likely scenario is that the hybrids are not stable evolutionary lineages, but rather transient hybrid clones.     

Polymorphisms of the SLC11A1 gene and resistance to bovine tuberculosis in African Zebu cattle

Bovine tuberculosis (BTB) is a considerable health threat to livestock keepers and general communities in many developing countries. Information on genetic resistance or susceptibility because of polymorphisms of candidate genes could be used in making selection decisions for breeding disease tolerant/resistant animals. Here, we investigated associations between polymorphisms at the solute carrier family 11 (proton‐coupled divalent metal ion transporters), member 1 gene (SLC11A1, previously known as natural resistant associated macrophage protein 1, NRAMP1), with BTB phenotypes in Chadian cattle. Phenotypes were (i) single intradermal comparative cervical tuberculin test (SICCT) outcome, (ii) presence of gross visible lung lesions, (iii) a bacteriological culture test outcome and (iv) a predicted true BTB infection status using a Bayesian model. All traits were recorded as binary (presence or absence) traits. A total of 211 cattle were genotyped for a microsatellite within the SLC11A1 candidate gene. Standard linear and threshold‐liability models regressing BTB traits on copy number of SLC11A1 alleles revealed statistically significant effects of SLC11A1 alleles (P < 0.001) on most BTB traits. Polymorphisms (alleles 211, 215 and 217) are significantly related to lower incidence of BTB traits in Chadian cattle. This is the first study to report the association of SLC11A1 gene polymorphisms with BTB traits in Chadian or any other African cattle breeds.     

SLC7A9 cDNA cloning and mutational analysis of SLC3A1 and SLC7A9 in canine cystinuria

Cystinuria is a genetic disorder in the domestic dog that leads to recurrent urolith formation. The genetic basis of the disorder is best characterized in humans and is caused by mutations in one of the amino acid transporter genes SLC3A1 or SLC7A9, which results in hyperexcretion of cystine and the dibasic amino acids in the urine and subsequent precipitation of cystine due to its low solubility in urine. In this study we describe the cloning of the canine SLC7A9 cDNA and present a thorough mutation analysis of the coding SLC3A1 and SLC7A9 regions in cystinuric dogs of different breeds. Mutation analysis of the two cystinuria disease genes revealed one SLC7A9 mutation (A217T) and two SLC3A1 mutations (I192V and S698G) in French and English Bulldogs that affect nonconserved amino acid residues, arguing against functional impact on the proteins. The absence of deleterious mutations linked to cystinuria in the remainder of our panel of cystinuric dogs is surprising because SLC3A1 or SLC7A9 mutations explain approximately 70% of all human cystinuria cases studied. The present study, along with previous investigations of canine and human cystinuria, implies that regulatory parts of the SLC3A1 and SLC7A9 genes as well as other unknown genes may harbor mutations causing cystinuria.     

Molecular Mechanism of SLC5A8 Inactivation in Breast Cancer

SLC5A8 is a putative tumor suppressor that is inactivated in more than 10 different types of cancer, but neither the oncogenic signaling responsible for SLC5A8 inactivation nor the functional relevance of SLC5A8 loss to tumor growth has been elucidated. Here, we identify oncogenic HRAS (HRAS^G12V) as a potent mediator of SLC5A8 silencing in human nontransformed normal mammary epithelial cell lines and in mouse mammary tumors through DNMT1. Further, we demonstrate that loss of Slc5a8 increases cancer-initiating stem cell formation and promotes mammary tumorigenesis and lung metastasis in an HRAS-driven murine model of mammary tumors. Mammary-gland-specific overexpression of Slc5a8 (mouse mammary tumor virus-Slc5a8 transgenic mice), as well as induction of endogenous Slc5a8 in mice with inhibitors of DNA methylation, protects against HRAS-driven mammary tumors. Collectively, our results provide the tumor-suppressive role of SLC5A8 and identify the oncogenic HRAS as a mediator of tumor-associated silencing of this tumor suppressor in mammary glands. These findings suggest that pharmacological approaches to reactivate SLC5A8 expression in tumor cells have potential as a novel therapeutic strategy for breast cancer treatment.     

SLC11A1 (NRAMP1) polymorphisms and tuberculosis susceptibility: updated systematic review and meta-analysis

Background

Natural resistance associated macrophage protein 1 (NRAMP1), encoded by the SLC11A1 gene, has been described to regulate macrophage activation and be associated with infectious and autoimmune diseases. The relation between SLC11A1 polymorphisms and tuberculosis susceptibility has been studied in different populations.

Methods

We systematically reviewed published studies on SLC11A1 polymorphisms and tuberculosis susceptibility until September 15, 2010 and quantitatively summarized associations of the most widely studied polymorphisms using meta-analysis.

