Paola Chiarugi, Ph.D

Present appointment:
Full Professor of Biochemistry.
Department of Biochemical Sciences,
University of Florence
Viale Morgagni 50,
50134 Firenze, Italy

tel: 00-11-39-055-4598343
fax: 00-11-39-055-4598905
paola.chiarugi@unifi.it

Actual position:
Paola Chiarugi is Full professor of Biochemistry in the Faculty of Medicine and Surgery at the University of Florence. She is member of the Excellence and Research Center for Tranfer and High Formation: Studies at Molecular and Clinical Level of Chronic, Inflamatory, Degenerative and Neoplastic Diseases.

Curriculum Vitae

Born in September 5th 1965 in Firenze. Married with two daughters.

1989: Degree in Biological Sciences to the University of Florence
1989-90: Assistant to The Department of Animal Biology and Genetics of the University of Florence
1990-1998: Assistant of Biological Chemistry in The Faculty of Medicine and Surgery of the University of Florence
1994: PhD in Biochemistry
1998: Specialist in Biochemistry and Clinical Chemistry
1998: Researcher of Biochemistry to the Faculty of Medicine and Surgery in the University of Florence
2001: Associate Professor in Biochemistry to the Faculty of Medicine and Surgery in the University of Florence
2005: Full Professor of Biochemistry in the University of Florence

Cell Signaling Members

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Paola Chiarugi Full Professor Group Leader	Tania Fiaschi PhD Technician	Maria Letizia Taddei PhD Post Doctoral Fellow
Giusy Comito Phd Student	Elisa Giannoni PhD Associate Professor	Maura Calvani Post Doctoral Fellow
Matteo Parri Phd Student	Domenico Cirelli Dr. Mag in Biotecnologie Mediche Borsista	Barbara Onnis Postdoctoral Fellow National Cancer Institute, NIH

Reactive Oxygen Species as Intracellular Messengers governing cell migration and proliferation

Oxygen radicals have been implicated in a number of conditions ranging from aging to atherosclerosis. Relatively little is known regarding how ROS like superoxide and hydrogen peroxide are regulated in cells and what specific aspects of cellular activity might be influenced by physiological and pathophysiological levels of these molecules. We are attempting to use a molecular biological approach to address these issues. It is our hope that we can gain a broader and more complete understanding of how cellular ROS are regulated. In addition, we are attempting to identify the direct molecular targets of cellular oxidants. Finally, we are hopeful that this molecular understanding will lead to new insights into disease states in which oxidant stress plays a role and help in the design of new therapeutic agents. Cancer cells can generate constitutively high levels of ROS, which are thought to promote cell proliferation, cell motility, invasion and angiogenesis, all of them prerequisites for tumor metastasis.

One of the main goal of this Lab is the study of the regulative role of reactive oxygen species (ROS) during cancer and invasive growth. The central role of oxygen species in integrin signaling suggests that ROS may contribute to malignant growth, through a deregulation of cell cell-cell/ matrix interaction and cell motility, by a regulation of gene expression and adaptation to oxidative stress and, finally, by an upregulation of neoangiogenesis processes. Although a general pro-carcinogenic effect of oxygen species has been long recognized, the potential function of oxygen species as intracellular mediators of invasiveness has been very little investigated so far. We are therefore interested in verifying the relevance of the ROS-dependent signaling pathways in the molecular genesis of invasive growth. We are now focusing on the redox regulation of LMW-PTP, SHP2, Src tyrosine kinase and of the cytoskeletal proteins actin and heavy chain myosin. This objective has two important implications: to provide a new theoretical framework for explaining the complex effects of pro and anti-oxidant agents on cell malignancy; and to offer a molecular rationale for the design and development of new redox-based anti cancer compounds, aimed to modulate critical steps of oncogenic signaling.

