Biomedical subjects

Nathalie Scamuffa

Publications and source records attributed to Nathalie Scamuffa.

8 recordsLinked to original sources

PubMed2007

Potential opportunity in the development of new therapeutic agents based on endogenous and exogenous inhibitors of the proprotein convertases.

The proprotein convertases (PCs) are responsible for the endoproteolytic processing of various protein precursors (e.g., growth factors, receptors, adhesion molecules, and matrix metalloproteinases) implicated in several diseases such as obesity, diabetes, atherosclerosis, cancer, and Alzheimer disease. The potential clinical and pharmacological role of the PCs has fostered the development of various PC-inhibitors. In this review we summarized the recent findings on PCs inhibitors, their mode of actions and potential use in the therapy of various diseases.

Humans↗

PubMed2006

Proprotein convertases: lessons from knockouts.

The physiological role of the subtilisin/kexin-like proprotein convertases (PCs) in rodents has been examined through the use of knockout mice. This review will summarize the major in vivo defects that result from the disruption of the expression of their genes. This includes abnormal embryonic development, hormonal disorder, infertility, and/or modified lipid/sterol metabolism. Members of the PC family play a central role in the processing of various protein precursors ranging from hormones and growth factors to bacterial toxins and viral glycoproteins. Proteolysis occurring at basic residues is mediated by the basic amino acid-specific proprotein convertases, namely: PC1/3, PC2, furin, PACE4, PC4, PC5/6, and PC7. In contrast, proteolysis at nonbasic residues is performed by the subtilisin/kexin-like isozyme-1 (SKI-1/S1P) and the newly identified neural apoptosis-regulated convertase-1 (PCSK9/NARC-1). In addition to their requirement for many physiological processes, these enzymes are also involved in various pathologies such as cancer, obesity, diabetes, lipid disorders, infectious diseases, atherosclerosis and neurodegenerative diseases.

Animals↗

PubMed2005

Regulation of the stepwise proteolytic cleavage and secretion of PDGF-B by the proprotein convertases.

Platelet-derived growth factor-B (PDGF-B) is important for normal tissue growth and maintenance and its overexpression has been linked to several diseases, including cancer, fibrotic disease and atherosclerosis. Here, we show that synthesized as a precursor, proPDGF-B is converted to a mature form by proteolytic cleavage at two sites and its N-terminal cleavage is a prerequisite for processing at its C-terminus. The first cleavage occurs at residues RGRR81/, and the second cleavage close to residues ARPVT190, just before the C-terminal amino-acid sequence crucial for PDGF-B retention to cell surface. Cotransfection of a Furin-deficient cell line LoVo-C5 with proPDGF-B and different PC members revealed that Furin, PACE4, PC5, and PC7 are candidate proPDGF-B convertases. This finding is consistent with the in vitro digestions of a synthetic peptide mimicking the cleavage site of proPDGF-B. The processing of proPDGF-B is blocked by site-directed mutagenesis of the RGRR81/ sequence and by various PC inhibitors. Mutation of the PDGF-A and/or PDGF-B convertase sites, revealed that processing of both A and B chains is required for the formation of mature PDGF-B dimers and that the processing of the B chain controls the level of secreted and matrix-bound PDGF-BB forms. Our findings emphasize the importance of the convertase-directed processing of proPDGF-B at the RGRR81/ sequence for PDGF-B maturation and secretion.

Amino Acid Sequence↗

PubMed2003

Evolutionary discrimination of mammalian conserved non-genic sequences (CNGs).

Analysis of the human and mouse genomes identified an abundance of conserved non-genic sequences (CNGs). The significance and evolutionary depth of their conservation remain unanswered. We have quantified levels and patterns of conservation of 191 CNGs of human chromosome 21 in 14 mammalian species. We found that CNGs are significantly more conserved than protein-coding genes and noncoding RNAS (ncRNAs) within the mammalian class from primates to monotremes to marsupials. The pattern of substitutions in CNGs differed from that seen in protein-coding and ncRNA genes and resembled that of protein-binding regions. About 0.3% to 1% of the human genome corresponds to a previously unknown class of extremely constrained CNGs shared among mammals.

Animals↗

PubMed2002

Human chromosome 21 gene expression atlas in the mouse.

