Identification of the Interactors of Human Nibrin (NBN) and of Its 26 kDa and 70 kDa Fragments Arising from the NBN 657del5 Founder Mutation

Nibrin (also named NBN or NBS1) is a component of the MRE11/RAD50/NBN complex, which is involved in early steps of DNA double strand breaks sensing and repair. Mutations within the NBN gene are responsible for the Nijmegen breakage syndrome (NBS). The 90% of NBS patients are homozygous for the 657del5 mutation, which determines the synthesis of two truncated proteins of 26 kDa (p26) and 70 kDa (p70). Here, HEK293 cells have been exploited to transiently express either the full-length NBN protein or the p26 or p70 fragments, followed by affinity chromatography enrichment of the eluates. The application of an unsupervised proteomics approach, based upon SDS-PAGE separation and shotgun digestion of protein bands followed by MS/MS protein identification, indicates the occurrence of previously unreported protein interacting partners of the full-length NBN protein and the p26 fragment containing the FHA/BRCT1 domains, especially after cell irradiation. In particular, results obtained shed light on new possible roles of NBN and of the p26 fragment in ROS scavenging, in the DNA damage response, and in protein folding and degradation. In particular, here we show that p26 interacts with PARP1 after irradiation, and this interaction exerts an inhibitory effect on PARP1 activity as measured by NAD⁺ levels. Furthermore, the p26-PARP1 interaction seems to be responsible for the persistence of ROS, and in turn of DSBs, at 24 h from IR. Since some of the newly identified interactors of the p26 and p70 fragments have not been found to interact with the full-length NBN, these interactions may somehow contribute to the key biological phenomena underpinning NBS.     

CH(3)ReO(3)-catalyzed oxidation of cholesta-5,7-dien-3beta-yl acetate with the urea-hydrogen peroxide adduct under various conditions. Synthesis of the natural epoxy sterol 9alpha,11alpha-epoxy-5alpha-cholest-7-en-3beta,5,6beta-triol

This article describes the oxidation of cholesta-5,7-dien-3beta-yl acetate (4) with the urea-hydrogen peroxide adduct (UHP) using methyltrioxorhenium (MTO) as catalyst, under various conditions. Specifically, the effects of using different solvents (CHCl(3) and ethers) and additives (EtOH and pyridine) on the course of the MTO-catalyzed oxidation of 4 were investigated. Some new steroids (6, 9, 10 and 11), obtained from this oxidation, were isolated and characterized on the basis of chemical evidence and interpretation of spectroscopic data including H-H COSY and HMBC experiments. The optimal solvent for the oxidation of 4 with MTO/UHP oxidizing system was diethyl ether. In this solvent the reaction is clean and gave as the main product 5,6beta-dihydroxy-5alpha-cholest-7-en-3beta-yl acetate (8, 65% yield), obtained with a more simple procedure and with a higher yield than that reported in literature. Sterol 8 is a key intermediate compound in the synthesis of many steroids of marine origin, biologically active, oxygenated at the B/C rings. In fact, starting from diol 8, we performed the synthesis of the natural cytotoxic epoxy sterol 9alpha,11alpha-epoxy-5alpha-cholest-7-en-3beta,5,6beta-triol (15, 21% yield) with an improvement in yield and number of steps over a synthesis of the same natural product previously reported. When the oxidation of 4 with the MTO/UHP system in diethyl ether was performed in the presence of pyridine as ligand, the unsaturated epoxide 5,6alpha-epoxy-5alpha-cholest-7-en-3beta-yl acetate (10, 90% yield) was obtained after only 5 min in good yield. In fact, pyridine, besides having beneficial effect on the reaction rate, shuts down the ring opening reactions, as reported in literature.     

RNA editing by ADARs is important for normal behavior in Caenorhabditis elegans

Here we take advantage of the well-characterized and simple nervous system of Caenorhabditis elegans to further our understanding of the functions of RNA editing. We describe the two C.elegans ADAR genes, adr-1 and adr-2, and characterize strains containing homozygous deletions in each, or both, of these genes. We find that adr-1 is expressed in most, if not all, cells of the C.elegans nervous system and also in the developing vulva. Using chemotaxis assays, we show that both ADARs are important for normal behavior. Biochemical, molecular and phenotypic analyses indicate that ADR-1 and ADR-2 have distinct roles in C.elegans, but sometimes act together.     

Protective effects of anthocyanins from blackberry in a rat model of acute lung inflammation

Anthocyanins are a group of naturally occuring phenolic compounds related to the coloring of plants, flowers and fruits. These pigments are important as quality indicators, as chemotaxonomic markers and for their antioxidant activities. Here, we have investigated the therapeutic efficacy of anthocyanins contained in blackberry extract (cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents) in an experimental model of lung inflammation induced by carrageenan in rats. Injection of carrageenan into the pleural cavity elicited an acute inflammatory response characterized by fluid accumulation which contained a large number of neutrophils as well as an infiltration of polymorphonuclear leukocytes in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NOx) and prostaglandin E

2

(PGE

2

). All parameters of inflammation were attenuated in a dose-dependent manner by anthocyanins (10, 30 mg kg

-1

30 min before carrageenan). Furthermore, carrageenan induced an upregulation of the adhesion molecule ICAM-1, nitrotyrosine and poly (ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining was lowered by anthocyanins treatment. Thus, the anthocyanins contained in the blackberry extract exert multiple protective effects in carrageenan-induced pleurisy.     