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Ephrin signal transduction pathways and function in normal and oncogenic development

The synchronized movement of cells and cell layers is a necessary process involved in determining vertebrate development, while abnormal cell migration and adhesion in adult organisms are trademarks of metastatic cancer progression. Eph-like receptors and their ligands called ‘ephrins’, are necessary in facilitating and directing the movement of cells during various developmental processes. While barely expressed in adult tissues except the central nervous system, Eph and ephrin expression is eminent in highly invasive breast, colon, lung and brain tumours, as well as leukemia and in malignant melanoma. Our laboratory searchs for elucidating the molecular mechanism by which Eph receptors affect cell adhesion and migration during embryogenesis and oncogenesis. Primary interests of my laboratory are the molecular mechanisms governing tumor metastasis, a frequently fatal phase of tumor progression in cancer patients. There are two key steps in tumor metastasis. One is tumor cell dissemination to a distal organ; the other is metastatic tumor cell development at the distal location. Cell motility plays a critical role in tumor cell dissemination. Ephrin kinases and their ephrin ligands transduce repulsion of cells in axon guidance, migration, invasiveness and tumor growth, exerting a negative signalling on cell proliferation and adhesion. A key role of their kinase activity has been confirmed by mutant kinase inactive receptors which shift the cellular response from repulsion to adhesion. Our present study is aimed to investigate the role of tyrosine phosphorylation of EphA2 kinase on repulsive cues. We recently demonstrated that LMW-PTP, by means of dephosphorylation of EphA2 kinase, negatively regulates the ephrinA1-mediated repulsive response, cell proliferation, cell adhesion and spreading, and the formation of retraction fibres, thereby confirming the relevance of the net level of tyrosine phosphorylation of Eph receptors. A second approach to the focus is the effect of single tyrosine substitution of EphA2 on the ephrinA1-mediated repulsive response, cell adhesion and spreading. The integration of both PTP-mediated and tyrosine mutants-mediated studies will permit a comprehensive picture of the tyrosine kinase dependent and independent responses.

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The influence of the hypoxic environment on tumour dissemination

The growing of solid tumour cells leads to a progressive decrease in oxygen concentration within in the inner part of the neoplasm. Normal and cancer cells react to low oxygen tension through the activation of hypoxia inducible factor (HIF), thereby controlling the expression of more than 70 genes linked to cell survival, angiogenesis, energy metabolism and tumour spreading. The major control of HIF functional state is exerted by prolyl-hydroxylase-domain proteins (PHD) classically acting as oxygen-sensor proteins. PHD has also recently been proposed as an intracellular redox state sensor. Indeed, growth factor and cytokines, as well as respiratory ROS, have been shown to mediate oxidation/inhibition of PHD, thus leading to HIF activity upregulation. The emerging picture is therefore that hypoxia and ROS can synergize in inducing HIF-mediated outcomes. In addition since PHD are oxoglutarate dependent, factors that vary the availability of oxoglutarate may contribute to PHD regulation and hence HIF biology. In this regard, mitochondrial GSH may modulate PHD through the mitochondrial transport of oxoglutarate in exchange from cytosol GSH. Interestingly hypoxia itself has been causally linked to an increase in intracellular/mitochondrial ROS, thereby stressing that hypoxic conditions could exert a powerful induction on HIF activity in tumours. Hypoxia is clinically associated with metastasis and poor patient outcome, although the underlying processes remain unclear. In ovarian carcinomas low oxygen conditions has been causally linked with EMT and the consequent acquisition of an invasive behaviour. Furthermore lysyl oxidase (LOX) and Snail-induced repression of E-cadherin have been implicated in the motile response stimulated by hypoxic conditions.

In this context in our laboratory we are investigating the specific role of the redox component of hypoxia-induced metastasis. Specifically we are taking into consideration the effect of hypoxia on:

tumour motility and invasive phenotype
the choice of transformed cells between the different opportunities of motility/invasion pathways, with particular focus on epithelial mesenchymal transition
cancer cell survival and resistance to anoikis within the primary and the secondary site of carcinogenesis
the redox regulation of motile and pro-survival proteins (including MMP and LOX expression, Akt/PKB activation, the BH3-only protein family, the transcription factors NFκB, Snail, Twist and FOXO, the small GTPases Rac, Rho, the tyrosine kinase Src and the cancer-related tyrosine phosphatases).

We are therefore carrying out studies on the identification of hypoxic ROS sources during cancer cell adhesion to ECM and motility and correlation with O2 pressure, as well as on the engagement of a motile and invasive phenotype of cancer cells in hypoxic conditions (between 0,1 and 3% O2) in models of human mammary and prostate carcinomas.

