Publications by authors named "Claudia Colombrita"

34 Publications

Chronic stress induces formation of stress granules and pathological TDP-43 aggregates in human ALS fibroblasts and iPSC-motoneurons.

Neurobiol Dis 2020 11 20;145:105051. Epub 2020 Aug 20.

Istituto Auxologico Italiano, IRCCS, Department of Neurology-Stroke Unit and Laboratory of Neuroscience, Piazzale Brescia 20, 20149 Milan, Italy. Electronic address:

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative diseases characterized by the presence of neuropathological aggregates of phosphorylated TDP-43 (P-TDP-43) protein. The RNA-binding protein TDP-43 participates also to cell stress response by forming stress granules (SG) in the cytoplasm to temporarily arrest translation. The hypothesis that TDP-43 pathology directly arises from SG has been proposed but is still under debate because only sub-lethal stress conditions have been tested experimentally so far. In this study we reproduced a mild and chronic oxidative stress by sodium arsenite to better mimic the persistent and subtle alterations occurring during the neurodegenerative process in primary fibroblasts and induced pluripotent stem cell-derived motoneurons (iPSC-MN) from ALS patients carrying mutations in TARDBP and C9ORF72 genes. We found that not only the acute sub-lethal stress usually used in literature, but also the chronic oxidative insult was able to induce SG formation in both primary fibroblasts and iPSC-MN. We also observed the recruitment of TDP-43 into SG only upon chronic stress in association to the formation of distinct cytoplasmic P-TDP-43 aggregates and a significant increase of the autophagy marker p62. A quantitative analysis revealed differences in both the number of cells forming SG in mutant ALS and healthy control fibroblasts, suggesting a specific genetic contribution to cell stress response, and in SG size, suggesting a different composition of these cytoplasmic foci in the two stress conditions. Upon removal of arsenite, the recovery from chronic stress was complete for SG and P-TDP-43 aggregates at 72 h with the exception of p62, which was reduced but still persistent, supporting the hypothesis that autophagy impairment may drive pathological TDP-43 aggregates formation. The gene-specific differences observed in fibroblasts in response to oxidative stress were not present in iPSC-MN, which showed a similar formation of SG and P-TDP-43 aggregates regardless their genotype. Our results show that SG and P-TDP-43 aggregates may be recapitulated in patient-derived neuronal and non-neuronal cells exposed to prolonged oxidative stress, which may be therefore exploited to study TDP-43 pathology and to develop individualized therapeutic strategies for ALS/FTD.
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http://dx.doi.org/10.1016/j.nbd.2020.105051DOI Listing
November 2020

Reprogramming fibroblasts and peripheral blood cells from a C9ORF72 patient: A proof-of-principle study.

J Cell Mol Med 2020 04 3;24(7):4051-4060. Epub 2020 Mar 3.

Department of Neurology and Laboratory of Neuroscience, Istituto Auxologico Italiano IRCCS, Milan, Italy.

As for the majority of neurodegenerative diseases, pathological mechanisms of amyotrophic lateral sclerosis (ALS) have been challenging to study due to the difficult access to alive patients' cells. Induced pluripotent stem cells (iPSCs) offer a useful in vitro system for modelling human diseases. iPSCs can be theoretically obtained by reprogramming any somatic tissue although fibroblasts (FB) remain the most used cells. However, reprogramming peripheral blood cells (PB) may offer significant advantages. In order to investigate whether the choice of starting cells may affect reprogramming and motor neuron (MNs) differentiation potential, we used both FB and PB from a same C9ORF72-mutated ALS patient to obtain iPSCs and compared several hallmarks of the pathology. We found that both iPSCs and MNs derived from the two tissues showed identical properties and features and can therefore be used interchangeably, giving the opportunity to easily obtain iPSCs from a more manageable source of cells, such as PB.
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http://dx.doi.org/10.1111/jcmm.15048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7171411PMC
April 2020

Inter-Species Differences in Regulation of the Progranulin-Sortilin Axis in TDP-43 Cell Models of Neurodegeneration.

Int J Mol Sci 2019 Nov 22;20(23). Epub 2019 Nov 22.

Istituto Auxologico Italiano, IRCCS, Department of Neurology-Stroke Unit and Laboratory of Neuroscience, Via Zucchi 18, 20095 Cusano Milanino, Milan, Italy.

Cytoplasmic aggregates and nuclear depletion of the ubiquitous RNA-binding protein TDP-43 have been described in the autoptic brain tissues of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTLD) patients and both TDP-43 loss-of-function and gain-of-function mechanisms seem to contribute to the neurodegenerative process. Among the wide array of RNA targets, TDP-43 regulates progranulin () mRNA stability and sortilin () splicing. Progranulin is a secreted neurotrophic and neuro-immunomodulatory factor whose endocytosis and delivery to the lysosomes are regulated by the neuronal receptor sortilin. Moreover, loss-of-function mutations are causative of a subset of FTLD cases showing TDP-43 pathological aggregates. Here we show that TDP-43 loss-of-function differently affects the progranulin-sortilin axis in murine and human neuronal cell models. We demonstrated that although TDP-43 binding to mRNA occurs similarly in human and murine cells, upon TDP-43 depletion, a different control of sortilin splicing and protein content may determine changes in extracellular progranulin uptake that account for increased or unchanged secreted protein in murine and human cells, respectively. As targeting the progranulin-sortilin axis has been proposed as a therapeutic approach for -FTLD patients, the inter-species differences in TDP-43-mediated regulation of this pathway must be considered when translating studies from animal models to patients.
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http://dx.doi.org/10.3390/ijms20235866DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6928728PMC
November 2019

TDP-43 and NOVA-1 RNA-binding proteins as competitive splicing regulators of the schizophrenia-associated TNIK gene.

Biochim Biophys Acta Gene Regul Mech 2019 09 2;1862(9):194413. Epub 2019 Aug 2.

