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Amyloid-treated microglia prime and sustain neuroinflammatory processes in the central nervous system activating different signalling pathways inside the cells. Since a key role for PARP-1 has been demonstrated in inflammation and in neurodegeneration, we investigated PARylated proteins in resting and in β-amyloid peptide treated BV2 microglial cells. A total of 1158 proteins were identified by mass spectrometry with 117 specifically modified in the amyloid-treated cells. Intervention of PARylation on the proteome of microglia showed to be widespread in different cellular districts and to affect various cellular pathways, highlighting the role of this dynamic post-translational modification in cellular regulation. Ubiquitination is one of the more enriched pathways, encompassing PARylated proteins like NEDD4, an E3 ubiquitine ligase and USP10, a de-ubiquitinase, both associated with intracellular responses induced by β-amyloid peptide challenge. PARylation of NEDD4 may be involved in the recruiting of this protein to the plasma membrane where it regulates the endocytosis of AMPA receptors, whereas USP10 may be responsible for the increase of p53 levels in amyloid stimulated microglia. Unfolded protein response and Endoplasmic Reticulum Stress pathways, strictly correlated with the Ubiquitination process, also showed enrichment in PARylated proteins. PARylation may thus represent one of the molecular switches responsible for the transition of microglia towards the inflammatory microglia phenotype, a pivotal player in brain diseases including neurodegenerative processes. The establishment of trials with PARP inhibitors to test their efficacy in the containment of neurodegenerative diseases may be envisaged. [ABSTRACT FROM AUTHOR]

Background Several studies suggest that pathological changes in Alzheimer’s disease (AD) brain begin around 10–20 years before the onset of cognitive impairment. Biomarkers that can support early diagnosis and predict development of dementia would, therefore, be crucial for patient care and evaluation of drug efficacy. Although cerebrospinal fluid (CSF) levels of Aβ42, tau, and p-tau are well-established diagnostic biomarkers of AD, there is an urgent need to identify additional molecular alterations of neuronal function that can be evaluated at the systemic level. Objectives This study was focused on the analysis of oxidative stress-related modifications of the CSF proteome, from subjects with AD and amnestic mild cognitive impairment (aMCI). Methods A targeted proteomics approach has been employed to discover novel CSF biomarkers that can augment the diagnostic and prognostic accuracy of current leading CSF biomarkers. CSF samples from aMCI, AD and control individuals (CTR) were collected and analyzed using a combined redox proteomics approach to identify the specific oxidatively modified proteins in AD and aMCI compared with controls. Results The majority of carbonylated proteins identified by redox proteomics are found early in the progression of AD, i.e., oxidatively modified CSF proteins were already present in aMCI compared with controls and remain oxidized in AD, thus suggesting that dysfunction of selected proteins initiate many years before severe dementia is diagnosed. Conclusions The above findings highlight the presence of early oxidative damage in aMCI before clinical dementia of AD is manifested. The identification of early markers of AD that may be detected peripherally may open new prospective for biomarker studies. [ABSTRACT FROM AUTHOR]

Abstract: Down syndrome (DS) is the most common genetic cause of intellectual disability, due to partial or complete triplication of chromosome 21. DS subjects are characterized by a number of abnormalities including premature aging and development of Alzheimer disease (AD) neuropathology after approximately 40 years of age. Several studies show that oxidative stress plays a crucial role in the development of neurodegeneration in the DS population. Increased lipid peroxidation is one of the main events causing redox imbalance within cells through the formation of toxic aldehydes that easily react with DNA, lipids, and proteins. In this study we used a redox proteomics approach to identify specific targets of 4-hydroxynonenal modifications in the frontal cortex from DS cases with and without AD pathology. We suggest that a group of identified proteins followed a specific pattern of oxidation in DS vs young controls, probably indicating characteristic features of the DS phenotype; a second group of identified proteins showed increased oxidation in DS/AD vs DS, thus possibly playing a role in the development of AD. The third group of comparison, DS/AD vs old controls, identified proteins that may be considered specific markers of AD pathology. All the identified proteins are involved in important biological functions including intracellular quality control systems, cytoskeleton network, energy metabolism, and antioxidant response. Our results demonstrate that oxidative damage is an early event in DS, as well as dysfunctions of protein-degradation systems and cellular protective pathways, suggesting that DS subjects are more vulnerable to oxidative damage accumulation that might contribute to AD development. Further, considering that the majority of proteins have been already demonstrated to be oxidized in AD brain, our results strongly support similarities with AD in DS. [Copyright &y& Elsevier]

