Latest PUBLICATIONS

  • Gene expression in the squid giant axon: neurotransmitter modulation of RNA transfer from periaxonal glia to the axon.
    Publication Date: 01/10/2002, on The Biological bulletin
    by Giuditta A, Eyman M, Kaplan BB
    DOI: 10.2307/1543389

  • Molecular epidemiology of Stenotrophomonas maltophilia in a university hospital.
    Publication Date: 01/10/2002, on The Journal of hospital infection
    by Crispino M, Boccia MC, Bagattini M, Villari P, Triassi M, Zarrilli R
    DOI:

    The aim of this investigation was to study the molecular epidemiology of Stenotrophomonas maltophilia in a university hospital in Italy. Sixty-one clinical isolates were collected from 43 patients during a two-year period. The majority of specimens were from the respiratory tract (41 of 43) of patients in the adult intensive care unit (ICU) (19 of 43) or cystic fibrosis (CF) patients (13 of 43). Genotypic analysis by pulsed-field gel electrophoresis (PFGE) of clinical isolates identified 31 different PFGE patterns. Although most patients were infected or colonized by different S. maltophilia clones, clones with identical genotype were isolated in patients from ICU, where two separate outbreaks were identified. Antimicrobial susceptibility identified a multi-resistant phenotype in all S. maltophilia PFGE clones. The majority of PFGE clones identified (six of seven clones from patients in the ICU) were susceptible to fluoroquinolones. Mechanical ventilation was associated with S. maltophilia acquisition in the ICU.

  • Solution structure of nociceptin peptides.
    Publication Date: 01/09/2002, on Journal of peptide science : an official publication of the European Peptide Society
    by Amodeo P, Guerrini R, Picone D, Salvadori S, Spadaccini R, Tancredi T, Temussi PA
    DOI: 10.1002/psc.412

    Peptides embedded in the sequence of pre-pro-nociceptin, i.e. nociceptin, nocistatin and orphanin FQ2, have shed light on the complexity of the mechanisms involving the peptide hormones related to pain and have opened up new perspectives for the clinical treatment of pain. The design of new ligands with high selectivity and bioavailability, in particular for ORL1, is important both for the elucidation and control of the physiological role of the receptor and for their therapeutic importance. The failure to obtain agonists and antagonists when using, for nociceptin, the same substitutions that are successful for opioids, and the conformational flexibility of them all, justify systematic efforts to study the solution conformation under conditions as close as possible to their natural environment. Structural studies of linear peptides in solution are hampered by their high flexibility. A direct structural study of the complex between a peptide and its receptor would overcome this difficulty, but such a study is not easy since opioid receptors are membrane proteins. Thus, conformational studies of lead peptides in solution are still important for drug design. This review deals with conformational studies of natural pre-nociceptin peptides in several solvents that mimic in part the different environments in which the peptides exert their action. None of the structural investigations yielded a completely reliable bioactive conformation, but the global conformation of the peptides in biomimetic environments can shed light on their interaction with receptors.

  • Axonal and presynaptic protein synthesis: new insights into the biology of the neuron.
    Publication Date: 01/08/2002, on Trends in neurosciences
    by Giuditta A, Kaplan BB, van Minnen J, Alvarez J, Koenig E
    DOI:

    The presence of a local mRNA translation system in axons and terminals was proposed almost 40 years ago. Over the ensuing period, an impressive body of evidence has grown to support this proposal -- yet the nerve cell body is still considered to be the only source of axonal and presynaptic proteins. To dispel this lingering neglect, we now present the wealth of recent observations bearing on this central idea, and consider their impact on our understanding of the biology of the neuron. We demonstrate that extrasomatic translation sites, which are now well recognized in dendrites, are also present in axonal and presynaptic compartments.

  • Ontogeny of kainate receptor gene expression in the developing rat midbrain and striatum.
    Publication Date: 15/07/2002, on Brain research. Molecular brain research
    by Lilliu V, Perrone-Capano C, Pernas-Alonso R, Diaz Trelles R, Luca Colucci d'Amato G, Zuddas A, di Porzio U
    DOI:

