Combinatorial effects of splice variants modulate function of Aiolos

The transcription factor Aiolos (also known as IKZF3), a member of the Ikaros family of zinc-finger proteins, plays an important role in the control of B lymphocyte differentiation and proliferation. Previously, multiple isoforms of Ikaros family members arising from differential splicing have been described and we now report a number of novel isoforms of Aiolos. It has been demonstrated that full-length Ikaros family isoforms localize to heterochromatin and that they can associate with complexes containing histone deacetylase (HDAC). In this study, for the first time we directly investigate the cellular localization of various Aiolos isoforms, their ability to heterodimerize with Ikaros and associate with HDAC-containing complexes, and the effects on histone modification and binding to putative targets. Our work demonstrates that the cellular activities of Aiolos isoforms are dependent on combinations of various functional domains arising from the differential splicing of mRNA transcripts. These data support the general principle that the function of an individual protein is modulated through alternative splicing, and highlight a number of potential implications for Aiolos in normal and aberrant lymphocyte function.

Aggravation of chronic stress effects on hippocampal neurogenesis and spatial memory in LPA₁ receptor knockout mice.

BACKGROUND The lysophosphatidic acid LPA₁ receptor regulates plasticity and neurogenesis in the adult hippocampus. Here, we studied whether absence of the LPA₁ receptor modulated the detrimental effects of chronic stress on hippocampal neurogenesis and spatial memory. METHODOLOGY/PRINCIPAL FINDINGS Male LPA₁-null (NULL) and wild-type (WT) mice were assigned to control or chronic stress conditions (21 days of restraint, 3 h/day). Immunohistochemistry for bromodeoxyuridine and endogenous markers was performed to examine hippocampal cell proliferation, survival, number and maturation of young neurons, hippocampal structure and apoptosis in the hippocampus. Corticosterone levels were measured in another a separate cohort of mice. Finally, the hole-board test assessed spatial reference and working memory. Under control conditions, NULL mice showed reduced cell proliferation, a defective population of young neurons, reduced hippocampal volume and moderate spatial memory deficits. However, the primary result is that chronic stress impaired hippocampal neurogenesis in NULLs more severely than in WT mice in terms of cell proliferation; apoptosis; the number and maturation of young neurons; and both the volume and neuronal density in the granular zone. Only stressed NULLs presented hypocortisolemia. Moreover, a dramatic deficit in spatial reference memory consolidation was observed in chronically stressed NULL mice, which was in contrast to the minor effect observed in stressed WT mice. CONCLUSIONS/SIGNIFICANCE These results reveal that the absence of the LPA₁ receptor aggravates the chronic stress-induced impairment to hippocampal neurogenesis and its dependent functions. Thus, modulation of the LPA₁ receptor pathway may be of interest with respect to the treatment of stress-induced hippocampal pathology.

Adipose tissue gene expression of factors related to lipid processing in obesity.

BACKGROUND Adipose tissue lipid storage and processing capacity can be a key factor for obesity-related metabolic disorders such as insulin resistance and diabetes. Lipid uptake is the first step to adipose tissue lipid storage. The aim of this study was to analyze the gene expression of factors involved in lipid uptake and processing in subcutaneous (SAT) and visceral (VAT) adipose tissue according to body mass index (BMI) and the degree of insulin resistance (IR). METHODS AND PRINCIPAL FINDINGS VLDL receptor (VLDLR), lipoprotein lipase (LPL), acylation stimulating protein (ASP), LDL receptor-related protein 1 (LRP1) and fatty acid binding protein 4 (FABP4) gene expression was measured in VAT and SAT from 28 morbidly obese patients with Type 2 Diabetes Mellitus (T2DM) or high IR, 10 morbidly obese patients with low IR, 10 obese patients with low IR and 12 lean healthy controls. LPL, FABP4, LRP1 and ASP expression in VAT was higher in lean controls. In SAT, LPL and FABP4 expression were also higher in lean controls. BMI, plasma insulin levels and HOMA-IR correlated negatively with LPL expression in both VAT and SAT as well as with FABP4 expression in VAT. FABP4 gene expression in SAT correlated inversely with BMI and HOMA-IR. However, multiple regression analysis showed that BMI was the main variable contributing to LPL and FABP4 gene expression in both VAT and SAT. CONCLUSIONS Morbidly obese patients have a lower gene expression of factors related with lipid uptake and processing in comparison with healthy lean persons.

Cancer genes hypermethylated in human embryonic stem cells.

