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PubMed2003

Identification and expression analysis of a novel splice variant of human Sprouty1 gene.

Sprouty (SPRY) was first identified in a genetic screen in Drosophila to be an antagonist of fibroblast growth factor (FGF) and epidermal growth factor (EGF) signaling, seemingly by inhibiting the Ras/MAP kinase pathway. During large scale DNA sequencing of the human fetal brain cDNA library, we cloned a novel splice variant of human Sprouty1 gene, and termed it human Sprouty1b (SPRY1b). It has the same deduced protein as Sprouty1a, which has been reported. And like other members of Sprouty family, SPRY1b deduced protein also has a C-terminal cysteine-rich region. According to the search against human genome database, SPRY1b was mapped to 4q25-28. Expression analysis of SPRY1a and SPRY1b shows that they are hardly expressed in adult human, but have different expression patterns in fetus, which confirmed that SPRY1 is an important gene during fetal development.

Adaptor Proteins, Signal Transducing↗
PubMed1992

[Malignant lymphomas of the mantle zone].

A series of mantle zone malignant lymphomas rendered ideas about their common features. Patients of higher age prevailed, prognosis was favourable even up to a steady state. Small cell blastic (centrocytoid) malignant lymphoma of the mantle zone (in lymphnodes, spleen, skin, parotid gland) tended to produce lymphoepithelial lesions, angioinvasion, and especially to spread into sinuses which did not influence prognosis in a positive way. B monocytoid medium cell malignant lymphoma (in lymphnodes, stomach, skin) was closer to classic malignant lymphomas in its behaviour but varied localization and usual mixed cytology produced rather controversial pictures. Independence of further variants (plasmacytoid, clear celled) was doubtful. Nevertheless, to be familiar with them was useful for their identification in mixed cytology variants which were very frequent. Relation of clear cell lymphomas to hairy cell leukaemias and independence of so called paracortex mixed malignant lymphoma as well as reticulohistiocytic malignant lymphoma was discussed.

Adult↗
PubMed1988

D-serine dehydratase from Escherichia coli. DNA sequence and identification of catalytically inactive glycine to aspartic acid variants.

We have identified two glycyl residues whose integrity is essential for the catalytic competence of a model pyridoxal 5'-phosphate requiring enzyme, D-serine dehydratase from Escherichia coli. This was accomplished by isolating and sequencing the structural gene from wild type E. coli and from two mutant strains that produce inactive D-serine dehydratase. DNA sequencing indicated the presence of a single glycine to aspartic acid replacement in each variant. The amino acid replacements lie in a glycine-rich region of D-serine dehydratase well removed from pyridoxal 5'-phosphate-binding lysine 118 in the primary structure of the enzyme. The striking effect of these two glycine to aspartic acid replacements on catalytic activity, the conservation of the glycine-rich region in several pyridoxal 5'-phosphate-dependent enzymes that catalyze alpha/beta-eliminations, and the placement of similar glycine-rich sequences in well-characterized active site structures suggest that the glycine-rich region interacts with the cofactor at the active site of the enzyme.

Amino Acid Sequence↗
PubMed1984

Human apolipoprotein A-I polymorphism. Identification of amino acid substitutions in three electrophoretic variants of the Münster-3 type.

Variant forms of apolipoprotein A-I (apo-A-I) have been shown to exist in the human population. One mutant form, referred to as apo-A-I-Münster-3, is one charge unit more basic than normal apo-A-I on isoelectric focusing gels. This variant has the same immunologic characteristics and molecular weight as normal apo-A-I. The apo-A-I-Münster-3 from subjects in three unrelated families (in two of which the trait has been shown to be transmitted as an autosomal co-dominant) has been analyzed by partial amino acid sequencing to define the cause of the electrophoretic abnormality. In the apo-A-I of family A, the abnormality was shown to occur in the smallest cyanogen bromide fragment, CB-2 (residues 87-112), and amino acid sequencing revealed asparagine instead of the usual aspartic acid at residue 103. Subjects with this mutant form have shown no signs of dyslipoproteinemia. The NH2-terminal cyanogen bromide fragment (CB-1, residues 1-86) from the apo-A-I of family B was shown to differ electrophoretically from normal CB-1, and amino acid sequencing revealed that a substitution of arginine for proline at residue 4 was responsible for this variant form. Analysis of the plasma lipids of one affected family B member demonstrated that the percentage of the total cholesterol that was esterified was somewhat lower than that normally observed. In a third family, family C, a variant having the same electrophoretic abnormality as the other two was determined to have an amino acid substitution at yet a different position. In this variant, histidine was found at residue 3 in the apo-A-I sequence, rather than the usual proline. In all three cases, the substitution could account for the electrophoretic abnormality. It is proposed that these three apo-A-I-Münster-3 variants be designated apo-A-I(Asp103----Asn), apo-A-I(Pro4----Arg), and apo-A-I(Pro3----His), respectively, to indicate the substitution that accounts for the abnormality in isoelectric focusing gels.