    Kainate (KA) receptors are a family of ionotropic glutamate receptors, which mediate the excitatory synaptic transmission in various areas of the mammalian CNS. We have studied the expression pattern of the genes encoding for KA receptor subunits (Glur5-1, Glur5-2, Glur6, Glur7, KA1 and KA2) in rat prenatal (E), postnatal and adult ventral mesencephalon (MES) and striatum (STR) and in fetal midbrain primary cultures. Each receptor subunit shows a unique area- and temporal-expression pattern. In MES the onset of both Glur5 subunits is delayed when compared to the other subunits. In addition, most of the transcripts for KA subunits gradually increase during embryonic development and show a slight decrease during the first postnatal week. Differently, Glur6 and KA2 mRNAs show a sharp increase at E14.5 and decrease thereafter, reaching the lowest levels during late embryonic and postnatal development. In the STR, the gene expression of all KA subunit mRNAs is higher during embryonic development than after birth, except KA1 transcripts, that show a peak at P5. In embryonic MES primary cultures, Glur5-2, Glur6 and KA2 mRNAs are higher at the beginning of the culture when compared to older cultures, while the other subunit mRNAs do not show significant variation throughout the days in vitro. Thus, all the KA receptor subunit transcripts appear independently regulated during MES and STR development, probably contributing to the establishment of the fine tuning of the excitatory circuits reciprocally established between these CNS areas.

  • Tracking the mind's image in the brain I: time-resolved fMRI during visuospatial mental imagery.
    Publication Date: 03/07/2002, on Neuron
    by Formisano E, Linden DE, Di Salle F, Trojano L, Esposito F, Sack AT, Grossi D, Zanella FE, Goebel R
    DOI:

    Mental imagery, the generation and manipulation of mental representations in the absence of sensory stimulation, is a core element of numerous cognitive processes. We investigate the cortical mechanisms underlying imagery and spatial analysis in the visual domain using event-related functional magnetic resonance imaging during the mental clock task. The time-resolved analysis of cortical activation from auditory perception to motor response reveals a sequential activation of the left and right posterior parietal cortex, suggesting that these regions perform distinct functions in this imagery task. This is confirmed by a trial-by-trial analysis of correlations between reaction time and onset, width, and amplitude of the hemodynamic response. These findings pose neurophysiological constraints on cognitive models of mental imagery.

  • Do visuospatial and constructional disturbances differentiate frontal variant of frontotemporal dementia and Alzheimer's disease? an experimental study of a clinical belief.
    Publication Date: 01/07/2002, on International journal of geriatric psychiatry
    by Grossi D, Fragassi NA, Chiacchio L, Valoroso L, Tuccillo R, Perrotta C, Rapone P, Conchiglia G, Trojano L
    DOI: 10.1002/gps.654

    In recent years several attempts have been made to distinguish frontotemporal dementia (FTD) from Alzheimer's disease (AD) on neuropsychological grounds; in particular, it has been suggested that FTD patients show spared spatial abilities with respect to AD patients.

  • Endosomal-lysosomal proteolysis mediates death signalling by TNFalpha, not by etoposide, in L929 fibrosarcoma cells: evidence for an active role of cathepsin D.
    Publication Date: 01/07/2002, on Biological chemistry
    by Démoz M, Castino R, Cesaro P, Baccino FM, Bonelli G, Isidoro C
    DOI: 10.1515/BC.2002.137

    In several 'in vitro' models of apoptosis, lysosomal proteolysis has been shown to play an active role in mediating the death signal by cytokines or antiblastic drugs. Depending on the experimental cell model and the cytotoxic stimulus applied, an increased expression and the cytosolic translocation of either cathepsin D or B have been reported in apoptotic cells. We have analysed the involvement of these lysosomal proteases in a canonical apoptotic cell model, namely L929 fibroblasts, in which apoptosis was induced by cytotoxic agents acting through different mechanisms: (i) the cytokine TNFalpha, which triggers the cell suicide via interaction with its membrane receptor, and (ii) the topoisomerase II-inhibitor etoposide (VP16), which directly causes DNA damage. In both cases the activity of cathepsins B and D increased in apoptosing cultures. CA074-Me, a specific inhibitor of cathepsin B, and Leupeptin, a broad inhibitor of serine and cysteine proteases (among which is cathepsin B), did not exert any protection from TNFalpha. In contrast, pre-loading the cells with pepstatin A, a specific inhibitor of cathepsin D, protected L929 cells from TNFalpha cytotoxicity by more than 50%. However, no protection was observed if pepstatin A was added concomitantly with the cytokine. Inhibition of either cathepsin B or D did not impede apoptosis induced by etoposide. Lysosomal integrity was preserved and cathepsin D remained still confined in vesicular structures in apoptotic cells treated with either TNFalpha or etoposide. It follows that proteolysis by cathepsin D is likely to represent an early event in the death pathway triggered by TNFalpha and occurs within the endosomal-lysosomal compartment.

