Isolation and characterization of a novel trisialoganglioside, GT1a, from human brain

A novel trisialoganglioside has been isolated from normal adult human brain in a yield of 0.6% of the total gangkioside. By graded neuraminidase treatment, mild acid hydrolysis and periodate oxidation analysis, the ganglioside was identified as GT1a having the following structure: NeuAc(alpha, 2-8)NeuAc(alpha, 2-3)Gal(beta, 1-3)GalNAc(beta, 1-4) [NeuAc(alpha, 2-3)]Gal(beta, 1-4)Glc(1-1)ceramide.     

Minibrain (MNBH) is a single copy gene mapping to human chromosome 21q22.2

We have identified a human homologue of the Drosophila mnb gene (MNBH) on chromosome 21, while another study mapped an EST clone (R38268) with similarity to minibrain to human chromosome 1. This report describes the mapping of MNBH to a single locus on human chromosome 21q22.2 by FISH and Southern blotting. Comparison of the similarities between the two sequences and mnb demonstrates that MNBH on chromosome 21 is the true human homologue of Drosophila mnb.     

Assignment of the human connexin43 gene, GJA1, to chromosome 6q22.3

Metabolism is probably disturbed in patients with abnormal liver function who have undergone a successful Kasai procedure. We examined bone mineral metabolism in patients who have successfully undergone Kasai procedure. Bone mineral metabolism was examined in 8 patients with biliary atresia after a successful Kasai procedure. Five patients were female and 3 were male. The ages at Kasai procedure ranged from 50 to 80 days, and the follow-up periods ranged from 3 to 27 years after the operation. All patients eat a normal oral diet. We examined plasma levels of 25-OH-D3, 1, 25-(OH)2-D3, Ca and phosphorus (P). Bone mineral content of the lumbar spine (L2-L4) was assessed by dual energy x-ray absorptiometry (DEXA), and the data were expressed as a bone mineral density (BMD). Two patients showed abnormal levels on hepatic function tests. Plasma levels of 1, 25-(OH)2-D3, Ca, and P were normal in all patients. The level of 25-OH-D3 was normal in 7 patients. BMD levels were normal in 6 patients, but low in 2 who had undergone partial splenic embolization and splenectomy, respectively, due to hypersplenism. In long-term survivors of Kasai procedure, measurement of BMD may detect bone mineral deficiency earlier than measurements of serum levels of 25-OH-D, 1, 25-(OH)2-D, Ca and P.     

The human HNRPD locus maps to 4q21 and encodes a highly conserved protein

The hnRNP D protein interacts with nucleic acids both in vivo and in vitro. Like many other proteins that interact with RNA, it contains RBD (or "RRM") domains and arg-gly-gly (RGG) motifs. We have examined the organization and localization of the human and murine genes that encode the hnRNP D protein. Comparison of the predicted sequences of the hnRNP D proteins in human and mouse shows that they are 96.9% identical (98.9% similar). This very high level of conservation suggests a critical function for hnRNP D. Sequence analysis of the human HNRPD gene shows that the protein is encoded by eight exons and that two additional exons specify sequences in the 3' UTR. Use of two of the coding exons is determined by alternative splicing of the HNRPD mRNA. The human HNRPD gene maps to 4q21. The mouse Hnrpd gene maps to the F region of chromosome 3, which is syntenic with the human 4q21 region.     

Isolation of cDNA for a novel human protein KNP-I that is homologous to the E. coli SCRP-27A protein from the autoimmune polyglandular disease type I (APECED) region of chromosome 21q22.3

We have isolated cDNA clones for a novel human protein KNP-I from fetal brain and bone marrow cDNA libraries. Northern blot analysis indicated that the KNP-I gene is ubiquitously expressed in various human tissues. Significant homology of the KNP-I protein with Escherichia coli anti-sigma cross-reacting protein (SCRP-27A) (44% identity) and zebrafish (Brachydanio rerio) esl protein (49% identity) suggested that the KNP-I protein may be involved in a basic cellular function. Genomic sequencing revealed that the KNP-I gene consists of seven exons spanning 12 kb. Exon 5 was involved in alternative splicing. The KNP-I gene was mapped between D21S1460 and D21S25 on human chromosome 21q22.3, 26 kb distal to a Not 1 site of D21S1460. Thus, this novel KNP-I gene could be a candidate gene for autoimmune polyglandular disease type I (APECED) and other disorders mapped to this region.     

