Neoplastic transformation of RK3E by mutant beta-catenin requires deregulation of Tcf/Lef transcription but not activation of c-myc expression

Current models predict that beta-catenin (beta-cat) functions in Wnt signaling via activation of Tcf/Lef target genes and that its abundance is regulated by the adenomatous polyposis coli (APC) and glycogen synthase kinase 3beta (GSK3beta) proteins. In colon and other cancers, mutations in APC or presumptive GSK3beta phosphorylation sites of beta-cat are associated with constitutive activation of Tcf/Lef transcription. In spite of assumptions about its oncogenic potential, prior efforts to demonstrate that mutated beta-cat will induce neoplastic transformation have yielded equivocal results. We report here that mutated, but not wild-type, beta-cat proteins induced neoplastic transformation of RK3E, an adenovirus E1A-immortalized epithelial cell line. Analysis of the properties of mutant beta-cat proteins and studies with a dominant negative Tcf-4 mutant indicated that the ability of beta-cat to bind and activate Tcf/Lef factors is crucial for transformation. c-myc has recently been implicated as a critical Tcf-regulated target gene. However, c-myc was not consistently activated in beta-cat-transformed RK3E cells, and a dominant negative c-Myc mutant protein failed to inhibit beta-cat transformation. Our findings underscore the role of beta-cat mutations and Tcf/Lef activation in cancer and illustrate a useful system for defining critical factors in beta-cat transformation.

Heterodimerization of Msx and Dlx homeoproteins results in functional antagonism

Protein-protein interactions are known to be essential for specifying the transcriptional activities of homeoproteins. Here we show that representative members of the Msx and Dlx homeoprotein families form homo- and heterodimeric complexes. We demonstrate that dimerization by Msx and Dlx proteins is mediated through their homeodomains and that the residues required for this interaction correspond to those necessary for DNA binding. Unlike most other known examples of homeoprotein interactions, association of Msx and Dlx proteins does not promote cooperative DNA binding; instead, dimerization and DNA binding are mutually exclusive activities. In particular, we show that Msx and Dlx proteins interact independently and noncooperatively with homeodomain DNA binding sites and that dimerization is specifically blocked by the presence of such DNA sites. We further demonstrate that the transcriptional properties of Msx and Dlx proteins display reciprocal inhibition. Specifically, Msx proteins act as transcriptional repressors and Dlx proteins act as activators, while in combination, Msx and Dlx proteins counteract each other's transcriptional activities. Finally, we show that the expression patterns of representative Msx and Dlx genes (Msx1, Msx2, Dlx2, and Dlx5) overlap in mouse embryogenesis during limb bud and craniofacial development, consistent with the potential for their protein products to interact in vivo. Based on these observations, we propose that functional antagonism through heterodimer formation provides a mechanism for regulating the transcriptional actions of Msx and Dlx homeoproteins in vivo.

Occupational, commuting, and leisure-time physical activity in relation to risk for Type 2 diabetes in middle-aged Finnish men and women

AIM/HYPOTHESIS

Leisure-time physical activity can reduce the risk of Type 2 diabetes, but the potential effect of different types of physical activity is still uncertain. This study is to examine the relationship of occupational, commuting and leisure-time physical activity with the incidence of Type 2 diabetes.

METHODS

We prospectively followed 6898 Finnish men and 7392 women of 35 to 64 years of age without a history of stroke, coronary heart disease, or diabetes at baseline. Hazards ratios of incidence of Type 2 diabetes were estimated by levels of occupational, commuting, and leisure-time physical activity.

RESULTS

During a mean follow-up of 12 years, there were 373 incident cases of Type 2 diabetes. In both men and women combined, the hazards ratios of diabetes associated with light, moderate and active work were 1.00, 0.70 and 0.74 (p=0.020 for trend) after adjustment for confounding factors (age, study year, sex, systolic blood pressure, smoking, education, the two other types of physical activity and BMI). The multivariate-adjusted hazards ratios of diabetes with none, 1 to 29, and more than 30 min of walking or cycling to and from work were 1.00, 0.96, and 0.64 (p=0.048 for trend). The multivariate-adjusted hazards ratios of diabetes for low, moderate, high levels of leisure-time physical activity were 1.00, 0.67, and 0.61 (p=0.001 for trend); after additional adjustment for BMI, the hazards ratio was no longer significant.