  • Glycolipids from sponges. 11. Isocrasserides, novel glycolipids with a five-membered cyclitol widely distributed in marine sponges.
    Publication Date: 01/06/2002, on Journal of natural products
    by Costantino V, Fattorusso E, Imperatore C, Mangoni A
    DOI:

    In addition to the previously reported crasserides (1a-m), marine sponges contain smaller amounts of the isomeric isocrasserides (3a-m). The structures of these new glycoglycerolipid analogues were determined by NMR analysis and chemical degradation. Crasserides and isocrasserides were present in all the species of marine sponges we analyzed and therefore appear to be characteristic of the phylum Porifera.

  • Novel deletion at the M and P promoters of the human dystrophin gene associated with a Duchenne muscular dystrophy.
    Publication Date: 01/06/2002, on Neuromuscular disorders : NMD
    by Frisso G, Sampaolo S, Pastore L, Carlomagno A, Calise RM, Di Iorio G, Salvatore F
    DOI:

    Despite numerous reports about dystrophin alterations in Duchenne and Becker muscular dystrophies and dilated cardiomyopathy, the function of dystrophin gene promoters has not yet been completely elucidated. We report the first case of a DNA segment deletion encompassing promoters M and P of the human dystrophin gene, which caused a very severe muscle phenotype without cardiomyopathy, in a 13-year-old boy. These data indicate that the simultaneous lack of promoters P and M results in dramatic consequences in skeletal muscle but not in the heart.

  • Structural characterization of the M* partly folded intermediate of wild type and P138A aspartate aminotransferase from Escherichia coli.
    Publication Date: 17/05/2002, on The Journal of biological chemistry
    by Birolo L, Dal Piaz F, Pucci P, Marino G
    DOI: 10.1074/jbc.M200650200

    A combination of spectroscopic techniques, hydrogen/deuterium exchange, and limited proteolysis experiments coupled to mass spectrometry analysis was used to depict the topology of the monomeric M* partly folded intermediate of aspartate aminotransferase from Escherichia coli in wild type (WT) as well as in a mutant form in which the highly conserved cis-proline at position 138 was replaced by a trans-alanine (P138A). Fluorescence analysis indicates that, although M* is an off-pathway intermediate in the folding of WT aspartate aminotransferase from E. coli, it seems to coincide with an on-pathway folding intermediate for the P138A mutant. Spectroscopic data, hydrogen/deuterium exchange, and limited proteolysis experiments demonstrated the occurrence of conformational differences between the two M* intermediates, with P138A-M* being conceivably more compact than WT-M*. Limited proteolysis data suggested that these conformational differences might be related to a different relative orientation of the small and large domains of the protein induced by the presence of the cis-proline residue at position 138. These differences between the two M* species indicated that in WT-M* Pro138 is in the cis conformation at this stage of the folding process. Moreover, hydrogen/deuterium exchange results showed the occurrence of few differences in the native N(2) forms of WT and P138A, the spectroscopic features and crystallographic structures of which are almost superimposable.

  • Decreased mitochondrial carnitine translocase in skeletal muscles impairs utilization of fatty acids in insulin-resistant patients.
    Publication Date: 01/05/2002, on Frontiers in bioscience : a journal and virtual library
    by Peluso G, Petillo O, Margarucci S, Mingrone G, Greco AV, Indiveri C, Palmieri F, Melone MA, Reda E, Calvani M
    DOI:

    Insulin resistance (IR) and its health consequences (diabetes, hypertension, cardiovascular disease, obesity etc.) affect between 25 and 35% of Westernized populations. Decreased fatty acid (FA) oxidation in skeletal muscle is implicated in obesity-related IR. Carnitine-acylcarnitine translocase (CACT) transports long-chain FAs both into mitochondria (as carnitine esters for energy-generating processes) and out of mitochondria. To determine whether CACT activity correlates with decreased FA oxidation we measured CACT concentrations in cellular and mitochondrial extracts from the skeletal muscle of 19 obese IR individuals and of 19 lean controls. We also evaluated carnitine transport in skeletal muscle mitochondria in both groups. Mitochondrial CACT was decreased at translational and transductional level, and carnitine-carnitine and acylcarnitine-carnitine exchange rates were significantly lower in IR subjects. Aberrant acylcarnitine flux into mitochondria was not correlated with decreased activity of other components of the mitochondrial carnitine system (i.e., carnitine palmitoyl transferase-I and II). Our data suggest that by restraining entry of FA-coenzyme A into mitochondria, low CACT levels increase cytosolic FA levels and their incorporation into glycerolipids. The low level of CACT in IR muscle may contribute to the elevated muscle concentrations of triglycerides, diacylglycerol, and FA-coenzyme A characteristic of IR muscle.

