Publications by authors named "Mariangela Sebastiani"

7 Publications

  • Page 1 of 1

Enhanced ROS production by NADPH oxidase is correlated to changes in antioxidant enzyme activity in human heart failure.

Biochim Biophys Acta 2010 Mar 3;1802(3):331-8. Epub 2009 Nov 3.

Department of Biochemical Sciences, University of Florence, Viale Morgagni, 50, 50134 Florence, Italy.

In pathological conditions, the balance between reactive oxygen species (ROS) and antioxidants may shift toward a relative increase of ROS, resulting in oxidative stress. Conflicting data are available on antioxidant defenses in human failing heart and they are limited to the left ventricle. Thus, we aimed to investigate and compare the source of oxidant and antioxidant enzyme activities in the right (RV) and left (LV) ventricles of human failing hearts. We found a significant increase in superoxide production only by NADPH oxidase in both failing ventricles, more marked in RV. Despite unchanged mRNA or protein expression, catalase (CAT) and glutathione peroxidase (GPx) activities were increased, and their increases reflected the levels of Tyr phosphorylation of the respective enzyme. Manganese superoxide dismutase (Mn-SOD) activity appeared unchanged. The increase in NADPH oxidase-dependent superoxide production positively correlated with the activation of both CAT and GPx. However, the slope of the linear correlation (m) was steeper in LV than in RV for GPx (LV: m=2.416; RV: m=1.485) and CAT (LV: m=1.007; RV: m=0.354). Accordingly, malondialdehyde levels, an indirect index of oxidative stress, were significantly higher in the RV than LV. We conclude that in human failing RV and LV, oxidative stress is associated with activation of antioxidant enzyme activity. This activation is likely due to post-translational modifications and more evident in LV. Overall, these findings suggest a reduced protection of RV against oxidative stress and its potential contribution to the progression toward overt heart failure.
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http://dx.doi.org/10.1016/j.bbadis.2009.10.014DOI Listing
March 2010

Gastrointestinal dysmotility in mitochondrial neurogastrointestinal encephalomyopathy is caused by mitochondrial DNA depletion.

Am J Pathol 2008 Oct 11;173(4):1120-8. Epub 2008 Sep 11.

Dipartimento di Medicina Sperimentale, Sapienza, Università di Roma, Roma, Italy.

Chronic intestinal pseudo-obstruction is a life-threatening condition of unknown pathogenic mechanisms. Chronic intestinal pseudo-obstruction can be a feature of mitochondrial disorders, such as mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), a rare autosomal-recessive syndrome, resulting from mutations in the thymidine phosphorylase gene. MNGIE patients show elevated circulating levels of thymidine and deoxyuridine, and accumulate somatic mitochondrial DNA (mtDNA) defects. The present study aimed to clarify the molecular basis of chronic intestinal pseudo-obstruction in MNGIE. Using laser capture microdissection, we correlated the histopathological features with mtDNA defects in different tissues from the gastrointestinal wall of five MNGIE and ten control patients. We found mtDNA depletion, mitochondrial proliferation, and smooth cell atrophy in the external layer of the muscularis propria, in the stomach and in the small intestine of MNGIE patients. In controls, the lowest amounts of mtDNA were present at the same sites, as compared with other layers of the gastrointestinal wall. We also observed mitochondrial proliferation and mtDNA depletion in small vessel endothelial and smooth muscle cells. Thus, visceral mitochondrial myopathy likely causes gastrointestinal dysmotility in MNGIE patients. The low baseline abundance of mtDNA molecules may predispose smooth muscle cells of the muscularis propria external layer to the toxic effects of thymidine and deoxyuridine, and exposure to high circulating levels of nucleosides may account for the mtDNA depletion observed in the small vessel wall.
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http://dx.doi.org/10.2353/ajpath.2008.080252DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2543079PMC
October 2008

OPG and RANKL mRNA and protein expressions in the primary and secondary metaphyseal trabecular bone of PTH-treated rats are independent of that of SOST.

J Mol Histol 2008 Apr 20;39(2):237-42. Epub 2007 Dec 20.

Dipartimento di Medicina Sperimentale, Sezione di Anatomia Patologica, "Sapienza" University of Rome, Azienda Policlinico Umberto I, Viale Regina Elena, 324, Roma, 00161, Italy.

