Publications by authors named "Lucia Barazzuol"

8 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

A split-GFP tool reveals differences in the sub-mitochondrial distribution of wt and mutant alpha-synuclein.

Cell Death Dis 2019 11 12;10(11):857. Epub 2019 Nov 12.

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

Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by dopaminergic neuronal loss that initiates in the substantia nigra pars compacta and by the formation of intracellular inclusions mainly constituted by aberrant α-synuclein (α-syn) deposits known as Lewy bodies. Most cases of PD are sporadic, but about 10% are familial, among them those caused by mutations in SNCA gene have an autosomal dominant transmission. SNCA encodes α-syn, a small 140-amino acids protein that, under physiological conditions, is mainly localized at the presynaptic terminals. It is prevalently cytosolic, but its presence has been reported in the nucleus, in the mitochondria and, more recently, in the mitochondria-associated ER membranes (MAMs). Whether different cellular localizations may reflect specific α-syn activities is presently unclear and its action at mitochondrial level is still a matter of debate. Mounting evidence supports a role for α-syn in several mitochondria-derived activities, among which maintenance of mitochondrial morphology and modulation of complex I and ATP synthase activity. α-syn has been proposed to localize at the outer membrane (OMM), in the intermembrane space (IMS), at the inner membrane (IMM) and in the mitochondrial matrix, but a clear and comparative analysis of the sub-mitochondrial localization of WT and mutant α-syn is missing. Furthermore, the reasons for this spread sub-mitochondrial localization under physiological and pathological circumstances remain elusive. In this context, we decided to selectively monitor the sub-mitochondrial distribution of the WT and PD-related α-syn mutants A53T and A30P by taking advantage from a bimolecular fluorescence complementation (BiFC) approach. We also investigated whether cell stress could trigger α-syn translocation within the different mitochondrial sub-compartments and whether PD-related mutations could impinge on it. Interestingly, the artificial targeting of α-syn WT (but not of the mutants) to the mitochondrial matrix impacts on ATP production, suggesting a potential role within this compartment.
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http://dx.doi.org/10.1038/s41419-019-2092-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6851186PMC
November 2019

ER-Mitochondria Calcium Transfer, Organelle Contacts and Neurodegenerative Diseases.

Adv Exp Med Biol 2020 ;1131:719-746

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

It is generally accepted that interorganellar contacts are central to the control of cellular physiology. Virtually, any intracellular organelle can come into proximity with each other and, by establishing physical protein-mediated contacts within a selected fraction of the membrane surface, novel specific functions are acquired. Endoplasmic reticulum (ER) contacts with mitochondria are among the best studied and have a major role in Ca and lipid transfer, signaling, and membrane dynamics.Their functional (and structural) diversity, their dynamic nature as well as the growing number of new players involved in the tethering concurred to make their monitoring difficult especially in living cells. This review focuses on the most established examples of tethers/modulators of the ER-mitochondria interface and on the roles of these contacts in health and disease by specifically dissecting how Ca transfer occurs and how mishandling eventually leads to disease. Additional functions of the ER-mitochondria interface and an overview of the currently available methods to measure/quantify the ER-mitochondria interface will also be discussed.
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http://dx.doi.org/10.1007/978-3-030-12457-1_29DOI Listing
October 2019

splitGFP Technology Reveals Dose-Dependent ER-Mitochondria Interface Modulation by α-Synuclein A53T and A30P Mutants.

Cells 2019 09 12;8(9). Epub 2019 Sep 12.

Department of Biology, University of Padova, Padova 35131, Italy.

Familial Parkinson's disease (PD) is associated with duplication or mutations of α-synuclein gene, whose product is a presynaptic cytosolic protein also found in mitochondria and in mitochondrial-associated ER membranes. We have originally shown the role of α-syn as a modulator of the ER-mitochondria interface and mitochondrial Ca transients, suggesting that, at mild levels of expression, α-syn sustains cell metabolism. Here, we investigated the possibility that α-syn action on ER-mitochondria tethering could be compromised by the presence of PD-related mutations. The clarification of this aspect could contribute to elucidate key mechanisms underlying PD. The findings reported so far are not consistent, possibly because of the different methods used to evaluate ER-mitochondria connectivity. Here, the effects of the PD-related α-syn mutations A53T and A30P on ER-mitochondria relationship were investigated in respect to Ca handling and mitochondrial function using a newly generated SPLICS sensor and aequorin-based Cameasurements. We provided evidence that A53T and A30P amino acid substitution does not affect the ability of α-syn to enhance ER/mitochondria tethering and mitochondrial Ca transients, but that this action was lost as soon as a high amount of TAT-delivered A53T and A30P α-syn mutants caused the redistribution of α-syn from cytoplasm to foci. Our results suggest a loss of function mechanism and highlight a possible connection between α-syn and ER-mitochondria Ca cross-talk impairment to the pathogenesis of PD.
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http://dx.doi.org/10.3390/cells8091072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769576PMC
September 2019