  • Regulation of androgen receptor mRNA expression in primary culture of Harderian gland cells: cross-talk between steroid hormones.
    Publication Date: 01/05/2002, on Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology
    by Esposito T, Astore E, Cardone A, Angelini F, Varriale B
    DOI:

    The androgen receptor (AR) must be considered a transcription factor belonging to the steroid-thyroid hormones receptor superfamily. Previous results gained from the Harderian gland, a tubulo-alveolar gland located in the orbital cavity of the golden hamster, indicate that Harderian gland cells express mRNAs encoding for androgen, glucocorticoid, thyroid hormone (T(3)), and estrogen receptors, respectively. Since in other systems, these receptors have been related to the expression of the androgen receptor, we have studied the regulation of AR expression in primary cultures of the male hamster Harderian gland. Our in vitro experiments show that androgen, and thyroid hormones increase the expression of AR. Retinoic acids also show a positive effect on AR expression, while exposure to glucocorticoid or estrogen blocks AR expression. Since these steroids differently modulate AR expression, our results must be considered in the context of multi-hormonal control of gene expression that could act through cross-talk between members of the steroid-thyroid hormones.

  • Protein synthesis in synaptosomes: a proteomics analysis.
    Publication Date: 01/05/2002, on Journal of neurochemistry
    by Jiménez CR, Eyman M, Lavina ZS, Gioio A, Li KW, van der Schors RC, Geraerts WP, Giuditta A, Kaplan BB, van Minnen J
    DOI:

    A proteomics approach was used to identify the translation products of a unique synaptic model system, squid optic lobe synaptosomes. Unlike its vertebrate counterparts, this preparation is largely free of perikaryal cell fragments and consists predominantly of pre-synaptic terminals derived from retinal photoreceptor neurones. We metabolically labelled synaptosomes with [(35)S] methionine and applied two-dimensional gel electrophoresis to resolve newly synthesized proteins at high resolution. Autoradiographs of blotted two-dimensional gels revealed de novo synthesis of about 80 different proteins, 18 of which could be matched to silver-stained gels that were run in parallel. In-gel digestion of the matched spots and mass spectrometric analyses revealed the identities of various cytosolic enzymes, cytoskeletal proteins, molecular chaperones and nuclear-encoded mitochondrial proteins. A number of novel proteins (i.e. not matching with database sequences) were also detected. In situ hybridization was employed to confirm the presence of mRNA and rRNA in synaptosomes. Together, our data show that pre-synaptic endings of squid photoreceptor neurones actively synthesize a wide variety of proteins involved in synaptic functioning, such as transmitter recycling, energy supply and synaptic architecture.

  • Differential recognition of a tyrosine-dependent signal in the basolateral and endocytic pathways of thyroid epithelial cells.
    Publication Date: 01/04/2002, on Endocrinology
    by Lipardi C, Ruggiano G, Perrone L, Paladino S, Monlauzeur L, Nitsch L, Le Bivic A, Zurzolo C
    DOI: 10.1210/endo.143.4.8734

    Trafficking of receptors is of crucial importance for the physiology of most exocrine and endocrine organs. It is not known yet if the same mechanisms are used for sorting in the exocytic and endocytic pathways in the different epithelial tissues. In this work, we have used a deletion mutant of the human neurotrophin receptor p75(hNTR) that is normally localized on the apical membrane when expressed in Madin-Darby canine kidney cells. This internal 57-amino acid deletion of the cytoplasmic tail leads to a relocation of the protein from the apical to the basolateral membrane and to rapid and efficient endocytosis. These events are mediated by a signal localized within 9 amino acids of the mutated cytoplasmic tail that is strictly dependent on a tyrosine residue (Tyr-308). We have analyzed the basolateral sorting efficiency and endocytic capacity of this signal in Fischer rat thyroid (FRT) cells, in which basolateral and endocytic determinants have not yet been identified. We found that this targeting signal can mediate efficient transport to the basolateral membrane also in FRT cells with similar tyrosine dependence as in MDCK cells. In contrast to MDCK cells, this Tyr-based signal was not able to mediate coated pits localization and endocytosis in FRT cells. These data represent the first characterization of basolateral/endocytic signals in thyroid epithelial cells. Furthermore, our results indicate that requirements for tyrosine-dependent basolateral sorting signals are conserved among cell lines from different tissues but that the recognition of the colinear endocytic signal is tissue specific.