Istituto Auxologico Italiano, IRCCS, Department of Neurology-Stroke Unit and Laboratory of Neuroscience, Via Zucchi 18, 20095, Cusano Milanino, Milan, Italy; Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Via Fratelli Cervi 93, 20090, Segrate, Milan, Italy. Electronic address:

The RNA-binding protein TDP-43, associated to amyotrophic lateral sclerosis and frontotemporal dementia, regulates the alternative splicing of several genes, including the skipping of TNIK exon 15. TNIK, a genetic risk factor for schizophrenia and causative for intellectual disability, encodes for a Ser/Thr kinase regulating negatively F-actin dynamics. Here we show that in the human adult nervous system TNIK exon 15 is mostly included compared to the other tissues and that, during neuronal differentiation of human induced pluripotent stem cells and of human neuroblastoma cells, TNIK exon 15 inclusion increases independently of TDP-43 protein content. By studying the possible molecular interplay of TDP-43 with brain-specific splicing factors, we found that the neuronal NOVA-1 protein competitively inhibits both TDP-43 and hnRNPA2/B1 skipping activity on TNIK by means of a RNA-dependent interaction and that this competitive mechanism is common to other TDP-43 RNA targets. We also show that the TNIK protein isoforms including/excluding exon 15 differently regulate cell spreading in non-neuronal cells and neuritogenesis in primary cortical neurons. Our data suggest a complex regulation between the ubiquitous TDP-43 and the neuron-specific NOVA-1 splicing factors in the brain that may help better understand the pathobiology of both neurodegenerative diseases and schizophrenia.
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http://dx.doi.org/10.1016/j.bbagrm.2019.194413DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818381PMC
September 2019

Response to the commentary "The effect of C9orf72 intermediate repeat expansions in neurodegenerative and autoimmune diseases" by Biasiotto G and Zanella I..

Mult Scler Relat Disord 2019 01 14;27:79-80. Epub 2018 Oct 14.

Istituto Auxologico Italiano, IRCCS, Department of Neurology-Stroke Unit and Laboratory of Neuroscience, 20149 Milan, Italy; Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, Università degli Studi di Milano, 20122 Milan, Italy.

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http://dx.doi.org/10.1016/j.msard.2018.10.007DOI Listing
January 2019

No C9orf72 repeat expansion in patients with primary progressive multiple sclerosis.

Mult Scler Relat Disord 2018 Oct 1;25:192-195. Epub 2018 Aug 1.

Istituto Auxologico Italiano, IRCCS, Department of Neurology-Stroke Unit and Laboratory of Neuroscience, Milan 20145, Italy; Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, Università degli Studi di Milano, Milan 20122, Italy. Electronic address:

Pathological repeat expansion (RE) of the C9orf72 hexanucleotide sequence is associated to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia disease continuum, although other heterogeneous clinical phenotypes have been documented. The occurrence of multiple sclerosis (MS) in some C9orf72 carriers with a more severe ALS disease course has suggested a possible modifying role for MS. However, C9orf72 RE seems not to play a role in MS pathogenesis. In this study, we screened C9orf72 in 189 Italian patients with primary progressive MS (PPMS), a rare clinical form characterized by less inflammation over neurodegenerative features. We failed to detect C9orf72 RE, but a significant representation of intermediate alleles (≥ 20 units) was observed in our PPMS cohort (2.1%) compared to healthy controls (0%, p < 0.05). In the normal range, allele distribution showed a trimodal pattern (2,5,8-repeat units) in PPMS and healthy controls with no significant difference. Our findings further demonstrate that C9orf72 RE is not genetically associated to MS spectrum, but suggest that intermediate alleles may represent risk factors as already reported for Parkinson disease.
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http://dx.doi.org/10.1016/j.msard.2018.07.047DOI Listing
October 2018

Characterization of the c9orf72 GC-rich low complexity sequence in two cohorts of Italian and Turkish ALS cases.

Amyotroph Lateral Scler Frontotemporal Degener 2018 08 28;19(5-6):426-431. Epub 2018 Feb 28.

a Department of Health Sciences, Interdisciplinary Research Center of Autoimmune Diseases , Universita' del Piemonte Orientale , Novara , Italy.

Large expansions of a noncoding GGGGCC repeat in the C9orf72 gene are the main cause of amyotrophic lateral sclerosis (ALS). The GGGGCC repeat is contiguous with another GC-rich region. Recent studies reported a significantly higher frequency of insertions/deletions within the GC-rich region in patients carrying the GGGGCC expansion. A GTGGT motif comprised within the GC-rich region, which joins two 100% GC sequences, was frequently deleted, supporting the hypothesis that these deletions could make the region more prone to slippage and pathological expansion. To confirm this hypothesis, we sequenced the GC-rich region adjacent the GGGGCC repeat in ALS patients, 116 C9orf72 expansion carriers, 219 non-carriers, and 223 healthy controls, from Italian and Turkish cohorts. Deletions were significantly more frequent in C9orf72 expansion carriers (6%) compared to non-carrier ALS patients (0.46%, OR =14.00, 95% CI =1.71-306.59, p = 0.003), to controls (0%, OR =16.29, 95% CI =2.12-725.99, p = 4.86 × 10) and to the whole cohort of non-carriers (0.2%, OR =28.51, 95% CI =3.47-618.91, p = 9.58 × 10). Among expansion carriers, deletions with or without the GTGGT motif were equally distributed (4 vs. 3). The frequency of insertions was not statistically different between C9orf72 expansion carriers and any other group including the whole cohort of non-carriers (p = 0.439, Fisher's exact test). Our data confirmed the association between deletions within GC-rich region and the GGGGCC expansion in Italian and Turkish cases, although we did not confirm a role of the GTGGT element deletion. Further studies will be therefore necessary to assess the causal relationships between contiguous deletions of the GC-rich region and the GGGGCC expansion.
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http://dx.doi.org/10.1080/21678421.2018.1440407DOI Listing
August 2018

A novel nonsense pathogenic variant in a family exhibiting a variable occipital horn syndrome phenotype.

