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Biomedical subjects

R Ravazzolo

Publications and source records attributed to R Ravazzolo.

At least 19 recordsLinked to original sources
PubMed2001

A novel human homologue of the SH3BGR gene encodes a small protein similar to Glutaredoxin 1 of Escherichia coli.

Glutaredoxins (GRXs) are ubiquitous GSH-dependent oxidoreductases, which catalyze the reduction of protein-glutathionyl-mixed disulfides and are considered to play an important role in the enzymatic regulation of redox-sensitive proteins. In this paper, we describe the identification and characterization of a new human homologue of the SH3BGR gene, named SH3BGRL3 (SH3 domain binding glutamic acid-rich protein like 3). SH3BGRL3 is widely expressed and codes for a highly conserved small protein, which shows a significant similarity to Glutaredoxin 1 (GRX1) of Escherichia coli and is predicted to belong to the Thioredoxin Superfamily. However, the SH3BGRL3 protein lacks both the conserved cysteine residues, which characterize the enzymatic active site of GRX. This structural feature raises the possibility that SH3BGRL3 could function as an endogenous modulator of GRX biological activity. EGFP-SH3BGRL3 fusion protein expressed in COS-7 cells localizes both to the nucleus and to the cytoplasm. The SH3BGRL3 gene was mapped to chromosome 1p34.3-35.

Amino Acid Sequence↗
PubMed2001

Fontaine-Farriaux craniosynostosis: second report in the literature.

Craniosynostosis is determined by the precocious fusion of one or more calvarial sutures leading to an abnormal skull shape. Additionally, nodular heterotopia is a disorder of neuronal migration and/or proliferation. We describe a very rare multiple congenital anomalies (MCA) syndrome in which craniosynostosis is associated with bilateral periventricular nodular heterotopia (BPNH) of the gray matter and other malformations involving hands, feet, and the gut. Clinical findings and further investigations suggest the diagnosis of craniosynostosis Fontaine-Farriaux type. To the best of our knowledge, this case is only the second report of this MCA syndrome. Based on the clinical and radiological data of the two cases reported, we hypothesize that this malformative complex may be considered a new BPNH/MCA syndrome and propose to classify it as BPNH/craniosynostosis. Previous studies demonstrated that at least two BPNH/MCA syndromes have been mapped to the Xq28 chromosomal region in which a causative gene for isolated BPNH is located. The same authors hypothesized that other BPNH syndromes could be due to microrearrangements at the same Xq28 region. Our case presents several overlapping features with some BPNH/MCA syndromes and it is possible that this new complex disorder may be caused by rearrangements at the same chromosomal region that could alter expression of different genes in Xq28.

Abnormalities, Multiple↗
PubMed2001

A point mutation in ABC1 gene in a patient with severe premature coronary heart disease and mild clinical phenotype of Tangier disease.

The proband is a 50 year-old woman born from a consanguineous marriage. She has been suffering from angina pectoris since the age of 38 and underwent coronary bypass surgery for three-vessel disease at 48. The presence of low plasma levels of total cholesterol and high density lipoprotein (HDL) cholesterol (2.4 and 0.1 mmol/l) and apo AI (<15 mg/dl), associated with corneal lesions and a mild splenomegaly suggested the diagnosis of Tangier disease. However, none of the other features of Tangier disease, including hepatomegaly, anemia and peripheral neuropathy, were present. The analysis of the dinucleotide microsatellites located in chromosome 9q31 region demonstrated that the proband was homozygous for the alleles of D9S53, D9S1784 and D9S1832. The mother and son of the proband, both with low levels of HDL cholesterol, shared one of the proband's haplotypes, whereas neither of these haplotypes was present in the normolipidemic proband's sister. The sequence of ATP-binding cassette transporter 1 (ABC1-1) cDNA obtained by reverse transcription-PCR (RT-PCR) of total RNA isolated from cultured fibroblasts showed that the proband was homozygous for a C>T transition in exon 13, which caused a tryptophane for arginine substitution (R527W). This mutation was confirmed by direct sequencing of exon 13 amplified from genomic DNA. It can be easily screened, as the nucleotide change introduces a restriction site for the enzyme Afl III. R527W substitution occurs in a highly conserved region of the NH2 cytoplasmic domain of ABC1 protein. R527W co-segregates with the low HDL phenotype in the family and was not found in 200 chromosomes from normolipidemic individuals.

ATP Binding Cassette Transporter 1↗
PubMed2001

5,10-Methylenetetrahydrofolate reductase polymorphism and early organ damage in primary hypertension.