CONCLUSIONS/INTERPRETATION

Moderate and high occupational, commuting or leisure-time physical activity independently and significantly reduces risk of Type 2 diabetes among the middle-aged general population.

Frequent nuclear/cytoplasmic localization of beta-catenin without exon 3 mutations in malignant melanoma

Beta-Catenin has a critical role in E-cadherin-mediated cell-cell adhesion, and it also functions as a downstream signaling molecule in the wnt pathway. Mutations in the putative glycogen synthase kinase 3beta phosphorylation sites near the beta-catenin amino terminus have been found in some cancers and cancer cell lines. The mutations render beta-catenin resistant to regulation by a complex containing the glycogen synthase kinase 3beta, adenomatous polyposis coli, and axin proteins. As a result, beta-catenin accumulates in the cytosol and nucleus and activates T-cell factor/ lymphoid enhancing factor transcription factors. Previously, 6 of 27 melanoma cell lines were found to have beta-catenin exon 3 mutations affecting the N-terminal phosphorylation sites (Rubinfeld B, Robbins P, Elgamil M, Albert I, Porfiri E, Polakis P: Stabilization of beta-catenin by genetic defects in melanoma cell lines. Science 1997, 275:1790-1792). To assess the role of beta-catenin defects in primary melanomas, we undertook immunohistochemical and DNA sequencing studies in 65 melanoma specimens. Nuclear and/or cytoplasmic localization of beta-catenin, a potential indicator of wnt pathway activation, was seen focally within roughly one third of the tumors, though a clonal somatic mutation in beta-catenin was found in only one case (codon 45 Ser-->Pro). Our findings demonstrate that beta-catenin mutations are rare in primary melanoma, in contrast to the situation in melanoma cell lines. Nonetheless, activation of beta-catenin, as indicated by its nuclear and/or cytoplasmic localization, appears to be frequent in melanoma, and in some cases, it may reflect focal and transient activation of the wnt pathway within the tumor.

Siah-1 N-terminal RING domain is required for proteolysis function, and C-terminal sequences regulate oligomerization and binding to target proteins

The Drosophila seven in absentia (sina) gene was initially discovered because its inactivation leads to R7 photoreceptor defects. Recent data indicate that Sina binds to the Sevenless pathway protein Phyllopod, and together they mediate degradation of Tramtrack, a transcriptional repressor of R7 cell fate. Independent studies have shown that Sina and its highly related mammalian homologues Siah-1 and Siah-2 bind to the DCC (deleted in colorectal cancer) protein and promote its proteolysis via the ubiquitin-proteasome pathway. To determine the roles of mammalian Siahs in proteolysis and their interactions with target proteins, we sought to define Siah-1 domains critical for regulation of DCC. Mutant Siah-1 proteins, harboring missense mutations in the carboxy (C)-terminal domain analogous to those present in Drosophila sina loss-of-function alleles, failed to promote DCC degradation. Point mutations and deletion of the amino (N)-terminal RING finger domain of Siah-1 abrogated its ability to promote DCC proteolysis. In the course of defining Siah-1 sequences required for DCC degradation, we found that Siah-1 is itself rapidly degraded via the proteasome pathway, and RING domain mutations stabilized the Siah-1 protein. Siah-1 was found to oligomerize with itself and other Sina and Siah proteins via C-terminal sequences. Finally, evidence that endogenous Siah-1 regulates DCC proteolysis in cells was obtained through studies of an apparent dominant negative mutant of Siah-1, as well as via an antisense approach. The data indicate that the Siah-1 N-terminal RING domain is required for its proteolysis function, while the C-terminal sequences regulate oligomerization and binding to target proteins, such as DCC.

The effects of physical activity and body mass index on cardiovascular, cancer and all-cause mortality among 47 212 middle-aged Finnish men and women

OBJECTIVE

To examine the association of physical activity and body mass index (BMI), and their combined effect, with the risk of total, cardiovascular disease (CVD) and cancer mortality.

DESIGN

Prospective follow-up study.

SUBJECTS

In all, 22 528 men and 24 684 women aged 25-64 y at baseline having 7394 deaths during a mean follow-up of 17.7 y.