Efficacy of treatment with glycosaminoglycans on experimental collagen-induced arthritis in rats

To evaluate the antioxidant activity of the glycosaminoglycans hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S), we used a rat model of collagen-induced arthritis (CIA). Arthritis was induced in Lewis rats by multiple intradermal injections of 250 μl of emulsion containing bovine type II collagen in complete Freund's adjuvant at the base of the tail and into three to five other sites on the back. Rats were challenged again with the same antigen preparation 7 days later. Disease developed about 11 days after the second immunization. The effects of treatment in the rats were monitored by biochemical parameters and by macroscopic and histological evaluations in blood, synovial tissue and articular cartilage. Arthritis produced the following symptoms: severe periarticular erythema, edema and inflammation in the hindpaws; membrane peroxidation in the cartilage of the joints; endogenous antioxidant wasting; high tumour necrosis factor-α (TNF-α) plasma levels; and synovial neutrophil accumulation. Treatment with HYA and C4S, starting at the onset of arthritis for 10 days, limited the erosive action of the disease in the articular joints of knee and paw, reduced lipid peroxidation, restored the endogenous antioxidants reduced glutathione (GSH) and superoxide dismutase, decreased plasma TNF-α levels, and limited synovial neutrophil infiltration. These data confirm that erosive destruction of the joint cartilage in CIA is due at least in part to free radicals released by activated neutrophils and produced by other biochemical pathways. The beneficial effects obtained with the treatment suggest that HYA and C4S could be considered natural endogenous macromolecules to limit erosive damage in CIA or as a useful tool with which to study the involvement of free radicals in rheumatoid arthritis.     

A dual role for Integrin α6β4 in modulating hereditary neuropathy with liability to pressure palsies

Peripheral myelin protein 22 (PMP 22) is a component of compact myelin in the peripheral nervous system. The amount of PMP 22 in myelin is tightly regulated, and PMP 22 over or under‐expression cause Charcot‐Marie‐Tooth 1A (CMT 1A) and Hereditary Neuropathy with Pressure Palsies (HNPP ). Despite the importance of PMP 22 , its function remains largely unknown. It was reported that PMP 22 interacts with the β4 subunit of the laminin receptor α6β4 integrin, suggesting that α6β4 integrin and laminins may contribute to the pathogenesis of CMT 1A or HNPP . Here we asked if the lack of α6β4 integrin in Schwann cells influences myelin stability in the HNPP mouse model. Our data indicate that PMP 22 and β4 integrin may not interact directly in myelinating Schwann cells, however, ablating β4 integrin delays the formation of tomacula, a characteristic feature of HNPP . In contrast, ablation of integrin β4 worsens nerve conduction velocities and non‐compact myelin organization in HNPP animals. This study demonstrates that indirect interactions between an extracellular matrix receptor and a myelin protein influence the stability and function of myelinated fibers.

     

Propylthiouracil prevents cutaneous and pulmonary fibrosis in the reactive oxygen species murine model of systemic sclerosis

Introduction

Recent advances suggest that the cellular redox state may play a significant role in the progression of fibrosis in systemic sclerosis (SSc). Another, and as yet poorly accounted for, feature of SSc is its overlap with thyroid abnormalities. Previous reports demonstrate that hypothyroidism reduces oxidant stress. The aim of this study was therefore to evaluate the effect of propylthiouracil (PTU), and of the hypothyroidism induced by it, on the development of cutaneous and pulmonary fibrosis in the oxidant stress murine model of SSc.

Methods

Chronic oxidant stress SSc was induced in BALB/c mice by daily subcutaneous injections of hypochlorous acid (HOCl) for 6 weeks. Mice (n = 25) were randomized into three arms: HOCl (n = 10), HOCl plus PTU (n = 10) or vehicle alone (n = 5). PTU administration was initiated 30 minutes after HOCl subcutaneous injection and continued daily for 6 weeks. Skin and lung fibrosis were evaluated by histologic methods. Immunohistochemical staining for alpha-smooth muscle actin (α-SMA) in cutaneous and pulmonary tissues was performed to evaluate myofibroblast differentiation. Lung and skin concentrations of vascular endothelial growth factor (VEGF), extracellular signal-related kinase (ERK), rat sarcoma protein (Ras), Ras homolog gene family (Rho), and transforming growth factor (TGF) β were analyzed by Western blot.

Results

Injections of HOCl induced cutaneous and lung fibrosis in BALB/c mice. PTU treatment prevented both dermal and pulmonary fibrosis. Myofibroblast differentiation was also inhibited by PTU in the skin and lung. The increase in cutaneous and pulmonary expression of VEGF, ERK, Ras, and Rho in mice treated with HOCl was significantly prevented in mice co-administered ////with PTU.

Conclusions

PTU, probably through its direct effect on reactive oxygen species or indirectly through thyroid function inhibition, prevents the development of cutaneous and pulmonary fibrosis by blocking the activation of the Ras-ERK pathway in the oxidant-stress animal model of SSc.     

Synthesis of a thymine-functionalized nucleoamino acid for the solid phase assembly of cationic nucleopeptides

In this work, we report the synthesis of a thymine-functionalized nucleoamino acid suitable for the solid phase synthesis of nucleopeptides. The monomer was obtained in solution starting from commercial compounds and after NMR (¹H and ¹³C) and ESIMS (positive ions) characterization it was used for the assembly of a cationic nucleopeptide obtained by sequentially introducing underivatized l-lysine units and nucleoamino acid monomers. After detachment from the resin, performed in acidic conditions, the oligomer was purified by HPLC and characterized by LC-ESIMS (positive ions) which confirmed the identity of the thymine-based nucleopeptide. The cationic nucleobase-containing peptide, well soluble in water, was studied by CD spectroscopy which allowed us to exclude any helical pre-organization of the nucleopeptide in the experimental conditions used. Furthermore, CD behavior of the oligomer at different temperatures was also studied as described in this work.