Amino Acids↗
PubMed1995

Identification and characterization of a novel apolipoprotein E variant, apolipoprotein E3' (Arg136-->His): association with mild dyslipidemia and double pre-beta very low density lipoproteins.

Apolipoprotein (apo) E mediates the removal of chylomicron and VLDL remnants from plasma. In a proband with mild hyperlipidemia and a family history of premature coronary artery disease, we have identified a new mutant of apoE with an isoelectric point close to but distinct from that of apoE3. Sequencing of the apoE gene from this subject (JB) revealed that the subject was heterozygous for a G to A substitution in codon 136, resulting in the substitution of histidine for arginine; therefore, we have designated this isoform apoE3' (Arg136-->His). Examination of the proband's kindred revealed that the nine carriers (all heterozygotes) of the variant isoform displayed a twofold elevation in the concentration of very low density lipoprotein (VLDL) cholesterol (40 +/- 8 mg/dl) and triglyceride (109 +/- 19) compared to the nine noncarriers (19 +/- 3 and 55 +/- 13, respectively). In all carriers, the VLDL displayed an abnormal double pre-beta pattern upon electrophoresis. The low density lipoprotein receptor-binding activity of purified apoE3' (Arg136-->His) when complexed with DMPC was slightly defective (80% of the activity of normal apoE). The mutant apoE also displayed a reduced affinity for heparin compared to apoE3. As both of these biochemical parameters are known to be important in VLDL clearance, the defects associated with this variant are likely responsible for the increase in VLDL observed in carriers. None of the carriers displayed clinical features of type III hyperlipoproteinemia, suggesting that the relatively mild dyslipoproteinemic phenotype associated with this variant might be associated with recessive expression of this disorder. However, the abnormal VLDL phenotype appears to be dominantly expressed.

Adult↗
PubMed1995

Identification of tuberous sclerosis 2 messenger RNA splice variants that are conserved and differentially expressed in rat and human tissues.

Tuberous sclerosis 2 (Tsc2) gene is the target of a germline insertion in the Eker rat model of inherited cancer susceptibility. This tumor suppressor gene, when mutated, gives rise to a spectrum of epithelial and nonepithelial neoplasms in the rat, as well as multisystem involvement of hamartomas in the human. In this study, we characterized the rat Tsc2 cDNA and found that it is highly homologous with the human gene, including a conserved rap1GAP catalytic domain. Sequence analysis of independent rat clones from a kidney cDNA library revealed distinct but related variants of the Tsc2 transcripts stemming from alternative splicing involving two noncontiguous exons within the translated region. The first of these, located at amino acids 947 to 990, gives rise to isoforms with or without the 129-bp exon. There exists another variant related to the use of a "cryptic" splice acceptor site in the downstream exon that results in an in-frame 3-bp deletion. A separate 69-bp exon encoding a novel serine-rich amino acid sequence (1272 to 1295) was also alternatively spliced. Together, we have found a minimum of four and potentially eight Tsc2 isoforms that are differentially expressed in a tissue-specific manner. These splice variants are highly conserved in the human gene, suggesting a possible functional role of these Tsc2 isoforms in various cell regulatory and developmental processes.

Amino Acid Sequence↗
PubMed1995

Identification and genetic analysis of a common molecular variant of histidine-rich glycoprotein with a difference of 2kD in apparent molecular weight.