Abstract: DS is the most frequent genetic cause of intellectual disability characterized by the anomalous presence of three copies of chromosome 21. One of the peculiar features of DS is the onset of Alzheimer's disease neuropathology after the age of 40years characterized by deposition of senile plaques and neurofibrillary tangles. Growing studies demonstrated that increased oxidative damage, accumulation of unfolded/damaged protein aggregates and dysfunction of intracellular degradative system are key players in neurodegenerative processes. In this study, redox proteomics approach was used to analyze the frontal cortex from DS subjects under the age of 40 compared with age-matched controls, and proteins found to be increasingly carbonylated were identified. Interestingly, our results showed that oxidative damage targets specifically different components of the intracellular quality control system such as GRP78, UCH-L1, V0-ATPase, cathepsin D and GFAP that couples with decreased activity of the proteasome and autophagosome formation observed. We also reported a slight but consistent increase of Aβ 1–42 SDS- and PBS-soluble form and tau phosphorylation in DS versus CTR. We suggest that disturbance in the proteostasis network could contribute to the accumulation of protein aggregates, such as amyloid deposits and NFTs, which occur very early in DS. It is likely that a sub-optimal functioning of degradative systems occur in DS neurons, which in turn provide the basis for further accumulation of toxic protein aggregates. The results of this study suggest that oxidation of protein members of the proteostatis network is an early event in DS and might contribute to neurodegenerative phenomena. [Copyright &y& Elsevier]

Abstract: Background: Molecular mechanisms underlying abdominal aneurysm (AAA) formation and rupture are not well understood. Early detection and repair of AAA may reduce the high mortality rates associated with rupture. Serum proteomics allows the detection of alterations in the expression of proteins, guiding further studies on these target molecules as potential markers. Analysis of proteomic profile of asymptomatic patients with AAA allows the identification of reliable predictors or markers of disease presence or progression. Methods: A proteomics approach based on two-dimensional electrophoresis and mass spectrometry was used to compare serum proteomic profiles of patients with AAA who are candidates for surgical repair compared with healthy controls. We analyzed in parallel the proteomic profile of subjects with cardiac heart failure to discriminate these two pathologies, which show similar pattern of systemic inflammation process. Results: We identified in AAA subjects four serum proteins that show altered expression profile and that could be specifically linked to AAA pathology. We discuss the role of our identified proteins with their possible implications in disease outcome. Conclusions: This approach could provide an initial screening tool that may drive the basis for further research in the field of cardiovascular diseases. These results need to be validated in larger studies to find potential markers of AAA presence or progression to use in clinical settings. Summary: A proteomics approach was used to compare serum proteomic profiles of patients with abdominal aortic aneurysm who are candidates for surgical repair compared with healthy controls. Four serum proteins showed altered expression profile that could be correlated with the pathology. This approach could provide an initial screening tool that may drive the basis for further research in the field of cardiovascular diseases. [Copyright &y& Elsevier]

CcmH (cytochromes c maturation protein H) is an essential component of the assembly line necessary for the maturation of c-type cytochromes in the periplasm of Gram-negative bacteria. The protein is a membrane-anchored thiol-oxidoreductase that has been hypothesized to be involved in the recognition and reduction of apocytochrome c, a prerequisite for covalent heme attachment. Here, we present the 1.7 Å crystal structure of the soluble periplasmic domain of CcmH from the opportunistic pathogen Pseudomonas aeruginosa (Pa-CcmH*). The protein contains a three-helix bundle, i.e. a fold that is different from that of all other thiol-oxidoreductases reported so far. The catalytic Cys residues of the conserved LRCXXC motif (Cys25 and Cys28), located in a long loop connecting the first two helices, form a disulfide bond in the oxidized enzyme. We have determined the pKa values of these 2 Cys residues of Pa-CcmH* (both >8) and propose a possible mechanistic role for a conserved Ser36 and a water molecule in the active site. The interaction between Pa-CcmH* and Pa-apocyt c551 (where cyt c551 represents cytochrome c551) was characterized in vitro following the binding kinetics by stopped-flow using a Trp-containing fluorescent variant of Pa-CcmH* and a dansylated peptide, mimicking the apocytochrome c551 heme binding motif. The kinetic results show that the protein has a moderate affinity to its apocyt substrate, consistent with the role of Pa-CcmH as an intermediate component of the assembly line for c-type cytochrome biogenesis. [ABSTRACT FROM AUTHOR]