Hyperhomocyst(e)inemia is a known risk factor for the development of atherosclerotic vascular damage. Plasma homocyst(e)ine levels are influenced by nutritional and hereditary factors. A point mutation (cytosine to thymidine substitution; C677T) in the gene encoding 5,10-methylenetetrahydrofolate reductase (MTHFR) makes the enzyme thermolabile and has been associated with elevated homocyst(e)ine levels in homozygous carriers (TT genotypes). We evaluated the relationship between the T allele encoding for the thermolabile variant of MTHFR and several biochemical risk factors and early signs of hypertensive and atherosclerotic organ damage in 206 untreated patients with primary hypertension. The MTHFR genotype was evaluated by polymerase chain reaction. Albuminuria was measured as albumin-to-creatinine ratio in three nonconsecutive first morning urine samples (negative urine culture). Persistent Mi (Alb+) was defined as an average albumin-to-creatinine ratio between 2.38 and 19 (men) and 2.96 and 20 (women). Left ventricular (LV) mass index (LVMI) was assessed by M-B mode echocardiography (LV hypertrophy, LVH = LVMI > or = 125 g/m2), carotid geometry by high-resolution ultrasound scan, and retinal vascular changes by direct ophthalmoscopy (Keith-Wagener classification). The prevalence of Mi, LVH, and retinopathy was 14%, 45%, and 42%, respectively. The prevalence of carotid plaque was 25%. Allele frequencies for C (wild-type allele) and T allele (mutant allele) were 56% and 44%, respectively. Genotype frequencies were CC 29%, CT 54%, TT 17% according to Hardy Weinberg equilibrium. There were no differences as for age, sex, body mass index, blood pressure levels, lipid profile, smoking habits, and alcohol intake, and LVMI and urinary albumin excretion on the basis of MTHFR genotype. Patients with TT polymorphism showed a higher prevalence of retinal vascular changes (TT, 61% v CT + CC, 38%; P < .02) and carotid plaque (TT, 42% v CT + CC, 21%; P < .05) compared to patients with CC and CT polymorphism. Moreover, patients with T allele showed increased carotid artery size as demonstrated by intima plus media thickness (IT, 0.79 +/- 0.05 mm v CT + CC, 0.67 +/- 0.02 mm; P < .02), relative wall thickness (TT, 0.23 +/- 0.01 mm v CT + CC, 0.20 +/- 0.005 mm; P < .02), and surface area (TT, 19 +/- 1.9 mm2 v CT + CC, 15 +/- 0.55 mm2; P < .05). Multiple linear regression analysis demonstrated that MTHFR genotype and systolic blood pressure independently influence intima-media thickness and together account for about 11% of its variations (r2 = 0.11, F = 9.7, dF = 1-205, P < .0001). Homozygosity for the T allele of the MTHFR gene is an independent risk factor for the development of early atherosclerotic organ damage in hypertensive patients.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed2001

Genomic organisation of the mouse Ret proto-oncogene.

The RET proto-oncogene is involved in the development of both kidney and neural crests derived tissues. RET deleterious mutations cause hereditary neuroendocrine tumours and congenital intestinal aganglionosis. Ongoing efforts aimed at elucidating the function of this gene include expression studies in different species and in transgenic mice. As first step in the study of Ret expression in mouse, we obtained the mouse Ret genomic structure. Intron-exon boundaries were determined and sequenced, all introns but the first one were amplified and cloned, and exons positioned in a restriction map. Mouse and human genes comparison indicates a highly conserved genomic organisation, except for exon 21 which is not conserved in mouse. A region extending 386 bp 5' to the first exon was sequenced and compared with its human counterpart. Some features, reported for the human promoter, like the absence of TATA or CAAT boxes and a high GC content, are conserved.

Animals↗
PubMed2000

Adenovirus E1A down-regulates the EGF receptor via repression of its promoter.

The epidermal growth factor receptor (EGF-R), after activation by its ligands, stimulates a cascade of intracellular events leading to cellular proliferation. Its expression is increased in various forms of cancer as a consequence of altered regulation. Our objective was to study potential negative regulators of EGF-R expression; we investigated the effect of adenovirus E1A proteins. E1A proteins can exert both positive and negative effects on cell growth, depending on the cell type and cellular context, and have anti-tumorigenic features on human cancer cells. We show that human cell lines stably transformed with the adenovirus E1 region show significantly reduced expression of EGF-R protein and mRNA compared to their control, non-E1A-expressing counterparts. Furthermore, the promoter activity of EGF-R can be specifically repressed by E1A in transient co-transfection analysis in multiple cell types. Transfections with deleted promoter fragments and constructs containing short fragments of the putative E1A-responsive region fused to a heterologous promoter indicate that E1A-responsive elements are contained in a promoter region (from -150 to -76). Analysis of E1A mutants showed that both E1A gene products, 12S and 13S, repress EGF-R promoter activity and that full repression requires the presence of an intact CR1 domain.