MEASUREMENT

A self-administered questionnaire data on smoking, socioeconomic factors, physical activity and medical history, together with measured height, weight, blood pressure and serum cholesterol using standardized protocol.

RESULT

Physically active subjects had significantly lower age-adjusted mortality from cardiovascular, cancer and all causes compared with sedentary ones. Further adjustment for smoking, systolic blood pressure, cholesterol, BMI, diabetes and education affected the results only slightly. Obese subjects (BMI> or =30 kg/m(2)) had significantly higher cardiovascular and total mortality than the normal weight (18.5< or =BMI<25 kg/m(2)) subjects. Part of increased mortality among obese subjects was mediated through obesity-related cardiovascular risk factors. BMI had an inverse association with cancer mortality among men and almost significant direct association among women. Total mortality was also increased among the lean (BMI<18.5 kg/m(2)) subjects. However, less than 0.3% of deaths were attributed to low body weight, whereas in men 5.5% and in women 17.7% of deaths were attributed to obesity.

CONCLUSION

Regular physical activity and normal weight are both important indicators for a decreased risk of mortality from all causes, CVD and cancer. Physical activity had a strong independent effect on mortality, whereas the effect of BMI was partly mediated through other obesity-related risk factors.

Exosome-mediated shuttling of microRNA-29 regulates HIV Tat and morphine-mediated neuronal dysfunction

Neuronal damage is a hallmark feature of HIV-associated neurological disorders (HANDs). Opiate drug abuse accelerates the incidence and progression of HAND; however, the mechanisms underlying the potentiation of neuropathogenesis by these drugs remain elusive. Opiates such as morphine have been shown to enhance HIV transactivation protein Tat-mediated toxicity in both human neurons and neuroblastoma cells. In the present study, we demonstrate reduced expression of the tropic factor platelet-derived growth factor (PDGF)-B with a concomitant increase in miR-29b in the basal ganglia region of the brains of morphine-dependent simian immunodeficiency virus (SIV)-infected macaques compared with the SIV-infected controls. In vitro relevance of these findings was corroborated in cultures of astrocytes exposed to morphine and HIV Tat that led to increased release of miR-29b in exosomes. Subsequent treatment of neuronal SH-SY5Y cell line with exosomes from treated astrocytes resulted in decreased expression of PDGF-B, with a concomitant decrease in viability of neurons. Furthermore, it was shown that PDGF-B was a target for miR-29b as evidenced by the fact that binding of miR-29 to the 3′-untranslated region of PDGF-B mRNA resulted in its translational repression in SH-SY5Y cells. Understanding the regulation of PDGF-B expression may provide insights into the development of potential therapeutic targets for neuronal loss in HIV-1-infected opiate abusers.

Neutralizing antibodies against adeno-associated virus examined prospectively in pediatric patients with hemophilia

Recombinant adeno-associated virus (rAAV) is a promising gene delivery vector and has recently been used in patients with hemophilia. One limitation of AAV application is that most humans have experienced wild-type AAV serotype 2 exposure, which frequently generates neutralizing antibodies (NAbs) that may inhibit rAAV2 vector transduction. Employing alternative serotypes of rAAV vectors may circumvent this problem. We investigated the development of NAbs in early childhood by examining sera gathered prospectively from 62 children with hemophilia A, participating in a multi-institutional hemophilia clinical trial (the Joint Outcome Study). Clinical applications in hemophilia therapy have been suggested for serotypes AAV2, AAV5 and AAV8, therefore NAbs against these serotypes were serially assayed over a median follow-up of 4 years. NAbs prevalence increased during early childhood for all serotypes. NAbs against AAV2 (43.5%) were observed more frequently and at higher titers compared with both AAV5 (25.8%) and AAV8 (22.6%). NAbs against AAV5 or AAV8 were rarely observed in the absence of co-prevalent and higher titer AAV2 NAbs, suggesting that NAbs to AAV5 and AAV8 were detected following AAV2 exposure due to partial cross-reactivity of AAV2-directed NAbs. The results may guide rational design of clinical trials using alternative AAV serotypes and suggest that younger patients who are given AAV gene therapy will benefit from the lower prevalence of NAbs.