Developmental genes are silenced in embryonic stem cells by a bivalent histone-based chromatin mark. It has been proposed that this mark also confers a predisposition to aberrant DNA promoter hypermethylation of tumor suppressor genes (TSGs) in cancer. We report here that silencing of a significant proportion of these TSGs in human embryonic and adult stem cells is associated with promoter DNA hypermethylation. Our results indicate a role for DNA methylation in the control of gene expression in human stem cells and suggest that, for genes repressed by promoter hypermethylation in stem cells in vivo, the aberrant process in cancer could be understood as a defect in establishing an unmethylated promoter during differentiation, rather than as an anomalous process of de novo hypermethylation.

Impact of dietary betaine and conjugated linoleic acid on insulin sensitivity, protein and fat metabolism of obese pigs.

To determine possible mechanisms of action that might explain the nutrient partitioning effect of betaine and conjugated linoleic acid (CLA) in Iberian pigs and to address potential adverse effects, twenty gilts were restrictively fed from 20 to 50 kg BW Control, 0.5% betaine, 1% CLA or 0.5% betaine + 1% CLA diets. Serum hormones and metabolites profile were determined at 30 kg BW and an oral glucose test was performed before slaughter. Pigs were slaughtered at 50 kg BW and livers were obtained for chemical and histological analysis. Decreased serum urea in pigs fed betaine and betaine + CLA diets (11%; P = 0.0001) indicated a more efficient N utilization. The increase in serum triacylglycerol (58% and 28%, respectively; P = 0.0098) indicated that CLA and betaine + CLA could have reduced adipose tissue triacylglycerol synthesis from preformed fatty acids. Serum glucose, low-density lipoprotein (LDL) cholesterol and non-esterified fatty acids were unaffected. CLA and betaine + CLA altered serum lipids profile, although liver of pigs fed CLA diet presented no histopathological changes and triglyceride content was not different from Control pigs. Compared with controls, serum growth hormone decreased (20% to 23%; P = 0.0209) for all treatments. Although serum insulin increased in CLA, and especially in betaine + CLA pigs (28% and 83%; P = 0.0001), indices of insulin resistance were unaffected. In conclusion, CLA, and especially betaine + CLA, induced changes in biochemical parameters and hormones that may partially explain a nutrient partitioning effect in young pigs. Nevertheless, they exhibited weak, although detrimental, effects on blood lipids. Moreover, although livers were chemically and histologically normal, pigs fed CLA diet challenged with a glucose load had higher serum glucose than controls.

Aider les étudiants en médecine à approcher la mort [Helping medical students to approach death].

A project recently launched by the Faculty of biology and medicine of Lausanne introduces the approach of facing death during both the dissection and the course of clinical activities. Existential questions relating to mortality are bound to arise sooner or later during the course of the study. For the sake of humanized clinical practice, these questions must be confronted. In response to a request by a student association, an accompanying curriculum with active student's contribution through encounters with death in anatomy and clinical situations was created in Lausanne. Students will benefit from this new program throughout their curriculum. This program is the first of its kind in Switzerland.

Long-term consequences of uninephrectomy in male and female rats.

We investigated the effects of uninephrectomy (UNX) in 6-week-old male and female rats on blood pressure (BP), renal sodium handling, salt sensitivity, oxidative stress, and renal injury over 18 months postsurgery, studying control sham-operated and UNX-operated rats at 6, 12, and 18 months postsurgery, evaluating their renal sodium handling, BP, urinary isoprostanes, N-acetyl-β-D-glucosaminidase, and proteinuria before and after a 2-week high-salt intake period. At 18 months, plasma variables were measured and kidney samples were taken for the analysis of renal morphology and tissue variables. BP was increased at 6 months in male UNX rats versus controls and at 12 and 18 months in both male and female UNX rats and was increased in male versus female UNX groups at 18 months. UNX did not affect water and sodium excretion under basal conditions and after the different test in male and female rats at different ages. However, the renal function curve was shifted to the right in both male and female UNX rats. High-salt intake increased BP in both UNX groups at 6, 12, and 18 months and in the female control group at 18 months, and it increased proteinuria, N-acetyl-β-D-glucosaminidase, and isoprostanes in both UNX groups throughout the study. Renal lesions at 18 months were more severe in male versus female UNX rats. In summary, long-term UNX increased the BP, creatinine, proteinuria, pathological signs of renal injury, and salt sensitivity. Earlier BP elevation was observed and morphological lesions were more severe in male than in female UNX rats.

Higher red blood cell distribution width is associated with a worse virologic and clinical situation in HIV-infected patients.

