AtLACS7 interacts with the TPR domains of the PTS1 receptor PEX5

Long-chain acyl-CoA synthetases (LACSs) activate fatty acids for further metabolism and are encoded by a multi-gene family in Arabidopsis. AtLACS6 possesses a type 2 (PTS2) peroxisomal targeting sequence, whilst AtLACS7 has both a type 1 and type 2 peroxisomal targeting sequence. AtLACS7 was used as bait in a yeast two-hybrid screen. Multiple clones of the PTS1 receptor PEX5 were isolated. Quantitative beta-galactosidase assay indicated that full-length PEX5 interacts with AtLACS7 with higher affinity than the TPR domains alone. The interaction between PEX5 and AtLACS7 was confirmed by co-immunoprecipitation and shown to be specific for the PTS1, therefore the AtLACS7 PTS1 is accessible to bind PEX5 in the full-length AtLACS7 protein. The expression profile of AtLACS6, AtLACS7, AtPEX5, and AtPEX7 revealed that AtLACS6 and 7 have distinct patterns of expression and we speculate that the possession of two targeting signals may be advantageous for the import of AtLACS7 when receptors may be limiting.     

Reciprocally interacting domains of protein phosphatase 1 and focal adhesion kinase

The Murine double-minute clone 2 (Mdm2) onco-protein is the principal regulator of the tumour suppressor, p53. Mdm2 acts as an E3-type ubiquitin ligase that mediates the ubiquitylation and turnover of p53 under normal, unstressed circumstances. In response to cellular stress, such as DNA damage, the Mdm2–p53 interaction is disrupted. Part of the mechanism of uncoupling p53 from Mdm2-mediated degradation involves hypo-phosphorylation of a cluster of phosphorylated serine residues in the central acidic domain of Mdm2. Here, we show that two of the residues within this domain that are phosphorylated in vivo, Ser-260 and Ser-269, are phosphorylated by CK2 in vitro. Treatment of cells with the CK2 inhibitor, 4,5,6,7-tetrabromo-2-azabenzimidazole (TBB), leads to the induction of p53 and downstream targets of p53 including Mdm2 itself and p21. These data are consistent with the idea that CK2-mediated phosphorylation of Mdm2 may regulate Mdm2-mediated p53 turnover.     

Comparison of the chemical composition and the organoleptic profile of virgin olive oil from two wild and two cultivated Tunisian Olea europaea

With the aim to select new olive cultivars with superior physical and chemical properties than the cultivar Chemlali Sfax, the present study focused on the comparison of the chemical composition and the sensory profile of the virgin olive oils (VOOs) of two wild olive trees (Oleasters K and M) with those of VOOs obtained from Chemlali Sfax and Neb Jmel olive cultivars, all growing in the coastal region of Tunisia. Despite the variability in the chemical composition (fatty acids, pigments, and phenolic and volatile compounds) and the organoleptic profile of the VOOs of the oleasters and the cultivars, the quality indices (free fatty acids, peroxide value, and spectrophotometric indices K232 and K270) as well as the fatty acid composition of all VOOs studied met the commercial standards. Both the α-tocopherol and phenol contents varied between the genotypes. The Neb Jmel and Oleaster K VOOs had more than two times higher total phenol levels than the Chemlali Sfax and Oleaster M VOOs. Also the contents of volatile compounds differed between the olive oils studied. Chemlali Sfax and Oleaster K oils were more abundant in aldehydes, whereas Oleaster M VOO had higher contents of alcohols. These results were confirmed by a sensorial analysis showing that the later oil was deprived for consumption despite its abundance in α-tocopherol. In conclusion, the oleasters studied revealed to be interesting, since they produced oils with good quality characteristics in terms of minor compounds (phenols and volatiles) compared to the Chemlali Sfax cultivar.     

Pericentric inversion of chromosome 19 in three families

Summary Pericentric inversion of chromosome 19 has been found in several members of three unrelated families from a restricted geographical region. In one of the families, an additional pericentric inversion of chromosome 9 was observed. Reproductive problems, multiple abortions in two families and a neonatal death in the third, were present. A review of previously described cases is included, and the genetic risk connected with this type of rearrangement is also discussed.     