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Low Mw Protein tyrosine phosphatase function

The classic, tyrosine-specific PTPs are encoded by 40 genes in humans and belong to a big family of cysteine-based phosphatases. These cysteine-dependent phosphatases utilize a conserved 'C[X]5R’ sequence logo to hydrolyze phosphoester bonds in phospho-proteins (classical PTPs) and non-protein substrates (non-classical PTPs). They are divided into five categories on the basis of structural homology and substrate specificity: (i) classic, tyrosine-specific phosphatases (PTPs); (ii) dual-specificity phosphatases (DSPs); (iii) Cdc25 phosphatases; (iv) myotubularin-related; and (iv) low molecular weight phosphatases. We have studied for up to 10 years the structure-function relationship of tyrosine phosphatases mainly focusing on the low molecular weight phosphatases subfamily. Our studies contributed to the elucidation of the mechanism of action of these enzymes with mutagenesis techniques and then to the definition of their role in the control of cell proliferation, adhesion and motility. LMW-PTPs are a family of 18 kDa enzymes involved in cell growth regulation. Despite very limited sequence similarity to the PTP superfamily they display a conserved signature motif in the catalytic site. LMW-PTP associates and dephosphorylates many growth factors receptors as platelet derived growth factor receptor (PDGF-r), insulin receptor and ephrin receptor, thus down-regulating many of the tyrosine kinase receptor functions leading to cell division. In particular LMW-PTP acts on both growth factor-induced mitosis, through its dephosphorylation of activated PDGF-r and on cytoskeleton rearrangement through the dephosphorylation of p190RhoGAP and the consequent regulation of the small GTPase Rho. LMW-PTP activity is modulated by tyrosine phosphorylation on two specific residues, each of them with specific characteristics. LMW-PTP activity on specific substrates depends also on its different localization. Moreover, LMW-PTP is reversibly oxidized during growth factor signaling, leading to the inhibition of its enzymatic activity. The recovery of phosphatase activity depends upon the availability of reduced glutathione and involves the formation of an S-S bridge between the two catalytic site cysteines. Furthermore, studies on the redox state of LMW-PTP in contact-inhibited cells and in mature myoblasts propose LMW-PTP as a general and versatile modulator of growth inhibition. We are now focusing on the role of LMW-PTP in Ephrin receptor signaling in tumor development and in its role in the regulation of cell motility through dephosphorylation of the Src kinase.

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Metabolic and Non-Metabolic effects of adiponectin

Recently, our group focused on the study of adiponectin, an adipokine with antidiabetic and antiatherogenic activity. Adiponectin circulates in the plasma in both its globular and full length forms, associating in complex structures (trimers, hexamers and high molecular weight forms). Although the biological activities of Adiponectin are poorly understood, a decrease of plasma adiponectin content correlates with obesity, diabetes and insulin resistance, conditions that can be reversed in mice by the treatment with exogenous adiponectin. The physiological effects of the hormone on glucose and lipid metabolism are mediated by two receptors (AdipoR1 and AdipoR2) whose disruption abrogates adiponectin binding and metabolic actions. Adiponectin exerts its metabolic effects mainly in liver and skeletal muscle. In liver, adiponectin leads to reduced gluconeogenesis and increase of both glycogen synthesis and aerobic glucose consumption. Recently, in our laboratory we found that in hepatic cells the metabolic effects of globular adiponectin are linked to a transient burst of reactive oxygen species. This oxidant production leads to a ligand-independent trans-activation of insulin receptor and mediates the intracellular signalling and the metabolic effects of the globular adiponectin in liver. In muscle, globular adiponectin has been correlated to fatty acids oxidation, glucose uptake and lactate production. 5'-AMP-activated protein kinase (AMPK) constitutes a key signalling protein for the metabolic effect of adiponectin both in muscle (for glucose up-take, lactate production and inhibition of acetyl-Coenzyme A-carboxylase) and in liver (where AMPK activation is essential for the decrease of gluconeogenesis enzymes induced by adiponectin). Lately, we found that globular adiponectin is able to induce skeletal muscle differentiation in C2C12 murine myoblasts. The hormone undergoes an autocrine loop in differentiating myoblasts, leading to a clear increase in muscle lineage markers through a redox-dependent circuitry involving p38, Akt and AMPK signalling. Based on these recent findings we therefore plan to study the involvement of adiponectin in muscle regeneration. We are now studying the effect of adiponectin on two different stem cell populations: satellite cells, a muscle-resident cell population endowed with high stemness, and mesangioblasts, pluripotent stem cells isolated from dorsal aorta. Our preliminary data demonstrate that globular adiponectin induces proliferation and survival of both muscle- resident and non-resident stem cell populations, thus opening new avenues for adiponectin-mediated cell therapy of skeletal myopathies.

