Enzo Martegani

Enzo Martegani
Università degli Studi di Milano-Bicocca | UNIMIB · Department of Biotechnology and Biosciences

Professor of Molecular Biology

About

206
Publications
12,825
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
5,549
Citations
Additional affiliations
January 2006 - December 2008
Universidade Federal de Ouro Preto
Description
  • Joint research project on phosphoinositol signaling in yeast
January 2000 - present
Università degli Studi di Milano-Bicocca
Position
  • Professor
January 1993 - December 1994
Ecole Polytechnique, France

Publications

Publications (206)
Article
In Saccharomyces cerevisiae, the protein kinase A (PKA) plays a central role in the control of metabolism, stress resistance and cell cycle progression. In a previous work, we used a FRET-based A-kinase activity reporter (AKAR3 probe) to monitor changes in PKA activity in vivo in single S. cerevisiae cells. Since this procedure is quite complex and...
Article
Full-text available
RalGPS2 is a Ras-independent Guanine Nucleotide Exchange Factor for RalA GTPase that is involved in several cellular processes, including cytoskeletal organization. Previously, we demonstrated that RalGPS2 also plays a role in the formation of tunneling nanotubes (TNTs) in bladder cancer 5637 cells. In particular, TNTs are a novel mechanism of cell...
Preprint
Full-text available
In previous papers, using the eGFP-RBD3 probe, which binds Ras-GTP with high affinity, we showed that activated Ras proteins are localized to the plasma membrane and in the nucleus in wild-type Saccharomyces cerevisiae cells growing exponentially on glucose, while an aberrant accumulation of activated Ras in mitochondria correlates to mitochondrial...
Article
Full-text available
Caloric restriction mimetics (CRMs) are promising molecules to prevent age-related diseases as they activate pathways driven by a true caloric restriction. Hydroxycitric acid (HCA) is considered a bona fide CRM since it depletes acetyl-CoA pools by acting as a competitive inhibitor of ATP citrate lyase (ACLY), ultimately repressing protein acetylat...
Article
In previous papers we showed that activated Ras proteins are localized to the plasma membrane and in the nucleus in wild-type yeast cells growing exponentially on glucose, while an aberrant accumulation of activated Ras in mitochondria correlated to mitochondrial dysfunction, accumulation of ROS and regulated cell death. Here we show that also in a...
Article
Full-text available
Spermatids are haploid differentiating cells that, in the meantime they differentiate, translocate along the seminiferous epithelium towards the tubule lumen to be just released as spermatozoa. The success of such a migration depends on dynamic of spermatid–Sertoli cell contacts, the molecular nature of which has not been well defined yet. It was d...
Article
Full-text available
Aspirin and its main metabolite salicylate are promising molecules in preventing cancer and metabolic diseases. S. cerevisiae cells have been used to study some of their effects: (i) salicylate induces the reversible inhibition of both glucose transport and the biosyntheses of glucose-derived sugar phosphates, (ii) Aspirin/salicylate causes apoptos...
Article
Full-text available
Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing....
Article
Full-text available
Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing....
Article
RalGPS2 is a Ras-independent Guanine Nucleotide Exchange Factor (GEF) for RalA containing a PH domain and an SH3-bindind region and it is involved in several cellular processes, such as cytokinesis, control of cell cycle progression, differentiation, cytoskeleton organization and rearrangement. Up to now, few data have been published regarding RalG...
Article
In Saccharomyces cerevisiae the second messenger cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) play a central role in metabolism regulation, stress resistance and cell cycle progression. To monitor cAMP levels and PKA activity in vivo in single S. cerevisiae cells, we expressed an Epac-based FRET probe and a FRET-based A-kinase a...
Article
We recently showed that in hxk2Δ cells, showing constitutive localization of active Ras at the mitochondria, addition of acetic acid caused an increase of both apoptotic and necrotic cells compared with the wild type strain, providing a new role for hexokinase 2 (EC 2.7.1.1) as an antiapoptotic factor, besides its known role as a glycolytic enzyme...
Article
Full-text available
Ribosome-inactivating proteins (RIPs) are either single-chain (type 1) or two-chain (type 2) toxins. They are toxic to eukaryotic cells by cleaving a N-glycosidic bond in an extremely conserved loop located in the 28S RNA. This releases a specific adenine and inactivates the ribosome, ultimately inhibiting protein synthesis. Plant RIPs have been in...
Article
Full-text available
To investigate the specific target of PKA in the regulation of cell cycle progression and cell size we developed a new approach using the yeast strain GG104 bearing a deletion in adenylate cyclase gene and permeable to cAMP ( cyr1Δ, pde2Δ, msn2Δ, msn4Δ). In this strain the PKA activity is absent and can be activated by addition of cAMP in the mediu...