Reversible and irreversible modifications ofβ-lactoglobulin upon exposure to heat

Modifications in the exposure to the solvent of hydrophobic residues, changes in their organization into surface hydrophobic patches, and alterations in the dimerization equilibrium ofβ-lactoglobulin upon thermal treatment at neutralpH were studied. Exposure of tryptophan residues was temperature dependent and was essentially completed on the time scale of seconds. Reorganization of generic hydrophobic protein patches on the protein surface was monitored through binding of 1,8-anilinonaphthalenesulfonate, and was much slower than changes in tryptophan exposure. Different phases in surface hydrophobicity changes were related to the swelling and the subsequent collapse of the protein, which formed a metastable swollen intermediate. Heat treatment ofβ-lactoglobulin also resulted in the formation of soluble oligomeric aggregates. The aggregation process was studied as a function of temperature, demonstrating that (i) dimer dissociation was a necessary step in a sequential polymerization mechanism and (ii) cohesion of hydrophobic patches was the major driving force for aggregation.     

Oxidative stress and neurodegeneration: the involvement of iron

Many evidences indicate that oxidative stress plays a significant role in a variety of human disease states, including neurodegenerative diseases. Iron is an essential metal for almost all living organisms due to its involvement in a large number of iron-containing proteins and enzymes, though it could be also toxic. Actually, free iron excess generates oxidative stress, particularly in brain, where anti-oxidative defences are relatively low. Its accumulation in specific regions is associated with pathogenesis in a variety of neurodegenerative diseases (i.e., Parkinson’s disease, Alzheimer’s disease, Huntington’s chorea, Amyotrophic Lateral Sclerosis and Neurodegeneration with Brain Iron Accumulation). Anyway, the extent of toxicity is dictated, in part, by the localization of the iron complex within the cell (cytosolic, lysosomal and mitochondrial), its biochemical form, i.e., ferritin or hemosiderin, as well as the ability of the cell to prevent the generation and propagation of free radical by the wide range of antioxidants and cytoprotective enzymes in the cell. Particularly, ferrous iron can act as a catalyst in the Fenton reaction that potentiates oxygen toxicity by generating a wide range of free radical species, including hydroxyl radicals (·OH). The observation that patients with neurodegenerative diseases show a dramatic increase in their brain iron content, correlated with the production of reactive oxigen species in these areas of the brain, conceivably suggests that disturbances in brain iron homeostasis may contribute to the pathogenesis of these disorders. The aim of this review is to describe the chemical features of iron in human beings and iron induced toxicity in neurodegenerative diseases. Furthermore, the attention is focused on metal chelating drugs therapeutic strategies.     

Gender-Specific Effects of Depression and Suicidal Ideation in Prosocial Behaviors

Background

Prosocial behaviors are essential to the ability to relate to others. Women typically display greater prosocial behavior than men. The impact of depression on prosocial behaviors and how gender interacts with those effects are not fully understood. We explored the role of gender in the potential effects of depression on prosocial behavior.

Methods

We examined prosocial behaviors using a modified version of the Trust Game in a clinical population and community controls. Study participants were characterized on the severity of depression and anxiety, presence of suicidal ideation, history of childhood trauma, recent stressful life events, and impulsivity. We correlated behavioral outcomes with gender and clinical variables using analysis of variance and multiple regression analysis.

Results

The 89 participants comprised four study groups: depressed women, depressed men, healthy women and healthy men (n = 16–36). Depressed men exhibited reciprocity more frequently than healthy men. Depression induced an inversion of the gender-specific pattern of self-centered behavior. Suicidal ideation was associated with increased reciprocity behavior in both genders, and enhancement of the effect of depression on gender-specific self-centered behavior.

Conclusions

Depression, particularly suicidal ideation, is associated with reversal of gender-specific patterns of prosocial behavior, suggesting abnormalities in sexual hormones regulation. This explanation is supported by known abnormalities in the hypothalamus-pituitary-adrenal and hypothalamus-pituitary-gonadal axes found in depression.     

