Peptidyl-prolyl cis-trans isomerase A participates in the selenium transport into the rat brain

Selenium, an essential micronutrient, plays vital roles in the brain. Selenoprotein P (SELENOP), a major plasma selenoprotein, is thought to transport selenium to the brain. However, Selenop-knockout mice fed a diet containing an adequate amount of selenium shows no objective neurological dysfunction which is observed in the selenium-deficient diet-fed Selenop-knockout mice. This fact indicated that selenium from low-mass selenium-source compounds can be transported by SELENOP-independent alternative pathways to the brain. In this study, to obtain the basic information about the SELENOP-independent transport pathways, we performed ex vivo experiments in which the rat brain cell membrane fraction was analyzed to find selenium-binding and/or -interactive proteins using its reactive metabolic intermediate, selenotrisulfide (STS), and MALDI TOF-mass spectrometry. Several membrane proteins with the cysteine (C) thiol were found to be reactive with STS through the thiol-exchange reaction. One of the C-containing proteins in the brain cell membrane fraction was identified as peptidyl-prolyl cis-trans isomerase (PPIase) A from tryptic fragmentation experiments and database search. Among the 4 C residues in rat PPIase A, 21st C was proved to react with STS by assessment using C mutated recombinant proteins. PPIase A is ubiquitously expressed and also associates with a variety of biologically important events such as immunomodulation, intracellular signaling, transcriptional regulation and protein trafficking. Consequently, PPIase A was thought to participate in the selenium transport into the rat brain.

iTRAQ-based proteomic analysis to identify molecular mechanisms of the selenium deficiency response in the Przewalski's gazelle

The Przewalski's gazelle shows long-term survival in a selenium (Se)-deficient environment, but fails to exhibit obvious pathological manifestations. To reveal proteomic changes in the Przewalski's gazelle in response to Se-deficiency, twenty Przewalski's gazelle were randomly divided into control group and Se-deficient group. After induction of Se-deficiency animal model, blood samples were collected from eight animals. An isobaric tag for relative and absolute quantitation (iTRAQ)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was employed to explore blood protein alterations and potential mechanisms of the response to Se-deficiency challenge. Se deficiency contributed to a remarkable change in blood Se levels and routine blood indexes. In proteomic analyses, 130 proteins were differentially accumulated in the Se-deficient and control groups. The differentially expressed proteins were annotated mainly as single-organism process, extracellular region, or binding, respectively, and they were highly enriched in the coagulation and complement cascades. Protein-protein interaction analysis showed several important nodal proteins involved in the regulation of binding, cellular biochemical processes, and signal transduction pathways. To our knowledge, this study is the first to comprehensively analyze blood protein changes in the Przewalski's gazelle under Se-deficient conditions, which reveal that this species has developed physiological mechanisms of adaptation in response to Se-deficiency stress. SIGNIFICANCE: The present study is the first to comprehensively analyze alterations in the protein profiles induced by Se deficiency in the blood of the Przewalski's gazelle, showing that Se-deficiency contributed to a significant reduction in blood Se levels and marked changes in blood parameters, which will likely contribute to a better understanding of the molecular mechanisms of the changes in protein abundance in the Przewalski's gazelle in response to Se-deficiency stress.

Sulforaphane-conjugated selenium nanoparticles: towards a synergistic anticancer effect

Sulforaphane-modified selenium nanoparticles can be prepared in a simple aqueous-phase redox reaction through reduction of selenite with ascorbic acid. The sulforaphane molecules present in the reaction mixture adsorb on the nanoparticle surface, forming an adlayer. The resulting conjugate was examined with several physicochemical techniques, including microscopy, spectroscopy, x-ray diffraction, dynamic light scattering and zeta potential measurements. As shown in in vivo investigations on rats, the nanomaterial administered intraperitoneally is eliminated mainly in urine (and, to a lesser extent, in feces); however, it is also retained in the body. The modified nanoparticles mainly accumulate in the liver, but the basic parameters of blood and urine remain within normal limits. The sulforaphane-conjugated nanoparticles reveal considerable anticancer action, as demonstrated on several cancer cell cultures in vitro. This finding is due to the synergistic effect of elemental selenium and sulforaphane molecules assembled in one nanostructure (conjugate). On the other hand, the cytotoxic action on normal cells is relatively low. The high antitumor activity and selectivity of the conjugate with respect to diseased and healthy cells is extremely promising from the point of view of cancer treatment.