Mol Genet Metab Rep 2017 Dec 21;13:14-17. Epub 2017 Jul 21.

Neurology Unit and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Ospedale San Luca, piazzale Brescia 20, 20149 Milan, Italy.

We report on a family with occipital horn syndrome (OHS) diagnosed in the proband's late fifties. A novel pathogenic variant (c.4222A > T, p.(Lys1408*)), representing the first nonsense variant and the second late truncation causing OHS rather than classic Menkes disease, was found to segregate in the family. The predicted maintenance of transmembrane domains is consistent with a residual protein activity, which may explain the mild clinical presentation.
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http://dx.doi.org/10.1016/j.ymgmr.2017.07.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522958PMC
December 2017

PKC Activation Counteracts ADAM10 Deficit in HuD-Silenced Neuroblastoma Cells.

J Alzheimers Dis 2016 09;54(2):535-47

Department of Drug Sciences, Pharmacology Section, University of Pavia, Pavia, Italy.

Neuronal ELAV/Hu (nELAV) are RNA-binding proteins that mainly regulate gene expression by increasing the stability and/or translation rate of target mRNAs bearing ARE (adenine and uracil-rich elements) sequences. Among nELAV target transcripts there is ADAM10, an α-secretase involved in the non-amyloidogenic processing of the amyloid-β protein precursor (AβPP) which leads to the production of the neuroprotective sAβPPα peptide. The aim of this study was to evaluate if nELAV depletion affects ADAM10 expression in human SH-SY5Y neuroblastoma cells. We also studied the effects of Bryostatin-1, a molecule able to activate nELAV protein cascade. The specific HuD/nELAV gene silencing decreased both nELAV and ADAM10 protein contents; similar results were obtained by Aβ40 treatment in wild-type SH-SY5Y cells. In HuD-silenced cells, the exposure to Bryostatin-1 counteracted both nELAV and ADAM10 proteins downregulation, by restoring nELAV/ADAM10 basal levels. We also found that sAβPPα release, which seemed not to be compromised by Aβ40 challenge or HuD-silencing, was favored by Bryostatin-1. Overall, these findings strongly suggest that a deficiency in nELAV content negatively affects ADAM10 expression and may play a role in neurodegenerative diseases, which may benefit by molecules activating ELAV cascade.
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http://dx.doi.org/10.3233/JAD-160299DOI Listing
September 2016

NEK1 variants confer susceptibility to amyotrophic lateral sclerosis.

Nat Genet 2016 09 25;48(9):1037-42. Epub 2016 Jul 25.

Neurogenetics Group, Division of Brain Sciences, Imperial College London, London, UK.

To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology.
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http://dx.doi.org/10.1038/ng.3626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5560030PMC
September 2016

Gene-specific mitochondria dysfunctions in human TARDBP and C9ORF72 fibroblasts.

Acta Neuropathol Commun 2016 05 5;4(1):47. Epub 2016 May 5.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Via Zucchi, 18, Cusano Milanino, 20095, MI, Italy.

Dysregulation of RNA metabolism represents an important pathogenetic mechanism in both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) due to the involvement of the DNA/RNA-binding proteins TDP-43 and FUS and, more recently, of C9ORF72. A potential link between dysregulation of RNA metabolism and mitochondrial dysfunction is recently emerged in TDP-43 disease models. To further investigate the possible relationship between these two pathogenetic mechanisms in ALS/FTD, we studied mitochondria functionality in human mutant TARDBP(p.A382T) and C9ORF72 fibroblasts grown in galactose medium to induce a switch from a glycolytic to an oxidative metabolism. In this condition we observed significant changes in mitochondria morphology and ultrastructure in both mutant cells with a fragmented mitochondria network particularly evident in TARDBP(p.A382T) fibroblasts. From analysis of the mitochondrial functionality, a decrease of mitochondria membrane potential with no alterations in oxygen consumption rate emerged in TARDBP fibroblasts. Conversely, an increased oxygen consumption and mitochondria hyperpolarization were observed in C9ORF72 fibroblasts in association to increased ROS and ATP content. We found evidence of autophagy/mitophagy in dynamic equilibrium with the biogenesis of novel mitochondria, particularly in mutant C9ORF72 fibroblasts where an increase of mitochondrial DNA content and mass, and of PGC1-α protein was observed. Our imaging and biochemical data show that wild-type and mutant TDP-43 proteins do not localize at mitochondria so that the molecular mechanisms responsible for such mitochondria impairment remain to be further elucidated. For the first time our findings assess a link between C9ORF72 and mitochondria dysfunction and indicate that mitochondria functionality is affected in TARDBP and C9ORF72 fibroblasts with gene-specific features in oxidative conditions. As in neuronal metabolism mitochondria are actively used for ATP production, we speculate that TARDBP and C9ORF72 mutations might trigger cell death by impairing not only RNA metabolism, but also mitochondria activity in ALS/FTD neurons.
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http://dx.doi.org/10.1186/s40478-016-0316-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4858818PMC
May 2016

Dendritic targeting of short and long 3' UTR BDNF mRNA is regulated by BDNF or NT-3 and distinct sets of RNA-binding proteins.

Front Mol Neurosci 2015 29;8:62. Epub 2015 Oct 29.

Department of Life Sciences, University of Trieste Trieste, Italy.