Article
The relationship between the positioning of ligands on the surface of nanoparticles and the structural features of nanoconjugates has been underestimated for a long time albeit of primary importance to promote specific biological recognition at the nanoscale. In particular, it has been formerly observed that a proper molecular orientation can play...
Article
The tropomyosin-related kinase (Trk) family of receptor tyrosine kinases controls synaptic function, plasticity and sustains differentiation, morphology, and neuronal cell survival. Understanding Trk receptors down-regulation and recycling is a crucial step to point out sympathetic and sensory neurons function and survival. PC12 cells derived from...
Article
This protocol describes the use of the jellyfish Aequorea victoria aequorin protein to measure Ca(2+) levels in living yeast cells. All yeast strains to be analyzed must express the A. victoria apoprotein of the aequorin calcium biosensor, to be reconstituted into fully active aequorin by association with its cofactor, coelenterazine, which cannot...
Article
A photoelectric flame photometer is a device used in inorganic chemical analysis for determining the concentrations of certain metals in solution. It does this by measuring the intensity of the light emitted by the metal when the solution is sprayed under controlled conditions into a nonluminous flame. This protocol describes how to measure total c...
Article
This protocol describes how to measure calcium uptake in yeast by (45)Ca radioactive isotope incorporation. © 2015 Cold Spring Harbor Laboratory Press.
Article
Dependance of the initial rate of hypotonic shock-induced (HTS) cytosolic calcium concentration increase upon extracellular free calcium concentration in the wild-type (left) or in the flc2(strain (right). Flc2 is a TRP-like channel localized in the ER and plasma membrane with close similarity to N. crassa spray protein and far similarity to mammal...
Article
Data in literature suggest that budding yeast adenylate cyclase forms a membrane-associated complex with the upstream components of the cAMP/PKA pathway. Here we provide evidences that adenylate cyclase (Cyr1p) acts as a scaffold protein keeping Ras2 available for its regulatory factors. We show that in a strain with deletion of the CYR1 gene (cyr1...
Article
Full-text available
For centuries yeast species have been popular hosts for classical biotechnology processes, such as baking, brewing, and wine making, and more recently for recombinant proteins production, thanks to the advantages of unicellular organisms (i.e., ease of genetic manipulation and rapid growth) together with the ability to perform eukaryotic posttransl...
Article
Full-text available
Ras proteins were highly conserved during evolution. They function as a point of convergence for different signalling pathways in eukaryotes and are involved in a wide range of cellular responses (shift from gluconeogenic to fermentative growth, breakdown of storage carbohydrates, stress resistance, growth control and determination of life span, mo...
Article
The third edition of the Handbook of Proteolytic Enzymes aims to be a comprehensive reference work for the enzymes that cleave proteins and peptides, and contains over 800 chapters. Each chapter is organized into sections describing the name and history, activity and specificity, structural chemistry, preparation, biological aspects, and distinguis...
Article
Full-text available
Using an eGFP-RBD3 probe, which specifically binds Ras-GTP, we recently showed that the fluorescent probe was localized to the plasma membrane and to the nucleus in wild type cells growing exponentially on glucose medium, indicating the presence of active Ras in these cellular compartments. To investigate the nuclear function of Ras-GTP, we generat...
Article
Full-text available
We recently showed that activated Ras proteins are localized to the plasma membrane and in the nucleus in wild-type cells growing exponentially on glucose, while in the hxk2 Δ strain they accumulated mainly in mitochondria. An aberrant accumulation of activated Ras in these organelles was previously reported and correlated to mitochondrial dysfunct...
Article
Ras proteins function as a point of convergence for different signalling pathways in eukaryotes and are involved in many cellular responses; their different subcellular locations could regulate distinct functions. To investigate the localization of active Ras in vivo in Saccharomyces cerevisiae, we expressed a probe consisting of a GFP fusion with...
Article
Full-text available
In the yeast Saccharomyces cerevisiae, the Ras/cAMP/PKA pathway is involved in the regulation of cell growth and proliferation in response to nutritional sensing and stress conditions. The pathway is tightly regulated by multiple feedback loops, exerted by the protein kinase A (PKA) on a few pivotal components of the pathway. In this article, we in...
Article
In Saccharomyces cerevisiae, cAMP/pKA pathway plays a major role in metabolism, stress resistance and proliferation control. cAMP is produced by adenylate cyclase, which is activated both by Gpr1/Gpa2 system and Ras proteins, regulated by Cdc25/Sdc25 guanine exchange factors and Ira GTPase activator proteins. Recently, both Ras2 and Cdc25 RasGEF we...
Article
In Saccharomyces cerevisiae the Cdc25/Ras/cAMP pathway is involved in cell growth and proliferation regulation. Ras proteins are regulated by Ira1/2 GTPase activating proteins (GAPs) and Cdc25/Sdc25 guanine nucleotide exchange factors (GEFs). Most of cytosolic Cdc25 protein was found on internal membranes in exponentially growing cells, while upon...