Isolation and characterization of a novel gene from human glioblastoma multiforme tumor tissue

The therapeutic application of high-dose interleukin (IL) 2 in human malignancy is limited by severe multiorgan toxicities that are mediated, in part, by tumor necrosis factor (TNF) and IL-1. CT1501R (lisofylline; LSF) is one of several methyl xanthine congeners that inhibit the effects of TNF by the interruption of specific signal transduction pathways. This randomized, placebo-controlled trial was designed to assess the activity of LSF in reducing the toxicities of high-dose IL-2 therapy. Fifty-three patients with metastatic renal cancer or malignant melanoma were treated with i.v. bolus IL-2, 600, 000 IU/kg every 8 h for 5 days (14 doses), followed by 9 days of rest and another 5-day course of IL-2. Patients were randomly assigned to LSF, 1.5 mg/kg i.v. bolus, or placebo every 6 h during IL-2 therapy. All patients were to be treated to individual maximum tolerance of IL-2 at the intensive care unit level of support. The end points for statistical analysis were the number of IL-2 doses administered during the first cycle of treatment (maximum, 28) and the toxicities experienced by each group after the first 8 planned IL-2 doses. There was no difference between the LSF and placebo groups in the mean number of IL-2 doses tolerated in the entire first cycle of therapy (19.6 +/- 5.4 versus 19.5 +/- 5.8, P = 0.86) or in the first or second 5-day course of IL-2. The only significant difference in toxicities occurring through the eighth dose of IL-2 was in the maximum elevation of serum creatinine (mean, 1.7 +/- 0.8 for placebo versus 1.5 +/- 0.6 mg/dl for LSF, P = 0.013). A Monte Carlo analysis of major toxicities over the first 14-dose course of therapy showed a statistically significant difference favoring the LSF-treated group (P = 0.025). LSF was well tolerated, associated only with mildly increased nausea (P = 0.006 after eight IL-2 doses, but not significant for the entire first cycle). The antitumor activity was comparable in both groups (objective responses, 2 of 28 with LSF versus 4 of 24 with placebo). The mean peak plasma concentrations of LSF on days 1, 5, and 19 were 6.24, 3.83, and 5.04 micromol/liter, respectively. In conclusion, with this dose and schedule, LSF did not alter the toxicities of high-dose i.v. IL-2 sufficiently to impact the overall dose intensity of IL-2. Successful IL-2 toxicity modulation may require the use of higher doses of LSF, the development of agents with more potent anti-TNF activity, and/or combined modulating agents that function via distinct mechanisms to interrupt cytokine-mediated signaling.     

Isolation, characterization, and mapping of two human potassium channels

Electron microscopy of negatively stained myosin has previously revealed three discrete regions within the heads of the molecule. However, despite a probable resolution of approximately 2 nm, it is difficult to discern directly consistent details within these regions. This is due to variability in both head conformation and in staining. In this study, we applied single-particle image processing and classified heads into homogeneous groups. The improved signal-to-noise ratio after averaging these groups reveals substantially improved detail. The image averages were compared to a model simulating negative staining of the atomic structure of subfragment-1 (S1). This shows that the three head regions correspond to the motor domain and the essential and regulatory light chains. The image averages were very similar to particular views of the S1 model. They also revealed considerable flexibility between the motor and regulatory domains, despite the molecules having been prepared in the absence of nucleotide. This flexibility probably results from rotation of the regulatory domain about the motor domain, where the relative movement of the regulatory light chain is up to 12 nm, and is most clearly illustrated in animated sequences (available at http://www.leeds.ac.uk/chb/muscle/myosinhead.htm l). The sharply curved conformation of the atomic model of S1 is seen only rarely in our data, with straighter heads being more typical.     

