Publications by authors named "Flavia Giamogante"

11 Publications

  • Page 1 of 1

Mitochondria Associated Membranes (MAMs): Architecture and physiopathological role.

Cell Calcium 2021 03 2;94:102343. Epub 2021 Jan 2.

Department of Biomedical Sciences, University of Padova, Padova, Italy. Electronic address:

In the last decades, the communication between the Endoplasmic reticulum (ER) and mitochondria has obtained great attention: mitochondria-associated membranes (MAMs), which represent the contact sites between the two organelles, have indeed emerged as central hub involved in different fundamental cell processes, such as calcium signalling, apoptosis, autophagy and lipid biosynthesis. Consistently, dysregulation of ER-mitochondria crosstalk has been associated with different pathological conditions, ranging from diabetes to cancer and neurodegenerative diseases. In this review, we will try to summarize the current knowledge on MAMs' structure and functions in health and their relevance for human diseases.
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http://dx.doi.org/10.1016/j.ceca.2020.102343DOI Listing
March 2021

An expanded palette of improved SPLICS reporters detects multiple organelle contacts in vitro and in vivo.

Nat Commun 2020 11 27;11(1):6069. Epub 2020 Nov 27.

Department of Biomedical Sciences, University of Padova, Padova, Italy.

Membrane contact sites between virtually any known organelle have been documented and, in the last decades, their study received momentum due to their importance for fundamental activities of the cell and for the subtle comprehension of many human diseases. The lack of tools to finely image inter-organelle proximity hindered our understanding on how these subcellular communication hubs mediate and regulate cell homeostasis. We develop an improved and expanded palette of split-GFP-based contact site sensors (SPLICS) for the detection of single and multiple organelle contact sites within a scalable distance range. We demonstrate their flexibility under physiological conditions and in living organisms.
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http://dx.doi.org/10.1038/s41467-020-19892-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7699637PMC
November 2020

ER-Mitochondria Contact Sites Reporters: Strengths and Weaknesses of the Available Approaches.

Int J Mol Sci 2020 Oct 31;21(21). Epub 2020 Oct 31.

Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy.

Organelle intercommunication represents a wide area of interest. Over the last few decades, increasing evidence has highlighted the importance of organelle contact sites in many biological processes including Ca signaling, lipid biosynthesis, apoptosis, and autophagy but also their involvement in pathological conditions. ER-mitochondria tethering is one of the most investigated inter-organelle communications and it is differently modulated in response to several cellular conditions including, but not limited to, starvation, Endoplasmic Reticulum (ER) stress, and mitochondrial shape modifications. Despite many studies aiming to understand their functions and how they are perturbed under different conditions, approaches to assess organelle proximity are still limited. Indeed, better visualization and characterization of contact sites remain a fascinating challenge. The aim of this review is to summarize strengths and weaknesses of the available methods to detect and quantify contact sites, with a main focus on ER-mitochondria tethering.
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http://dx.doi.org/10.3390/ijms21218157DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663704PMC
October 2020

Sorcin is an early marker of neurodegeneration, Ca dysregulation and endoplasmic reticulum stress associated to neurodegenerative diseases.

Cell Death Dis 2020 10 15;11(10):861. Epub 2020 Oct 15.

Institute of Molecular Biology and Pathology, Italian National Research Council, IBPM-CNR, Rome, Italy.