Two forms of histidine-rich glycoprotein (HRG) were detected on SDS-PAGE by silver staining and immunoblotting after isolation of the protein from pooled plasma using immuno-affinity chromatography followed by chromatography with heparin-Sepharose. Both forms were single-chain molecules and the apparent molecular weights of form 1 and form 2 were 77 kD and 75 kD respectively. Mendelian inheritance of both HRG forms was observed in four families with 24 informative meioses, strongly suggesting that the two forms are encoded by different alleles. The frequency of form 1 and form 2 in a group of 36 individuals was 0.35 and 0.65 respectively. The difference between the two molecular variants was studied by direct sequence analysis of amplified exons of the HRG gene from 6 individuals who were homozygous either for form 1 or form 2. Five amino acid polymorphisms in three different exons were observed: Ile/Thr in exon4; Pro/Ser in exon 5; His/Arg, Arg/Cys and Asn/Ile in exon 7. Analysis of these polymorphisms in 20 volunteers showed that only the Pro/Ser polymorphism at position 186 in exon 5 was coupled to the form of the HRG protein. Ser was found in form 1 and Pro in form 2. The presence of Ser at position 186 introduces a consensus sequence for a N-glycosylation site (Asn-X-Ser/Thr). By removing N-linked sugars with N-glycanase, it could be demonstrated that the difference between the two forms of HRG is caused by an extra carbohydrate group at Asn 184 in form 1.

Amino Acid Sequence↗
PubMed1996

Identification, molecular cloning, and distribution of a short variant of the 5-hydroxytryptamine2C receptor produced by alternative splicing.

The actions of the neurotransmitter 5-hydroxytryptamine (5-HT) (serotonin) are mediated by multiple receptor subtypes. One of the prominent serotonin receptors in the brain is the 5-HT2C receptor (5-HT2C-R). We report the occurrence of a second 5-HT2C-R transcript, first identified using S1 nuclease protection of total RNA isolated from the choroid plexus. Analyses of the distribution of these two RNAs revealed that the short form is expressed in the same structures as the 5-HT2C-R mRNA, including choroid plexus, striatum, hippocampus, hypothalamus, olfactory tubercles, and spinal cord. Cloning and sequence analyses revealed a second cDNA with a 95-nt deletion in the region coding for the putative second intracellular loop and the fourth transmembrane domain of the 5-HT2C-R. This deletion leads to a frameshift in the coding sequence and the introduction of a premature stop codon. The predicted truncated protein (5-HT2C-tr) contains 172 amino acids, with 153 residues at the amino terminus, identical to the 5-HT2C-R, and 19 carboxyl-terminal amino acids that are unique. Although antibodies specific to the 5-HT2C-tr protein showed that the truncated form is expressed in a transfected fibroblast cell model system, there was no serotonergic ligand binding activity or phosphoinositide hydrolysis. Analyses of the 5-HT2C-R gene revealed that the two transcripts arise from a single gene by differential splicing using alternative donor sites and a common 3'-splice acceptor. Polymerase chain reaction amplification of mouse and human brain cDNAs demonstrated the occurrence of the same splicing patterns in these species. Although this study demonstrates tissue-specific expression of two 5-HT2C mRNA splice variants in rat, mouse, and human, the significance of the truncated form in these three species remains to be established.

3T3 Cells↗
PubMed1998

Comparison of tsa417-like variant-specific surface protein (VSP) genes in Giardia intestinalis and identification of a novel locus in genetic group II isolates.

A gene (vsp417-3A-II) encoding a new member of the variant-specific surface protein (VSP) family of Giardia is described. Vsp417-3A-II is detected exclusively in isolates belonging to the genetic Assemblage A/Group II sublineage of G. intestinalis, and it is closely related to a previously characterized VSP gene (tsp11, herein renamed vsp417-2A-I) found in Group I isolates of G. intestinalis. Analysis of DNA amplified from the genomes of Group II isolates using consensus primers also revealed products corresponding to the vsp417-2 locus (vsp417-2A-II allele), indicating that vsp417-2A-II and vsp417-3A-II represent separate loci in these organisms. Southern hybridizations revealed a single genomic copy of vsp417-3A-II in Group II isolates, but efforts to detect this locus in Group I organisms were unsuccessful. Together with the vsp417-1 (tsa417) locus that was first identified in the genetic Group I isolate WB and which has been detected since in all tested genetic Group I isolates (as vsp417-1A-I) and in genetic Group II isolates (as vsp417-1A-II), vsp417-3A-II represents a third member of a stable subset of tsa417-like VSP genes in genetic Group II G. intestinalis. The encoded polypeptide, VSP417-3A-II (667 residues, predicted M(r) 69120) possesses a high cysteine content (12.1 mol%), 28 copies of the metal-binding -CXXC- motif, and a highly conserved C-terminal hydrophobic domain--similar to all other characterized Giardia VSP. A revised nomenclature for Giardia VSP genes is proposed, prompted by the need to describe the homologues found in the various major genotypes of the species complex, G. intestinalis.