Sclerostin, encoded by the SOST gene, is a recently identified protein which seems to affect bone remodeling by inhibiting bone formation via Wnt pathways. A previous study on OPG and RANKL, two cytokines involved in the control of osteoclastogenesis, showed that the anabolic effect produced by intermittent treatment with parathyroid hormone was characterized by an increase in OPG/RANKL mRNA ratio in the primary spongiosa of metaphyseal bone of rat femur, and by its falling in the secondary spongiosa, in comparison to controls (Silvestrini et al. (2007a)). Considering that Wnt pathway components seem to regulate osteoclast formation and bone resorption by repression of RANKL transcription and by positive regulation of OPG gene in osteoblastic cells, we have evaluated, in the same rats, whether and how SOST mRNA and protein in the primary and secondary metaphyseal bone are affected by PTH. SOST mRNA and protein significantly fell in both primary and secondary spongiosa where only a few osteocytes were positive to sclerostin. These data show that in the two metaphyseal areas no relationship does exist between the trends of OPG and RANKL mRNA and that of SOST, suggesting that there are no direct links between the effects induced by PTH on these molecules, at least in terms of gene expression.
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http://dx.doi.org/10.1007/s10735-007-9158-6DOI Listing
April 2008

Induction of mitochondrial biogenesis is a maladaptive mechanism in mitochondrial cardiomyopathies.

J Am Coll Cardiol 2007 Oct 17;50(14):1362-9. Epub 2007 Sep 17.

Dipartimento di Medicina Sperimentale, Polo Pontino, Sapienza, Università di Roma, Rome, Italy.

Objectives: The purpose of this study was to clarify the molecular mechanisms linking human mitochondrial deoxyribonucleic acid (mtDNA) dysfunction to cardiac remodeling.

Background: Defects of the mitochondrial genome cause a heterogeneous group of clinical disorders, including mitochondrial cardiomyopathies (MIC). The molecular events linking mtDNA defects to cardiac remodeling are unknown. Energy derangements and increase of mitochondrial-derived reactive oxygen species (ROS) could both play a role in the development of cardiac dysfunction in MIC. In addition, mitochondrial proliferation could interfere with sarcomere alignment and contraction.

Methods: We performed a detailed morphologic and molecular analysis on failing hearts from 3 patients with MIC, failing human hearts due to ischemic heart disease (IHD) or dilated cardiomyopathies (DCM), and nonfailing hearts.

Results: The MIC hearts showed marked mitochondrial proliferation with myofibril displacement. Consistent with morphologic features, increase in mtDNA content per cell and induction of genes involved in mitochondrial biogenesis, fatty acid metabolism, and glucose transport were observed. Down-regulation of these genes characterized DCM and IHD hearts. A pronounced increase in mitochondrial-derived ROS was observed in MIC hearts compared with failing hearts due to other causes. This was paralleled by up-regulation of genes encoding for uncoupling proteins and antioxidant enzymes. However, there was not a significant increase in antioxidant enzyme activity.

Conclusions: Our results suggest that besides energy deficiency, mitochondrial biogenesis per se is a maladaptive response in MIC and, possibly, in other metabolic cardiomyopathies.
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http://dx.doi.org/10.1016/j.jacc.2007.06.035DOI Listing
October 2007

Effects of the administration of corticosterone, parathyroid hormone, or both, and of their withdrawal, on rat bone and cartilage histomorphometric parameters, and on osteoprotegerin and RANKL mRNA expression and proteins.

J Mol Histol 2007 Jun 3;38(3):215-26. Epub 2007 May 3.

Dipartimento di Medicina Sperimentale, Sezione di Anatomia Patologica, Università degli Studi di Roma La Sapienza, Azienda Policlinico Umberto I, Viale Regina Elena, 324, 00161 Rome, Italy.

We have studied the effects of the treatment with corticosterone (CORT), parathyroid hormone (PTH), or both (CORT + PTH), and of their withdrawal (CORT-rec and CORT + PTH-rec), on the osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) localization and expression and on histomorphometric parameters in primary and secondary spongiosa of rat femur and tibia metaphyses. In the secondary spongiosa of the CORT group, the bone remodeling and the OPG/RANKL mRNA ratio decreased. In the PTH group, the bone turnover and the structural and connectivity indices increased, and the OPG/RANKL mRNA ratio fell; this ratio rose, however, in the primary spongiosa. In the CORT + PTH group, remodeling values intermediate between those of the CORT and PTH groups, were detected in the secondary spongiosa, where OPG and RANKL mRNA rose. Return towards control values was found in the recovery groups. The Cartilage Growth Plate Width was reduced in the CORT and CORT + PTH groups and returned to normal values in the recovery groups, while it was not affected by PTH. Independently of treatments, both OPG and RANKL mRNA and proteins were co-localized in the same cartilage and bone cells and in several bone marrow cells. In conclusion, the catabolic effects induced by CORT treatment occur together with an OPG fall and a RANKL rise. In the PTH group in which the bone turnover increase, the OPG and RANKL mRNA expressions differ in the primary and secondary spongiosa, confirming that the bone tissue in these sites can have different metabolic trends.
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http://dx.doi.org/10.1007/s10735-007-9090-9DOI Listing
June 2007

