A possible role for miRNA silencing in disease phenotype variation in Swedish transthyretin V30M carriers

Background

Familial amyloidosis with polyneuropathy (FAP) is an autosomal dominant disease caused by transthyretin (TTR) mutations, of which V30M (TTR c.148G > A, p.Val50Met, "Val30Met") is the most common. Swedish V30M carriers display later age at onset and lower penetrance compared to other populations.

Methods

In the study, 130 Swedish V30M carriers (32 early, 30 late onset and 68 asymptomatic carriers) and 50 controls, 23 French symptomatic V30M carriers and 29 controls and 18 Japanese symptomatic V30M carriers and 29 controls were included. We aimed to identify additional genetic factors in the TTR gene and its surrounding region that could have an impact on phenotype.

Results

We identified three SNPs (rs71383038, rs3794885 and rs62093482) with a significant difference in allele frequency between Swedish V30M carriers and controls. The two Swedish V30M homozygous patients present in the study also displayed homozygosity for the CA10 (rs71383038), A (rs3794885) and T (rs62093482) alleles in these SNPs. Hence, these alleles are present on the Swedish V30M haplotype. Of these, rs62093482 is located in the 3'UTR of TTR gene and thus more interesting since SNPs in the 3'UTR can affect gene expression levels by modifying microRNA (miRNA) targeting activity. miRNA target predictions revealed four potential miRNAs with predicted targets unique for the polymorphic allele.

Conclusions

Our results are the first to show the presence of a 3'UTR polymorphism on the V30M haplotype in Swedish carriers, which can serve as a miRNA binding site potentially leading to down-regulated expression from the mutated TTR allele. This finding may be related to the low penetrance and high age at onset of the disease observed in the Swedish patient population.

Meanings of feeling well for women with multiple sclerosis

In research concerning multiple sclerosis (MS), the factors that impact on people's well-being and quality of life have been studied, but little has been written about what it means to feel well for women with MS. Therefore, in this study our aim was to describe meanings of feeling well for women with MS. We interviewed 15 women with MS, and a phenomenological hermeneutic interpretation was utilized to analyze the interviews. Through this study it can be understood that finding a pace where daily life goes on means that women with MS feel well when the illness is kept in check and is not the dominant experience. The findings of this study can be used to confirm women's experiences of feeling well, despite living with the consequences of MS. Health care professionals will find the results of this study useful when they reflect on and formulate the care of women with MS when attempting to support the latter's desire to feel well in their daily lives.

Giving offspring a head start in life: field and experimental evidence for selection on maternal basking behaviour in lizards

The timing of birth is often correlated with offspring fitness in animals, but experimental studies that disentangle direct effects of parturition date and indirect effects mediated via variation in female traits are rare. In viviparous ectotherms, parturition date is largely driven by female thermal conditions, particularly maternal basking strategies. Our field and laboratory studies of a viviparous lizard (Niveoscincus ocellatus) show that earlier-born offspring are more likely to survive through their first winter and are larger following that winter, than are later-born conspecifics. Thus, the association between parturition date and offspring fitness is causal, rather than reflecting an underlying correlation between parturition date and maternal attributes. Survival selection on offspring confers a significant advantage for increased maternal basking in this species, mediated through fitness advantages of earlier parturition. We discuss the roles of environmentally imposed constraints and parent-offspring conflict in the evolution of maternal effects on parturition date.

Report of five rare or previously unknown amyloidogenic transthyretin mutations disclosed in Sweden

The number of amyloidogenic transthyretin (TTR) mutations described in the literature is more than 100. However, for several mutations, the phenotype has been described in a few individuals only; thus, the knowledge of the clinical course and the outcome after therapeutical interventions such as liver transplantation is limited. We describe the phenotype associated with five rare amyloidogenic TTR mutations that lately were discovered in Sweden: ATTR Val30Leu, Ala45Ser, Leu55Gln, Gly57Arg and Tyr69His of which ATTR Gly57Arg is previously unknown. The symptoms at onset differed, but cardiomyopathy and peripheral neuropathy were observed in all except the ATTR Tyr69His mutation. Likewise, carpal tunnel syndrome was found or had been present in all cases except the case with the ATTR Val30Leu mutation. The phenotype of the ATTR Tyr69His mutation was characterised by oculo-meningeal symptoms with seizures and a steadily progressing dementia, symptoms rarely found in ATTR amyloidosis, but similar to those previously described for this mutation, where all cases appear to originate from one Swedish family. Two patients with the ATTR Leu55Gln and Ala45Ser mutations have been subjected to liver transplantation, but echocardiographic examination has revealed an increasing cardiomyopathy after transplantation in both cases, the ATTR Leu55Gln patient succumbed 2 years after transplantation from progressive disease.

