Effects of antioxidant supplementation on oxidative stress balance in young footballers- a randomized double-blind trial.

BACKGROUND: Intensive physical exercise that competitive sports athletes participate in can negatively affect their pro-oxidative-antioxidant balance. Compounds with high antioxidant potential, such as those present in chokeberry (Aronia melanocarpa), can prevent these adverse changes. We here investigated the effect of antioxidant supplementation on oxidative stress balance in young footballers. METHODS: The study was designed as a double-blind randomized trial. Diet of a group of young football players (male; n = 20; mean age, 15.8 years-old) was supplemented with 200 ml of chokeberry juice per day, for 7 weeks. The players were randomly assigned to the experimental (supplemented, FP-S; n = 12) and control (placebo, FB-C; n = 8) groups. Before and after the supplementation period, the participants performed a beep test. Venous blood was sampled for serum analysis before, immediately after, 3 h, and 24 h after the beep test. Serum levels of thiobarbituric acid reactive products, 8-hydroxy-2'-deoxyguanosine, total antioxidant capacity, iron, hepcidin, ferritin, myoglobin, and albumin, and morphological blood parameters (red blood cells, (RBC), haemoglobin (HGB), haematocrit (HCT) mean corpuscular volume (MCV) mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and lactic acid) were determined. RESULTS: Chokeberry juice supplementation did not significantly affect the outcome of the beep test. The supplementation did not significantly affect any of the morphological, biochemical, or performance parameters analysed. CONCLUSIONS: Chokeberry juice supplementation did not affect the measured parameters in the studied population, which may indicate insufficient antioxidant capacity of the juice.

Release of an ~55kDa fragment containing the actin-binding domain of ß-spectrin by caspase-8 during FND-induced apoptosis depends on the presence of protein 4.1.

Analyses of the status of the membrane spectrin-based skeleton during fludarabine/mitoxantrone/dexamethasone-induced (FND-induced) apoptosis revealed proteolytic degradation of ß-spectrin, with the prevalent appearance of a specific fragment with a molecular weight of ~55kDa, containing the actin-binding domain (ABD). Appearance of this fragment was dependent on induction of apoptosis. In silico proteolysis of spectrin identified caspase-8 as a candidate protease responsible for the generation of this ~55kDa ABD-containing fragment. Analyses of spectrin and procaspase-8 localization during early apoptosis indicated temporary (<30-120min) submembranous colocalization of both proteins. Proteolytic release of the N-terminal ~55kDa fragment of purified spectrin by recombinant caspase-8 does not occur in normal cells, but does occur in isolated membrane, such as red blood cell ghosts, or in vitro in the presence of apoptotic cell extracts. Surprisingly, proteolysis of purified spectrin by recombinant caspase-8 resulted in the generation of the ~55kDa fragment only in the presence of purified protein 4.1. This suggests that only the appropriate spatial arrangement of the spectrin-based membrane skeleton or the appropriate conformational state of spectrin, which are both known to be induced by 4.1, can sensitize ß-spectrin to cleavage by caspase-8 at the N-terminal ABD-containing region.

Palmitoylation of MPP1 (membrane-palmitoylated protein 1)/p55 is crucial for lateral membrane organization in erythroid cells.

S-Acylation of proteins is a ubiquitous post-translational modification and a common signal for membrane association. The major palmitoylated protein in erythrocytes is MPP1, a member of the MAGUK family and an important component of the ternary complex that attaches the spectrin-based skeleton to the plasma membrane. Here we show that DHHC17 is the only acyltransferase present in red blood cells (RBC). Moreover, we give evidence that protein palmitoylation is essential for membrane organization and is crucial for proper RBC morphology, and that the effect is specific for MPP1. Our observations are based on the clinical cases of two related patients whose RBC had no palmitoylation activity, caused by a lack of DHHC17 in the membrane, which resulted in a strong decrease of the amount of detergent-resistant membrane (DRM) material. We confirmed that this loss of detergent-resistant membrane was due to the lack of palmitoylation by treatment of healthy RBC with 2-bromopalmitic acid (2-BrP, common palmitoylation inhibitor). Concomitantly, fluorescence lifetime imaging microscopy (FLIM) analyses of an order-sensing dye revealed a reduction of membrane order after chemical inhibition of palmitoylation in erythrocytes. These data point to a pathophysiological relationship between the loss of MPP1-directed palmitoylation activity and perturbed lateral membrane organization.

Human DHHC proteins: a spotlight on the hidden player of palmitoylation.

Palmitoylation is one of the most common posttranslational lipid modifications of proteins and we now know quite a lot about it. However, the state of knowledge about the enzymes that catalyze this process is clearly insufficient. This review is focused on 23 human DHHC genes and their products - protein palmitoyltransferases. Here we describe mainly the structure and function of these proteins, but also, to a lesser degree, what the substrates of the enzymes are and whether they are related to various diseases. The main aim of this review was to catalogue existing information concerning the human DHHC family of genes/proteins, making them and their functions easier to understand.