Sorting of mRNAs in neuronal dendrites relies upon inducible transport mechanisms whose molecular bases are poorly understood. We investigated here the mechanism of inducible dendritic targeting of rat brain-derived neurotrophic factor (BDNF) mRNAs as a paradigmatic example. BDNF encodes multiple mRNAs with either short or long 3' UTR, both hypothesized to harbor inducible dendritic targeting signals. However, the mechanisms of sorting of the two 3' UTR isoforms are controversial. We found that dendritic localization of BDNF mRNAs with short 3' UTR was induced by depolarization and NT3 in vitro or by seizures in vivo and required CPEB-1, -2 and ELAV-2, -4. Dendritic targeting of long 3' UTR was induced by activity or BDNF and required CPEB-1 and the relief of soma-retention signals mediated by ELAV-1, -3, -4, and FXR proteins. Thus, long and short 3' UTRs, by using different sets of RNA-binding proteins provide a mechanism of selective targeting in response to different stimuli which may underlay distinct roles of BDNF variants in neuronal development and plasticity.
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http://dx.doi.org/10.3389/fnmol.2015.00062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624863PMC
November 2015

From transcriptomic to protein level changes in TDP-43 and FUS loss-of-function cell models.

Biochim Biophys Acta 2015 Dec 26;1849(12):1398-410. Epub 2015 Oct 26.

Department of Pathophysiology and Transplantation, 'Dino Ferrari' Center - Università degli Studi di Milano, Milan 20122, Italy; Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy. Electronic address:

The full definition of the physiological RNA targets regulated by TDP-43 and FUS RNA-binding proteins (RBPs) represents an important issue in understanding the pathogenic mechanisms associated to these two proteins in amyotrophic lateral sclerosis and frontotemporal dementia. In the last few years several high-throughput screenings have generated a plethora of data, which are difficult to compare due to the different experimental designs and models explored. In this study by using the Affymetrix Exon Arrays, we were able to assess and compare the effects of both TDP-43 and FUS loss-of-function on the whole transcriptome using the same human neuronal SK-N-BE cell model. We showed that TDP-43 and FUS depletion induces splicing and gene expression changes mainly distinct for the two RBPs, although they may regulate common pathways, including neuron differentiation and cytoskeleton organization as evidenced by functional annotation analysis. In particular, TDP-43 and FUS were found to regulate splicing and expression of genes related to neuronal (SEPT6, SULT4A1, TNIK) and RNA metabolism (DICER, ELAVL3/HuC, POLDIP3). Our extended analysis at protein level revealed that these changes have also impact on the protein isoform ratio and content, not always in a direct correlation with transcriptomic data. Contrarily to a loss-of-function mechanism, we showed that mutant TDP-43 proteins maintained their splicing activity in human ALS fibroblasts and experimental cell lines. Our findings further contribute to define the biological functions of these two RBPs in physiological and disease state, strongly encouraging the evaluation of the identified transcriptomic changes at protein level in neuronal experimental models.
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http://dx.doi.org/10.1016/j.bbagrm.2015.10.015DOI Listing
December 2015

Exome-wide rare variant analysis identifies TUBA4A mutations associated with familial ALS.

Neuron 2014 Oct 22;84(2):324-31. Epub 2014 Oct 22.

Unidad de ELA, Instituto de Investigación Hospital 12 de Octubre de Madrid, SERMAS, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER U-723), 28041 Madrid, Spain.

Exome sequencing is an effective strategy for identifying human disease genes. However, this methodology is difficult in late-onset diseases where limited availability of DNA from informative family members prohibits comprehensive segregation analysis. To overcome this limitation, we performed an exome-wide rare variant burden analysis of 363 index cases with familial ALS (FALS). The results revealed an excess of patient variants within TUBA4A, the gene encoding the Tubulin, Alpha 4A protein. Analysis of a further 272 FALS cases and 5,510 internal controls confirmed the overrepresentation as statistically significant and replicable. Functional analyses revealed that TUBA4A mutants destabilize the microtubule network, diminishing its repolymerization capability. These results further emphasize the role of cytoskeletal defects in ALS and demonstrate the power of gene-based rare variant analyses in situations where causal genes cannot be identified through traditional segregation analysis.
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http://dx.doi.org/10.1016/j.neuron.2014.09.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4521390PMC
October 2014

hnRNPA2/B1 and nELAV proteins bind to a specific U-rich element in CDK5R1 3'-UTR and oppositely regulate its expression.

Biochim Biophys Acta 2014 Jun 2;1839(6):506-16. Epub 2014 May 2.

Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy. Electronic address:

Cyclin-dependent kinase 5 regulatory subunit 1 (CDK5R1) encodes p35, a specific activator of cyclin-dependent kinase 5 (CDK5). CDK5 and p35 have a fundamental role in neuronal migration and differentiation during CNS development. Both the CDK5R1 3'-UTR's remarkable size and its conservation during evolution strongly indicate an important role in post-transcriptional regulation. We previously validated different regulatory elements in the 3'-UTR of CDK5R1, which affect transcript stability, p35 levels and cellular migration through the binding with nELAV proteins and miR-103/7 miRNAs. Interestingly, a 138 bp-long region, named C2.1, was identified as the most mRNA destabilizing portion within CDK5R1 3'-UTR. This feature was maintained by a shorter region of 73 bp, characterized by two poly-U stretches. UV-CL experiments showed that this region interacts with protein factors. UV-CLIP assays and pull-down experiments followed by mass spectrometry analysis demonstrated that nELAV and hnRNPA2/B1 proteins bind to the same U-rich element. These RNA-binding proteins (RBPs) were shown to oppositely control CDK5R1 mRNA stability and p35 protein content at post-trascriptional level. While nELAV proteins have a positive regulatory effect, hnRNPA2/B1 has a negative action that is responsible for the mRNA destabilizing activity both of the C2.1 region and of the full-length 3'-UTR. In co-expression experiments of hnRNPA2/B1 and nELAV RBPs we observed an overall decrease of p35 content. We also demonstrated that hnRNPA2/B1 can downregulate nELAV protein content but not vice versa. This study, by providing new insights on the combined action of different regulatory factors, contributes to clarify the complex post-transcriptional control of CDK5R1 gene expression.
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http://dx.doi.org/10.1016/j.bbagrm.2014.04.018DOI Listing
June 2014

C9orf72 repeat expansions are restricted to the ALS-FTD spectrum.