Mammalian homologs of seven in absentia regulate DCC via the ubiquitin-proteasome pathway

DCC (deleted in colorectal cancer) is postulated to function as transmembrane receptor for the axon and cell guidance factor netrin-1. We report here that the DCC cytoplasmic domain binds to proteins encoded by mammalian homologs of the Drosophila seven in absentia (sina) gene, as well as Drosophila Sina. Sina has a critical role in R7 photoreceptor development and shows upward of 85% amino acid identity with its mammalian homologs (termed Siahs), but the function of the Sina/Siah proteins has not been defined. We sought, therefore, to characterize further their interaction with DCC. Immunofluorescence studies suggested the Sina/Siah proteins localized predominantly in the cytoplasm and in association with DCC. DCC was found to be ubiquitinated and the Sina/Siah proteins regulated its expression. Proteasome inhibitors blocked the effects of Sina/Siah on DCC, and the Sina/Siah proteins interacted with ubiquitin-conjugating enzymes (Ubcs). A mutant Siah protein lacking the amino-terminal Ubc-binding sequences complexed with DCC, but did not degrade it. The in vivo interaction between Sina/Siah and DCC was confirmed through studies of transgenic Drosophila lines in which DCC and Sina were ectopically expressed in the eye. Taken together, the data imply that the Sina/Siah proteins regulate DCC and perhaps other proteins via the ubiquitin-proteasome pathway.

A porphyrin pathway impairment is responsible for the phenotype of a dominant disease lesion mimic mutant of maize

The maize lesion mimic gene Les22 is defined by dominant mutations and characterized by the production of minute necrotic spots on leaves in a developmentally specified and light-dependent manner. Phenotypically, Les22 lesions resemble those that are triggered during a hypersensitive disease resistance response of plants to pathogens. We have cloned Les22 by using a Mutator-tagging technique. It encodes uroporphyrinogen decarboxylase (UROD), a key enzyme in the biosynthetic pathway of chlorophyll and heme in plants. Urod mutations in humans are also dominant and cause the metabolic disorder porphyria, which manifests itself as light-induced skin morbidity resulting from an excessive accumulation of photoexcitable uroporphyrin. The phenotypic and genetic similarities between porphyria and Les22 along with our observation that Les22 is also associated with an accumulation of uroporphyrin revealed what appears to be a case of natural porphyria in plants.

Total cholesterol and the risk of Parkinson disease

OBJECTIVE

To examine the association between serum total cholesterol at baseline and the risk of Parkinson disease (PD).

METHODS

Study cohorts included 24,773 Finnish men and 26,153 women aged 25 to 74 years without a history of PD and stroke at baseline. Hazard ratios (HRs) of incident PD were estimated for different levels of total cholesterol.

RESULTS

During a mean follow-up period of 18.1 years, 321 men and 304 women developed incident PD. After adjustment for confounding factors (age, study years, body mass index, systolic blood pressure, education, leisure-time physical activity, smoking, alcohol consumption, coffee and tea consumption, and history of diabetes), the HRs of PD at different levels of total cholesterol (<5, 5-5.9, 6-6.9, and >or=7 mmol/L) were 1.00, 1.33, 1.53, and 1.84 (p for trend = 0.035) in men; 1.00, 1.55, 1.57, and 1.86 (p for trend = 0.113) in women; and 1.00, 1.42, 1.56, and 1.86 (p for trend = 0.002) in men and women combined (adjusted also for sex). In both sexes combined, the increased risk of PD associated with increasing levels of serum total cholesterol was present both in subjects aged 25-44 years and in subjects aged 45-54 years at baseline, and in never smokers and smokers; however, no association was found among subjects aged 55 years or older at baseline.

CONCLUSION

This large prospective study suggests that high total cholesterol at baseline is associated with an increased risk of Parkinson disease.

Increasing prevalence of gestational diabetes mellitus in Chinese women from 1999 to 2008

AIMS

To investigate the trend in the prevalence of gestational diabetes mellitus during 1999-2008 in women living in urban Tianjin, China.