Amino Acid Sequence↗
PubMed1998

Analysis of deleted variant of hepatocyte growth factor by alanine scanning mutagenesis: identification of residues essential for its biological function and generation of mutants with enhanced mitogenic activity on rat hepatocytes.

To understand the structure-function relationship of hepatocyte growth factor (HGF) in more detail, we analyzed one of the other forms of HGF, deleted variant of HGF (dHGF), by alanine scanning mutagenesis. We show here that there are at least four sites important for dHGF to stimulate DNA synthesis in cultured adult rat hepatocytes, and that the residues of HGF essential for exerting its biological activity are not identical to those of dHGF. In addition, two mutants showed a decrease (approximately three-fold) in EC50 compared with wild-type dHGF in an assay of mitogenic activity on rat hepatocytes.

Alanine↗
PubMed1989

Use of transgenic mice for the characterization of human alpha 1-acid glycoprotein (orosomucoid) variants.

Sera from transgenic mice (TM) carrying human genes of alpha 1-acid glycoprotein (orosomucoid or ORM) have been analyzed by isoelectrofocusing and subsequent immunoblotting with antihuman ORM antibodies. With this technique it is possible to reveal selectively the human protein secreted in the TM sera. Orosomucoid bands present in TM sera have been compared with those of the most common human ORM phenotypes to correlate the products of specific genes to previously identified genetic variants. In this paper, we report the identification of the genes encoding for variants ORM1 F1 and ORM2 A, which are genes AGP-A and AGP-B/B' respectively. The nucleotide sequences of these genes are known; therefore a direct correlation between variants and specific amino acid sequences can be established.

Animals↗
PubMed1982

Genetic variants of placental alkaline phosphatase as detected by a monoclonal antibody.

Human placental alkaline phosphatase (PLAP) is a highly polymorphic enzyme. Several common as well as rare allelic forms of PLAP are characterized in this paper in terms of their reactivity with a murine monoclonal antibody (F11). The common type 1 (S) and 3 (I) variants, and the rare type 4 (S2) and 18 (D) variants were found to react with the F11 antibody, so as did three new electrophoretically defined variants (19, 20, and 21). In contrast, the common type 2 (F1) variant and the rare type 8 (F3) and 9 (F2) variants do not react with the F11 antibody. This selective reactivity of F11 has also allowed the identification of two molecular variants of PLAP with identical electrophoretic mobility. These results establish monoclonal antibodies as invaluable adjuncts in the study of PLAP polymorphism.

Alkaline Phosphatase↗
PubMed1985

Molecular aspects of erythroenzymopathies associated with hereditary hemolytic anemia.

Since the discovery of glucose 6-phosphate dehydrogenase (G6PD) and of pyruvate kinase deficiencies, erythroenzymopathies associated with hereditary hemolytic anemia have been extensively investigated. Kinetic and electrophoretic studies have shown that most, if not all, erythroenzymopathies are caused by the production of a mutant enzyme. Except for a few enzymes that are abundant in blood and tissues, it is difficult to obtain enough sample to study the functional and structural abnormalities of mutant enzymes associated with genetic disorders in man. The primary structures of only two normal red cell enzymes which can cause hereditary hemolytic anemia, phosphoglycerate kinase (PGK) and adenylate kinase, have been determined. Single amino acid substitutions of PGK variants have been found, and the identification of the exact molecular abnormalities of such variants has helped us to understand the accompanying functional abnormality. Gene cloning makes possible the identification of the DNA sequence that codes for enzyme proteins. Recently, human complementary DNA (cDNA) for aldolase, PGK, G6PD, and adenosine deaminase (ADA) have been isolated, and the nucleotide sequences for PGK and ADA determined. In the near future, human cDNA sequencing should permit identification of the gene alteration that gives rise to the mutant enzymes.

5'-Nucleotidase↗
PubMed2001

Monitoring resistance to human immunodeficiency virus type 1 protease inhibitors by pyrosequencing.

