Abnormal N-glycosylation pattern for brain nucleotide pyrophosphatase-5 (NPP-5) in Mecp2-mutant murine models of Rett syndrome

Metabolites derived from radical oxidation of PUFA: NEO-PUFAs, promising molecules for health?

Oxidative stress plays a critical role in numerous pathological processes. Under these stress conditions, the free radical-catalyzed lipid peroxidation generates in vivo a large number of key products that are involved in many physiological and pathophysiological processes. Among these products are neuroprostanes, which arise from the peroxidation of docosahexaenoic acid (DHA), and isoprostanes, resulting from arachidonic acid (AA) and eicosapentaenoic acid (EPA) through the same peroxidation process. These non-enzymatic oxygenated metabolites newly appointed NEO-PUFAs have gained recognition as reliable markers of oxidative stress in neurogenerative and cardiovascular diseases. Moreover, some of them display a wide range of biological activities. The ability to detect and measure these metabolites offers precious insights into the mechanisms of oxidative damage and holds potential therapeutic implications for various health conditions, including neurodegenerative diseases. This review focuses on the role of neuroprostanes as biomarkers for oxidative stress and related diseases, highlighting their potential applications in medical research and treatment.

Biochemical and molecular determinants of the subclinical inflammatory mechanisms in Rett syndrome

To date, Rett syndrome (RTT), a genetic disorder mainly caused by mutations in the X-linked MECP2 gene, is increasingly considered a broad-spectrum pathology, instead of just a neurodevelopmental disease, due to the multitude of peripheral co-morbidities and the compromised metabolic pathways, affecting the patients. The altered molecular processes include an impaired mitochondrial function, a perturbed redox homeostasis, a chronic subclinical inflammation and an improper cholesterol metabolism. The persistent subclinical inflammatory condition was first defined ten years ago, as a previously unrecognized feature of RTT, playing a role in the pathology progress and modulation of phenotypical severity. In light of this, the present work aims at reviewing the current knowledge on the chronic inflammatory status and the altered immune/inflammatory functions in RTT, as well as investigating the emerging mechanisms underlying this condition with a special focus on the latest findings about inflammasome system, autoimmunity responses and intestinal micro- and mycobiota. On these bases, although further research is needed, future therapeutic strategies able to re-establish an adequate immune/inflammatory response could represent potential approaches for RTT patients.

Circulating microRNA sequencing revealed miRNome patterns in hematology and oncology patients aiding the prognosis of invasive aspergillosis

Invasive aspergillosis (IA) may occur as a serious complication of hematological malignancy. Delays in antifungal therapy can lead to an invasive disease resulting in high mortality. Currently, there are no well-established blood circulating microRNA biomarkers or laboratory tests which can be used to diagnose IA. Therefore, we aimed to define dysregulated miRNAs in hematology and oncology (HO) patients to identify biomarkers predisposing disease. We performed an in-depth analysis of high-throughput small transcriptome sequencing data obtained from the whole blood samples of our study cohort of 50 participants including 26 high-risk HO patients and 24 controls. By integrating in silico bioinformatic analyses of small noncoding RNA data, 57 miRNAs exhibiting significant expression differences (P < 0.05) were identified between IA-infected patients and non-IA HO patients. Among these, we found 36 differentially expressed miRNAs (DEMs) irrespective of HO malignancy. Of the top ranked DEMs, we found 14 significantly deregulated miRNAs, whose expression levels were successfully quantified by qRT-PCR. MiRNA target prediction revealed the involvement of IA related miRNAs in the biological pathways of tumorigenesis, the cell cycle, the immune response, cell differentiation and apoptosis.