METHODS

A universal screening for gestational diabetes mellitus has become an integral part of the antenatal care in Tianjin, China from 1998. A total of 105,473 pregnant women living in the six urban districts of Tianjin, China, participated in the gestational diabetes mellitus screening programme between December 1998 and December 2008. The screening test consisted of a 50-g 1-h glucose test. Women who had a glucose reading ≥7.8 mmol/l at the initial screening were invited to undergo the standard 2-h oral glucose tolerance test with a 75-g glucose load. Gestational diabetes mellitus was confirmed using the World Health Organization's diagnostic criteria.

RESULTS

The adjusted prevalence of gestational diabetes mellitus increased by 2.8 times during 1999-2008, from 2.4 to 6.8% (P<0.0001 for linear trend). In 2008, the age-specific prevalence of gestational diabetes mellitus was the highest among women aged 30-34 years (11.3%) and lowest among women aged 25 and under (1.2%). In women aged 35 years and more, the prevalence was 5.3%.

CONCLUSIONS

The prevalence of gestational diabetes mellitus has markedly been increasing in a universally screened urban Chinese female population and has become an important public health problem in China.

Antioxidant nutrients and pulmonary function: the Third National Health and Nutrition Examination Survey (NHANES III)

Recent studies of chronic obstructive pulmonary disease have raised interest in its relation to nutrition. Several dietary antioxidants have been positively associated with lung function in healthy, general population samples. This study considered the separate and joint effects of vitamin C, vitamin E, beta-carotene, and selenium intake and used both dietary assessment and serum biomarkers of antioxidant status. The authors used data from the Third National Health and Nutrition Examination Survey comprising a sample representative of the US population in 1988-1994 (n = 18,162 subjects aged > or =17 years). Multiple linear regression analysis examined the separate and joint effects of the antioxidants on the ratio of forced expiratory volume in the first second (FEV1)/height2 adjusted for covariates. Each of the dietary and serum antioxidant nutrients was significantly associated with FEV1. When they were considered simultaneously (dietary and serum variables considered in separate models), independent associations were observed for most nutrients. Serum beta-carotene was less positively associated with FEV1 in smokers than nonsmokers, while serum selenium had a stronger positive association with FEV1 in smokers. The authors found that higher levels of antioxidant nutrients are associated with better lung function. The finding that the antioxidants differ in both their overall association with lung function and in whether this association varies by smoking status has implications for further research.

Age, body mass index and Type 2 diabetes-associations modified by ethnicity

AIMS/HYPOTHESIS

The aim of this study was to assess the effect of ethnicity on the association between age and body mass index as well as the prevalence of diabetes.

METHODS

We selected population-based studies carried out after 1980 in the DECODE/A studies representing different ethnic groups: 11 European, 1 Maltese, 3 Indian, 2 Chinese and 3 Japanese surveys. The total numbers of subjects were 14,240 men and 15,129 women who were 30 to 89 years of age. Diabetes was diagnosed according to the 1999 World Health Organization criteria based on a standard 75 g OGTT. Sex-specific prevalence of diabetes by age and BMI was stratified by ethnic group, in particular the interaction of ethnicity on the associations between age/BMI and the prevalence of diabetes.

RESULTS

The prevalence of diabetes was higher in studies from India and Malta compared to Japan, China, and the rest of Europe. The association between BMI and diabetes, adjusted for age, showed noticeable differences between the ethnic groups with an increase in prevalence starting at a BMI between 15 and 20 kg/m(2) in the Maltese and Indian populations compared to 25 kg/m(2 )in Europeans.

CONCLUSION/INTERPRETATION

The effect of BMI on the age-adjusted prevalence of Type 2 diabetes was modified by ethnicity with considerably lower thresholds in Indian and Maltese subjects compared to those from the rest of Europe. This difference should be reflected in national and international recommendations regarding "optimal" BMI.

Body mass index and the risk of Parkinson disease

OBJECTIVE

To examine the association between body mass index (BMI) and the risk of Parkinson disease (PD).

METHODS

Study cohorts included 22,367 Finnish men and 23,439 women 25 to 59 years of age without a history of PD at baseline. Hazards ratios (HRs) of incident PD were estimated for different levels of BMI.