The emergence of drug-resistant viral variants is the inevitable consequence of incomplete suppression of human immunodeficiency virus type 1 (HIV-1) replication during treatment with antiretroviral drugs. Sequencing to determine the resistance profiles of these variants has become increasingly important in the clinical management of HIV-1 patients, both in the initial design of a therapeutic plan and in selecting a salvage regimen. Here we have developed a pyrosequencing assay for the rapid characterization of resistance to HIV-1 protease inhibitors (PIs). Twelve pyrosequencing primers were designed and were evaluated on the MN strain and on viral DNA from peripheral blood mononuclear cells from eight untreated HIV-1-infected individuals. The method had a limit of detection of 20 to 25% for minor sequence variants. Pattern recognition (i.e., comparing actual sequence data with expected wild-type and mutant sequence patterns) simplified the identification of minor sequence variants. This real-time pyrosequencing method was applied in a longitudinal study monitoring the development of PI resistance in plasma samples obtained from four patients over a 2 1/2-year period. Pyrosequencing identified eight primary PI resistance mutations as well as several secondary mutations. This sequencing approach allows parallel analysis of 96 reactions in 1 h, facilitating the monitoring of drug resistance in eight patients simultaneously and, in combination with viral load analysis, should be a useful tool in the future to monitor HIV-1 during therapy.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Endothelial nitric oxide synthase gene polymorphism in dialysis patients.

Nitric oxide is an important factor in the regulation of vasodilator tone. In vascular cells, NO is synthesized by endothelial nitric oxide synthase, a key enzyme of the endogenous vasodilator system. Some studies have described the interaction between NO and the other factors that promote vasodilatation in vascular smooth muscular cells. Some of those factors are angiotensin-converting enzyme (ACE), transforming growth factor beta (TGF beta), and endothelial oxide nitric synthase (eNOS). Polymorphism that can alter the expression or the function of the eNOS protein has been identified in the eNOS gene in the promoter and codification zones. We studied the Glu298Asp variant of the eNOS gene in 52 hemodialysis (HD) patients, 22 peritoneal dialysis (PD) patients, and 93 healthy controls. Identification of the Glu298Asp variant in exon 7 was performed by enzymatic amplification and restriction fragment length polymorphism (RFLP) analysis. The frequencies of eNOS genotypes in the control group were GG, 39.8%; GT, 43%; and TT, 17.2%. In HD patients, the frequencies were GG, 40.3%; GT, 38.7%; and TT, 21.7%. In PD patients, they were GG, 41.6%; GT, 50%; and TT, 8.6%. No significant differences were seen between the control group and the dialysis patients, or between the HD and the PD patients.

Endothelium, Vascular↗
PubMed1989

Identification of a human transcription unit affected by the variant chromosomal translocations 2;8 and 8;22 of Burkitt lymphoma.

Chromosomal translocations in Burkitt lymphoma and mouse plasmacytomas typically lie within or near the protooncogene MYC. In some instances, however, these tumors contain variant translocations with breakpoints located more distant from and downstream of MYC, in a domain commonly known as pvt-1. Until now, there has been no evidence that pvt-1 marks the location of a functional gene. Here we report the identification of a large transcriptional unit in human DNA that includes pvt-1. We have designated this unit as PVT. PVT begins 57 kilobase pairs downstream of MYC and occupies a minimum of 200 kilobase pairs of DNA. Some of the translocations that occur downstream of MYC in Burkitt lymphoma transect PVT; others lie between the two genes. None of the translocations we have studied appear to enhance transcription from an intact allele of PVT (indeed, they may inactivate that transcription), but some are associated with the production of abundant and anomalous 0.8- to 1.0-kilobase RNAs that contain the 5' exon of PVT and sequences transcribed from the constant region of an immunoglobulin gene (the reciprocal participant in the translocation). Identification of PVT should facilitate the exploration of how translocations downstream of MYC and insertions of retroviral DNA in the vicinity of pvt-1 might contribute to tumorigenesis.

Base Composition↗
PubMed1984

[Data from a serological survey of the population of the Republic of Congo for the presence of antibodies to orthopoxviruses. II. The species identification of the antibodies by using a solid-phase variant of immunoenzyme method].

To differentiate antibodies to monkeypox and vaccinia viruses, the solid-phase ELISA with preliminary adsorption of sera with vaccinia virus was used. The identification of antibodies in 99 serum samples obtained in the Republic of Congo from children without vaccination scars was carried out by means of this assay. No antibodies to monkeypox virus were revealed. In 62% of cases the presence of antibodies was due to vaccinia virus. In the sera of 32% of children under examination antibodies differing from those to vaccinia and monkeypox viruses were revealed. To find out the origin of these antibodies, further seroepidemiological studies are necessary.

Adolescent↗