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V Nigro

Publications and source records attributed to V Nigro.

At least 37 records · Page 2Linked to original sources
PubMed1999

Dystrophin and utrophin complexed with different associated proteins in cardiac Purkinje fibres.

Abnormal dystrophin expression is directly responsible for Duchenne and Becker muscular dystrophies. In skeletal muscle, dystrophin provides a link between the actin network and the extracellular matrix via the dystrophin-associated protein complex. In mature skeletal muscle, utrophin is a dystrophin-related protein localized mainly at the neuromuscular junction, with the same properties as dystrophin in terms of linking the protein complex. Utrophin could potentially overcome the absence of dystrophin in dystrophic skeletal muscles. In cardiac muscle, dystrophin and utrophin were both found to be present with a distinct subcellular distribution in Purkinje fibres, i.e. utrophin was limited to the cytoplasm, while dystrophin was located in the cytoplasmic membrane. In this study, we used this particular characteristic of cardiac Purkinje fibres and demonstrated that associated proteins of dystrophin and utrophin are different in this structure. We conclude, contrary to skeletal muscle, dystrophin-associated proteins do not form a complex in Purkinje fibres. In addition, we have indirect evidence of the presence of two different 400 kDa dystrophins in Purkinje fibres.

Animals↗
PubMed1998

Interaction of vault particles with estrogen receptor in the MCF-7 breast cancer cell.

A 104-kD protein was coimmunoprecipitated with the estrogen receptor from the flowtrough of a phosphocellulose chromatography of MCF-7 cell nuclear extract. mAbs to this protein identified several cDNA clones coding for the human 104-kD major vault protein. Vaults are large ribonucleoprotein particles of unknown function present in all eukaryotic cells. They have a complex morphology, including several small molecules of RNA, but a single protein species, the major vault protein, accounts for >70% of their mass. Their shape is reminiscent of the nucleopore central plug, but no proteins of known function have been described to interact with them. Western blot analysis of vaults purified on sucrose gradient showed the presence of estrogen receptor co-migrating with the vault peak. The AER317 antibody to estrogen receptor coimmunoprecipitated the major vault protein and the vault RNA also in the 20,000 g supernatant fraction. Reconstitution experiments of estrogen receptor fragments with the major vault protein mapped the site of the interaction between amino acids 241 and 280 of human estrogen receptor, where the nuclear localization signal sequences are located. Estradiol treatment of cells increased the amount of major vault protein present in the nuclear extract and coimmunoprecipitated with estrogen receptor, whereas the anti-estrogen ICI182,780 had no effect. The hormone-dependent interaction of vaults with estrogen receptor was reproducible in vitro and was prevented by sodium molybdate. Antibodies to progesterone and glucocorticoid receptors were able to coimmunoprecipitate the major vault protein. The association of nuclear receptors with vaults could be related to their intracellular traffic.

Animals↗
PubMed1998

Identification and characterization of a novel member of the dystrobrevin gene family.

A new member of the dystrobrevin gene family was identified using a bioinformatics approach. Sequence analysis indicates that this gene, named DTN-B, is highly homologous to the rabbit A0, the previously described dystrobrevin (DTN), Torpedo 87 kDa and to the C-terminus of dystrophin. The coiled-coil domain, shown to be the site of interaction between dystrobrevins and dystrophin, is highly conserved. Immunostaining studies indicate that DTN-B and DTN expression is absent in affected muscle fibers from DMD patients and carriers.

Amino Acid Sequence↗
PubMed1998

A first missense mutation in the delta sarcoglycan gene associated with a severe phenotype and frequency of limb-girdle muscular dystrophy type 2F (LGMD2F) in Brazilian sarcoglycanopathies.

Among the heterogeneous group of autosomal recessive limb-girdle muscular dystrophies (AR LGMDs), the sarcoglycanopathies (LGMD2C-2F) represent a subgroup characterised by defects in the gamma, alpha, beta, and delta sarcoglycan genes, respectively. Genotype-phenotype correlations in these forms of AR LGMD are important to enhance our understanding of protein function. Regarding LGMD2F, only two homozygous frameshift mutations have been reported to date in patients with a severe phenotype. In the present report, through screening 23 unrelated AR LGMD patients, we identified three subjects with LGMD2F, two with a previously reported frameshift mutation and the other homozygous for a new missense mutation in the delta sarcoglycan gene. Interestingly, this new mutation is also associated with a severe clinical course. In addition, our results suggest that this form of severe AR LGMD is not very rare in our population.