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Teaching

Paola Chiarugi teaches in the University of Florence:

Biochemistry and Molecular Biology I and II, for the Faculty of Medicine and Surgery I II
Biochemistry for the Biotechnology Degree in the Faculty of Physics, Mathematical and Natural Sciences
Cellular Biochemistry for the Medical Biotechnology Degree in the Faculty of Medicine and Surgery
Methods of cell cultures in the study of cell proliferation, senescence and apoptosis for the Medical Biotechnology Degree in the Faculty of Medicine and Surgery

Recent pubblications

Chiarugi, P., From anchorage-dependent proliferation to survival: lessons from redox signalling. IUMBM Life, 2008 in press.
Giannoni E, Buricchi F, Grimaldi, G., Parri, M., Cialdai, F., Taddei, M. L., Raugei G, Ramponi G, Chiarugi P. Redox regulation of anoikis: reactive oxygen species as essential mediators of cell survival. Cell Death and Digg. 2008 in press.
Fiaschi T, Buricchi F, Cozzi G, Matthias S, Parri M, Raugei G, Ramponi G, Chiarugi P. Redox-dependent and ligand-independent trans-activation of insulin receptor by globular adiponectin. Hepatology. 2007 Jul;46(1):130-9.
Lluis JM, Buricchi F, Chiarugi P, Morales A, Fernandez-Checa JC. Dual role of mitochondrial reactive oxygen species in hypoxia signaling: activation of nuclear factor-{kappa}B via c-SRC and oxidant-dependent cell death. Cancer Res. 2007 Aug 1;67(15):7368-77.
F.Buricchi, E.Giannoni, G.Grimaldi, M.Parri, G.Raugei, G. Ramponi, P.Chiarugi Redox regulation of ephrin/integrin cross-talk. Cell Adhesion & Migration, 2007, 1: 45-52.
Taddei ML, Parri M, Mello T, Catalano A, Levine AD, Raugei G, Ramponi G, Chiarugi P. Integrin-mediated cell adhesion and spreading engage different sources of reactive oxygen species. Antioxid Redox Signal. 2007 Apr;9(4):469-81.
Parri M, Buricchi F, Giannoni E, Grimaldi G, Mello T, Raugei G, Ramponi G, Chiarugi P. EphrinA1 activates a Src/focal adhesion kinase-mediated motility response leading to rho-dependent actino/myosin contractility. J Biol Chem. 2007 Jul 6;282(27):19619-28.
Fiaschi T, Cozzi G, Raugei G, Formigli L, Ramponi G, Chiarugi P. Redox regulation of beta-actin during integrin-mediated cell adhesion. J Biol Chem. 2006 Aug 11;281(32):22983-91. 2006 Jun 5.
Giannoni E, Raugei G, Chiarugi P, Ramponi G. A novel redox-based switch: LMW-PTP oxidation enhances Grb2 binding and leads to ERK activation. Biochem Biophys Res Commun. 2006 Sep 22;348(2):367-73. 2006 Jul 28.
Chiarugi P, Buricchi F. Protein Tyrosine Phosphorylation and Reversible Oxidation: Two Cross-Talking Posttranslation Modifications. Antioxid Redox Signal. 2007;9(1):1-24.
Chiarugi P, Fiaschi T. Redox signalling in anchorage-dependent cell growth. Cell Signal. 2007 Apr;19(4):672-82. Epub 2006 Nov 28.
Taddei ML, Parri M, Mello T, Catalano A, Levine AD, Raugei G, Ramponi G, Chiarugi P. Integrin-mediated cell adhesion and spreading engage different sources of reactive oxygen species. Antioxid Redox Signal. 2007;9(4):469-81.
Taddei ML, Chiarugi P, Cuevas C, Ramponi G, Raugei G., Oxidation and inactivation of low molecular weight protein tyrosine phosphatase by the anticancer drug Aplidin. Int J Cancer. 2005 Nov 14;
