Insight into a Novel p53 Single Point Mutation (G389E) by Molecular Dynamics Simulations

The majority of inactivating mutations of p53 reside in the central core DNA binding domain of the protein. In this computational study, we investigated the structural effects of a novel p53 mutation (G389E), identified in a patient with congenital adrenal hyperplasia, which is located within the extreme C-terminal domain (CTD) of p53, an unstructured, flexible region (residues 367–393) of major importance for the regulation of the protein. Based on the three-dimensional structure of a carboxyl-terminal peptide of p53 in complex with the S100B protein, which is involved in regulation of the tumor suppressor activity, a model of wild type (WT) and mutant extreme CTD was developed by molecular modeling and molecular dynamics simulation. It was found that the G389E amino acid replacement has negligible effects on free p53 in solution whereas it significantly affects the interactions of p53 with the S100B protein. The results suggest that the observed mutation may interfere with p53 transcription activation and provide useful information for site-directed mutagenesis experiments

Protein kinase C mediates caspase 3 activation: A role for erythrocyte morphology changes.

We have previously showed that morphological alterations in Red Blood Cells (RBCs) are correlated to an impaired eNOS enzymatic activity and a concomitant reduced NO derived metabolites formation. Here we extend our previous observations, reporting that RBC morphology is regulated by a series of specific cell signaling events linked to Protein Kinase C (PKC)-mediated activation of caspase 3. Pretreatment of RBCs with the PKC inhibitor chelerythrine, prior to the addition of phorbol-12-myristate-13-acetate (PMA), an activator of PKC, blocks the appearance of the morphology alterations and the sustained decrease in nitrates and nitrites levels induced by PMA. Inhibition of PKC also completely inhibits PMA mediated caspase-3 activation. On the other hand, caspase 3 inhibition, lessens the PMA induced-effects on the appearance of RBC morphology alterations, although it enhances PMA-mediated effects on nitric oxide (NO) derived metabolites levels. These data demonstrate that PKC-mediated activation of caspase 3 is an integral and essential part of signaling pathway in RBCs, that may be a regulatory factor of RBC mechanical properties, through regulation of NO metabolism

Erythrocytes as potential link between diabetes and Alzheimer's disease

Many studies support the existence of an association between type 2 diabetes (T2DM) and Alzheimer's disease (AD). In AD, in addition to brain, a number of peripheral tissues and cells are affected, including red blood cell (RBC) and because there are currently no reliable diagnostic biomarkers of AD in the blood, a gradually increasing attention has been given to the study of RBC's alterations. Recently it has been evidenced in diabetes, RBC alterations superimposable to the ones occurring in AD RBC. Furthermore, growing evidence suggests that oxidative stress plays a pivotal role in the development of RBC's alterations and vice versa. Once again this represents a further evidence of a shared pathway between AD and T2DM. The present review summarizes the two disorders, highlighting the role of RBC in the postulated common biochemical links, and suggests RBC as a possible target for clinical trials

Methionine 35 sulphoxide reduces toxicity of Abeta in red blood cell

Background: The oxidation of methionine residue in position 35 of Ab to sulphoxide (Ab-sulphoxide) has the ability to deeply modify wild-type Ab 1â42 (Ab) neurotoxic action. Our previous studies suggest that in nucleated cells, lower toxicity of Ab-sulphoxide might result not from structural alteration, but from elevation of methionine sulphoxide reductase A (MsrA) activity and mRNA levels. Design: On this basis, we hypothesised that red blood cell (RBC), a cell devoid almost completely of MsrA activity, shares with nucleated cells an antioxidant system induced by methionine 35 sulphoxide, responsible for the lower toxicity of Ab-sulphoxide in RBC. (Results) Supporting this hypothesis, we found that the low toxicity of Ab-sulphoxide in RBC correlated with pentose phosphate pathway (PPP) flux increase, and this event was associated with a low level of methionine oxidation in total proteins. None of these effects were observed when cells were exposed to Ab native. Discussion: These results outline the importance of the redox state of methionine 35 in the modulation of Ab-mediated events and suggest an important protective role for PPP in RBC of patients affected by Alzheimer's disease