Genome-wide expression analyses have a crucial role in functional genomics. High resolution methods, such as RNA in situ hybridization provide an accurate description of the spatiotemporal distribution of transcripts as well as a three-dimensional 'in vivo' gene expression overview. We set out to analyse systematically the expression patterns of genes from an entire chromosome. We chose human chromosome 21 because of the medical relevance of trisomy 21 (Down's syndrome). Here we show the expression analysis of all identifiable murine orthologues of human chromosome 21 genes (161 out of 178 confirmed human genes) by RNA in situ hybridization on whole mounts and tissue sections, and by polymerase chain reaction with reverse transcription on adult tissues. We observed patterned expression in several tissues including those affected in trisomy 21 phenotypes (that is, central nervous system, heart, gastrointestinal tract, and limbs). Furthermore, statistical analysis suggests the presence of some regions of the chromosome with genes showing either lack of expression or, to a lesser extent, co-expression in specific tissues. This high resolution expression 'atlas' of an entire human chromosome is an important step towards the understanding of gene function and of the pathogenetic mechanisms in Down's syndrome.

Animals↗

PubMed2002

Numerous potentially functional but non-genic conserved sequences on human chromosome 21.

The use of comparative genomics to infer genome function relies on the understanding of how different components of the genome change over evolutionary time. The aim of such comparative analysis is to identify conserved, functionally transcribed sequences such as protein-coding genes and non-coding RNA genes, and other functional sequences such as regulatory regions, as well as other genomic features. Here, we have compared the entire human chromosome 21 with syntenic regions of the mouse genome, and have identified a large number of conserved blocks of unknown function. Although previous studies have made similar observations, it is unknown whether these conserved sequences are genes or not. Here we present an extensive experimental and computational analysis of human chromosome 21 in an effort to assign function to sequences conserved between human chromosome 21 (ref. 8) and the syntenic mouse regions. Our data support the presence of a large number of potentially functional non-genic sequences, probably regulatory and structural. The integration of the properties of the conserved components of human chromosome 21 to the rapidly accumulating functional data for this chromosome will improve considerably our understanding of the role of sequence conservation in mammalian genomes.

Animals↗

PubMed2002

The transmembrane serine protease (TMPRSS3) mutated in deafness DFNB8/10 activates the epithelial sodium channel (ENaC) in vitro.

TMPRSS3 encodes a transmembrane serine protease that contains both LDLRA and SRCR domains and is mutated in non-syndromic autosomal recessive deafness (DFNB8/10). To study its function, we cloned the mouse ortholog which maps to Mmu17, which is structurally similar to the human gene and encodes a polypeptide with 88% identity to the human protein. RT-PCR and RNA in situ hybridization on rat and mouse cochlea revealed that Tmprss3 is expressed in the spiral ganglion, the cells supporting the organ of Corti and the stria vascularis. RT-PCR on mouse tissues showed expression in the thymus, stomach, testis and E19 embryos. Transient expression of wild-type or tagged TMPRSS3 protein showed a primary localization in the endoplasmic reticulum. The epithelial amiloride-sensitive sodium channel (ENaC), which is expressed in many sodium-reabsorbing tissues including the inner ear and is regulated by membrane-bound channel activating serine proteases (CAPs), is a potential substrate of TMPRSS3. In the Xenopus oocyte expression system, proteolytic processing of TMPRSS3 was associated with increased ENaC mediated currents. In contrast, 6 TMPRSS3 mutants (D103G, R109W, C194F, W251C, P404L, C407R) causing deafness and a mutant in the catalytic triad of TMPRSS3 (S401A), failed to undergo proteolytic cleavage and activate ENaC. These data indicate that important signaling pathways in the inner ear are controlled by proteolytic cleavage and suggest: (i) the existence of an auto-catalytic processing by which TMPRSS3 would become active, and (ii) that ENaC could be a substrate of TMPRSS3 in the inner ear.

Animals↗

PubMed2002

Mutations in the DNAH11 (axonemal heavy chain dynein type 11) gene cause one form of situs inversus totalis and most likely primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD; MIM 242650) is an autosomal recessive disorder of ciliary dysfunction with extensive genetic heterogeneity. PCD is characterized by bronchiectasis and upper respiratory tract infections, and half of the patients with PCD have situs inversus (Kartagener syndrome). We characterized the transcript and the genomic organization of the axonemal heavy chain dynein type 11 (DNAH11) gene, the human homologue of murine Dnah11 or lrd, which is mutated in the iv/iv mouse model with situs inversus. To assess the role of DNAH11, which maps on chromosome 7p21, we searched for mutations in the 82 exons of this gene in a patient with situs inversus totalis, and probable Kartagener syndrome associated with paternal uniparental disomy of chromosome 7 (patUPD7). We identified a homozygous nonsense mutation (R2852X) in the DNAH11 gene. This patient is remarkable because he is also homozygous for the F508del allele of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Sequence analysis of the DNAH11 gene in an additional 6 selected PCD sibships that shared DNAH11 alleles revealed polymorphic variants and an R3004Q substitution in a conserved position that might be pathogenic. We conclude that mutations in the coding region of DNAH11 account for situs inversus totalis and probably a minority of cases of PCD.

Axonemal Dyneins↗