Brazil↗
PubMed1997

Exon-intron organization of the human dystrophin gene.

Analysis of the exon-intron organization of the human dystrophin gene has been hampered by its enormous size. By using a YAC-based exon mapping approach and long PCR, we have succeeded in defining the size of the gene and its organization. Our results, compared with data on the distribution of deletion breakpoints by intron, elucidate the topography of the intragenic deletion-prone regions. Within the central high-frequency deletion region, the small, 6.6-kb, intron 49 shows a much higher density of deletion breakpoints than intron 44, which was previously believed to coincide with the most mutable zone of the gene. On the other hand, in the proximal part of the gene, deletion breakpoints do not preferentially occur in a few introns, but are spread over a large DNA segment containing introns 2 to 42.

Chromosome Mapping↗
PubMed1997

The fourth component of the sarcoglycan complex.

We found a novel dystrophin-associated protein (DAP) exhibiting almost the same mobility as gamma-sarcoglycan on SDS-PAGE. This novel DAP with basic charge is separated from gamma-sarcoglycan by 2-dimensional PAGE or de-N-glycosylation followed by SDS-PAGE. This DAP is most likely the rabbit homologue of "delta-sarcoglycan", the gamma-sarcoglycan-like protein identified previously [Nigro et al. (1996) Hum. Mol. Genet. 5, 1179-1186], since an internal amino acid sequence from the DAP matched the predicted amino acid sequence of "human delta-sarcoglycan" within the limits of species difference and this DAP was recognized by anti-"delta-sarcoglycan" antibody. The DAP was found to be contained in the sarcoglycan fraction which was prepared by treatment of the dystrophin-DAP complex with n-octyl beta-D-glucoside and crosslinked with beta- and/or gamma-sarcoglycan by a chemical crosslinker, dithiobis(succinimidyl propionate). Therefore, we concluded that the DAP is the fourth component of the sarcoglycan complex.

Amino Acid Sequence↗
PubMed1997

X-linked Emery-Dreifuss muscular dystrophy can be diagnosed from skin biopsy or blood sample.

We have raised an anti-emerin polyclonal antibody against a fusion protein encompassing most of the hydrophilic portion of emerin. Using this antibody, we have analyzed emerin expression in Emery-Dreifuss muscular dystrophy (EDMD) patients and controls, by immunocytochemistry, in skeletal muscle and skin, and by immunoblot, in peripheral blood mononuclear cells and lymphoblasts. Emerin was localized on the surfaces of nuclei in control skeletal muscle and skin but was absent or reduced in patient skeletal muscle, was absent from the skin of patients, and was expressed only in a few nuclei in a patient's mother. Immunoblot of peripheral blood cells from EDMD patients showed absence of the emerin band, altered-size emerin, or a protein of normal molecular mass but slightly reduced quantity. The diagnosis of X-linked EDMD is normally confirmed by genetic analysis of the STA gene coding for emerin. We propose immunocytochemical evaluation of emerin expression in skin biopsies as a sensitive and more convenient tool for diagnosing X-linked EDMD and, in particular, for distinguishing it from the autosomal dominant form. This technique may be applied to suspected EDMD patients, especially sporadic cases or those with incomplete clinical phenotype, and also suspected carriers. Immunoblot of peripheral blood cells is also useful, but it may not unequivocally identify carriers and some patients.

Adolescent↗
PubMed1997

Identification of the Syrian hamster cardiomyopathy gene.

The BIO14.6 hamster is a widely used model for autosomal recessive cardiomyopathy. These animals die prematurely from progressive myocardial necrosis and heart failure. The primary genetic defect leading to the cardiomyopathy is still unknown. Recently, a genetic linkage map localized the cardiomyopathy locus on hamster chromosome 9qa2.1-b1, excluding several candidate genes. We now demonstrate that the cardiomyopathy results from a mutation in the delta-sarcoglycan gene that maps to the disease locus. This mutation was completely coincident with the disease in backcross and F2 pedigrees. This constitutes the first animal model identified for human sarcoglycan disorders.

Amino Acid Sequence↗
PubMed1996

Prostaglandin E2 induction of binding activity to CRE and AP-2 elements in human T lymphocytes.