Dysregulation of calcium signaling is emerging as a key feature in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), and targeting this process may be therapeutically beneficial. Under this perspective, it is important to study proteins that regulate calcium homeostasis in the cell. Sorcin is one of the most expressed calcium-binding proteins in the human brain; its overexpression increases endoplasmic reticulum (ER) calcium concentration and decreases ER stress in the heart and in other cellular types. Sorcin has been hypothesized to be involved in neurodegenerative diseases, since it may counteract the increased cytosolic calcium levels associated with neurodegeneration. In the present work, we show that Sorcin expression levels are strongly increased in cellular, animal, and human models of AD, PD, and HD, vs. normal cells. Sorcin partially colocalizes with RyRs in neurons and microglia cells; functional experiments with microsomes containing high amounts of RyR2 and RyR3, respectively, show that Sorcin is able to regulate these ER calcium channels. The molecular basis of the interaction of Sorcin with RyR2 and RyR3 is demonstrated by SPR. Sorcin also interacts with other ER proteins as SERCA2 and Sigma-1 receptor in a calcium-dependent fashion. We also show that Sorcin regulates ER calcium transients: Sorcin increases the velocity of ER calcium uptake (increasing SERCA activity). The data presented here demonstrate that Sorcin may represent both a novel early marker of neurodegenerative diseases and a response to cellular stress dependent on neurodegeneration.
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http://dx.doi.org/10.1038/s41419-020-03063-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566454PMC
October 2020

PINK1/Parkin Mediated Mitophagy, Ca Signalling, and ER-Mitochondria Contacts in Parkinson's Disease.

Int J Mol Sci 2020 Mar 5;21(5). Epub 2020 Mar 5.

Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.

Endoplasmic reticulum (ER)-mitochondria contact sites are critical structures for cellular function. They are implicated in a plethora of cellular processes, including Ca signalling and mitophagy, the selective degradation of damaged mitochondria. Phosphatase and tensin homolog (PTEN)-induced kinase (PINK) and Parkin proteins, whose mutations are associated with familial forms of Parkinson's disease, are two of the best characterized mitophagy players. They accumulate at ER-mitochondria contact sites and modulate organelles crosstalk. Alterations in ER-mitochondria tethering are a common hallmark of many neurodegenerative diseases including Parkinson's disease. Here, we summarize the current knowledge on the involvement of PINK1 and Parkin at the ER-mitochondria contact sites and their role in the modulation of Ca signalling and mitophagy.
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http://dx.doi.org/10.3390/ijms21051772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084677PMC
March 2020

Shmt2: A Stat3 Signaling New Player in Prostate Cancer Energy Metabolism.

Cells 2019 09 6;8(9). Epub 2019 Sep 6.

Department of Biochemical Sciences "A. Rossi Fanelli" and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University, P.le A. Moro 5, 00185 Rome, Italy.

Prostate cancer (PCa) is a multifactorial disease characterized by the aberrant activity of different regulatory pathways. STAT3 protein mediates some of these pathways and its activation is implicated in the modulation of several metabolic enzymes. A bioinformatic analysis indicated a STAT3 binding site in the upstream region of SHMT2 gene. We demonstrated that in LNCaP, PCa cells' SHMT2 expression is upregulated by the JAK2/STAT3 canonical pathway upon IL-6 stimulation. Activation of SHTM2 leads to a decrease in serine levels, pushing PKM2 towards the nuclear compartment where it can activate STAT3 in a non-canonical fashion that in turn promotes a transient shift toward anaerobic metabolism. These results were also confirmed on FFPE prostate tissue sections at different Gleason scores. STAT3/SHMT2/PKM2 loop in LNCaP cells can modulate a metabolic shift in response to inflammation at early stages of cancer progression, whereas a non-canonical STAT3 activation involving the STAT3/HIF-1α/PKM2 loop is responsible for the maintenance of Warburg effect distinctive of more aggressive PCa cells. Chronic inflammation might thus prime the transition of PCa cells towards more advanced stages, and SHMT2 could represent a missing factor to further understand the molecular mechanisms responsible for the transition of prostate cancer towards a more aggressive phenotype.
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http://dx.doi.org/10.3390/cells8091048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770108PMC
September 2019

STAT3 Post-Translational Modifications Drive Cellular Signaling Pathways in Prostate Cancer Cells.

Int J Mol Sci 2019 Apr 12;20(8). Epub 2019 Apr 12.

Department of Biochemical Sciences "A. Rossi Fanelli" and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University, P.le A. Moro 5, 00185 Rome, Italy.

