Transcription factor p53 exhibits increased binding to the A2-macroglobulin gene promoter and decreased glycosylation in fetal and adult rat liver during the acute-phase response

The binding affinity of p53 for the MG promoter was assessed by DNA-affinity chromatography with the extended α2-macroglobulin (MG) gene promoter (-852/+12) and immunoblot analysis. During the increased MG gene transcription observed in the fetus and the acute-phase (AP) response in both the fetus and the adult, p53 exhibited increased binding to the MG promoter. This increase was accompanied by decreased O-linked N-acetyl glucosamine glycosylation of p53. We suggest that the enzymatic removal of sugar moieties in vivo serves to activate the MG gene promoter binding potential of p53 and its participation in upregulated MG gene transcription.DNK afinitetna hromatografija, sa promotorskim regionom gena za alfa2-makroglobulin (MG) (-852/+12), i imunoblot analiza su pokazale povećan afinitet vezivanja p53 za promotorski region gena za MG u kontrolnoj jetri fetusa, kao i ulogup53 u transkripcionoj regulaciji gena za MG i u fetalnoj i adultnoj jetri tokom akutno-faznog odgovora (AFO). Povećanje vezivanja p53 za promotorski region gena za MG je praćeno smanjenjem stepena glikozilacije p53. Rezultati sugerišu da u in vivo uslovima uklanjanje šećernih ostataka sa p53 omogućava njegovo vezivanje za promotorski region MG gena, kao i ulogu u transkripcionoj aktivaciji ispitivanog gena tokom AFO.Projekat ministarstva br. 143002

Assesment of the fatigue behavior of repaired aluminium carbody structure

Aluminum carbody structures vs. steel structures have an increasing share in rail vehicle passenger fleet. New trams for Belgrade city transport with aluminum carbody structure after approximately three years of service, suffered from cracks. The first repair made by manufacturer was only partially successful. Two years after repair some cracks reappeared. This paper deals with some specificity of the aluminum structures repair process. The issue of the aluminum structures fatigue is compared with the fatigue of common carbody steel structures. Stress measurements in the repaired welding zone after second repair and reinforcement are presented. The test was performed with fully loaded tram under typical service conditions. Assessment of the future fatigue behavior is made based on the analysis of measured data

Dynamic associations of transcription factors with the rat liver nuclear matrix are functionally related to differential alpha-2-macroglobulin gene expression

Participation of the nuclear matrix in regulation of alpha-2-macroglobulin (α2M) gene transcription during rat liver development and the acute-phase (AP) response are examined. DNA affinity chromatography of fetal and adult liver internal nuclear matrix proteins under basal and AP conditions with the α2M gene promoter (-852/+12) and immunoblot analysis revealed diverse patterns of association of transcription factors with the nuclear matrix. HNF-6, C/EBPα, and STAT5b were involved in basal and C/EBPβ, STAT1, and STAT3 in AP-stimulated α2M expression. These findings support the assumption that transcription factor-nuclear matrix interactions serve to channel gene regulatory proteins to DNA sequences.Cilj rada je ispitivanje učešća jedarnog matriksa u regulaciji transkripcije gena za alfa-2-makroglobulin tokom razvića jetre pacova i akutno faznog odgovora (AFO). Nakon DNK afinitetne hromatografije proteina unutrašnje mreže jedarnog matriksa fetalne i adultne jetre, u bazalnim i AFO uslovima, sa promotorskim elementom gena za α2M (-852/+12) i imunoblot analize, identifikovane su dinamičke asocijacije transkripcionih faktora uključenih u regulaciju ekspresije gena za α2M sa jedarnim matriksom. HNF-6, C/EBPα, STAT5b su uključeni u regulaciju bazalne ekspresije gena za α2M, dok C/EBPβ, STAT1, STAT3 posreduju u regulaciji ekspresije ovog gena tokom AFO. Opisane interakcije doprinose razumevanju predloženih mehanizama kojima se transkripcioni faktori usmeravaju ka ciljnim regulatornim elementima DNK.Projekat ministarstva br. 143002

Ameliorating effects of antioxidative compounds from four plant extracts in experimental models of diabetes