Prostaglandins of the E series are immunomodulatory agents which exert inhibitory as well as stimulatory effects on a variety of immune responses. Since it is known that PGE2 is able to increase cAMP levels, we investigated whether it can affect gene expression through the activation of the transcription factors which bind enhancer elements in the promoter regions of cAMP-regulated genes. Using electrophoretic mobility shift assay, we demonstrated that a short treatment of human T lymphocytes with PGE2 induces specific binding activity to CRE and AP-2, but not AP-1, DNA elements. Since the okadaic acid, a potent protein phosphatase inhibitor, prolongs the induction of the binding activity, phosphorylation events are likely to occur. This activity seems to be due to increased cAMP levels because forskolin and IBMX mimic the effects of PGE2. More interestingly, transfection experiments with CRE-CAT plasmide show that PGE2 activates the transcription of a CRE-containing promoter. These data support the positive role for PGE2 on some immune functions.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Development of cardiomyopathy in female carriers of Duchenne and Becker muscular dystrophies.

OBJECTIVE: To characterize the presence and behavior of the dystrophinopathic myocardial damage in female carriers of a gene defect at the Xp21 locus of the X chromosome that causes Duchenne and Becker muscular dystrophies (DMD and BMD). DESIGN: Cohort study from April 1, 1985, to April 30, 1995, with cardiologic follow-up performed yearly for a minimum of 3 to a maximum of 10 years. SETTING: Counseling center for genetic muscular disorders. PATIENTS: A total of 197 women and girls aged 5 to 60 years ascertained to be carriers of the DMD (n = 152) or BMD (n = 45) gene. MAIN OUTCOME MEASURES: Cardiac status at yearly examinations as determined by 12-lead electrocardiogram (ECG), 24-hour ambulatory ECG, M-mode and 2-dimensional echocardiography, and carotid pulse tracing. Myocardial scintigram was performed on each individual at least twice during the study. Immunohistochemical analysis of dystrophin from myocardium and/or skeletal muscle biopsy was performed in 12 carriers. RESULTS: Preclinical or clinically evident myocardial involvement was found in 166 cases (84.3%), without significant differences in percentage and behavior between DMD and BMD carriers. Its occurrence increased significantly with age, from 54.5% (18 cases) in carriers aged between 5 and 16 years to 90.2% (148 cases) in carriers older than 16 years. Dystrophin anomalies were detected at the membrane level of the myocardial fibers in all endomyocardial biopsy specimens. CONCLUSIONS: Genetic anomalies can be considered the primary cause of myocardial damage in carriers of dystrophinopathic myopathies; myocardial damage shows the same behavior already described in DMD and BMD patients and progresses from preclinical to dilated cardiomyopathy, passing through stages of myocardial hypertrophy or dysrhythmias.

Adolescent↗
PubMed1996

Autosomal recessive limb-girdle muscular dystrophy, LGMD2F, is caused by a mutation in the delta-sarcoglycan gene.

Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of inherited neuromuscular disorders characterized by proximal muscular weakness of the pelvic and shoulder girdles and a variable progression with symptoms, ranging from very severe to mild. One autosomal dominant (LGMD1A, at chromosome 5q22.3-31.3) (ref. 3) and five autosomal recessive (AR) loci responsible for this phenotype have been identified: LGMD2A at 15q (ref. 4); LGMD2B at 2p (ref. 5), LGMD2C at 13q (ref. 6), LGMD2D at 17q (ref. 7) and LGMD2E at 4q (refs 8,9). In the muscle membrane, dystrophin associates with several proteins and glycoproteins organized in two main subcomplexes: the dystroglycan (DG) and sarcoglycan (SG) complexes. The genes for LGMD2C, LGMD2D and LGMD2E code for proteins of the SG complex. We recently mapped a sixth AR form of LGMD, LGMD2F, to chromosome 5q33-34 in two Brazilian families. In the same chromosomal interval we also mapped the delta SG gene, encoding a novel 35-kD component of the sarcoglycan (SG) complex. We now show that a homozygous mutation in the delta SG gene (a single nucleotide deletion that alters its reading frame) is the cause of LGMD2F.

Adolescent↗
PubMed1996

The sarcoglycan complex in the six autosomal recessive limb-girdle muscular dystrophies.

