Search PubMed⌕ Search

Biomedical subjects

M G Mattei

Publications and source records attributed to M G Mattei.

At least 91 records · Page 5Linked to original sources
PubMed1997

Molecular cloning of human RP105.

RP105 is a 105-kDa type I membrane protein of the leucine-rich repeat (LRR) family. Anti-RP105 sensitizes B cells to antigen-receptor-mediated apoptosis, but protects B cells from radiation-induced apoptosis and stimulates B cell proliferation. The sequence of the mouse RP105 has been reported. Here, we report the characterization of the human RP105. The 2.6-kb cDNA encodes a protein of 661 amino acids which displays 78% homology with mouse RP105. The 22 LRR and the 9 potential N-linked glycosylation sites within the extracellular region are conserved. While previous studies have shown that RP105 is expressed on surface IgM+IgD+2 B cells in mice, human RP105 was shown to be expressed on all subsets of mature B cells and dendritic cells. Human RP105 gene was mapped to the long arm of chromosome 5, where numerous cytokines and receptors have been localized.

Animals↗
PubMed1997

[Smith-Magenis syndrome].

BACKGROUND: The main features of the Smith-Magenis syndrome include broad flat midface, brachycephaly, broad nasal bridge, brachydactyly, hoarse deep voice, speech and developmental delay, and behavioral anomalies. This syndrome is due to interstitial deletion of chromosome 17p11.2. CASE REPORT: A 7-year-old girl was admitted for mental retardation. Clinical examination showed brachycephaly, broad flat midface, broad nasal bridge, malar hypoplasia, brachydactyly, decreased or absent deep tendon reflexes, and hoarse deep voice. She had a mild deafness, behavioral problems, and sleep disturbances. Chromosome analysis on lymphocytes identified a microdeletion of one chromosome subband 17p11.2. Molecular studies indicated loss of maternal allele. CONCLUSION: The Smith-Magenis syndrome is probably underdiagnosed because of its usually mild clinical features. High-resolution chromosome analysis is needed for diagnosis.

Abnormalities, Multiple↗
PubMed1997

Genetic control of diabetes progression.

Autoimmune diabetes in both the human and the nonobese diabetic mouse has elaborate genetics; in the latter case, the disease is influenced by at least 15-20 loci. We anticipated that the genetics would be simpler in the BDC2.5 T cell receptor transgenic mouse model of diabetes, wherein many T cells express a particular diabetogenic specificity. Initiation of insulitis in this model was the same on the two genetic backgrounds analyzed, but the kinetics and penetrance of diabetes were strikingly different, permitting us to focus on genetic influences during a defined window of disease progression. The differences correlated with variations in five genomic intervals, certain ones of which have been previously implicated in susceptibility to autoimmune disease. This reductionist approach indeed simplified the analysis of diabetes susceptibility loci.

Animals↗
PubMed1997

The human necdin gene, NDN, is maternally imprinted and located in the Prader-Willi syndrome chromosomal region.

Prader-Willi syndrome (PWS) is a neurogenetic disorder that results from the absence of a normal paternal contribution to the 15q11-13 region. The clinical manifestations of PWS are a transient severe hypotonia in the newborn period, with mental retardation, hypogonadism and obesity observed later in development. Five transcripts with exclusive expression from the paternal allele have been isolated, but none of these has been shown to be involved in PWS. In this study, we report the isolation and characterization of NDN, a new human imprinted gene. NDN is exclusively expressed from the paternal allele in the tissues analysed and is located in the PWS region. It encodes a putative protein homologous to the mouse brain-specific NECDIN protein, NDN; as in mouse, expression in brain is restricted to post-mitotic neurons. NDN displays several characteristics of an imprinted locus, including allelic DNA methylation and asynchronous DNA replication. A complete lack of NDN expression in PWS brain and fibroblasts indicates that the gene is expressed exclusively from the paternal allele in these tissues and suggests a possible role of this new gene in PWS.

Angelman Syndrome↗
PubMed1997

Subtractive cloning and characterization of DRAL, a novel LIM-domain protein down-regulated in rhabdomyosarcoma.