Given that oxidative stress plays a major role in pancreatic β-cell dysfunction and ultimate destruction, as well as in different complications of diabetes, therapy with antioxidants has assumed an important place in the management of diabetes. The relatively limited effects of established antioxidant compounds have stimulated efforts to develop new therapeutic strategies, e.g. to increase the endogenous antioxidant defences through pharmacological modulation of key antioxidant enzymes. Plant extracts are gaining popularity in treating diabetes because many substances synthesized by higher plants and fungi possess antioxidant activities and can prevent or protect tissues against the damaging effects of free radicals. This review summarizes experimental models of diabetes and possible mechanisms that lie behind the antioxidative effects of α-lipoic acid (LA), a powerful antioxidant and compound that stimulates cellular glucose uptake, as well as of plant extracts from sweet chestnut (Castanea sativa), edible mushroom (Lactarius deterrimus) and natural products containing β-glucans in the treatment of diabetes. Their roles in preventing pancreatic β-cell death and in ameliorating the effects of severe diabetic complications are discussed.Terapija antioksidansima zauzima značajno mesto u lečenju dijabetesa s obzirom da oksidativni stres u velikoj meri doprinosi narušavanju funkcije i strukture β-ćelija pankreasa kao i razvoju komplikacija u dijabetesu. Zbog ograničenog dejstva postojećih antioksidativnih jedinjenja traga se za novim terapijskim rešenjima u tretmanu dijabetesa, kao što je povećanje endogene antioksidativne zaštite organizma putem farmakološke modulacije ključnih antioksidativnih enzima. Primena biljnih ekstrakata u lečenju dijabetesa postaje sve popularnija. Mnoge supstance koje se nalaze u sastavu viših biljaka i gljiva poseduju antioksidativna svojstva koja mogu da zaštite tkiva od štetnih uticaja slobodnih radikala. U ovom revijalnom radu opisani su eksperimentalni modeli dijabetesa kao i mogući mehanizmi koji leže u osnovi antioksidativnog dejstva α-liponske kiseline (LA), snažnog antioksidansa i jedinjenja koje stimuliše ćelijsku apsorpciju glukoze, kao i biljnih ekstrakata izolovanih iz slatkog kestena (Castanea sativa), jestivih pečuraka (Lactarius deterrimus) i prirodnih proizvoda koji sadrže β-glukan u lečenju dijabetesa. Opisani su njihova uloga u sprečavanju smrti β-ćelija pankreasa kao i blagotvorno dejstvo na komplikacije u dijabetesu.Projekat ministarstva br. 17302

PARP-1 and YY1 Are Important Novel Regulators of CXCL12 Gene Transcription in Rat Pancreatic Beta Cells

Despite significant progress, the molecular mechanisms responsible for pancreatic beta cell depletion and development of diabetes remain poorly defined. At present, there is no preventive measure against diabetes. The positive impact of CXCL12 expression on the pancreatic beta cell prosurvival phenotype initiated this study. Our aim was to provide novel insight into the regulation of rat CXCL12 gene (Cxcl12) transcription. The roles of poly(ADP-ribose) polymerase-1 (PARP-1) and transcription factor Yin Yang 1 (YY1) in Cxcl12 transcription were studied by examining their in vitro and in vivo binding affinities for the Cxcl12 promoter in a pancreatic beta cell line by the electrophoretic mobility shift assay and chromatin immunoprecipitation. The regulatory activities of PARP-1 and YY1 were assessed in transfection experiments using a reporter vector with a Cxcl12 promoter sequence driving luciferase gene expression. Experimental evidence for PARP-1 and YY1 revealed their trans-acting potential, wherein PARP-1 displayed an inhibitory, and YY1 a strong activating effect on Cxcl12 transcription. Streptozotocin (STZ)-induced general toxicity in pancreatic beta cells was followed by changes in Cxcl12 promoter regulation. PARP-1 binding to the Cxcl12 promoter during basal and in STZ-compromised conditions led us to conclude that PARP-1 regulates constitutive Cxcl12 expression. During the early stage of oxidative stress, YY1 exhibited less affinity toward the Cxcl12 promoter while PARP-1 displayed strong binding. These interactions were accompanied by Cxcl12 downregulation. In the later stages of oxidative stress and intensive pancreatic beta cell injury, YY1 was highly expressed and firmly bound to Cxcl12 promoter in contrast to PARP-1. These interactions resulted in higher Cxcl12 expression. The observed ability of PARP-1 to downregulate, and of YY1 to upregulate Cxcl12 promoter activity anticipates corresponding effects in the natural context where the functional interplay of these proteins could finely balance Cxcl12 transcription

Lymphocytes' 'Last Stand' on the Nuclear Matrix After Whole Body Exposure of Rats To Low-Let Ionizing Radiation

We examined the functions of the rat lymphocyte nuclear matrix after a single exposure to total body irradiation with doses ranging from sublethal to lethal. Irradiation induced systemic oxidative stress, detected as increased activities of serum SOD and catalase, lymphocyte DNA damage, detected by the Comet assay, and apoptosis. After irradiation with lower doses, the recruitment of DNA repair centers on the matrix was observed by Western analysis as increased levels of matrix-associated PARP-1, p53 and PCNA. Augmented partitioning of the pro-survival transcription factor NF-κB on the matrix was also detected after irradiation. Exposure to a lethal dose caused breakdown of the matrix, observed as lamin B cleavage, and of the matrix-associated DNA repair centers, detected as caspase-mediated PARP-1 proteolysis and loss of protein associations with the matrix. These findings suggest that the nuclear matrix establishes functional 2 interactions in a defensive mechanism, integrated in a decision-making process that resolves cell fat

