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M Morabito

Publications and source records attributed to M Morabito.

16 recordsLinked to original sources
PubMed2005

Soluble beta-amyloid1-40 induces NMDA-dependent degradation of postsynaptic density-95 at glutamatergic synapses.

Amyloid-beta (Abeta) has been implicated in memory loss and disruption of synaptic plasticity observed in early-stage Alzheimer's disease. Recently, it has been shown that soluble Abeta oligomers target synapses in cultured rat hippocampal neurons, suggesting a direct role of Abeta in the regulation of synaptic structure and function. Postsynaptic density-95 (PSD-95) is a postsynaptic scaffolding protein that plays a critical role in synaptic plasticity and the stabilization of AMPA (AMPARs) and NMDA (NMDARs) receptors at synapses. Here, we show that exposure of cultured cortical neurons to soluble oligomers of Abeta(1-40) reduces PSD-95 protein levels in a dose- and time-dependent manner and that the Abeta1(1-40)-dependent decrease in PSD-95 requires NMDAR activity. We also show that the decrease in PSD-95 requires cyclin-dependent kinase 5 activity and involves the proteasome pathway. Immunostaining analysis of cortical cultured neurons revealed that Abeta treatment induces concomitant decreases in PSD-95 at synapses and in the surface expression of the AMPAR glutamate receptor subunit 2. Together, these data suggest a novel pathway by which Abeta triggers synaptic dysfunction, namely, by altering the molecular composition of glutamatergic synapses.

Amyloid beta-Peptides↗
PubMed2002

Glutamate-induced delta-catenin redistribution and dissociation from postsynaptic receptor complexes.

Delta-catenin (or neural plakophilin-related arm-repeat protein/neurojungin) is primarily a brain specific member of the p120(ctn) subfamily of armadillo/beta-catenin proteins that play important roles in neuronal development. Our previous studies have shown that the ectopic expression of delta-catenin induces the formation of dendrite-like extensions and that the overexpression of delta-catenin promotes dendritic branching and increases spine density. Here we demonstrate that delta-catenin displays a dendritic distribution pattern in the adult mouse brain and is co-enriched with postsynaptic density-95 (PSD-95) in the detergent insoluble postsynaptic scaffolds. Delta-catenin forms stable complexes with excitatory neurotransmitter receptors including ionotropic N-methyl-D-aspartic acid receptor 2A (NR2A), metabotropic glutamate receptor 1alpha (mGluR1alpha), as well as PSD-95 in vivo. In cultured primary embryonic neurons, delta-catenin clusters co-distribute with filamentous actin and resist detergent extraction. In dissociated hippocampal neurons overexpressing delta-catenin, glutamate stimulation leads to a rapid redistribution of delta-catenin that can be attenuated by 6-cyano-7-nitroquinoxaline-2,3-dione and dizocilpine, selective inhibitors of ionotropic glutamate receptors. Upon glutamate receptor activation, delta-catenin becomes down-regulated and its association with NR2A and mGluR1alpha in cultured neurons is diminished. These findings support a possible functional connection between delta-catenin and the glutamatergic excitatory synaptic signaling pathway during neuronal development.

Actin Cytoskeleton↗
PubMed2000

NUDEL is a novel Cdk5 substrate that associates with LIS1 and cytoplasmic dynein.

Disruption of one allele of the LIS1 gene causes a severe developmental brain abnormality, type I lissencephaly. In Aspergillus nidulans, the LIS1 homolog, NUDF, and cytoplasmic dynein are genetically linked and regulate nuclear movements during hyphal growth. Recently, we demonstrated that mammalian LIS1 regulates dynein functions. Here we characterize NUDEL, a novel LIS1-interacting protein with sequence homology to gene products also implicated in nuclear distribution in fungi. Like LIS1, NUDEL is robustly expressed in brain, enriched at centrosomes and neuronal growth cones, and interacts with cytoplasmic dynein. Furthermore, NUDEL is a substrate of Cdk5, a kinase known to be critical during neuronal migration. Inhibition of Cdk5 modifies NUDEL distribution in neurons and affects neuritic morphology. Our findings point to cross-talk between two prominent pathways that regulate neuronal migration.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1998

D2 dopamine antisense RNA expression vector, unlike haloperidol, produces long-term inhibition of D2 dopamine-mediated behaviors without causing Up-regulation of D2 dopamine receptors.