STAT3 is an oncoprotein overexpressed in different types of tumors, including prostate cancer (PCa), and its activity is modulated by a variety of post-translational modifications (PTMs). Prostate cancer represents the most common cancer diagnosed in men, and each phase of tumor progression displays specific cellular conditions: inflammation is predominant in tumor's early stage, whereas oxidative stress is typical of clinically advanced PCa. The aim of this research is to assess the correspondence between the stimulus-specificity of STAT3 PTMs and definite STAT3-mediated transcriptional programs, in order to identify new suitable pharmacological targets for PCa treatment. Experiments were performed on less-aggressive LNCaP and more aggressive DU-145 cell lines, simulating inflammatory and oxidative-stress conditions. Cellular studies confirmed pY705-STAT3 as common denominator of all STAT3-mediated signaling. In addition, acK685-STAT3 was found in response to IL-6, whereas glutC328/542-STAT3 and pS727-STAT3 occurred upon tert-butyl hydroperoxyde (tBHP) treatment. Obtained results also provided evidence of an interplay between STAT3 PTMs and specific protein interactors such as P300 and APE1/Ref-1. In accordance with these outcomes, mRNA levels of STAT3-target genes seemed to follow the differing STAT3 PTMs. These results highlighted the role of STAT3 and its PTMs as drivers in the progression of PCa.
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http://dx.doi.org/10.3390/ijms20081815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6514970PMC
April 2019

Influence of Ellagitannins Extracted by Pomegranate Fruit on Disulfide Isomerase PDIA3 Activity.

Nutrients 2019 Jan 17;11(1). Epub 2019 Jan 17.

Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi di Roma "La Sapienza", Piazzale Aldo Moro, 5-00185 Roma, Italy.

Pomegranate fruit is a functional food of high interest for human health due to its wide range of phytochemicals with antioxidant properties are implicated in the prevention of inflammation and cancer. Ellagitannins, such as punicalagin and ellagic acid, play a role as anti-atherogenic and neuroprotective molecules in the complex fighting against the degenerative diseases. The aim of this work was to evaluate the composition in punicalagins and ellagic acid of differently obtained extracts from whole fruit, peels and juices, prepared by squeezing or by centrifugation, of pomegranate belonging to different cultivars. Moreover, a wider phenolic fingerprint was also determined. The bioactivity of the extracts was tested on the redox activity of PDIA3 disulfide isomerase, an enzyme involved in the regulation of several cellular functions and associated with different diseases such as cancer, prion disorders, Alzheimer's and Parkinson's diseases. The results demonstrate that the different ratios between punicalagin and ellagic acid modulate the enzyme activity and other ellagitannins could interfere with this activity.
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http://dx.doi.org/10.3390/nu11010186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356990PMC
January 2019

STAT3, a Hub Protein of Cellular Signaling Pathways, Is Triggered by β-Hexaclorocyclohexane.

Int J Mol Sci 2018 Jul 20;19(7). Epub 2018 Jul 20.

Department of Biochemical Sciences, A. Rossi Fanelli, Sapienza University, P.le A. Moro 5, 00185 Rome, Italy.

Background: Organochlorine pesticides (OCPs) are widely distributed in the environment and their toxicity is mostly associated with the molecular mechanisms of endocrine disruption. Among OCPs, particular attention was focused on the effects of β-hexaclorocyclohexane (β-HCH), a widely common pollutant. A detailed epidemiological study carried out on exposed population in the "Valle del Sacco" found correlations between the incidence of a wide range of diseases and the occurrence of β-HCH contamination. Taking into account the pleiotropic role of the protein signal transducer and activator of transcription 3 (STAT3), its function as a hub protein in cellular signaling pathways triggered by β-HCH was investigated in different cell lines corresponding to tissues that are especially vulnerable to damage by environmental pollutants.

Materials And Methods: Human prostate cancer (LNCaP), human breast cancer (MCF-7 and MDA-MB 468), and human hepatoma (HepG2) cell lines were treated with 10 μM β-HCH in the presence or absence of specific inhibitors for different receptors. All samples were subjected to analysis by immunoblotting and RT-qPCR.