RESULTS

During a mean follow-up period of 18.8 years, 272 men and 254 women developed incident PD. After adjustment for confounding factors (age, study years, systolic blood pressure, total cholesterol, education, leisure-time physical activity, smoking, and alcohol, coffee, and tea consumption), the HRs of PD at different levels of BMI (<23, 23 to 24.9, 25 to 26.9, 27 to 29.9, and > or =30 kg/m(2)) were 1.00, 1.97 (95% CI: 1.21 to 3.22), 1.83 (95% CI: 1.12 to 2.99), 2.34 (95% CI: 1.45 to 3.78), and 2.44 (95% CI: 1.44 to 4.15) in men, and 1.00, 1.50 (95% CI: 0.95 to 2.37), 1.65 (95% CI: 1.05 to 2.59), 1.79 (95% CI: 1.15 to 2.80), and 1.77 (95% CI: 1.12 to 2.78) in women, and 1.00, 1.70 (95% CI: 1.23 to 2.37), 1.70 (95% CI: 1.23 to 2.37), 2.02 (95% CI: 1.46 to 2.79), and 2.03 (95% CI: 1.44 to 2.85) in men and women combined (adjusted also for sex). In both sexes combined, the multivariate-adjusted direct association between BMI and the risk of PD was present both in subjects aged 25 to 49 years and 50 to 59 years, in never smokers and smokers and in participants diagnosed PD before and after 65 years of age.

CONCLUSION

Body mass index is associated with a risk of Parkinson disease. The effect is graded and independent of other risk factors.

Msx homeobox genes inhibit differentiation through upregulation ofcyclin D1

During development, patterning and morphogenesis of tissues are intimately coordinated through control of cellular proliferation and differentiation. We describe a mechanism by which vertebrate Msx homeobox genes inhibit cellular differentiation by regulation of the cell cycle. We show that misexpression of Msx1 via retroviral gene transfer inhibits differentiation of multiple mesenchymal and epithelial progenitor cell types in culture. This activity of Msx1 is associated with its ability to upregulate cyclin D1 expression and Cdk4 activity, while Msx1 has minimal effects on cellular proliferation. Transgenic mice that express Msx1 under the control of the mouse mammary tumor virus long terminal repeat (MMTV LTR) display impaired differentiation of the mammary epithelium during pregnancy, which is accompanied by elevated levels of cyclin D1 expression. We propose that Msx1 gene expression maintains cyclin D1 expression and prevents exit from the cell cycle, thereby inhibiting terminal differentiation of progenitor cells. Our model provides a framework for reconciling the mutant phenotypes of Msx and other homeobox genes with their functions as regulators of cellular proliferation and differentiation during embryogenesis.

DNA polymerase-catalyzed addition of nontemplated extra nucleotides to the 3' end of a DNA fragment

Some prokaryotic and eukaryotic DNA polymerases are capable of adding an additional nontemplated nucleotide residue at the 3' end of a DNA fragment (Clark et al., 1987; Clark, 1988). The extra nucleotide at the 3' end of the PCR product has been shown to be a critical factor determining the efficiency of cloning PCR products into plasmids and can affect mutation analyses with a PCR-denaturing gradient gel electrophoresis (DGGE) approach (Pfeiffer and Hu, 1993). In the present work, the ability of various DNA polymerases to add an extra nontemplated nucleotide at the 3' end of DNA was studied. The results show that out of the eight studied enzymes, five can add, with varying efficiencies, an extra nucleotide residue at the 3' end of DNA. Which extra nucleotide is added depends on the terminal residue and the DNA polymerase. Among the enzymes, thermostable Pfu DNA polymerase is found to be the best choice for PCR due to its relatively high fidelity (Scott et al., 1991; Coller, unpublished), and ability to produce blunt-ended DNA fragments. The relationship between the DNA polymerases' ability to add an extra nucleotide and their 3'-->5' exonuclease activity is also discussed.

Targeted disruption of NDST-1 gene leads to pulmonary hypoplasia and neonatal respiratory distress in mice

In order to address the biological function of GlcNAc N-deacetylase/N-sulfotransferase-1 (NDST-1), we disrupted the NDST-1 gene by homologous recombination in mouse embryonic stem cells. The NDST-1 null mice developed respiratory distress and atelectasis that subsequently caused neonatal death. Morphological examination revealed type II pneumocyte immaturity, which was characterized by an increased glycogen content and a reduced number of lamellar bodies and microvilli. Biochemical analysis further indicated that both total phospholipids and disaturated phosphatidylcholine were reduced in the mutant lung. Our data revealed that NDST-1 was essential for the maturation of type II pneumocytes and its inactivation led to a neonatal respiratory distress syndrome.