Neurobiol Aging 2014 Apr 2;35(4):936.e13-7. Epub 2013 Oct 2.

Department of Neurology and Laboratory of Neuroscience, Istituto di Ricovero e Cura a Carattere Scientifico Istituto Auxologico Italiano, Milan, Italy; Department of Pathophysiology and Transplantation, Dino Ferrari Center, Università degli Studi di Milano, Milan, Italy.

Expansion of a GGGGCC repeat (RE) in the C9orf72 gene has been recently reported as the main genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Given the growing evidence of genetic and clinicopathologic overlap among ALS, FTD, and other neurodegenerative diseases, we investigated the occurrence of RE in a subset of 9 patients with ALS-plus syndromes, including Parkinson's disease (PD), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and multiple system atrophy. We identified RE in 2 ALS-plus individuals (22.2%) displaying PSP and CBS features. On the basis of this finding, we extended our analysis to a cohort composed of 190 PD, 103 CBS, 107 PSP, and 177 Alzheimer's disease cases. We did not identify any RE in these patients, indicating that C9orf72 is in all probability not involved in the pathogenesis of these disorders. However, the high frequency of C9orf72 RE in patients with ALS-plus syndromes suggests that, similar to ALS-FTD patients, individuals with combined motor neuron and extrapyramidal features should be screened for RE, independent of their family history.
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http://dx.doi.org/10.1016/j.neurobiolaging.2013.09.037DOI Listing
April 2014

ELAV proteins along evolution: back to the nucleus?

Mol Cell Neurosci 2013 Sep 22;56:447-55. Epub 2013 Feb 22.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Via Zucchi, 18, 20095 Cusano Milanino (Milan), Italy; Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, "Dino Ferrari" Center, Università degli Studi di Milano, Via Sforza, 35, 20122 Milan, Italy.

The complex interplay of post-transcriptional regulatory mechanisms mediated by RNA-binding proteins (RBP) at different steps of RNA metabolism is pivotal for the development of the nervous system and the maintenance of adult brain activities. In this review, we will focus on the highly conserved ELAV gene family encoding for neuronal-specific RBPs which are necessary for proper neuronal differentiation and important for synaptic plasticity process. In the evolution from Drosophila to man, ELAV proteins seem to have changed their biological functions in relation to their different subcellular localization. While in Drosophila, they are localized in the nuclear compartment of neuronal cells and regulate splicing and polyadenylation, in mammals, the neuronal ELAV proteins are mainly present in the cytoplasm where they participate in regulating mRNA target stability, translation and transport into neurites. However, recent data indicate that the mammalian ELAV RBPs also have nuclear activities, similarly to their fly counterpart, being them able to continuously shuttle between the cytoplasm and the nucleus. Here, we will review and comment on all the biological functions associated with neuronal ELAV proteins along evolution and will show that the post-transcriptional regulatory network mediated by these RBPs in the brain is highly complex and only at an initial stage of being fully understood. This article is part of a Special Issue entitled 'RNA and splicing regulation in neurodegeneration'.
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http://dx.doi.org/10.1016/j.mcn.2013.02.003DOI Listing
September 2013

Oligoclonal bands in the cerebrospinal fluid of amyotrophic lateral sclerosis patients with disease-associated mutations.

J Neurol 2013 Jan 1;260(1):85-92. Epub 2012 Jul 1.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milan, Italy; Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, 'Dino Ferrari' Center, Università degli Studi di Milano, 20122 Milan, Italy.

In amyotrophic lateral sclerosis (ALS) cerebrospinal fluid (CSF) analysis is usually performed to exclude inflammatory processes of the central nervous system. Although in a small subset of patients an intrathecal synthesis of IgG is detectable, usually there is no clear explanation for this evidence. This study investigates the occurrence of oligoclonal bands (OCBs) in the CSF of a large series of ALS patients, attempting a correlation with genotype data. CSF was collected from 259 ALS patients. CSF parameters were measured according to standard procedures, and detection of OCBs performed by isoelectric focusing. The patients were screened for mutations in SOD1, FUS, TARDBP, ANG, OPTN, and C9ORF72. We observed the presence of OCBs in the CSF of 9/259 ALS patients (3.5 %), and of disease-associated mutations in 12 cases. OCBs were significantly more frequent in mutation carriers compared to the remaining cohort (3/12 vs 6/247; p < 0.01). Among patients with OCBs, two patients had the TARDBP p.A382T mutation (one of which in homozygous state), and one the ANG p.P-4S variant. Both patients carrying the p.A382T mutation had an atypical phenotype, one of them manifesting signs suggestive of a cerebellar involvement, and the other presenting neuroradiological findings suggestive of an inflammatory disorder of the central nervous system. Our results suggest that ALS patients with OCBs may harbor mutations in disease-causing genes. We speculate that mutations in both TARDBP and ANG genes may disrupt the blood-brain barrier (BBB), promoting local immune responses and neuroinflammation. The role of mutant TARDBP and ANG genes on BBB integrity of ALS patients warrants further investigation.
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http://dx.doi.org/10.1007/s00415-012-6589-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4196642PMC
January 2013

TDP-43 and FUS RNA-binding proteins bind distinct sets of cytoplasmic messenger RNAs and differently regulate their post-transcriptional fate in motoneuron-like cells.

J Biol Chem 2012 May 16;287(19):15635-47. Epub 2012 Mar 16.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan 20149, Italy.