Results And Conclusions: The preliminary results allow us to hypothesize the involvement of STAT3, through both its canonical and non-canonical pathways, in response to β-HCH. Moreover, we ascertained the role of STAT3 as a master regulator of energy metabolism via the altered expression and localization of HIF-1α and PKM2, respectively, resulting in a Warburg-like effect.
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http://dx.doi.org/10.3390/ijms19072108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073614PMC
July 2018

Punicalagin, an active pomegranate component, is a new inhibitor of PDIA3 reductase activity.

Biochimie 2018 Apr 6;147:122-129. Epub 2018 Feb 6.

Department of Biochemical Sciences, "A. Rossi Fanelli" and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University, P.le A. Moro 5, 00185, Rome, Italy. Electronic address:

Background: Polyphenolic compounds isolated from pomegranate fruit possess several pharmacological activities including anti-inflammatory, hepatoprotective, antigenotoxic and anticoagulant activities. The present work focuses the attention on PDIA3 interaction with punicalagin and ellagic acid, the most predominant components of pomegranate extracts. PDIA3, a member of the protein disulfide isomerase family involved in several cellular functions, is associated with different human diseases and it has the potential to be a pharmacological target.

Methods: The interaction of polyphenols with PDIA3 purified protein was explored by fluorescence quenching and calorimetric techniques and their effect on PDIA3 activity was investigated.

Results: A higher affinity was observed for punicalagin which also strongly affects PDIA3 reductase activity in vitro as a non-competitive inhibitor. Isothermal titration calorimetry confirmed the high affinity of punicalagin for PDIA3. Considering the PDIA3 involvement in oxidative cellular stress response observed in neuroblastoma cells after treatment with hydrogen peroxide, a comparative study was conducted to evaluate the effect of punicalagin on wild type and PDIA3-silenced cells. Punicalagin increases the cell sensitivity to hydrogen peroxide in neuroblastoma cells, but this effect is drastically reduced in PDIA3-silenced cells treated in the same experimental conditions.

Conclusions: Punicalagin binds PDIA3 and inhibits its redox activity. Comparative experiments conducted on unsilenced and PDIA3-silenced neuroblastoma cells suggest the potential of punicalagin to modulate PDIA3 reductase activity also in a biological model.

General Significance: Punicalagin can be used as a new PDIA3 inhibitor and this can provide information on the molecular mechanisms underlying the biological activities of PDIA3 and punicalagin.
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http://dx.doi.org/10.1016/j.biochi.2018.01.008DOI Listing
April 2018

Comparative Analysis of the Interaction between Different Flavonoids and PDIA3.

Oxid Med Cell Longev 2016 4;2016:4518281. Epub 2016 Dec 4.

Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University, P.le A. Moro 5, 00185 Rome, Italy; Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University, P.le A. Moro 5, 00185 Rome, Italy.

Flavonoids, plant secondary metabolites present in fruits, vegetables, and products such as tea and red wine, show antioxidant, anti-inflammatory, antithrombotic, antiviral, and antitumor activity. PDIA3 is a member of the protein disulfide isomerase family mainly involved in the correct folding of newly synthetized glycoproteins. PDIA3 is associated with different human pathologies such as cancer, prion disorders, Alzheimer's disease, and Parkinson's diseases and it has the potential to be a pharmacological target. The interaction of different flavonoids with PDIA3 was investigated by quenching fluorescence analysis and the effects on protein activity were evaluated. A higher affinity was observed for eupatorin-5-methyl ether and eupatorin which also inhibit reductase activity of PDIA3 but do not significantly affect its DNA binding activity. The use of several flavonoids differing in chemical structure and functional groups allows us to make some consideration about the relationship between ligand structure and the affinity for PDIA3. The specific flavone backbone conformation and the degree of polarity seem to play an important role for the interaction with PDIA3. The binding site is probably similar but not equivalent to that of green tea catechins, which, as previously demonstrated, can bind to PDIA3 and prevent its interaction with DNA.
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http://dx.doi.org/10.1155/2016/4518281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5164911PMC
March 2017