Parri M, Buricchi F, Taddei ML, Giannoni E, Raugei G, Ramponi G, Chiarugi P. EphrinA1 repulsive response is regulated by an EphA2 tyrosine phosphatase. J Biol Chem. 2005 Oct 7;280(40):34008-18.
Giannoni E, Buricchi F, Raugei G, Ramponi G, Chiarugi P. Intracellular reactive oxygen species activate Src tyrosine kinase during cell adhesion and anchorage-dependent cell growth. Mol Cell Biol. 2005 Aug;25(15):6391-403
P. Chiarugi, M. L. Taddei and G. Ramponi “Oxidation and tyrosine phosphorylation: synergistic or antagonistic cues in PTP regulation” Cell. Mol. Life Science2005 May;62(9):931-6.
P. Chiarugi. “ PTPs versus PTKs: the redox side of the coin” Free Radic. Res. 2005 Apr;39(4):353-64.
P. Chiarugi. E. Giannoni “Anchorage dependent cell growth: tyrosine kinases and phosphatases meet redox regulation” Antioxidant and Redox Signalling. 2005 May-Jun;7(5-6):578-92.
Cirri P, Taddei ML, Chiarugi P, Buricchi F, Caselli A, Paoli P, Giannoni E,
Camici G, Manao G, Raugei G, Ramponi G.
Insulin inhibits platelet-derived growth factor-induced cell proliferation.
Mol Biol Cell. 2005 Jan;16(1):73-83. Epub 2004 Nov 03.
Chiarugi P, Taddei ML, Schiavone N, Papucci L, Giannoni E, Fiaschi T,
Capaccioli S, Raugei G, Ramponi G.
LMW-PTP is a positive regulator of tumor onset and growth.
Oncogene. 2004 May 13;23(22):3905-14.
Fiaschi T, Chiarugi P, Buricchi F, Giannoni E, Taddei ML, Magnelli L, Cozzi
G, Raugei G, Ramponi G.
Down-regulation of platelet-derived growth factor receptor signaling during
myogenesis.
Cell Mol Life Sci. 2003 Dec;60(12):2721-35.
Chiarugi P, Cirri P.
Redox regulation of protein tyrosine phosphatases during receptor tyrosine
kinase signal transduction.
Trends Biochem Sci. 2003 Sep;28(9):509-14. Review.
Chiarugi P.
Reactive oxygen species as mediators of cell adhesion.
Ital J Biochem. 2003 Mar;52(1):28-32. Review.
Giannoni E, Chiarugi P, Cozzi G, Magnelli L, Taddei ML, Fiaschi T, Buricchi
F, Raugei G, Ramponi G.
Lymphocyte function-associated antigen-1-mediated T cell adhesion is impaired
by low molecular weight phosphotyrosine phosphatase-dependent inhibition of FAK
activity.
J Biol Chem. 2003 Sep 19;278(38):36763-76. Epub 2003 Jun 18.
Chiarugi P, Pani G, Giannoni E, Taddei L, Colavitti R, Raugei G, Symons M,
Borrello S, Galeotti T, Ramponi G.
Reactive oxygen species as essential mediators of cell adhesion: the oxidative
inhibition of a FAK tyrosine phosphatase is required for cell adhesion.
J Cell Biol. 2003 Jun 9;161(5):933-44.
Taddei ML, Chiarugi P, Cirri P, Buricchi F, Fiaschi T, Giannoni E, Talini D,
Cozzi G, Formigli L, Raugei G, Ramponi G.
Beta-catenin interacts with low-molecular-weight protein tyrosine phosphatase
leading to cadherin-mediated cell-cell adhesion increase.
Cancer Res. 2002 Nov 15;62(22):6489-99.
Raugei G, Ramponi G, Chiarugi P.
Low molecular weight protein tyrosine phosphatases: small, but smart.
Cell Mol Life Sci. 2002 Jun;59(6):941-9. Review.
Chiarugi P, Cirri P, Taddei ML, Giannoni E, Fiaschi T, Buricchi F, Camici
G, Raugei G, Ramponi G.
Insight into the role of low molecular weight phosphotyrosine phosphatase