The RNA-binding proteins TDP-43 and FUS form abnormal cytoplasmic aggregates in affected tissues of patients with amyotrophic lateral sclerosis and frontotemporal lobar dementia. TDP-43 and FUS localize mainly in the nucleus where they regulate pre-mRNA splicing, but they are also involved in mRNA transport, stability, and translation. To better investigate their cytoplasmic activities, we applied an RNA immunoprecipitation and chip analysis to define the mRNAs associated to TDP-43 and FUS in the cytoplasmic ribonucleoprotein complexes from motoneuronal NSC-34 cells. We found that they bind different sets of mRNAs although converging on common cellular pathways. Bioinformatics analyses identified the (UG)(n) consensus motif in 80% of 3'-UTR sequences of TDP-43 targets, whereas for FUS the binding motif was less evident. By in vitro assays we validated binding to selected target 3'-UTRs, including Vegfa and Grn for TDP-43, and Vps54, Nvl, and Taf15 for FUS. We showed that TDP-43 has a destabilizing activity on Vegfa and Grn mRNAs and may ultimately affect progranulin protein content, whereas FUS does not affect mRNA stability/translation of its targets. We also demonstrated that three different point mutations in TDP-43 did not change the binding affinity for Vegfa and Grn mRNAs or their protein level. Our data indicate that TDP-43 and FUS recognize distinct sets of mRNAs and differently regulate their fate in the cytoplasm of motoneuron-like cells, therefore suggesting complementary roles in neuronal RNA metabolism and neurodegeneration.
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http://dx.doi.org/10.1074/jbc.M111.333450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3346140PMC
May 2012

RNA-binding proteins and RNA metabolism: a new scenario in the pathogenesis of Amyotrophic lateral sclerosis.

Arch Ital Biol 2011 Mar;149(1):83-99

Department of Neurology and Laboratory of Neuroscience IRCCS Istituto Auxologico Italiano, 20149 Milan, Italy.

Several RNA-processing genes have been implicated in the pathogenesis of Amyotrophic lateral sclerosis (ALS). In particular, causative mutations in the genes encoding for two DNA/RNA binding proteins, TAR DNA binding protein-43 (TDP-43) and fused in sarcoma/translocated in liposarcoma (FUS/TLS), were recently identified in ALS patients. These genetic findings and the presence of abnormal aggregates of these two RNA-binding proteins in ALS affected tissues suggest that molecular mechanisms regulating RNA metabolism are implicated in ALS pathogenesis through common pathways. In this review similarities and differences between TDP-43 and FUS/TLS proteins and their activities in physiological and pathological conditions will be discussed.
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http://dx.doi.org/10.4449/aib.v149i1.1261DOI Listing
March 2011

Genetics of familial Amyotrophic lateral sclerosis.

Arch Ital Biol 2011 Mar;149(1):65-82

Department of Neurology and Laboratory of Neuroscience IRCCS Istituto Auxologico Italiano, 20149 Milan, Italy.

Amyotrophic lateral sclerosis (ALS) is a late onset, rapidly progressive and ultimately fatal neurodegenerative disease, caused by the loss of motor neurons in the brain and spinal cord. About 10% of all ALS cases are familial (FALS), and constitute a clinically and genetically heterogeneous entity. To date, FALS has been linked to mutations in 10 different genes and to four additional chromosomal loci. Research on FALS genetics, and in particular the discoveries of mutations in the SOD1, TARDBP, and FUS genes, has provided essential information toward the understanding of the pathogenesis of ALS in general. This review presents a tentative classification of all FALS-associated genes identified so far.
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http://dx.doi.org/10.4449/aib.v149i1.1262DOI Listing
March 2011

Mutations of FUS gene in sporadic amyotrophic lateral sclerosis.

J Med Genet 2010 Mar 26;47(3):190-4. Epub 2009 Oct 26.

Department of Medical Sciences, Via Solaroli, 17, 28100 Novara, Italy.

Background: Mutations in the FUS gene have recently been discovered to be a major cause of familial amyotrophic lateral sclerosis (FALS).

Objective: To determine the identity and frequency of FUS gene mutations in a large cohort of Italian patients enriched in sporadic cases (SALS).

Methods: Exons 5, 6, 14 and 15 of the FUS gene were screened for mutations in 1009 patients (45 FALS and 964 SALS). The genetic analysis was extended to the entire coding sequence of FUS in all the FALS and 293 of the SALS patients.

Results: Seven missense mutations (p.G191S, p.R216C, p.G225V, p.G230C, p.R234C, p.G507D and p.R521C) were identified in nine patients (seven SALS and two FALS), and none in 500 healthy Italian controls. All mutations are novel except for the p.R521C mutation identified in one SALS and one FALS case. Both patients showed a similar unusual presentation, with proximal, mostly symmetrical, upper limb weakness, with neck and axial involvement. With the exception of p.G507D and p.R521C, the mutations identified in SALS patients are all localised in the glycine-rich region encoded by exon 6. In addition, eight different in-frame deletions in two polyglycine motifs were detected, the frequency of which was not significantly different in patients and controls.

Conclusions: The results show that FUS missense mutations are present in 0.7% of Italian SALS cases, and confirm the previous mutational frequency reported in FALS (4.4%). An unusual proximal and axial clinical presentation seems to be associated with the presence of the p.R521C mutation.
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http://dx.doi.org/10.1136/jmg.2009.071027DOI Listing
March 2010

TDP-43 is recruited to stress granules in conditions of oxidative insult.

J Neurochem 2009 Nov 16;111(4):1051-61. Epub 2009 Sep 16.

Department of Neurology and Laboratory of Neuroscience, Dino Ferrari Center, Università degli Studi di Milano - IRCCS Istituto Auxologico Italiano, Milan, Italy.