Article
Previous work from our laboratories demonstrated that the sugar-induced activation of plasma membrane H(+)-ATPase in Saccharomyces cerevisiae is dependent on calcium metabolism with the contribution of calcium influx from external medium. Our results demonstrate that a glucose-induced calcium (GIC) transporter, a new and still unidentified calcium...
Article
In the yeast Saccharomyces cerevisiae, the Ras/cAMP/PKA pathway plays a major role in the regulation of metabolism, stress resistance and cell cycle progression. We extend here a mechanistic model of the Ras/cAMP/PKA pathway that we previously defined by describing the molecular interactions and post-translational modifications of proteins, and per...
Article
Glucose addition to glucose-starved Saccharomyces cerevisiae cells triggers a quick and transient influx of calcium from the extracellular environment. In yeast at least two different carrier systems were identified: a high affinity system, requiring Cch1 channel, and a low affinity system. Here we report that another calcium transport system exist...
Article
The β-amyloid peptide is generated by the proteolysis of the amyloid precursor protein (APP) by the action of β- and γ-secretase. The mechanisms underlying this process are poorly understood. Using a cell-based reporter gene assay we analysed the possible signals and pathways that could be involved in APP cleavage. We used the stable cell line HeLa...
Article
Full-text available
This paper reports the synthesis of a panel of small molecules with arylamides and arylsulfonamides groups and their biological activity in inhibiting nucleotide exchange on human Ras. The design of these molecules was guided by experimental and molecular modelling data previously collected on similar compounds. Aim of this work is the validation o...
Article
Full-text available
This paper reports the synthesis of a panel of small molecules with arylamides and arylsulfonamides groups and their biological activity in inhibiting nucleotide exchange on human Ras. The design of these molecules was guided by experimental and molecular modelling data previously collected on similar compounds. Aim of this work is the validation o...
Article
RalGPS2 is a guanine nucleotide exchange factor for RalA GTPase characterized by a C-terminal Pleckstrin Homology (PH) domain; this GEF is endogenously expressed in PC12 cells and in rat brain but its role in PC12 cells and in cell differentiation is actually unknown. Here we have shown that transient expression of RalGPS2-PH-PxxP domain in PC12 an...
Article
Mutation of RAS genes is a critical event in the pathogenesis of different human tumors and in some developmental disorders. Here we present an arabinose-derived bicyclic compound displaying selective cytotoxicity in human colorectal cancer cells expressing K-Ras(G13D), that shows high intrinsic nucleotide exchange rate. We characterize binding of...
Article
Full-text available
Elucidating the mechanisms by which eukaryotic cells coordinate environmental signals with intracellular ;fate' decisions, such as apoptosis, remains one of the important challenges facing cell biologists. It has recently emerged that the dynamic nature of the actin cytoskeleton is an important factor in the linkage of sensation of extracellular st...
Article
A panel of new potential Ras ligands was generated by decorating a tricyclic levoglucosenone-derived scaffold with aromatic moieties. Some members of the panel show in vitro inhibitory activity toward the nucleotide exchange process on Ras and are toxic to some human cancer cell lines.
Article
The mechanisms regulating the activity of Saccharomyces cerevisiae Ras-GEF Cdc25 are still largely unknown. While the catalytical function of the C-terminal domain has been thoroughly studied, only recently a role of negative control on the protein activity has been suggested for the dispensable N-terminal domain. In order to investigate Cdc25 loca...
Article
Full-text available
The brain-specific Ras guanine nucleotide exchange factor RasGRF1 is a protein harbouring a complex array of structural motifs. It contains a pleckstrin homology (PH1) domain, a coiled coil region (CC) and an ilimaquinone (IQ) one in addition to the catalytic Ras and Rac exchange factor domains. In this study, we used the recombinant N-terminal PH1...
Article
Full-text available
We have applied transcriptomic and proteomic techniques to identify changes in the RNA and the protein levels in the mouse cerebellum after chronic treatment with Delta(9)-tetrahydrocannabinol (THC). Among approximately 14,000 transcripts in a mouse cDNA microarray library, we found 11 genes with altered expression. RasGRF1, a neuron-specific Ras g...
Article
The plasma membrane H(+)-ATPase from Saccharomyces cerevisiae is an enzyme that plays a very important role in the yeast physiology. The addition of protonophores, such as 2,4-dinitrophenol (DNP) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), also triggers a clear in vivo activation of this enzyme. Here, we demonstrate that CCCP-induced activ...