Adenovirus E1A Proteins↗
PubMed2000

Lysyl oxidase activates the transcription activity of human collagene III promoter. Possible involvement of Ku antigen.

Lysyl oxidase is an extracellular enzyme that controls the maturation of collagen and elastin. Lysyl oxidase and collagen III often show similar expression patterns in fibrotic tissues. Therefore, we investigated the influence of lysyl oxidase overexpression on the promoter activity of human COL3A1 gene. Our results showed that when COS-7 cells overexpressed the mature form of lysyl oxidase, the activity of the human COL3A1 promoter was increased up to an average of 12 times when tested by luciferase reporter assay. The effect was specific, because other promoters were not affected. Moreover, lysyl oxidase effect was abolished by beta-aminopropionitrile, a specific inhibitor of its catalytic activity. Electrophoretic mobility shift assay showed a binding activity in the region from -101 to -77 that was significantly increased by lysyl oxidase overexpression. The binding was specifically competed by the cold probe, and the mutagenesis of this region abolished both the binding activity in gel retardation and lysyl oxidase stimulation of COL3A1 promoter in transfection experiments. We identified the binding activity as Ku antigen in its two components: Ku80 and Ku70. This study suggests a new coordinated mechanism by which lysyl oxidase might control the development of fibrosis.

Aminopropionitrile↗
PubMed2000

Ectodermal dysplasias: not only 'skin' deep.

The ectodermal dysplasias (EDs) are a large and complex nosologic group of diseases; more than 170 different pathologic clinical conditions have been identified. Despite the great number of EDs described so far, few causative genes have been identified. We review EDs in the light of the most recent molecular findings and propose a new classification of EDs integrating both molecular-genetic data and corresponding clinical findings of related diseases.

Animals↗
PubMed2000

Mutations in MYH9 result in the May-Hegglin anomaly, and Fechtner and Sebastian syndromes. The May-Heggllin/Fechtner Syndrome Consortium.

The autosomal dominant, giant-platelet disorders, May-Hegglin anomaly (MHA; MIM 155100), Fechtner syndrome (FTNS; MIM 153640) and Sebastian syndrome (SBS), share the triad of thrombocytopenia, large platelets and characteristic leukocyte inclusions ('Döhle-like' bodies). MHA and SBS can be differentiated by subtle ultrastructural leukocyte inclusion features, whereas FTNS is distinguished by the additional Alport-like clinical features of sensorineural deafness, cataracts and nephritis. The similarities between these platelet disorders and our recent refinement of the MHA (ref. 6) and FTNS (ref. 7) disease loci to an overlapping region of 480 kb on chromosome 22 suggested that all three disorders are allelic. Among the identified candidate genes is the gene encoding nonmuscle myosin heavy chain 9 (MYH9; refs 8-10), which is expressed in platelets and upregulated during granulocyte differentiation. We identified six MYH9 mutations (one nonsense and five missense) in seven unrelated probands from MHA, SBS and FTNS families. On the basis of molecular modelling, the two mutations affecting the myosin head were predicted to impose electrostatic and conformational changes, whereas the truncating mutation deleted the unique carboxy-terminal tailpiece. The remaining missense mutations, all affecting highly conserved coiled-coil domain positions, imparted destabilizing electrostatic and polar changes. Thus, our results suggest that mutations in MYH9 result in three megakaryocyte/platelet/leukocyte syndromes and are important in the pathogenesis of sensorineural deafness, cataracts and nephritis.

Alleles↗
PubMed2000

A single-nucleotide polymorphic variant of the RET proto-oncogene is underrepresented in sporadic Hirschsprung disease.