Brain protein changes in Mecp2 mouse mutant models: Effects on disease progression of Mecp2 brain specific gene reactivation

Rett syndrome (RTT) is a leading cause of severe intellectual disability in females, caused by de novo loss-of function mutations in the X-linked methyl-CpG binding protein 2 (MECP2). To better investigate RTT disease progression/pathogenesis animal models of Mecp2 deficiency have been developed. Here, Mecp2 mouse models are employed to investigate the role of protein patterns in RTT. A proteome analysis was carried out in brain tissue from i) Mecp2 deficient mice at the pre-symptomatic and symptomatic stages and, ii) mice in which the disease phenotype was reversed by Mecp2 reactivation. Several proteins were shown to be differentially expressed in the pre-symptomatic (n = 18) and symptomatic (n = 20) mice. Mecp2 brain reactivated mice showed wild-type comparable levels of expression for twelve proteins, mainly related to proteostasis (n = 4) and energy metabolic pathways (n = 4). The remaining ones were found to be involved in redox homeostasis (n = 2), nitric oxide regulation (n = 1), neurodevelopment (n = 1). Ten out of twelve proteins were newly linked to Mecp2 deficiency. Our study sheds light on the relevance of the protein-regulation of main physiological process in the complex mechanisms leading from Mecp2 mutation to the RTT clinical phenotype. SIGNIFICANCE: We performed a proteomic study of a Mecp2^stop/y mouse model for Rett syndrome (RTT) at the pre-symptomatic and symptomatic Mecp2 deficient mice stage and for the brain specific reactivated Mecp2 model. Our results reveal major protein expression changes pointing out to defects in proteostasis or energy metabolic pathways other than, to a lesser extent, in redox homeostasis, nitric oxide regulation or neurodevelopment. The Mecp2 mouse rescued model provides the possibility to select target proteins more susceptible to the Mecp2 gene mutation, potential and promising therapeutical targets.

A key tyrosine substitution restricts nucleotide hydrolysis by the ectoenzyme NPP5

The ecto-nucleotide pyrophosphatase/phosphodiesterase (NPP) family of proteins mediates purinergic signaling by degrading extracellular nucleotides and also participates in phospholipid metabolism. NPP5 (ENPP5) is the least characterized member of this group and its specific role is unknown. This enzyme does not display activity on certain nucleotides and on other typical NPP substrates. In order to gain insights into its function, we determined the crystal structure of human and murine NPP5. Structural comparison with close homologs revealed a key phenylalanine to tyrosine substitution that prevents efficient hydrolysis of nucleotide diphosphates and triphosphates; reversal of this mutation enabled degradation of these molecules. Interestingly, NPP5 is able to cleave nicotinamide adenine dinucleotide (NAD), suggesting a potential role of this enzyme in NAD-based neurotransmission. An NPP5-specific metal binding motif is found adjacent to the active site, although its significance is unclear. These findings expand our understanding of substrate specificity within the NPP family.

DATABASE

Structural data are available in the Protein Data Bank under the accession numbers 5VEM, 5VEN, and 5VEO.

Persistent Unresolved Inflammation in the Mecp2-308 Female Mutated Mouse Model of Rett Syndrome

Rett syndrome (RTT) is a rare neurodevelopmental disorder usually caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). Several Mecp2 mutant mouse lines have been developed recapitulating part of the clinical features. In particular, Mecp2-308 female heterozygous mice, bearing a truncating mutation, are a validated model of the disease. While recent data suggest a role for inflammation in RTT, little information on the inflammatory status in murine models of the disease is available. Here, we investigated the inflammatory status by proteomic 2-DE/MALDI-ToF/ToF analyses in symptomatic Mecp2-308 female mice. Ten differentially expressed proteins were evidenced in the Mecp2-308 mutated plasma proteome. In particular, 5 positive acute-phase response (APR) proteins increased (i.e., kininogen-1, alpha-fetoprotein, mannose-binding protein C, alpha-1-antitrypsin, and alpha-2-macroglobulin), and 3 negative APR reactants were decreased (i.e., serotransferrin, albumin, and apolipoprotein A1). CD5 antigen-like and vitamin D-binding protein, two proteins strictly related to inflammation, were also changed. These results indicate for the first time a persistent unresolved inflammation of unknown origin in the Mecp2-308 mouse model.