Transactive response DNA-binding protein 43 (TDP-43) forms abnormal ubiquitinated and phosphorylated inclusions in brain tissues from patients with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration. TDP-43 is a DNA/RNA-binding protein involved in RNA processing, such as transcription, pre-mRNA splicing, mRNA stabilization and transport to dendrites. We found that in response to oxidative stress and to environmental insults of different types TDP-43 is capable to assemble into stress granules (SGs), ribonucleoprotein complexes where protein synthesis is temporarily arrested. We demonstrated that a specific aminoacidic interval (216-315) in the C-terminal region and the RNA-recognition motif 1 domain are both implicated in TDP-43 participation in SGs as their deletion prevented the recruitment of TDP-43 into SGs. Our data show that TDP-43 is a specific component of SGs and not of processing bodies, although we proved that TDP-43 is not necessary for SG formation, and its gene silencing does not impair cell survival during stress. The analysis of spinal cord tissue from ALS patients showed that SG markers are not entrapped in TDP-43 pathological inclusions. Although SGs were not evident in ALS brains, we speculate that an altered control of mRNA translation in stressful conditions may trigger motor neuron degeneration at early stages of the disease.
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http://dx.doi.org/10.1111/j.1471-4159.2009.06383.xDOI Listing
November 2009

Behavioral effects of dietary cholesterol in rats tested in experimental models of mild stress and cognition tasks.

Eur Neuropsychopharmacol 2008 Jun 28;18(6):462-71. Epub 2008 Jan 28.

Department of Experimental and Clinical Pharmacology, University of Catania, Catania, Italy.

Abnormalities in serum cholesterol levels of patients with mood disorders have been identified in epidemiological studies. However, evidence for an influence of dietary cholesterol on behavioral models is poor. Here, we investigated the behavioral changes of Wistar male rats fed a 2% cholesterol-enriched diet for 2 months in experimental models of depression and anxiety, such as the forced swim test (FST) paradigm and the novelty-induced grooming sampling test (NGT). The correlation between behavioral depression and impaired cognitive capacity was also examined testing rats in the Morris water maze (MWM) task one day after the FST. Different groups of rats fed various dietary regimens, were subjected to acute or repeated treatment (14 days) with clomipramine hydrochloride (50 or 25 mg/kg), diazepam (1 mg/kg) or with the peripheral benzodiazepine receptors (PBRs) antagonist, isoquinoline PK11195 (1 mg/kg) injected intraperitoneally (i.p.). Rats fed the cholesterol-enriched diet showed a significant decrease of grooming score in the NGT and of immobility time in the FST in comparison to animals fed a standard diet. Furthermore, the anxiolytic and antidepressant effects of diazepam and clomipramine were not affected by the different diets. Only after repeated treatment, PK11195 impaired the performance of animals fed a standard diet in the FST, and exhibited an anxiolytic-like profile in animals fed either the cholesterol-enriched or the standard diet. The improved performance in the FST was followed by a better learning performance in the acquisition phase of the MWM. These results suggest that effects of cholesterol-enriched diet on the behavioral reaction of rats in experimental models of mild stress may involve PBRs. They deserve attention in order to clarify the clinical correlation between plasma cholesterol levels and mood disorders in humans.
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http://dx.doi.org/10.1016/j.euroneuro.2007.11.006DOI Listing
June 2008

Post-transcriptional regulation of neuro-oncological ventral antigen 1 by the neuronal RNA-binding proteins ELAV.

J Biol Chem 2008 Mar 24;283(12):7531-41. Epub 2008 Jan 24.

Department of Neurological Sciences, Dino Ferrari Centre, University of Milan Medical School, IRCCS Istituto Auxologico Italiano, 20095 Cusano, Milan, Italy.

Alternative splicing of pre-mRNAs plays an important role in generating biological and functional diversity. Neuro-oncological ventral antigen 1 (Nova1) is a neuron-specific splicing factor that controls the alternative processing of a wide array of mRNAs important for synaptic activity. It is essential for the proper development of the mammalian motor system and for the survival of motoneurons. Because Nova1 gene contains putative regulatory AU-rich elements (ARE) in its highly conserved 3'-untranslated region, we investigated whether its expression is regulated by post-transcriptional mechanisms mediated by ARE-binding proteins. Among these, the neuronal ELAV (nELAV) factors are interesting candidates, because their RNA binding activity is necessary for neuronal differentiation and maintenance. By analysis of ribonucleoprotein complexes in vivo and in vitro we demonstrated that the Nova1 mRNA is a novel target of the nELAV proteins. We defined the nELAV binding site by functional experiments with luciferase reporter gene and Nova1 3'-untranslated region deletion sequences. Gene silencing and overexpression of the nELAV member HuD in motoneuronal NSC34 cells indicate that Nova1 mRNA stability and translation are positively and strongly controlled by the nELAV proteins. In addition, nELAV phosphorylation by a PKC-dependent pathway induces the recruitment of Nova1 mRNA to polysomes. Noteworthy, we found that nELAV proteins are also able to modulate Nova1 splicing activity on its target genes. Our data indicate nELAV proteins as the first factors affecting the expression and activity of the neuronal splicing regulator Nova1 and, consequently, as major candidates for the physiological modulation of Nova1-dependent processing of pre-mRNAs in neurons.
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http://dx.doi.org/10.1074/jbc.M706082200DOI Listing
March 2008

Identification of new ANG gene mutations in a large cohort of Italian patients with amyotrophic lateral sclerosis.

Neurogenetics 2008 Feb 18;9(1):33-40. Epub 2007 Dec 18.

Division of Biochemistry and Genetics, Fondazione IRCCS-Instituto Neurologico Carlo Besta, Milan, Italy.