Results

In total, 36 eligible articles were included in this review. In Meta-analysis, significant associations were observed between tuberculosis risk and widely studied SLC11A1 polymorphisms with summarized odds ratio of 1.35 (95%CI, 1.17–1.54), 1.25 (95% CI, 1.04–1.50), 1.23 (95% CI, 1.04–1.44), 1.31 (95%CI, 1.08–1.59) for 3′ UTR, D543N, INT4, and 5′ (GT)n, respectively. Heterogeneity between studies was not pronounced, and the associations did not remarkably vary in the stratified analysis with respect to study population and study base.

Conclusions

The association between SLC11A1 polymorphisms and tuberculosis susceptibility observed in our analyses supports the hypothesis that NRAMP1 might play an important role in the host defense to the development of tuberculosis.     

A Functional Variant rs1820453 in YAP1 and Breast Cancer Risk in Chinese Population

Background

To investigate the association between rs1820453 which located in the promoter region of yes-associated protein 1 (YAP1) gene and breast cancer (BC) risk.

Method and Findings

We conducted a hospital-based case-control study including a total of 480 BC cases and 545 cancer-free controls in Chinese population. Then the expression quantitative trait locus (e-QTL) analysis was performed to explore the possible function of rs1820453 to the YAP1 gene expression. The association between rs1820453 and BC risk was significantly identified with the odds ratio (OR) was 1.27 (95 % confidence interval (CI) =1.03-1.57) under allelic model when adjusted by age and menopausal status. In addition, the correlation analysis of rs1820453 and YAP1 expression level found that this variant was significantly associated with the gene expression in Chinese population. When compared with level of mRNA expression of the AA genotype (6.011±0.046), the mRNA expression level in CC genotype (5.903±0.026) was statistically lower (P=0.024).

Conclusion

The results from this study suggested that rs1820453 A>C change may affect the gene expression and contribute to the risk of developing BC in Chinese population though larger sample-size studies along with functional experiments were anticipated to warrant the results.     

Role of SLC11A1 (formerly NRAMP1) in regulation of signal transduction induced by Toll-like receptor 7 ligands

Modulation of immune responses using Toll-like receptor (TLR) ligands is fast becoming one of the main new approaches for the treatment of infectious and allergic diseases. Characterizing the role of genetic factors in modulating responses to these ligands will be crucial in determining the efficacy of a particular treatment. Our previous findings have shown that treatment of Mycobacterium bovis BCG infection with a synthetic TLR7 ligand resulted in a reduction of the splenic bacterial load only in mice carrying a wild-type allele of Nramp1. To understand further how natural resistance-associated macrophage protein 1 (NRAMP1) modulates responses to TLR7 ligands, we have analysed various important TLR7 signal transduction events in macrophage cell lines derived from B10.ANramp1r and B10.ANramp1-/- mice. The Nramp1 genotype did not affect TLR7 receptor expression, ligand uptake or intracellular processing. Following TLR7 ligand stimulation, p38 mitogen-activated protein kinase (MAPK) activation was significantly reduced in B10A.Nramp1-/- macrophages compared with B10A.Nramp1r cells. Interestingly, levels of protein kinase C zeta (PKCzeta) activation were also found to be lower in B10A.Nramp1-/- macrophages and inhibition of this kinase in B10A.Nramp1r cells led to a reduction in cytokine production. Taken together, the data demonstrate a role for NRAMP1 in modulating p38 MAPK and PKCzeta activity, which leads to reduced cytokine induction by TLR7 ligands.     

SLC11A1 Polymorphisms Are Associated with the Risk of Chronic Obstructive Pulmonary Disease in a Korean Population

The solute carrier family 11 member 1 (SLC11A1) protein plays important roles in macrophage activation and displays pleiotropic effects on various macrophage functions, including the regulation of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and oxidative burst. Considering the important roles of macrophage in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that the SLC11A1 gene may act as a low-penetrance susceptibility gene for COPD. To test this hypothesis, we first examined the frequencies of 12 candidate polymorphisms in the SLC11A1 gene in 27 healthy Korean individuals, and then genotyped 3 haplotype-tagging polymorphisms [IVS4 + 14G > C (rs3731865), D543 N (rs17235409), and (*)86A > G (rs1059823)] in 83 COPD patients and 203 healthy controls. Individuals with at least one variant allele of the D543 N and (*)86A > G polymorphisms were at a significantly increased risk for COPD compared with carriers with each homozygous wild-type allele [adjusted odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.24-4.02, P = 0.007; and adjusted OR = 1.92, 95% CI = 1.10-3.35, P = 0.022, respectively]. Consistent with the findings of the genotyping analysis, the 122 haplotype carrying both the 543 N and (*)86G alleles was associated with a significantly increased risk for COPD compared with the 111 haplotype with the 542D and (*)86A alleles (adjusted OR = 2.05, 95% CI = 1.19-3.51, P = 0.009 and Bonferroni corrected P = 0.027). These findings suggest that the SLC11A1 polymorphisms could be used as markers for genetic susceptibility to COPD. However, further studies with large numbers of subjects are needed to confirm our findings.