Article
Full-text available
Analysis of the structure of nerve growth factor (NGF)-tyrosine kinase receptor A (TrkA) complex, site-directed mutagenesis studies and results from chemical modification of amino acid residues have identified loop 1, loop 4, and the N-terminal region of the NGF molecule as the most relevant for its biological activity. We synthesized several pepti...
Article
Full-text available
Autophosphorylation of tyrosine residues on the cytoplasmic tail of the epidermal growth factor receptor (EGFR) upon ligand binding leads to recruitment of the Grb2/Sos complex to the activated receptor and to activation of the Ras pathway. The major aim of this study was to ascertain to which extent the EGFR module (receptor, Grb2, hSos1) could wo...
Article
In the yeast Saccharomyces cerevisiae, the Ras/cAMP/PKA pathway is involved in the regulation of metabolism and cell cycle progression. The pathway is tightly regulated by several control mechanisms, as the feedback cycle ruled by the activity of phosphodiesterase. Here, we present a discrete mathematical model for the Ras/cAMP/PKA pathway that con...
Article
The Saccharomyces cerevisiae CDC25 gene encodes a guanine nucleotide exchange factor for Ras proteins whose catalytic domain is highly homologous to Ras-guanine nucleotide exchange factors from higher eukaryotes. In this study, glucose-induced Ras activation and cAMP response were investigated in mutants lacking the N-terminal domain of Cdc25 or wh...
Article
Too complex to change. New glucose-derived phenylhydroxylamines inhibit nucleotide exchange on human Ras. NMR and SPR experiments indicated that the Ras-GEF interaction is inhibited when the Ras-ligand complex is formed. (Chemical Equation Presented).
Article
RalGPS2 is a murine guanine nucleotide exchange factor of the RalGPS family; it contains a Cdc25-like GEF domain and does not exhibit a Ras-binding domain. The main characteristic of RalGPS2 is its pleckstrin homology (PH) domain, present at the C terminus, that preferentially binds phosphatidylinositol-4,5-biphosphate and in HEK 293 cells localize...
Article
Novel inhibitors of Ras protein activation have been found, containing a bicyclic core derived from D-arabinose and benzyl and phenylhydroxylamine moieties. NMR studies (trNOE, saturation-transfer difference, STD) of the binding between these molecules and human p21 h-Ras are reported. A pharmacophore mapping indicates that both the benzyl and the...
Article
In this work, we show that glucose-induced activation of plasma membrane H(+)-ATPase from Saccharomyces cerevisiae is strongly dependent on calcium metabolism and that the glucose sensor Snf3p works in a parallel way with the G protein Gpa2p in the control of the pathway. The role of Snf3p is played by the Snf3p C-terminal tail, since in a strain w...
Article
In the yeast Saccharomyces cerevisiae, the Cdc25/Ras/cAMP/protein kinase A (PKA) pathway plays a major role in the control of metabolism, stress resistance and proliferation, in relation to the available nutrients and conditions. The budding yeast RasGEF Cdc25 was the first RasGEF to be identified in any organism, but very little is known about its...
Article
Full-text available
Recombinant human nerve growth factor (rhNGF) is regarded as the most promising therapy for neurodegeneration of the central and peripheral nervous systems as well as for several other pathological conditions involving the immune system. However, rhNGF is not commercially available as a drug. In this work, we provide data about the production on a...
Article
The design and synthesis of novel Ras inhibitors with a bicyclic scaffold derived from the natural sugar D-arabinose are presented. Molecular modelling showed that these ligands can bind Ras by accommodating the aromatic moieties and the phenylhydroxylamino group in a cavity near the Switch II region of the protein. All the synthetic compounds were...
Article
A new procedure to determine the durations of cell cycle phases is based on th autoradiography of labeled nuclei and a standard chemical determination of DNA content per cell. It has been used to study the cell cycle timing of a human established cell line, EUE cells, so far poorly characterized in its kinetic aspects. The cycle phase durations obt...
Article
The mouse USP8/mUBPy gene codifies a deubiquitinating enzyme expressed preferentially in testis and brain. While the ubiquitin-specific processing proteases (UBPs) are known to be important for the early development in invertebrate organisms, their specific functions remain still unclear in mammals. Using specific antibodies, raised against a recom...
Article
The Ras proteins, which regulate intracellular signaling by a cyclic process involving interconversion between active GTP-bound and inactive GDP-bound states, play an essential role in controlling the activity of several crucial signaling pathways regulating normal cellular proliferation. Mutational activation of RAS genes can induce cancer in huma...
Article
Full-text available
The activity of adenylate cyclase in the yeast Saccharomyces cerevisiae is controlled by two G-protein systems, the Ras proteins and the Gα protein Gpa2. Glucose activation of cAMP synthesis is thought to be mediated by Gpa2 and its G-protein-coupled receptor Gpr1. Using a sensitive GTP-loading assay for Ras2 we demonstrate that glucose addition al...