To enhance our understanding of the autosomal recessive limb-girdle muscular dystrophy (LGMD), patients from six genetically distinct forms (LGMD2A to LGMD2F) were studied with antibodies directed against four sarcoglycan subunits (alpha-, beta-, gamma-, delta-SG), dystrophin, beta-dystroglycan (beta-DG) and merosin. All patients with LGMD2A and 2B had a mild clinical course while those with a primary sarcoglycan mutation (LGMD2C to 2F) had a range of clinical severity. Dystrophin and merosin immunofluorescence pattern was positive in patients with all six AR LGMDs. The majority of patients with a severe Duchenne-like phenotype presented total absence of the SG complex. However, some exceptions were found in 13q linked patients, indicating that the presence of a certain labelling for components of the SG may not be prognostic for a milder phenotype. The observation that the primary absence of alpha-SG results in the total absence of beta- and delta-SG but not of gamma-SG suggests that the alpha-, beta- and delta-subunits of sarcoglycan may be more closely associated. A secondary reduction in dystrophin amount was seen in patients with primary sarcoglycan mutations, which was most marked in patients with primary beta-, gamma- and delta-SG deficiencies. In contrast, beta-DG staining was retained in all patients, suggesting that the association between SG and DG subcomplexes is not so strong. Based on the above findings, we have refined the model for the interaction among the known glycoproteins of the sarcoglycan complex, within the DGC.

Adolescent↗
PubMed1996

Identification of a novel sarcoglycan gene at 5q33 encoding a sarcolemmal 35 kDa glycoprotein.

Mutations in any of the genes encoding the alpha, beta or gamma-sarcoglycan components of dystrophin-associated glycoproteins result in both sporadic and familial cases of either limb-girdle muscular dystrophy or severe childhood autosomal recessive muscular dystrophy. The collective name 'sarcoglycanopathies' has been proposed for these forms. We report the identification of a fourth member of the human sarcoglycan family. We named this novel cDNA delta-sarcoglycan. Its mRNA expression is abundant in striated and smooth muscles, with a main 8 kb transcript, encoding a predicted basic transmembrane glycoprotein of 290 amino acids. Antibodies specifically raised against this protein recognized a single band at 35 kDa on western blots of human and mouse muscle. Immunohistochemical staining revealed a unique sarcolemmal localization. FISH, radiation hybrid and YAC mapping concordantly linked the delta-sarcoglycan gene to 5q33, close to D5S487 and D5S1439. The gene spans at least 100 kb and is composed of eight exons. The identification of a novel sarcoglycan component modifies the current model of the dystrophin-glycoprotein complex.

Amino Acid Sequence↗
PubMed1995

Evaluation of the cardiomyopathy in Becker muscular dystrophy.

To evaluate the features and the course of cardiomyopathy in Becker muscular dystrophy, 68 patients--identified by clinical assessment and by reduced dystrophin labeling and/or DNA analysis--were followed in the years 1976-1993, for periods ranging from 3 to 18 years (mean 8). Patients periodically underwent clinical, electrocardiographic, echocardiographic, nuclear, and radiological assessments. Preclinical cardiac involvement was found in 67.4% of patients under 16 years of age, decreasing to 30% in patients older than 40. Clinically evident cardiomyopathy was found in 15% of patients under 16 years of age, increasing to 73% in patients older than 40. A real, dilated cardiomyopathy is the most frequent type of myocardial involvement after the age of 20. Results show that the severity of cardiac involvement can be unrelated to the severity of skeletal muscle damage and confirm that cardiac dysfunction is a primary feature of Becker muscular dystrophy.

Adolescent↗
PubMed1995

Retinoic acid induces stage-specific antero-posterior transformation of rostral central nervous system.

We report a time-course analysis of the effect of retinoic acid (RA) on the development of the mouse central nervous system (CNS) from the beginning of gastrulation throughout induction and patterning of the neural tube. RA administration induces three different, stage-specific alterations of brain development, indicating perturbation of different morphogenetic steps during the establishment of a neural pattern. In particular, treatment at mid-late streak stage (7.2-7.4 days post coitum (d.p.c.)) results in early repression of Otx2 expression in the posterior neuroectoderm of the head fold and in the ventral mid line, including the prechordal plate and the rostralmost endoderm, followed by loss of forebrain morphological and molecular identities, as revealed by analysis of the expression of regionally-restricted brain genes (Otx2, Otx1, Emx2, Emx1 and Dlx1). In these embryos, reduction of the Otx2 expression domain correlates with hindbrain expansion marked by rostral extension of the Hoxb-1 expression domain. Our analysis indicates that RA interferes with the correct definition of both planar and vertical morphogenetic signals at specific developmental stages by affecting gene expression in the regions which are likely either to produce or to respond to these signals. We suggest that retinoids may contribute to early definition of head from trunk structures by selecting different sets of regulatory genes.

Animals↗