Hirschsprung disease (HSCR) is an inherited disorder characterised by absence of intrinsic ganglion cells in the distal gastrointestinal tract. Different susceptibility genes, involved in either the Ret-tyrosine kinase or the endothelin signalling pathways, contribute to HSCR phenotype. Interestingly, alterations of these genes are detected in only 30-50% of all HSCR patients, suggesting the involvement of modifier genes and/or additional genetic or environmental risk factors. In complex disorders common polymorphic variants can be associated with the disease phenotype, thus modifying the risk of recurrence. To investigate whether sequence variants of the RET proto-oncogene may be associated with the development of the HSCR phenotype, we analysed 92 Italian patients for the 2508C > T synonymous substitution in exon 14 (S836S) finding that the T allele is clearly less frequent than in control individuals (Fisher exact test P = 0.0002). On the other hand, this RET variant allele is overrepresented in patients affected with medullary thyroid carcinoma. Assuming a direct effect of this single-nucleotide polymorphism in predisposing to RET associated pathologies, we have performed functional tests which excluded any possible involvement of the C and T alleles in DNA-protein binding, transcript stability and RNA splicing and editing.

Alleles↗
PubMed2000

Localisation of the gene responsible for fechtner syndrome in a region <600 Kb on 22q11-q13.

Fechtner syndrome is an autosomal dominant disorder which has been thought to be a variant of Alport syndrome. It is characterised by nephritis, sensorineural hearing loss and eye abnormalities, as well as by macrothrombocytopenia and polymorphonuclear inclusion bodies. Recently, the Fechtner syndrome has been mapped in a 5.5 Mb region on the long arm of chromosome 22 by linkage analysis in an extended Israeli family. We describe here the genetic refinement of the Fechtner critical interval to a region less than 600 Kb by linkage analysis performed in a large Italian pedigree. The presence of several recombination events allowed the disease gene to be localised between markers D22S278 and D22S426, in a region containing only two non-recombinant markers, D22S1173 and D22S283. This interval, spanning <600 Kb on genomic DNA, has been entirely sequenced and contains six known and three putative genes.

Abnormalities, Multiple↗
PubMed2000

A refined physical and transcriptional map of the SPG9 locus on 10q23.3-q24.2.

Hereditary spastic paraplegia (HSP) is a genetically heterogeneous disorder characterised by progressive spasticity of the lower limbs. Beside 'pure' forms of HSP, 'complicated' forms are reported, where spasticity occurs associated with additional symptoms. We recently described an Italian family with a complicated dominant form of HSP (SPG9) and we mapped the gene responsible to 10q23.3-q24.2, in a 12cM interval between markers D10S564 and D10S603. The phenotypic manifestations in our family are reminiscent of those already described in a smaller British pedigree. We typed individuals from this British family using markers located in the SPG9 critical interval and haplotype reconstruction showed the disorder co-segregating with SPG9. To characterise the SPG9 region better, we constructed a contig of 22 YACs, assigned it to 18 polymorphic markers and positioned 54 ESTs. Furthermore, we searched for ESTs containing a trinucleotide repeat sequence, since anticipation of symptoms was reported in both families. Finally, analysis of a muscle biopsy specimen from one patient was normal, suggesting that, contrary to SPG7, mitochondrial disturbance could not be a primary feature of SPG9.

Biopsy↗
PubMed2000

A DNA element in the alpha1 type III collagen promoter mediates a stimulatory response by angiotensin II.

BACKGROUND: Angiotensin II (Ang II) plays an important role in extracellular matrix deposition and tissue scarring in the kidney and the heart. The mechanism for extracellular matrix stimulation by Ang II is currently hypothetical, with one possibility pointing to a direct effect on cell synthesis of specific collagens. METHODS: We studied the molecular mechanism for activation of type III collagen synthesis by Ang II in an in vitro cell model of myofibroblasts by evaluating (1) alpha1(III) collagen mRNA expression; (2) alpha1(III) collagen promoter activity; (3) DNA/protein binding with characterization of binding sites; (4) expression of transcription factors; and (5) the role of a short DNA segment as Ang II responsive element. RESULTS: We found a specific dose-dependent stimulation of alpha1(III) collagen mRNA expression and a parallel effect on alpha1(III) collagen promoter activity. Transfection of constructs containing alpha1(III) collagen promoter fragments of different lengths localized the site of activation within the shortest 178 bp construct. By gel-retardation experiments, we observed the formation of a DNA-protein complex with crude extracts from Ang II-stimulated cells and an oligonucleotide spanning the 3 to 20 sequence. This complex was due to a sequence-specific interaction and was abolished by a 3 bp substitution mutation. The introduction of this mutation into the 178 bp construct abolished the stimulatory effect of Ang II. CONCLUSIONS: These results demonstrate that Ang II stimulates the expression of alpha1(III) collagen mRNA in myofibroblasts in vitro by activating the alpha1(III) collagen promoter at the level of a factor recognition site localized immediately downstream of the transcription start site. This mechanism could be involved in Ang II-induced renal and heart fibrosis.

Angiotensin II↗