A subtractive cloning procedure was used to characterize the molecular changes involved in transformation of normal myoblasts to rhabdomyosarcoma (RMS) cells. Here we describe the cloning of DRAL, a novel LIM-domain protein expressed in primary myoblasts but down-regulated in the RMS cell line RD. DRAL is a LIM-only protein with five LIM domains whereby one LIM domain consists only of the second half of the consensus motif. Interestingly, down-regulation of DRAL was not confined to the RD RMS cells, but was a phenomenon extended to other RMS cell lines of both embryonal and alveolar subtype, and to some breast cancer cell lines. Analysis of the expression pattern in normal human tissues revealed that DRAL is expressed at high levels in the heart, suggesting an important function in the specification of the terminally differentiated phenotype of heart muscle cells. Immunofluorescence studies using an antibody directed against recombinant DRAL localized the protein predominantly in the nucleus of cultured cells. On the basis of these results, we conclude that down-regulation of DRAL correlates with the tumor phenotype of RMS cells.

Amino Acid Sequence↗
PubMed1997

Inherited DNA amplification of the proximal 15q region: cytogenetic and molecular studies.

In a 15 year old girl, referred for growth retardation, conventional cytogenetic analysis detected an abnormal 15q+ chromosome with extra material in the proximal region, inherited from her father and grandfather. Using various molecular cytogenetic techniques, including comparative genomic hybridisation, we showed that the extra chromatin resulted from in situ amplification of DNA sequences located between the loci D15Z1 and D15S18. On the basis of the clinical features of our patient and the late replication of the large amplified region, we searched for functional modifications in the adjacent Prader-Willi syndrome region.

Adolescent↗
PubMed1996

Genomic structure and developmental expression of the mouse cell cycle regulatory transcription factor DP1.

The E2F/DP family of transcription factors play an important role in the control of cell cycle progression. By direct regulatory interactions with the retinoblastoma family of proteins, they integrate extracellular growth promoting signals impinging on the cyclin and cyclin dependent kinase complex during the G1 phase, with cell cycle progression. This is accomplished by direct transcriptional activation of genes required for nucleotide biosynthesis and DNA replication in the S phase. In addition, these transcription factors also play a role in the control of genes involved in regulating G1 and S phase progression including, autoregulatory control, as in the case of E2F1 itself. In this report, we describe the characterisation of the genomic locus encoding DP1, a member of this family. The DP1 gene has a TATA-less promoter and transcription initiates at multiple sites. Using transient transfection assays we have delineated sequences in the upstream region which have promoter or enhancer activity. The DP1 gene was localised to mouse chromosome 8 by metaphase chromosome analysis. We describe a dynamic pattern of DP1 expression using in situ hybridisation on cryostat sections of mouse embryos at various stages of development and a variable level of expression by Northern blot analysis of RNA from various adult tissues.

Animals↗
PubMed1996

Structure and expression of the ATFa gene.

The human ATFa proteins belong to the ATF/CREB family of transcription factors. We have previously shown that they mediate the transcriptional activation by the largest E1a protein and can heterodimerize with members of the Jun/Fos family. ATFa proteins have also been found tightly associated with JNK2, a stress-activated kinase. We now report on the structure of the ATFa gene, which mapped to chromosome 12 (band 12q13). Sequence analysis revealed that ATFa isoforms are generated by alternative splice donor site usage. A minimal promoter region of approximately 200 base pairs was identified that retained nearly full transcriptional activity. Binding sites for potential transcription factors were delineated within a GC-rich segment by DNase I footprinting. Expression studies revealed that ATFa accumulates in the nuclei of transfected cells, and the nuclear localization signal was defined next to the leucine zipper domain. As revealed by hybridization with mouse ATFa sequences, low levels of ATFa mRNAs were ubiquitously distributed in fetal or adult mice, with enhanced expression in particular tissues, like squamous epithelia and specific brain cell layers. The possible significance of coexpression of ATFa, ATF-2, and Jun at similar sites in the brain is discussed.

Activating Transcription Factors↗
PubMed1996

Biochemical and genetic characterization of multiple splice variants of the Flt3 ligand.