Gene deficiency and pharmacological inhibition of caspase-1 confers resilience to chronic social defeat stress via regulating the stability of surface AMPARs

Both inflammatory processes and glutamatergic systems have been implicated in the pathophysiology of mood-related disorders. However, the role of caspase-1, a classic inflammatory caspase, in behavioral responses to chronic stress remains largely unknown. To address this issue, we examined the effects and underlying mechanisms of caspase-1 on preclinical murine models of depression. We found that loss of caspase-1 expression in Caspase-1^-/- knockout mice alleviated chronic stress-induced depression-like behaviors, whereas overexpression of caspase-1 in the hippocampus of wild-type (WT) mice was sufficient to induce depression- and anxiety-like behaviors. Furthermore, chronic stress reduced glutamatergic neurotransmission and decreased surface expression of glutamate receptors in hippocampal pyramidal neurons of WT mice, but not Caspase-1^-/- mice. Importantly, pharmacological inhibition of caspase-1-interleukin-1β (IL-1β) signaling pathway prevented the depression-like behaviors and the decrease in surface expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in stressed WT mice. Finally, the effects of chronic stress on both depression- and anxiety-like behaviors can be mimicked by exogenous intracerebroventricular (i.c.v.) administration of IL-1β in both WT and Caspase-1^-/- mice. Taken together, our findings demonstrate that an increase in the caspase-1/IL-1β axis facilitates AMPAR internalization in the hippocampus, which dysregulates glutamatergic synaptic transmission, eventually resulting in depression-like behaviors. These results may represent an endophenotype for chronic stress-induced depression.

Characterization of human homologs of the Drosophila seven in absentia (sina) gene

Studies of Drosophila photoreceptor development have illustrated the means by which signal transduction events regulate cell fate decisions in a multicellular organization. Development of the R7 photoreceptor is best understood, and its formation is dependent on the seven in absentia (sina) gene. We have characterized two highly conserved human homologs of sina, termed SIAH1 and SIAH2. SIAH1 maps to chromosome 16q12 and encodes a 282-amino-acid protein with 76% amino acid identity to the Drosophila SINA protein. SIAH2 maps to chromosome 3q25 and encodes a 324-amino-acid protein that shares 68% identity with Drosophila SINA and 77% identity with human SIAH1. SIAH1 and SIAH2 were expressed in many normal and neoplastic tissues, and only subtle differences in their expression were noted. However, one of three murine homologs, Siah1B, was strongly induced in fibroblasts undergoing apoptotic cell death. While a previous study suggested that SINA was a nuclear protein, epitope-tagged SINA and SIAH1 proteins were found in the cytoplasm of Drosophila and mammalian cells. Their substantial evolutionary conservation, role in specifying cell fate, and activation in apoptotic cells suggest the SIAH proteins have important roles in vertebrate development. Furthermore, given the role of sina in Drosophila photoreceptor development, SIAH2 is a candidate for the Usher syndrome type 3 gene at chromosome 3q21-q25.

Regulation of cell adhesion by PAI-1

Type I plasminogen activator inhibitor (PAI-1) is the primary inhibitor of tissue- and urokinase-type plasminogen activators. It circulates in plasma complexed with vitronectin (VN), the primary PAI-1 binding protein. The somatomedin B (SMB) domain of VN contains both the high affinity PAI-1 binding site and the specific site for urokinase plasminogen activator receptor (uPAR). PAI-1 is able to regulate uPAR-mediated cell adhesion by competing with uPAR for VN binding. Binding of PAI-1 to SMD may also affect integrin-mediated cell adhesion to VN by hindering integrin binding to the RGD sequence adjacent to the uPAR binding site.