Long-term inhibition of D2 dopamine receptors using classic D2 dopamine receptor antagonists such as haloperidol often causes a compensatory up-regulation of the D2 dopamine receptors. We investigated whether the long-term inhibition of D2 dopamine receptors using an eukaryotic expression vector housing a cDNA sequence encoding an antisense RNA directed to the D2 dopamine receptor transcript (D2 antisense vector) would also produce up-regulation of the D2 receptors. Single, bilateral injections of the D2 antisense vector into the corpora striata of mice inhibited the stereotypy induced by acute challenge injections with the D2/D3 dopamine receptor agonist quinpirole but did not inhibit the grooming induced by acute challenge injections with the D1 agonist SKF 38393. Similar treatment with the D2 antisense vector produced a long-term (>1 month) cataleptic response without producing tolerance to challenge injections with haloperidol. By contrast, catalepsy induced by a single injection of haloperidol lasted only approximately 2 days, and tolerance developed to its effects after long-term treatment. Repeated treatment of mice with haloperidol resulted in an inhibition of apomorphine-induced climbing behavior throughout the time of treatment with haloperidol, but the climbing behavior markedly increased to levels significantly higher than that of the control mice immediately after withdrawal from haloperidol treatment. This increased climbing was accompanied by increased levels of D2 dopamine receptors in the striatum. By contrast, single, bilateral intrastriatal injections of the D2 antisense vector significantly inhibited apomorphine-induced climbing for approximately 30 days but failed to increase the climbing behavior or the levels of D2 dopamine receptors in striatum over those of the control values. These results suggest that a single injection of a D2 antisense RNA expression vector into mouse striatum produces specific, long-term inhibition of D2 dopamine receptor behaviors without causing a compensatory increase in the levels or function of D2 dopamine receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

Expression of a D2 dopamine receptor antisense RNA in brain inhibits D2-mediated behaviors.

Drugs currently used to treat disorders of dopamine-mediated behaviors in the central nervous system are non-selective in that they interact not only with more than one isoform of dopamine receptor but also with receptors for other neurotransmitters. A new strategy to inhibit the actions of individual dopamine receptor subtypes is to inhibit the synthesis of the receptors through the use of oligonucleotides antisense to the transcripts encoding the different receptors. Earlier studies showed that oligodeoxynucleotides antisense to the D1 or D2 dopamine receptor messenger RNAs specifically inhibited the biological actions mediated by these individual isoforms of the dopamine receptor. However, these actions were relatively short-lasting. To determine whether one can achieve long-lasting inhibition of dopamine responses, while still taking advantage of the highly selective nature of an antisense strategy, an expression vector was employed that generates antisense RNA to the transcript encoding the D2 dopamine receptor. A single intrastriatal injection of this vector generated an antisense RNA to the D2 dopamine receptor, selectively reduced the levels of D2 dopamine receptors, and caused selective, long-term inhibition of behaviors mediated by D2 dopamine agonists. Such an antisense RNA strategy may find use in studying the function of dopaminergic receptors and in disorders associated with dopaminergic hyperactivity.

Animals↗
PubMed1996

An evolutionarily conserved binding site for serine proteinase inhibitors in large conductance calcium-activated potassium channels.