Serum levels of Selenium and C-reactive protein in comatose patients with severe traumatic brain injury during the first week of hospitalization: case-control study

Introduction

Mortality and morbidity related to traumatic brain injuries still remain high in patients. Many authors reported the importance of Selenium in maintaining the integrity of brain functions. This fact is supported by clinical evidence that therapy with selenium supplementation could help patients suffering from brain disorders like neurodegenerative diseases. The aim of our study was to assess the relationship between Selenium concentration in serum and evolution of comatose patients with severe traumatic brain injury, in the first week of admission, and the correlation between selenium and C-reactive protein.

Methods

This case-control study was conducted with 64 comatose patients with TBI, in the Department of Anesthesiology and Reanimation, IbnSina University Hospital and Hospital of specialties in Rabat-Morocco, and healthy volunteers recruited in Blood transfusion center of Rabat. Blood sampling was collected from TBI patients, in the first week (3h after admission and each 48h during one week), and from healthy volunteers one time. Concentration of Se in serum was determined by electrochemical atomic absorption spectrometry. Statistical analysis was performed using Statistical software (SPSS) and the cases and controls were compared using the Mann-Whitney U test. A P-value < 0.05 was considered to be statistically significant.

Results

Comparison selenium concentration in the first day (D0), third day (D2) and fifth day according to the death and survival statue in patients did not show statistical significance (p > 0.05). Selenium concentration of D0 in patients and Selenium concentration in control group also did not show statistical significance (p > 0.05). Similarly, we did not report a correlation between selenium and C-reactive protein.

Conclusion

According to our data selenium and CRP may not play a role in progression of coma state in patients with severe traumatic brain injury.

Selenoprotein L-inspired nano-vesicular peroxidase mimics based on amphiphilic diselenides

In this study, we developed selenoprotein L-inspired nano-vesicular peroxidase mimics based on amphiphilic diselenides. Selenocystine (SeCyst) was used as the starting material for the synthesis of four liposomal membrane-compatible diselenide derivatives (R-Se-Se-R') with two hydrophobic tails and a polar part. The diselenide derivatives were successfully incorporated into the phosphatidylcholine (PC)-based nano-vesicular scaffold. The results of the particle diameter and zeta-potential measurements suggested that the functional diselenide moiety was placed around the outer surface, not in the hydrophobic interior, of the liposomal membrane structures. The GPx-like catalytic activity of the diselenide/PC liposomes was determined by the conventional NADPH method using glutathione as the reducing substrate. For three peroxide substrates, i.e., hydrogen peroxide, organic tert-butyl hydroperoxide and cummen hydroperoxide, the cationic property-possessing diselenide derivatives in the PC-based liposomes resulted in a higher catalytic activity in comparison to electrically neutral and anionic derivatives. Overall, the diselenide derivatives at the surface of a liposomal colloidal scaffold could exert a GPx-like catalytic activity in physiological aqueous media.

Synthesis of Nanovesicular Glutathione Peroxidase Mimics with a Selenenylsulfide-Bearing Lipid

In this article, we describe the development of a nanosized-glutathione peroxidase (GPx) mimic based on liposomes of which the amphiphilic selenenylsulfide derivative (R-Se-S-R') was incorporated into a lipid membrane. A lipid membrane-compatible selenenylsulfide derivative, 1-oxo-headecyl-seleno-l-cysteine-methyl-Se-yl-S-l-penicillamine methyl ester (OHSeP), was synthesized. X-ray photoelectron spectroscopy revealed that the sulfur and selenium atoms of the OHSeP molecule formed a selenenylsulfide linkage. The use of OHSeP easily allowed the introduction of the seleno-l-cysteine (SeCys) moiety into the liposomal membranes by mixing with the phosphatidylcholines (PCs), which gave rise to the GPx-like catalytic activity because of the selenium atom in the SeCys moiety. The penicillamine moiety of the OHSeP molecule incorporated into the OHSeP/PC liposomes was thought to orient toward the outer water phase. The OHSeP/PC liposomes generated the GPx-like catalytic activity, which was ascribed to the SeCys moiety that was introduced into the PC-based liposomes. Consequently, the lipid/water interface of the liposomal membranes could possibly provide an effective colloidal platform for the development of water-soluble nanosized GPx mimics.