Repeated exposure to organic material alters inflammatory and physiological airway responses

Farmers and smokers are repeatedly exposed to airborne organic material. We hypothesised that farmers and smokers show altered airway responses to inhaled organic, pro-inflammatory agents. A total of 11 farmers, 12 smokers and 12 controls underwent lipopolysaccharide (LPS) bronchial challenge and spent 3 h in a pig barn. Lung function, exhaled nitric oxide and bronchial responsiveness were assessed and nasal lavage fluid and induced sputum were also collected. Symptoms and body temperature were recorded before and after exposures. Following exposure to the pig barn, bronchial responsiveness, exhaled nitric oxide, sputum interleukin (IL)-6, nasal lavage cell count and IL-8 were increased to a greater extent in controls compared to farmers. The sputum IL-6 response was also attenuated in farmers after LPS challenge. The response shown by smokers following exposure to the pig barn was similar to that of controls regarding measurements of exhaled nitric oxide, IL-8 in nasal lavage and IL-6 in sputum, but more similar to farmers concerning bronchial responsiveness and the cell numbers present in nasal lavage. Sputum IL-8 showed a greater increase in smokers than in the other groups following LPS challenge. We conclude that individuals who are repeatedly exposed to organic material develop an adaptation to the effects of acute exposure to inhaled organic material.

Evaluation of offspring size-number invariants in 12 species of lizard

The optimal division of resources into offspring size vs. number is one of the classic problems in life-history evolution. Importantly, models that take into account the discrete nature of resource division at low clutch sizes suggest that the variance in offspring size should decline with increasing clutch size according to an invariant relationship. We tested this prediction in 12 species of lizard with small clutch sizes. Contrary to expectations, not all species showed a negative relationship between variance in offspring size and clutch size, and the pattern significantly deviated from quantitative predictions in five of the 12 species. We suggest that the main limitation of current size-number models for small clutch sizes is that they rely on assumptions of hierarchical allocation strategies with independence between allocation decisions. Indeed, selection may favour alternative mechanisms of reproductive allocation that avoid suboptimal allocation imposed by the indivisible fraction at low clutch sizes.

Three microsatellites from the T1DGC MHC data set show highly significant association with type 1 diabetes, independent of the HLA-DRB1, -DQA1 and -DQB1 genes

AIM

The aim of this study was to test the microsatellites in the Type 1 Diabetes Genetics Consortium major histocompatibility complex (MHC) data set for association with type 1 diabetes (T1D) independent of the HLA-DRB1, -DQA1 and -DQB1 genes.

METHODS

The data set was edited to contain only one affected child per family, and broad ethnic subgroups were defined. Genotypes for HLA-DRB1, -DQA1 and -DQB1 were replaced by a haplotype code spanning all three loci, with phase inferred based on common haplotypes. The final data set contained 8190 samples in 2301 families, 59 microsatellites and the DRB1-DQA1-DQB1 haplotype code. Statistical analyses consisted of conditional logistic regression and haplotype estimations and linkage disequilibrium calculations.

RESULTS

The data set was screened using a main effects test approach adjusted for DRB1-DQA1-DQB1, and significant results tested for validity. After these procedures, four markers remained significant at the Bonferroni-corrected threshold: D6S2773 (p = 0.00014), DG6S185 (p = 0.00015), DG6S398 (p = 0.00043) and D6S2998 (p = 0.00015). These results were supported by allelic tests conditioned on DRB1-DQA1-DQB1 haplotypes, except for DG6S185, which may contain artefacts.

CONCLUSIONS

We have identified three microsatellites that mark additional risk factors for T1D at highly significant levels in the MHC. Further analyses are needed to establish the relationship with other possible genetic determinants in this region.