Complementary DNA coding for the channel-forming alpha-subunit of a large conductance Ca(2+)-activated K+ channel (maxi Kca channel) was cloned from bovine aortic smooth muscle cells. This cloned mammalian KCa channel (Bslo) and its homolog from Drosophila (Dslo) were expressed in the HEK293 human embryonic kidney cell line. Both Bslo and Dslo KCa channels were sensitive to inhibition by the internally applied serine proteinase inhibitors: bovine pancreatic trypsin inhibitor (BPTI, KD = 7.0 microM for Bslo and 2.6 microM for Dslo) and chicken ovoinhibitor (OI, KD = 1.5 microM for Bslo and 11.4 microM for Dslo). BPTI and OI are members of the Kunitz and Kazal families of proteinase inhibitors, respectively. The approximately 60-residue inhibitory domains of these proteins have a different tertiary structure except in the region of a loop formed by approximately 6 residues, in which the peptide backbone adopts a similar conformation complementary to the active site cleft of many serine proteinases. At the single-channel level, BPTI and OI were found to inhibit KCa channels by a similar mechanism involving the production of discrete low-conductance events. These two inhibitors also exhibited competitive behavior, suggesting that they bind to an overlapping site. Kinetic characterization revealed that the dissociation rate of BPTI from the bovine KCa channel is fast (k(off) = 0.41 s-1), whereas that from the Drosophila KCa channel is slow (k(off) = 9.0 x 10(-4) s-1) and indicative of a strong molecular interaction. The stable complex of BPTI and trypsin was inactive as a KCa channel inhibitor, further supporting the idea that the trypsin inhibitory loop of BPTI recognizes a specific site on the channel protein. These results lead to the conclusion that the alpha-subunit of maxi KCa channels contains a conserved proteinase inhibitor binding site. We hypothesize that this site corresponds to a C-terminal domain of the channel protein that structurally resembles serine proteinases.

Amino Acid Sequence↗
PubMed1996

Uptake and distribution of fluorescein-labeled D2 dopamine receptor antisense oligodeoxynucleotide in mouse brain.

To determine the uptake and distribution of oligodeoxynucleotides in brain, a 20-mer phosphorothioated oligodeoxynucleotide complementary to a portion of the D2 dopamine receptor mRNA was fluorescently labeled with fluorescein isothiocyanate (FITC) and injected into the lateral cerebral ventricles of mice. At various survival times after the injection, the brains were removed, fixed, sectioned, and viewed under a fluorescent microscope. The results showed that the oligodeoxynucleotide was rapidly taken up into the brain. Initially the label was relatively diffusely spread throughout the interstitial spaces of the brain, then became redistributed to the cellular compartments. The signal extended from those forebrain nuclei located immediately in contact with the ventricles, such as the corpus striatum, septum, and hippocampus, to areas further removed from the ventricles, such as the cerebral cortex, nucleus accumbens, and substantia nigra. When the FITC-labeled D2 antisense oligodeoxynucleotide was given once daily for 4 d, the signal intensity seen 24 h after the last injection appeared to be of greater intensity overall compared to that seen after a single injection. At early time-points the oligodeoxynucleotide signals appeared to be punctuated and were found in cell bodies as well as in proximal dendritic processes. However, not all cells were equally labeled, suggesting an uneven uptake and accumulation of the D2 antisense into the various cell types. At later time-points the fluorescent signal appeared granular; at these times the injected material was largely degraded. These studies show that a D2 dopamine receptor antisense oligodeoxynucleotide is rapidly taken up from cerebral ventricles into brain, becomes widely distributed throughout the brain tissue to areas far removed from direct contact with the ventricles, and appears to accumulate to a different extent in the various brain areas and cell types.

Animals↗
PubMed1990

Growth charts of Down syndrome in Sicily: evaluation of 382 children 0-14 years of age.

We present the results of a study performed on a Sicilian population of children with Down syndrome (DS) 0-14 years of age, observed between 1977 and 1988. Data from the present report concern 382 subjects with nonmosaic 21 trisomy, including 239 males (62.6%) and 143 females (37.4%). We excluded all DS children observed in the same period with associated pathology (congenital heart defects, gastrointestinal malformations, malabsorption, hypothyroidism, and thalassemia). Overall, 1,464 measurements were performed of length or height, weight, and head circumference. Means and standard deviation (SD) were calculated for all of these parameters. Our data confirm a trend toward a progressive improvement of growth in children with DS, as shown in other recent reports. The purpose of this study was also to create a "normal growth pattern" useful to evaluate DS children and also to diagnose early pathologic conditions affecting growth, such as autoimmune diseases.

Adolescent↗
PubMed1986

Growth hormone and somatomedin-C response to synthetic human pancreatic tumor GH-releasing factor in hypopituitary and constitutionally short children.