Angiogenin (ANG) gene, coding for an angiogenic factor up-regulated by hypoxia and expressed in ventral horn motor neurons, is a novel candidate for the pathogenesis of amyotrophic lateral sclerosis (ALS). ALS is a fatal neurodegenerative disease characterized by the selective loss of cortical and spinal motor neurons. Missense mutations in ANG gene have been identified in two ALS populations from Northern Europe and North America, both in familial (FALS) and sporadic (SALS) patients, but they do not seem to be frequent in the Italian population. We performed a mutational screening in a large cohort of 737 Italian ALS patients, including 605 SALS and 132 FALS cases. We identified seven different mutations, five of which are novel, in nine patients (six SALS and three FALS), but not in 515 healthy controls. Three mutations are located in the signal peptide region, three in the coding sequence, and one in the 3' untranslated region. In our ALS population, the observed mutational frequency of ANG gene accounts for about 1.2%, with an overrepresentation of FALS (2.3%) compared to SALS (1%) cases. We also found the previously described I46V substitution in six patients and four controls, suggesting that this mutation may represent a benign variant, at least in the Italian population. Our results provide further evidence of a tight link between angiogenesis and ALS pathogenesis and suggest that mutations in ANG gene are associated with an increased risk to develop ALS.
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http://dx.doi.org/10.1007/s10048-007-0111-3DOI Listing
February 2008

11,12-epoxyeicosatrienoic acid stimulates heme-oxygenase-1 in endothelial cells.

Prostaglandins Other Lipid Mediat 2007 Jan 30;82(1-4):155-61. Epub 2006 Aug 30.

Department of Clinical and Experimental Medicine, Clinica Medica 5, University of Padova, Via Giustiniani 2, 35100 Padova, Italy.

As epoxyeicosatrienoic acids (EETs), particularly 11,12-EET, and the heme oxygenase/carbon monoxide (HO/CO) system share overlapping biological activities, we examined a possible link between 11,12-EET and HO activity in endothelial cells. Confocal microscopy analysis of immunostaining of HO-1 and HO-2 in cultured endothelial cells treated with 11,12-EET (1 microM) showed an increase in florescence of HO-1 protein in the various cellular compartments, but not of HO-2. Incubation of endothelial cells with 11,12-EET (1 microM) for 24 h increased the level of HO-1 protein by about three-fold. Similarly, incubation of endothelial cells with 8,9-EET and sodium nitroprussiate, a known inducer of HO-1, increased HO-1 protein without any effect on HO-2. Upregulation of HO-1 by 11,12-EET, as well as 8,9-EET, was associated with an increase in HO activity, which was inhibited by stannous mesoporphirin (10 microM). Incubation of rat aortas with 11,12-EET (1 microM for 60 min) increased HO activity. These findings identify a novel effect of EETs on endothelial HO-1 and indicate that the signaling pathway of EETs in endothelial cells is possibly via an increase in HO-1 expression and activity.
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http://dx.doi.org/10.1016/j.prostaglandins.2006.07.001DOI Listing
January 2007

Curcumin activates defensive genes and protects neurons against oxidative stress.

Antioxid Redox Signal 2006 Mar-Apr;8(3-4):395-403

Institute of Neurological Sciences, National Research Council (CNR), Catania, Italy.

Spices and herbs often contain active phenolic substances endowed with potent antioxidative properties. We had previously shown that curcumin, the yellow pigment in curry, strongly induced HO-1 expression and activity in rat astrocytes. In the CNS, HO-1 has been reported to operate as a fundamental defensive mechanism for neurons exposed to an oxidant challenge. Treatment of astrocytes with curcumin upregulated expression of HO-1 protein at both cytoplasmic and nuclear levels, as shown by immunofluorescence analysis under laser-scanning confocal microscopy. A significant expression of quinone reductase and glutathione S transferase, two members of phase II detoxification enzymes, was found in astrocytes exposed to 5-15 microM curcumin. Moreover, the effects of curcumin on HO-1 activity were explored in cultured hippocampal neurons. Elevated expression of HO-1 mRNA and protein were detected after 6 h incubation with 5-25 microM curcumin. Higher concentrations of curcumin (50-100 microM) caused a substantial cytotoxic effect with no change in HO-1 protein expression. Interestingly, pre-incubation (18 h) with curcumin resulted in an enhanced cellular resistance to glucose oxidase-mediated oxidative damage; this cytoprotective effect was considerably attenuated by zinc protoporphyrin IX, an inhibitor of heme oxygenase activity. This study gives additional support to the possible use of curcumin as a dietary preventive agent against oxidative stress-related diseases.
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http://dx.doi.org/10.1089/ars.2006.8.395DOI Listing
September 2006

Heme oxygenase overexpression attenuates glucose-mediated oxidative stress in quiescent cell phase: linking heme to hyperglycemia complications.

Curr Neurovasc Res 2005 Apr;2(2):103-11

University of Padova, Department of Clinical and Experimental Medicine, Italy.

Heme oxygenase (HO-1) is a stress protein, which has been suggested to participate in defense mechanisms against glucose induced oxidative injury. The purpose of this study was to examine the role of human HO-1 in attenuating glucose-mediated oxidative stress. We investigated the effect of high ambient glucose (15, 33 and 66 mM) on HO-1 gene expression in endothelial cells grown in a serum deprived media compared to the effect of glucose on exponentially grown cells (10% FBS). High glucose at 15 and 33 mM caused significant inhibition of HO-1 protein and activity in G0/G1 and in cells exponentially grown. Glucose concentration at 66 mM caused a significant increase in HO-1. Addition of heme (10 microM) increased HO-1 protein and bilirubin formation in G0/G1, in a time dependent manner peaking at 16 h. Glucose attenuated heme mediated increase in HO-1 proteins. RT-PCR demonstrated that glucose decreased the levels of HO-1 mRNA in both G0/G1 or cells grown in 10% FBS. The rate of HO-1 induction in response to heme was several fold higher in serum-starved cells compared to cells cultured in 10% FBS. Cells exposed to high glucose for up to 24 h had a significant increase in cellular heme and potentiated heme-mediated increase in generation of superoxide anion and 8-epi-isoprostane PGF(2alpha). HO-1 gene transduction prevented glucose-mediated elevation of 8-epi-isoprostane PGF(2alpha). These results imply that expression of HO-1 in G0/G1 cells may be a key player in decreasing cellular heme, associated with increased generation of bilirubin, and in attenuating glucose mediated oxidative stress.
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http://dx.doi.org/10.2174/1567202053586802DOI Listing
April 2005