Background A high level of red blood cell distribution width (RDW) is a novel prognostic marker that may reflect an underlying inflammatory state. It has recently shown that when increased, it is related to cardiovascular disease, mortality, and metabolic syndrome (MetS) in the general population. Objectives To analyse the potential relation between high levels of RDW and cardiovascular risk (CVR) and MetS in HIVpatients. Patients and methods Observational, cross-sectional study of a series of HIVoutpatients attended in our Hospital. Demographic, anthropometric, clinical, and fasting lab data were recorded in all cases. CVR at 10 years was evaluated by Framingham equation, and MetS diagnosed according to the National Cholesterol Education Program criteria. Statistic program: SPSS 17.0. Results 666 patients were included, 79.3% were men, and mean age was 44.7 years. Mean CD4 count was 506 cells/ mm3 , 87.5% of the patients were on antiretroviral therapy, and 85.3% had undetectable HIV viral load. Mean RDW was 13.07% (range: 7.7-33.6%; 75th percentile 14,1%), with a prevalence of MetS of 15.7, 9.3, 18.8 and 16.6% first through fourth RDW quartile, and of patients with CVR >20% of 8.4, 4.0, 4.4 and 6.4%, respectively (p>0,05). The highest quartile of RDW (>14.1%) was associated with AIDS (OR 1.6, 95%CI 1.0-2.4; p 0.02), detectable HIV viral load (OR 1.5, 95%CI 1.01-2.4; p 0.04), and hypertension (OR 2.3, 95%CI 1.4-4.0; p 0.001). Conclusions In HIV-infected outpatients, higher RDW is related with detectable HIV viral load and with AIDS. Although it was associated with a traditional CVR factor as hypertension, we found no relation with MetS nor with higher CVR.

Contribution of physical education to overall physical activity.

For many children, physical activity (PA) during physical education (PE) lessons provides an important opportunity for being physically active. Although PA during PE has been shown to be low, little is known about the contribution of PA during PE to overall PA. The aim was therefore to assess children's PA during PE and to determine the contribution of PE to overall PA with special focus on overweight children. Accelerometer measurements were done in 676 children (9.3 ± 2.1 years) over 4-7 days in 59 randomly selected classes. Moderate-and-vigorous PA (MVPA; ≥ 2000 counts/min) during PE (MVPA(PE) ), overall MVPA per day (MVPA(DAY) ), and a comparison of days with and without PE were calculated by a regression model with gender, grade, and weight status (normal vs overweight) as fixed factors and class as a random factor. Children spent 32.8 ± 15.1% of PE time in MVPA. Weight status was not associated to MVPA(PE) . MVPA(PE) accounted for 16.8 ± 8.5% of MVPA(DAY) , and 17.5 ± 8.2% in overweight children. All children were more active on days with PE than on days without PE (differences: 16.1 ± 29.0 min of MVPA(DAY) ; P ≤ 0.001; 13.7 ± 28.0 min for overweight children). Although MVPA(PE) was low, PE played a considerable role in providing PA and was not compensated by reducing extracurricular MVPA.

Implementation of a nutrition education program in a handball team; consequences on nutritional status.

OBJECTIVE: To evaluate nutritional status and dietary habits after implementation of a nutritional education program in professional handball players. RESEARCH METHODS AND PROCEDURES: Longitudinal study of 14 handball players evaluated with 72-h recall, a questionnaire on food consumption and anthropometric measures during 4 months. The intervention consisted of a nutrition education program. RESULTS: Energy intake was consistently below the recommended allowances. Macronutrient intakes as a percentage of total energy intake were below the recommended allowances for carbohydrates, and above recommended allowances for fats. Nutritional education was followed by a significant increase (p < 0.01) in total energy and macronutrient intakes, with no significant changes in macronutrient or micronutrient intakes after adjustment for energy intake. DISCUSSION: The imbalance in nutrient intake in handball players suggests that detailed re-analysis is needed to determine specific recommendations for this population. Nutritional education with continuous follow-up to monitor athletes' dietary habits may lead them to adopt appropriate nutritional habits to optimize dietary intakes. The lack of specific recommendations for micronutrient intakes in athletes leads to confusion regarding appropriate intakes; biochemical tests that yield normal values (albeit approaching cut-off values for deficiency) may disguise deficient status for some nutrients when strenuous exercise is involved. CONCLUSION: In-depth studies with nutrition education programs that include long-term follow-up are advisable to avoid deficiencies that can lead to irreversible damage in competitive athletes.