Mitochondrial haplogroup is associated with the phenotype of familial amyloidosis with polyneuropathy in Swedish and French patients

Familial amyloidotic polyneuropathy (FAP) is a monogenic disease caused by mutations in the transthyretin (TTR) gene. The phenotype of the most common TTR mutation, V30M, varies within and between populations. Oxidative stress and protein misfolding are cellular processes involved in the development of FAP. Because the mitochondria are important for both these processes, we investigated if mitochondrial haplogroups are related to age at onset of the disease in Swedish and French FAP patients. Mitochondrial haplogroup analysis was performed on 25 early-onset (below 40 years) and 29 late-onset (above 51 years) Swedish FAP patients. DNA from 249 Swedish individuals served as controls. In addition, 6 early-onset and 17 late-onset French FAP patients were examined with 25 French controls. The haplogroup distribution among late-onset Swedish and French cases was similar to that found in the general populations, whereas among early-onset cases a different haplogroup distribution was seen. The relatively rare haplogroup K was significantly more common among early-onset cases. Our findings substantiate the suggestion that a genetic component, still to be found, affecting mitochondrial function has an impact on the amyloid generating process in transthyretin amyloidosis.

Males with high genetic similarity to females sire more offspring in sperm competition in Peron's tree frog Litoria peronii

Recent work has confirmed that genetic compatibility among mates can be an important determinant of siring success in sperm competition experiments and in free-ranging populations. Most of this work points towards mate choice of less related mates. However, there may also be the potential for mate choice for intermediate or even genetically similar mates to prevent outbreeding depression or hybridization with closely related taxa. We studied relatedness effects on post-copulatory gametic choice and/or sperm competition in an external fertilizer, Peron's tree frog (Litoria peronii), since external fertilizers offer exceptional control in order to test gametic interaction effects on probability of paternity and zygote viability. Sperm competition experiments were done blindly with respect to genetic relatedness among males and females. Thereafter, paternity of offspring was assigned using eight microsatellite loci. Three hybridization trials between L. peronii and a closely related sympatric species Litoria tyleri were also carried out. In the sperm competition trials, males that are more genetically similar to the female achieved higher siring success compared with less genetically similar males. The hybridization trials confirmed that the two species can interbreed and we suggest that the risk of hybridization may contribute to selection benefits for genetically more similar males at fertilization. To our knowledge, this study is the first to show evidence for post-copulatory selection of sperm from genetically more similar individuals within a natural population.

Conditional analyses on the T1DGC MHC dataset: novel associations with type 1 diabetes around HLA-G and confirmation of HLA-B

The major histocompatibility complex (MHC) is known to harbour genetic risk factors for type 1 diabetes (T1D) additional to the class II determinants HLA-DRB1, -DQA1 and -DQB1, but strong linkage disequilibrium (LD) has made efforts to establish their location difficult. This study utilizes a dataset generated by the T1D genetics consortium (T1DGC), with genotypes for 2965 markers across the MHC in 2321 T1D families of multiple (mostly Caucasian) ethnicities. Using a comprehensive approach consisting of complementary conditional methods and LD analyses, we identified three regions with T1D association, independent both of the known class II determinants and of each other. A subset of polymorphisms that could explain most of the association in each region included single nucleotide polymorphisms (SNPs) in the vicinity of HLA-G, particular HLA-B and HLA-DPB1 alleles, and SNPs close to the COL11A2 and RING1 genes. Apart from HLA-B and HLA-DPB1, all of these represent novel associations, and subpopulation analyses did not indicate large population-specific differences among Caucasians for our findings. On account of the unusual genetic complexity of the MHC, further fine mapping is demanded, with the possible exception of HLA-B. However, our results mean that these efforts can be focused on narrow, defined regions of the MHC.

Death through a tragedy: mitotic catastrophe

Mitotic catastrophe (MC) has long been considered as a mode of cell death that results from premature or inappropriate entry of cells into mitosis and can be caused by chemical or physical stresses. Whereas it initially was depicted as the main form of cell death induced by ionizing radiation, it is today known to be triggered also by treatment with agents influencing the stability of microtubule, various anticancer drugs and mitotic failure caused by defective cell cycle checkpoints. Although various descriptions explaining MC exist, there is still no general accepted definition of this phenomenon. Here, we present evidences indicating that death-associated MC is not a separate mode of cell death, rather a process ('prestage') preceding cell death, which can occur through necrosis or apoptosis. The final outcome of MC depends on the molecular profile of the cell.