GH and somatomedin-C response to acute hpGRF-44 iv administration (1 microgram/Kg bw) was studied in 16 patients with hypopituitarism (GHD) and in 7 constitutionally short subjects. GH-deficient patients evidenced a significant GH increase peaking between 15 and 60 min. (4.95 +/- 0.88 ng/ml, mean +/- SE) (p less than 0.01 vs placebo). In non GH-deficient subjects GH increase was more pronounced (peak 18.00 +/- 3.01 ng/ml; p less than 0.01 vs both placebo and GHD group). Acid-extractable somatomedin-C was slightly, but significantly higher than baseline at 12th h (p less than 0.01) in both patients with hypopituitarism (basal value: 0.067 +/- 0.021 U/ml; 12 h: 0.096 +/- 0.024 U/ml) and constitutionally short subjects (basal value 0.62 +/- 0.13; 12h 0.72 +/- 0.16 U/ml). In 3 subjects with hypopituitarism multiple iv administrations (1 microgram/kg bw at 09:30 and 21:30 h for 4 days) produced on the average a modest increase of the GH responsiveness, were more effective to enhance somatomedin-C concentration, but not sufficient to reach normal levels. Sc administration of the same dose at 4-h intervals by a programmable portable pump - performed on 6 GHD subjects - produced an increase of GH peak response on the 4th day of treatment (1.38 +/- 0.31 ng/ml) with respect to the one observed on the first day (0.42 +/- 0.09 ng/ml). Somatomedin-C increase was low and inconstant. These data support the use of a 4-5-day pulsatile treatment in the differentiation between hypothalamic and pituitary deficiency, and the possibility of therapeutical use of GRF with the same protocol when a response is evidenced.

Adolescent↗
PubMed1982

Human type I procollagen genes are located on different chromosomes.

A recombinant plasmid containing sequences complementary to human pro-alpha l(I) collagen mRNA was used for the chromosomal assignment of the pro-alpha l(I) collagen gene. Restriction endonuclease analysis of DNA from mouse-human and Chinese hamster-human somatic cell hybrids revealed cosegregation with human chromosome 17. Hybrids containing derivative chromosomes with a t(2;17)(q14;q21) translocation showed cosegregation of the pro-alpha l(I) gene with the segment 17q21 leads to qter. In situ hybridization on human metaphasic chromosomes confirmed this conclusion.

Amino Acid Sequence↗
PubMed1981

Control of globin gene expression in mouse yolk sac erythroid cells.

In the present paper are reported results from our laboratory and data of the literature on the structure and the expression of embryonic globin genes in mouse fetuses. The following aspects are presented: 1. Erythropoiesis and synthesis of globin chains in fetal mice. 2. The transcriptional and post-transcriptional control of embryonic globin gene expression. 3. The chromosomal location and organization of mouse embryonic globin genes.

Animals↗
PubMedDate not supplied

Human pro alpha 1(I) collagen gene structure reveals evolutionary conservation of a pattern of introns and exons.

The collagens represent an interesting example of a structurally related but genetically distinct family of proteins. Type I, the most abundant of the vertebrate collagens, comprises two pro alpha 1(I) chains and one pro alpha 2(I) chain, each containing terminal propeptides and a central domain of 338 (Gly, X, Y) repeats. The structure of the chicken pro alpha 2(I) gene shows an intriguing relationship between exon organization and the arrangement of (Gly, X, Y) repeats (see ref. 2 for review). This has led to the suggestion that the collagens evolved from a common ancestral unit of 54 base pairs (bp). Here we present the structure of the entire human pro alpha 1(I) gene and compare this with the chicken pro alpha 2(I). The exon arrangement of the two genes is remarkably similar, although the human pro alpha 1(I) is more compact because of the shorter length of its introns. The data strongly support the notion that the type I genes have evolved from an ancestral multi-exon unit, and that once the gene was translated, a strong evolutionary pressure caused it to maintain this elaborate structure.

Amino Acid Sequence↗
PubMedDate not supplied

Genetic factors of recurrent abortions.

A review of main genetic factors involved in pathogenesis of recurrent abortion is presented. The prevalence of chromosomal abnormalities in spontaneous abortions and the role of parental abnormalities of karyotype is pointed out, also in relation to many recent studies. The result of 354 karyotypes performed on couples with spontaneous abortion are presented; the prevalence of chromosomal abnormalities resulted 4.2%, with 73% of translocations, either reciprocal (40%) or robertsonian (33%), and 27% of inversions. The low number of minor abnormalities (0.8%) seems to confirm their poor clinical significance.

Abortion, Habitual↗