(LMW-PTP) on platelet-derived growth factor receptor (PDGF-r) signaling. LMW-PTP
controls PDGF-r kinase activity through TYR-857 dephosphorylation.
J Biol Chem. 2002 Oct 4;277(40):37331-8. Epub 2002 Jul 30.
Chiarugi P, Cirri P, Taddei ML, Talini D, Doria L, Fiaschi T, Buricchi F,
Giannoni E, Camici G, Raugei G, Ramponi G.
New perspectives in PDGF receptor downregulation: the main role of
phosphotyrosine phosphatases.
J Cell Sci. 2002 May 15;115(Pt 10):2219-32.
Chiarugi P.
The redox regulation of LMW-PTP during cell proliferation or growth inhibition.
IUBMB Life. 2001 Jul;52(1-2):55-9. Review.
Fiaschi T, Chiarugi P, Buricchi F, Giannoni E, Taddei ML, Talini D, Cozzi
G, Zecchi-Orlandini S, Raugei G, Ramponi G.
Low molecular weight protein-tyrosine phosphatase is involved in growth
inhibition during cell differentiation.
J Biol Chem. 2001 Dec 28;276(52):49156-63. Epub 2001 Oct 10.
Chiarugi P, Fiaschi T, Taddei ML, Talini D, Giannoni E, Raugei G, Ramponi
G.
Two vicinal cysteines confer a peculiar redox regulation to low molecular
weight protein tyrosine phosphatase in response to platelet-derived growth
factor receptor stimulation.
J Biol Chem. 2001 Sep 7;276(36):33478-87. Epub 2001 Jun 27.
Taddei ML, Chiarugi P, Cirri P, Talini D, Camici G, Manao G, Raugei G,
Ramponi G.
LMW-PTP exerts a differential regulation on PDGF- and insulin-mediated
signaling.
Biochem Biophys Res Commun. 2000 Apr 13;270(2):564-9.
Chiarugi P, Taddei ML, Cirri P, Talini D, Buricchi F, Camici G, Manao G,
Raugei G, Ramponi G.
Low molecular weight protein-tyrosine phosphatase controls the rate and the
strength of NIH-3T3 cells adhesion through its phosphorylation on tyrosine 131
or 132.
J Biol Chem. 2000 Dec 1;275(48):37619-27.
Fiaschi T, Chiarugi P, Veggi D, Raugei G, Ramponi G.
The inhibitory effect of the 5' untranslated region of muscle acylphosphatase
mRNA on protein expression is relieved during cell differentiation.
FEBS Lett. 2000 May 4;473(1):42-6.
Chiarugi P, Cirri P, Taddei L, Giannoni E, Camici G, Manao G, Raugei G,
Ramponi G.
The low M(r) protein-tyrosine phosphatase is involved in Rho-mediated
cytoskeleton rearrangement after integrin and platelet-derived growth factor
stimulation.
J Biol Chem. 2000 Feb 18;275(7):4640-6.

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Downloads

Biochimica per Biotecnologie
Biochimica e Biologia Molecolare per Medicina e Chirurgia - I
Biochimica e Biologia Molecolare per Medicina e Chirurgia - II
Biochimica Cellulare per Biotecnologie Mediche
Tecniche di Biochimica Cellulare
per la Laurea in Biotecnologie Mediche della Facoltà di Medicina e Chirurgia

Collaborations

Alan D. Levine, Ph.D. , Case Western Reserve University, Cleveland Ohio, USA

Martin Lackmann, Ludwig Institute for Cancer Research, Melbourne Australia

Tommaso Galeotti, Istituto di Patologia Generale, Università Cattolica
Sacro Cuore, Rome, Italy

Franca Esposito, Dipartimento di Biochimica e Biotecnologie Mediche, Universita di Napoli Federico II, Naples, Italy

Useful Resource

Free software for :

image viewing: Imagej, Confocal Assistant
protein 3d structure analyisis: SwissPDB viewer
sequence analysis: Bioedit