DNA damage induces two distinct modes of cell death in ovarian carcinomas

Activation of p53 by cellular stress may lead to either cell cycle arrest or apoptotic cell death. Restrictions in a cell's ability to halt the cell cycle might, in turn, cause mitotic catastrophe, a delayed type of cell death with distinct morphological features. Here, we have investigated the contribution of p53 and caspase-2 to apoptotic cell death and mitotic catastrophe in cisplatin-treated ovarian carcinoma cell lines. We report that both functional p53 and caspase-2 were required for the apoptotic response, which was preceded by translocation of nuclear caspase-2 to the cytoplasm. In the absence of functional p53, cisplatin treatment resulted in caspase-2-independent mitotic catastrophe followed by necrosis. In these cells, apoptotic functions could be restored by transient expression of wt p53. Hence, p53 appeared to act as a switch between apoptosis and mitotic catastrophe followed by necrosis-like lysis in this experimental model. Further, we show that inhibition of Chk2, and/or 14-3-3sigma deficiency, sensitized cells to undergo mitotic catastrophe upon treatment with DNA-damaging agents. However, apoptotic cell death seemed to be the final outcome of this process. Thus, we hypothesize that the final mode of cell death triggered by DNA damage in ovarian carcinoma cells is determined by the profile of proteins involved in the regulation of the cell cycle, such as p53- and Chk2-related proteins.

The PTPN22 promoter polymorphism -1123G>C association cannot be distinguished from the 1858C>T association in a Norwegian rheumatoid arthritis material

The protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene has, during the last 2 years, been recognized as a susceptibility gene for numerous autoimmune diseases, including rheumatoid arthritis (RA) and type 1 diabetes. An association between the exonic 1858C>T single nucleotide polymorphism (SNP) and RA has repeatedly been replicated in several Caucasian populations. The SNP is not associated with autoimmune diseases in Asian populations, as the 1858T allele is almost absent. Recently, a promoter polymorphism -1123G>C was proposed to be associated with acute-onset type 1 diabetes in Japanese and Korean populations. Furthermore, in Caucasian populations, the presence of additional PTPN22 risk variants has been suggested, indicating that the 1858C>T risk variant cannot explain the entire disease association observed in the region. In this study, we wanted to jointly address and integrate these separate findings to further elucidate the association between the PTPN22 gene and RA in a Norwegian material of 861 RA patients and 559 healthy controls. Our results revealed that the strength of the association with the PTPN22 promoter polymorphism, -1123G>C, is analogous to that observed for 1858C>T. As the -1123G>C variant is also polymorphic in Asian populations, our data underpin the need to further explore the association between this variant and autoimmune diseases in different populations.

Deletion polymorphism of the UGT2B17 gene is associated with increased risk for prostate cancer and correlated to gene expression in the prostate

Metabolism of androgens includes glucuronidation, the major pathway of steroid elimination in several steroid target tissues. Glucuronidation is catalysed by UDP-glucuronosyltransferases (UGTs). UGT2B17 has been shown to be particularly active against androgens and is highly abundant in the prostate. Recently, we discovered that deletion of the UGT2B17 gene is associated with low or undetectable urinary testosterone levels. Here, we determined the phenotypic outcome of the deletion by quantifying the UGT2B17 mRNA expression in normal prostate tissues in individuals with different genotypes. Additionally, the frequency of UGT2B17 deletion polymorphism was studied in a Swedish population-based case-control study including 176 patients diagnosed with prostate cancer and 161 controls. We found that the individuals homozygous for the insertion allele expressed 30 times more UGT2B17 mRNA in prostate tissue than the heterozygotes. Carriers of the deletion allele had a significantly increased risk of prostate cancer (OR=2.07; 95% CI=1.32-3.25). In conclusion, these results show the UGT2B17 deletion polymorphism is associated with prostate cancer risk.

Four outbreaks of norovirus gastroenteritis after consuming raspberries, Sweden, June-August 2006

So far in 2006, in Sweden, there have been four outbreaks of norovirus gastroenteritis where raspberries were the suspected vehicle of infection. The first outbreak occurred at the end of June,

Increased expression of aquaporin 3 in atopic eczema

BACKGROUND

Dry skin in atopic eczema depends on increased water loss. The mechanisms behind this are poorly understood. The aim of this work was to identify genes that may contribute to water loss in eczema.

METHODS

Affymetrix DNA microarrays U133A were used to analyse gene expression in skin biopsies from 10 patients with atopic eczema and 10 healthy controls.