Treatment of streptozotocin-induced diabetic rats with Castanea sativa and Lactarius deterrimus extracts decreases liver damage by initiating activation of the Akt prosurvival kinase

Diabetes is the most important non-infectious disease affecting 5% of the general population. Different plant and mushroom extracts with hypoglycemic and antioxidant properties have been used traditionally as antidiabetic herbal medicines. The aim of this study was to study the in vivo effect of extracts obtained from the edible mushroom, Lactarius deterrimus (Ld), and chestnut, Castanea sativa (Cs), on the alleviation of liver damage in streptozotocin (STZ)-induced diabetic rats. The extracts were applied, either alone or in combination, for four weeks, starting from the last day of STZ administration. Diabetic rats treated with the extracts exhibited reduced hyperglycemia and lower hepatic oxidative stress. Extract treatment decreased the level of O-linkage of N-acetylglucosamine modified superoxide dismutase, catalase and NF-κB. Masson trichrome staining showed a decrease in collagen fiber deposition in the liver. Immunoblot analysis revealed the activation of the prosurvival Akt kinase after extract application. The obtained results revealed that the hyperglycemia-reducing and antioxidant effects of the Ld and Cs extracts suppressed cytotoxic signaling pathways, attenuating the negative effects of diabetes on the liver. The examined extracts are beneficial in the prevention of liver damage and could be considered for prediabetes and diabetes management after a definitive phytochemical description of extract constituents and subsequent evaluation in preclinical and clinical studies

CXC Chemokine Ligand 12 Protects Pancreatic β-Cells from Necrosis through Akt Kinase-Mediated Modulation of Poly(ADP-ribose) Polymerase-1 Activity

The diabetes prevention paradigm envisages the application of strategies that support the maintenance of appropriate β-cell numbers. Herein we show that overexpression of CXC chemokine ligand12 (CXCL12) considerably improves the viability of isolated rat Langerhans islet cells and Rin-5F pancreatic β-cells after hydrogen peroxide treatment. In rat islets and wt cells hydrogen peroxide treatment induced necrotic cell death that was mediated by the rapid and extensive activation of poly(ADP-ribose) polymerase-1 (PARP-1). In contrast, CXCL12-overexpressing cells were protected from necrotic cell death as a result of significantly reduced PARP-1 activity. CXCL12 downstream signalling through Akt kinase was responsible for the reduction of PARP-1 activity which switched cell death from necrosis to apoptosis, providing increased protection to cells from oxidative stress. Our results offer a novel aspect of the CXCL12-mediated improvement of β-cell viability which is based on its antinecrotic action through modulation of PARP-1 activity

Beneficial effects of α-lipoic acid in diabetes- and drug- induced liver injury

This review summarizes the effects of α-lipoic acid (LA) on liver damage and complications in diabetes and drug toxicity. LA is a naturally occurring dithiol compound that plays an essential role in mitochondrial metabolism in its protein-bound form. In contrast, free LA in supplements has diverse biological actions, and its antioxidant effect is its most studied and important activity. Due to its strong antioxidant potential, LA could have a promising role in the treatment of pathologies resulting from an imbalance in redox homeostasis. This includes diabetes, which produces deleterious effects on many organs, including the liver. In diabetes specifically, LA prevents β-cell destruction, enhances glucose uptake, and its antioxidant effects may be particularly useful in slowing down the development of diabetic complications. Diabetes-related liver damage is a serious complication in which oxidative stress is the main contributor to tissue injury. Oxidative stress is regarded as one of the main pathological mechanisms underlying liver pathologies provoked by other insults, such as drug toxicity, where LA could also be a useful agent in therapeutic intervention. However, before wider application of LA in a clinical setting, experimental and clinical research needs to be extended

Water–Rock Interactions across Volcanic Aquifers of the Lece Andesite Complex (Southern Serbia): Geochemistry and Environmental Impact

The study of aquifers of the Lece andesite complex (LAC) and its surroundings yielded a new procedural stepwise analysis that allowed the assessment of the origin of elements, particularly in areas affected by both anthropogenic and natural influences. The methodology uses the mineralogical composition of the rocks, including the elements available in rocks and groundwater. This study analyzes the element ratios B/Cl−, Na+/Ca2+, Ca2+/Mg2+, HCO3−/Cl−, and Na+/Na+ + Cl−; the correlations are coupled with a statistical analysis. In addition to reevaluating the already published water content, we provide an important new dataset. The results show that the main source of the water contamination with the elements B, F, U, As, Cu, Fe, Zn, Co, and Ni is the processes occurring at the contact between the groundwaters and non-altered/altered (propylitized) andesite rocks. This is also observed in the waters extracted from crystalline schists. The results may help develop an efficient use and assessment of the qualitative water potential of the LAC reservoirs. Similarly, the results highlight the applicability of the groundwaters, facilitating their regional research and use, further encouraging new initiatives for the preservation and protection of human and animal health