We have performed a comprehensive analysis of cell lines and tissues to compare and contrast the expression patterns of Flt3 ligand (FL), c-Kit ligand (KL), and macrophage colony-stimulating factor as well as their receptors, Flt3, c-Kit, and c-Fms. The message for FL is unusually ubiquitous, whereas that of its receptor is quite restricted, apparently limiting the function of the ligand to fetal development and early hematopoiesis. We have also sequenced a mouse FL genomic clone, revealing how the three splice variant FL mRNAs that we have isolated arise. The chromosomal location of the FL gene has been mapped, by in situ hybridization, to chromosome 7 in mouse and chromosome 19 in human. Natural FL protein has been purified from a stromal cell line and shown to be a 65 kD nondisulfide-linked homodimeric glycoprotein comprised of 30 kD subunits, each containing 12 kD of N- and O-linked sugars. Pulse-chase experiments show that one of the splice variants (T110) is responsible for producing the bulk of soluble FL, but only after it has first been expressed at the cell surface as a membrane-bound form. The other splice-variant forms produce molecules that are either obligatorily soluble (T169) or membrane-bound but released only very slowly (T118). Finally, even though most cell lines express some amount of FL mRNA, we found that very little FL protein is actually made, with T cells and stromal cells being the major producers. The data suggests that FL plays its roles over very short distances, perhaps requiring cell-cell contact.

Amino Acid Sequence↗
PubMed1996

A unique gene encodes spliceoforms of the B-cell adhesion molecule cell surface glycoprotein of epithelial cancer and of the Lutheran blood group glycoprotein.

Two new members of the Ig superfamily, the Lutheran (Lu) blood group glycoprotein and the B-cell adhesion molecule (B-CAM) epithelial cancer antigen, have been recently cloned from human placenta and colon cancer HT29 cell line, respectively. Although amino acid sequences deduced from cDNA analysis suggested that B-CAM should represent an abridged form of the Lu glycoprotein lacking the last 40 amino acids of the putative cytoplasmic tail, the relationship between the genes encoding these polypeptides has not been determined. In the present report, we showed by Southern blot analysis that the Lu and B-CAM cDNAs derived from a unique LU gene which exhibited an HindIII RFLP associated with the Lua/Lub blood group polymorphism. Accordingly, in situ hybridization of the Lu cDNA probe confirmed the localization of the Lutheran blood group locus to chromosome 19 q13.2-13.3, as previously shown for a B-CAM DNA probe. Sequence comparison between cDNA and genomic PCR fragments indicated that the Lu and B-CAM transcripts previously isolated are generated through the alternative use of internal splice donor and acceptor sites within an exon located at the 3' end of the LU gene. These spliceoforms corresponded to 2.5 kb and 4.0 kb mRNA species detectable by Northern blot in all tissues and cell lines in which the LU gene is expressed; their primary structures are consistent with the presence of both the Lu and B-CAM antigens on two glycoprotein isoforms. However, the 4.0 kb transcript was very poorly expressed as compared to the 2.5 kb species except in the colon carcinoma HT29 cell line, suggesting a differential regulation of the Lu/B-CAM messenger RNA in some tumor tissues.

Amino Acid Sequence↗
PubMed1996

Definition of the tumor protein D52 (TPD52) gene family through cloning of D52 homologues in human (hD53) and mouse (mD52).

Cloning is reported of a cDNA homologue to the breast carcinoma-associated D52 cDNA, termed D53, and of a mouse D52 cDNA (HGMW-approved symbols TPD52L1 and TPD52). Human D53 and mouse D52 proteins are predicted to be 52 and 86% identical to human D52, respectively. Analysis of the three protein sequences identified a coiled-coil domain and N- and C-terminally located PEST domains in each. The conservation of homology between the D52 and the D53 sequences, combined with a lack of homology between these and known proteins, defines a new mammalian gene/protein family, the D52 family. The human D52 locus has been previously mapped to chromosome 8q21, and using in situ mapping in the present study, a human D53 locus was mapped to chromosome 6q22-q23. We observed coexpression of the human D52 and D53 genes in some breast tumors and derivative cell lines and found that maintenance of D52 and D53 transcript levels in estrogen receptor-positive MCF7 breast carcinoma cells depends upon estradiol. However, D52 and D53 genes were specifically expressed in HL-60 and K-562 leukemia cells, respectively, with 12-O-tetra-decanoylphorbol-13-acetate treatment decreasing D52 and D53 transcript levels in these cell lines. The presence of a coiled-coil domain, combined with observed co- or independent expression of the D52 and D53 genes, suggests that D52 and D53 proteins may be capable of hetero- and/or homodimer formation.