Phorbol 12-myristate 13-acetate induces resistance of human melanoma cells to natural-killer-and lymphokine-activated-killer-mediated cytotoxicity

Summary Human melanoma cells are sensitive to the lytic activity of natural killer (NK) and lymphokine-activated killer (LAK) cells in vitro. The events resulting in tumour cell killing by lymphocytic effectors have not been completely clarified, and the same target cell determinants regulating responsiveness to immune cytolysis have not yet been identified. Indeed, changes in the differentiative status of leukemia cells as well as in the expression of major histocompatibility complex (MHC) antigens have been described to modulate sensitivity to cytotoxic effectors; moreover surface expression of adhesion factors or extracellular matrix proteins by the cancer cells can promote the activation of the cytolytic effectors and has been described to correlate with tumour cell sensitivity to cytolytic cells. We reasoned that treatment with differentiation inducers could modulate melanoma cell sensitivity to NK and LAK cells. The present study demonstrates that human melanoma GLL-19 cells, when treated with the phorbol diester phorbol 12-myristate 13-acetate (PMA) in vitro, undergo growth inhibition and neuron-like differentiation. Moreover PMA treatment induces an evident inhibition of GLL-19 cell sensitivity to NK- and LAK-mediated cytotoxicity. GLL-19 cells express constitutively MHC class I antigens. PMA treatment, however, does not modify the expression of MHC class I and class II DR antigens in human melanoma GLL-19 cells. We have finally evaluated the effects of PMA on the expression at the cell surface of adhesion factors such as ICAM-1, and extracellular matrix proteins such as collagen IV, laminin and fibronectin; we have also studied the expression of the integrin vitronectin receptor, a membrane receptor for adhesive proteins. While adhesion factors and extracellular matrix proteins appear to play an important role in the interaction between immune effector and tumour target, it can be supposed that the modulation of such membrane-associated proteins or glycoproteins induces NK and LAK resistance in cancer cells. We indeed found that PMA treatment induced in GLL-19 a marked reduction of membrane expression of collagen IV and ICAM-1; moreover PMA reduced the cell membrane expression of the integrin vitronectin receptor. On the other hand, membrane expression of fibronectin and laminin was not affected by PMA. These data indicate that the acquisition of a NK- and LAK-resistant phenotype by GLL-19 cells occurs together with cell differentiation, down-regulation of membrane expression of collagen IV, ICAM-1 and vitronectin receptor, but in the absence of changes in MHC antigens.This work has been supported by the Italian Association for Cancer Research (A. I. R. C.) and by Istituto Superiore di Sanità, Italy-USA joint program on New Therapies on Neoplasia.     

Smoking Is Associated with More Abdominal Fat in Morbidly Obese Patients

IntroductionWhile the association between cigarette smoking and abdominal fat has been well studied in normal and overweight patients, data regarding the influence of tobacco use in patients with morbid obesity remain scarce. The aim of this study is to evaluate body fat distribution in morbidly obese smokers.MethodsWe employed a cross-sectional study and grouped severely obese patients (body mass index [BMI] >40 kg/m² or >35 kg/m² with comorbidities) according to their smoking habits (smokers or non-smokers). We next compared the anthropometrical measurements and body composition data (measured by electric bioimpedance) of both groups. We analyzed the effect of smoking on body composition variables using univariate and multiple linear regression (MLR); differences are presented as regression coefficients (b) and their respective 95% confidence intervals.ResultsWe included 536 morbidly obese individuals, 453 (84.5%) non-smokers and 83 (15.5%) smokers. Male smokers had a higher BMI (b=3.28 kg/m², p=0.036), larger waist circumference (b=6.07 cm, p=0.041) and higher percentage of body fat (b=2.33%, p=0.050) than non-smokers. These differences remained significant even after controlling for confounding factors. For females, the only significant finding in MLR was a greater muscle mass among smokers (b=1.34kg, p=0.028). No associations were found between tobacco load measured in pack-years and anthropometric measures or body composition.DiscussionPositive associations between smoking and BMI, and waist circumference and percentage of body fat, were found among male morbidly obese patients, but not among females. To the best of our knowledge, this study is the first investigation of these aspects in morbidly obese subjects. We speculate that our findings may indicate that the coexistence of morbid obesity and smoking helps to explain the more serious medical conditions, particularly cardiovascular diseases and neoplasms, seen in these patients.