RESULTS

DNA microarray analysis showed up-regulation of 262 genes and down-regulation of 129 genes in atopic eczema. The known functions of these genes were analysed using Gene Ontology to identify genes that could contribute to increased water loss. This led to identification of aquaporin 3 (AQP3), which has a key role in hydrating healthy epidermis. Increased expression of AQP3 was found in eczema compared with healthy skin. This was confirmed with real-time polymerase chain reaction (P<0.001). In healthy skin, epidermal AQP3 immunoreactivity was weak and mainly found in the stratum basale. A gradient was formed with decreasing AQP3 staining in the lower layers of the stratum spinosum. By contrast, in acute and chronic atopic eczema strong AQP3 staining was found in both the stratum basale and the stratum spinosum.

CONCLUSIONS

Aquaporin 3 is the predominant aquaporin in human skin. Increased expression and altered cellular distribution of AQP3 is found in eczema and this may contribute to water loss.

Functional connection between p53 and caspase-2 is essential for apoptosis induced by DNA damage

Recent findings have established caspase-2 as an important apical regulator in apoptotic pathways leading from DNA damage to release of mitochondrial cytochrome c and subsequent activation of effector caspases. Yet, the molecular map connecting the embarking stimuli of genotoxic stress with caspase-2 activation remains to be elucidated. Here, we address the question of potential caspase-2 regulators by examining 5-fluorouracil (5-FU)-induced apoptosis in wild-type and p53-deficient human colon carcinoma cells. Apoptosis was observed only in p53(+/+) cells and was preceded by caspase-2 activation. Hence, although no direct interaction between p53 and caspase-2 was observed in the cell system used, our data clearly demonstrate that a functional connection between these two proteins is essential for initiation of the 5-FU-induced apoptotic process. Proposed mediators of caspase-2 activation include PIDDosome complex proteins PIDD and RAIDD. Surprisingly, the presence of a complex encompassing at least RAIDD, PIDD and caspase-2 was verified in both p53(+/+) and p53(-/-) cells, also in the absence of 5-FU treatment. Thus, our results confirm the participation of PIDD and RAIDD in PIDDosome complex formation but question their role as sole mediators of caspase-2 activation. This assumption was further supported by siRNA transfections targeting PIDD or RAIDD. In conclusion, our findings support the hypothesis of p53 as an upstream regulator of caspase activity and provide data concerning caspase-2 processing mechanisms. As suppression of caspase-2 expression in 5-FU-treated cells also affects the level of the p53 protein, possibilities of a reciprocal interaction between these proteins are discussed.

Linkage disequilibrium and haplotype blocks in the MHC vary in an HLA haplotype specific manner assessed mainly by DRB1*03 and DRB1*04 haplotypes

First generation linkage disequilibrium (LD) and haplotype maps of the human major histocompatibility complex (MHC) have been generated in order to aid the unraveling of the numerous disease predisposing genes in this region by offering a first set of haplotype tagSNPs. Several parameters, like the population studied, the marker map used, the density of polymorphisms and the applied algorithm, are influencing the appearance of haplotype blocks and selection of tags. The MHC comprises a limited number of ancestral, conserved haplotypes. We address the impact of the underlying HLA haplotypes on the LD patterns, haplotype blocks and tag selection throughout the entire extended MHC (xMHC) by studying DR-DQ haplotypes, mainly those carrying DRB1*03 and DRB1*04 alleles. We observed significantly different degree and extent of LD calculated on different HLA backgrounds, as well as variation in the size and boundaries of the defined haplotype and tags selected. Our results demonstrate that the underlying ancestral HLA haplotypic architecture is yet another parameter to take into consideration when constructing LD maps of the xMHC. This may be essential for mapping of disease susceptibility genes since many diseases are associated with and map on particular HLA haplotypes.

Target cell CD47 regulates macrophage activation and erythrophagocytosis

The ubiquitously expressed cell surface glycoprotein CD47 (integrin-associated protein, IAP) was originally identified as a regulator of integrin-dependent leukocyte responses to extracellular matrix proteins. However, it has been shown that CD47 has several important functions in addition to regulating integrin activation. Extensive studies in murine systems have shown that CD47 on erythrocytes and other cells can function as a regulator of target cell phagocytosis, by binding to the inhibitory receptor SIRPalpha on macrophages. In this way, macrophages are less likely to phagocytose an autoimmune sensitized cell with CD47 on its surface than a CD47-deficient cell where this inhibitory mechanism will not be engaged. The CD47-SIRPalpha interaction seems to be important in limiting destruction of host cells in experimental models of autoimmune diseases like autoimmune hemolytic anemia (AIHA) or immune thrombocytopenia, where macrophages destroy antibody or complement opsonized cells.