Amino Acid Sequence↗
PubMed1996

Genomic structure and chromosomal localization of the mouse CDEI-binding protein CDEBP (APLP2) gene and promoter sequences.

The genomic structure of the mouse gene encoding the CDEBP protein has been established. The protein was initially identified on the basis of its ability to bind the CDEI motif (GTCACATG). The same locus has been independently described under the name APLP2, on the basis of sequence similarities with the Amyloid Precursor Protein (APP). The exon-intron distribution of Cdebp appears strikingly similar to that of the App gene in the regions encoding the conserved domains, with a divergent structure in the other parts. The transcription start site has been localized, and sequences with promoter activity have been identified immediately upstream of it by their ability to direct the expression of a reporter luciferase gene in transfected cells. This region is devoid of either TATA or CAAT boxes. The gene has been mapped to mouse chromosome 9 by in situ hybridization on metaphase chromosomes.

Animals↗
PubMed1996

The human hnRNP-M proteins: structure and relation with early heat shock-induced splicing arrest and chromosome mapping.

With anti-hnRNP monoclonal antibody 6D12 we previously showed in HeLa cells that as early as 10 min after the onset of a heat shock at 45 degrees C, a 72.5-74 kDa antigen doublet leaves the hnRNPs and strongly associates with the nuclear matrix, the effect being reversed after a 6 h recovery at 37 degrees C. cDNA cloning and sequencing enabled us to identify these antigens as hnRNP-M proteins and further to show that the correct sequence differs by an 11 amino acid stretch from the originally published sequence. We also show that monoclonal antibodies raised against synthetic hnRNP-M peptides can directly inhibit in vitro splicing. Furthermore, stressing cells at 45 degrees C for 10 min is sufficient to abolish the splicing capacity of subsequently prepared nuclear extracts which, interestingly, do not contain the hnRNP-M proteins any more. Taken together, our data suggest that these proteins are involved in splicing as well as in early stress-induced splicing arrest. Further in situ hybridization assays located the hnRNP-M encoding gene on human chromosome 19.

Amino Acid Sequence↗
PubMed1996

Identification and characterization of a widely expressed form of adenylyl cyclase.

A novel mammalian adenylyl cyclase was identified by reverse transcription-polymerase chain reaction amplification using degenerate primers based on a conserved region of previously described adenylyl cyclases (Premont, R. T. (1994) Methods Enzymol. 238, 116-127). The full-length cDNA sequence obtained from mouse brain predicts a 1353-amino acid protein possessing a 12-membrane span topology, and containing two regions of high similarity with the catalytic domains of adenylyl cyclases. Comparison of this novel adenylyl cyclase with the eight previously described mammalian enzymes indicates that this type 9 adenylyl cyclase sequence is the most divergent, defining a sixth distinct subclass of mammalian adenylyl cyclases. The AC9 gene has been localized to human chromosome band 16p13.3-13.2. The 8.5-kb mRNA encoding the type 9 adenylyl cyclase is widely distributed, being readily detected in all tissues tested, and is found at very high levels in skeletal muscle and brain. AC9 mRNA is found throughout rat brain but is particularly abundant in hippocampus, cerebellum, and neocortex. An antiserum directed against the carboxyl terminus of the type 9 adenylyl cyclase detects native and expressed recombinant AC9 protein in tissue and cell membranes. Levels of the AC9 protein are highest in mouse brain membranes. Characterization of expressed recombinant AC9 reveals that the protein is a functional adenylyl cyclase that is stimulated by Mg2+, forskolin, and mutationally activated Gsalpha. AC9 activity is not affected by Ca2+/calmodulin or by G protein betagamma-subunits. Thus AC9 represents a functional G protein-regulated adenylyl cyclase found in brain and in most somatic tissues.

Adenylyl Cyclases↗