NADPH oxidase-dependent redox signaling in human heart failure: relationship between the left and right ventricle.

J Mol Cell Cardiol 2007 Apr 31;42(4):826-34. Epub 2007 Jan 31.

Department of Biochemical Sciences, University of Florence, Viale Morgagni, 50, 50134 Florence, Italy.

Oxidative stress resulting from increased superoxide generation by NADPH oxidase is implicated in the pathophysiology of human heart failure. Downstream targets of NADPH oxidase remain undefined and available information is restricted to the left ventricle (LV). Thus, we aimed to assess the cascade of events triggered by increased NADPH oxidase activity (lipid peroxidation and activation of mitogen-activated protein kinases ERK1/2, JNK and p38) and their mutual relationship in right (RV) and (LV) of end-stage failing human hearts. When compared to control ventricles, diseased RV and LV showed a significant increase in NADPH oxidase superoxide production that positively correlated with p47(phox) membrane translocation (RV: r=0.76, P<0.001; LV: r=0.79, P<0.001). MDA content, a marker of lipid peroxidation, was also enhanced and ERK and p38, but not JNK, were activated. For all these relevant steps of the oxidative stress pathway, a significant correlation was observed between LV and RV from the same heart (NADPH-dependent superoxide production: r=0.678, P<0.0055; MDA: r=0.95, P<0.0001; p-p38/p38 ratio: r=0.926, P<0.0001; p-ERK/ERK ratio: r=0.913, P<0.0001). We concluded that in human heart failure, both ventricles are targets of NADPH oxidase superoxide generation which in turn may trigger the coordinated activation of downstream signaling components. This pathway may contribute to adverse remodeling of the LV and RV and subsequent progression toward end-stage heart failure, suggestive of new therapeutic targeting strategy.
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http://dx.doi.org/10.1016/j.yjmcc.2007.01.009DOI Listing
April 2007

Mitochondrial neurogastrointestinal encephalomyopathy: evidence of mitochondrial DNA depletion in the small intestine.

Gastroenterology 2006 Mar;130(3):893-901

Dipartimento di Medicina Sperimentale e Patologia, Universita' di Roma La Sapienza, Rome, Italy.

Background & Aims: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease clinically defined by gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy, white-matter changes in brain magnetic resonance imaging, and mitochondrial abnormalities. Loss-of-function mutations in thymidine phosphorylase gene induce pathologic accumulations of thymidine and deoxyuridine that in turn cause mitochondrial DNA (mtDNA) defects (depletion, multiple deletions, and point mutations). Our study is aimed to define the molecular basis of gastrointestinal dysmotility in a case of MNGIE.

Methods: By using laser capture microdissection techniques, we correlated histologic features with mtDNA abnormalities in different tissue components of the gastrointestinal wall in a MNGIE patient and ten controls.

Results: The patient's small intestine showed marked atrophy and mitochondrial proliferation of the external layer of muscularis propria. Genetic analysis revealed selective depletion of mtDNA in the small intestine compared with esophagus, stomach, and colon, and microdissection analysis revealed that mtDNA depletion was confined to the external layer of muscularis propria. Multiple deletions were detected in the upper esophagus and skeletal muscle. Site-specific somatic point mutations were detected only at low abundance both in the muscle and nervous tissue of the gastrointestinal tract. Analysis of the gastrointestinal tract from 10 controls revealed a non-homogeneous distribution of mtDNA content; the small intestine had the lowest levels of mtDNA.

Conclusion: Atrophy, mitochondrial proliferation, and mtDNA depletion in the external layer of muscularis propria of small intestine indicate that visceral myopathy is responsible for gastrointestinal dysmotility in this MNGIE patient.
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http://dx.doi.org/10.1053/j.gastro.2006.01.004DOI Listing
March 2006