Angiogenin promotes invasiveness of cultured endothelial cells by stimulation of cell-associated proteolytic activities

Angiogenin, a potent inducer of neovascularization in the chicken chorioallantoic membrane and rabbit cornea, promotes endothelial cell invasion of Matrigel basement membrane. A transformed bovine aortic endothelial cell line, GM 7373, is 5 times more invasive when cultured in the presence of 1 microgram of bovine angiogenin per ml than in its absence. A polyclonal anti-angiogenin antibody and alpha 2-antiplasmin neutralize the effect of angiogenin, but an angiogenin-binding protein (actin) does not. Further, this concentration of angiogenin induces a 14-fold increase in the cell-associated proteolytic activity of cultured endothelial cells, determined with a tissue-type plasminogen activator-specific peptide as the substrate. In addition, cells cultured on a three-dimensional fibrin gel in the presence of angiogenin are 3 times more capable of dissolving the gel and forming focal defects in the underlying matrix. The results indicate that angiogenin can enhance the ability of endothelial cells to digest extracellular matrix components and degrade basement membrane, thereby facilitating cell invasion and migration. Binding of angiogenin to its cell-surface binding protein (actin) followed by dissociation of the angiogenin-actin complex from the cell surface and subsequent activation of tissue-type plasminogen activator/plasmin are likely steps involved in the processes of endothelial cell invasion and angiogenesis.

Gender difference in all-cause and cardiovascular mortality related to hyperglycaemia and newly-diagnosed diabetes

AIM/HYPOTHESIS

Diabetic women generally have a greater relative risk of cardiovascular diseases than diabetic men in comparison with non-diabetic women and men. Reasons for this excess risk in diabetic women is still unclear. The aim of this study is to evaluate whether the association between different degrees of hyperglycaemia and the risk of all-cause and cardiovascular mortality is different in women and men.

METHODS

We analysed baseline glucose concentrations from 14 prospective European cohorts including 8172 men and 9407 women aged 30 to 89 years without history of diabetes, with a median follow-up of 8.3 years. Hazards ratios for all-cause and cardiovascular mortality were estimated adjusting for other risk factors.

RESULTS

The mortality rates for all-cause and cardiovascular diseases were higher in men than in women in normoglycaemia, impaired glucose regulation and newly-diagnosed diabetes; the largest sex differential for cardiovascular mortality was in normoglycaemic people. The hazards ratios for all-cause and cardiovascular mortality were higher in newly-diagnosed diabetic women than men compared with normoglycaemic women and men, respectively; however, this sex difference was only significant for cardiovascular mortality. For smokers and for subjects with hypertension, hypercholesterolaemia or who where overweight, the hazards ratios for cardiovascular mortality in diabetic patients compared with normoglycaemic people were also higher in women than in men.

CONCLUSIONS/INTERPRETATION

Newly diagnosed diabetic women showed higher relative risks for death from cardiovascular disease than diabetic men. Thus a more aggressive control of hyperglycaemia as well as of other cardiovascular risk factors might be appropriate in women with asymptomatic hyperglycaemia.

Prediction of the risk of cardiovascular mortality using a score that includes glucose as a risk factor. The DECODE Study

AIMS/HYPOTHESIS

Risk scores have been developed to predict cardiovascular or coronary risk, and while most have included diabetes as a risk factor, none have included lower glucose concentrations, either at fasting or following a 2-h oral glucose tolerance test. This article develops 5- and 10-year risk scores for cardiovascular mortality that include glucose concentrations as well as known diabetes status.

METHODS

Data is from the DECODE cohort: 16,506 men and 8,907 women from 14 European studies. The risk factors studied were as follows: age, fasting and 2-h glucose (including cases of known diabetes), fasting glucose alone (including cases of known diabetes), cholesterol, smoking status, systolic blood pressure and BMI. For an absolute risk score the 1995 country- and sex-specific cardiovascular death rates were used.

RESULTS

In men, for both 5- and 10-year cardiovascular mortality, after adjusting for age and study centre, all studied risk factors, except BMI, were significantly associated with cardiovascular mortality (p<0.05). These results were unchanged in multivariate models with all factors included. In women, after adjusting for age and centre, glucose categories, systolic blood pressure and BMI were predictive of 5-year cardiovascular mortality. With all factors in the model, only age and glucose categories were predictive. In terms of 10-year cardiovascular mortality, smoking status and blood pressures were also predictive in the women. For men and women, the same scores were used for the risk factors, except for age and glucose categories where the hazard ratios differed significantly.

CONCLUSIONS/INTERPRETATION

Including glucose concentrations as well as diabetic status provides quantitative information on cardiovascular risk prediction.