Molecular characterization of a novel amplicon at 1q21-q22 frequently observed in human sarcomas

Suppressors of position-effect variegation (Su(var)s) in Drosophila melanogaster are usually studied in the presence of chromosomal rearrangements, which exhibit variegated expression of euchromatic genes moved near to, or heterochromatic genes moved away from, centromeric heterochromatin. However, the effects of Su(var) mutations on heterochromatic gene expression in the absence of a variegating re-arrangement have not yet been defined. Here we present a number of results which suggest that Su(var) gene products can interact to affect the expression of the light gene in its normal heterochromatic location. We initially observed that eye pigment was reduced in several Su(var) double mutants; the phenotype resembled that of light mutations and was more severe when only one copy of the light gene was present. This reduced pigmentation could be alleviated by a duplication for the light gene or by a reduction in the amount of cellular heterochromatin. In addition, the viability of most Su(var) double mutant combinations tested was greatly reduced in a genetic background of reduced light gene dosage, when extra heterochromatin is present. We conclude that Su(var) gene products can affect expression of the heterochromatic light gene in the absence of any chromosomal rearrangements. However, it is noteworthy that mutations in any single Su(var) gene have little effect on light expression; we observe instead that different pairings of Su(var) mutations are required to show an effect on light expression. Interestingly, we have obtained evidence that at least two of the second chromosome Su(var) mutations are gain-of-function lesions, which also suggests that there may be different modes of interaction among these genes. It may therefore be possible to use this more sensitive assay of Su(var) effects on heterochromatic genes to infer functional relationships among the products of the 50 or more known Su(var) loci.     

Isolation and characterization of the heat-responsive genes in Escherichia coli

Isocitrate lyase from Escherichia coli has been expressed in transformed E. coli JE10 cells lacking the isocitrate lyase (icl) gene. After directed mutagenesis of icl by the restriction-site elimination method, partially purified isocitrate lyase mutants in which His 356 has been converted to Lys, Arg, Gln, Asp, or Leu have been characterized after induction of transformed, induced JE10 cells. Values of kcat compared to those for wild-type (wt) enzyme (100) at 37 degrees C, pH 7.3, are 18, 1, <1, 0, and 0 for H356K, H356R, H356E, H356Q, and H356L mutant enzymes, respectively. Km values for the 1:1 Mg-isocitrate complex (in millimolar units) are: 0.13, wt; 0.11, H356K; and 0.63, H356R. Further chromatographic purification of isocitrate lyase yields highly purified wt, H356K, and H356R enzymes. The pH profile of the stability of isocitrate lyase, which has never been reported, showed that the H356R enzyme was unstable in the pH range investigated; the wt and H356R variant differed but each was sufficiently stable to study the pH dependence of catalysis. The log kcat/pH profiles for highly purified wt and H356K enzymes are roughly bell-shaped and have pKa and pKb values for dissociation of an ionizable group on the enzyme-substrate complex of <6.3 and 8.4 for wt and 5.9 and 7.9 for H356K enzymes. Plots of pKm vs pH were different for the wt and H356K variant. Values of pKa and pKb (derived from log kcat/Km plots vs pH) for the dissociation of an activity-related ionizable group on the variant were 5.3 and 7.6, whereas the analogous pKb value for the wt enzyme was 8.4. The data suggest that His 356 is an important functional residue in isocitrate lyase, perhaps in deprotonating isocitrate during catalytic cleavage.     

Isolation and characterization of a novel human pancreas-specific gene, pancpin, that is down-regulated in pancreatic cancer cells

We reviewed 19 children and adolescents with cervical spine congenital synostosis as in Klippel-Feil syndrome (KFS), with an average follow-up of 12.5 years. We paid particular attention to neurologic complications associated with cervical spine abnormalities. Five patients were affected by neurologic complications; four underwent a surgical procedure; and 14 had no neurologic finding. Two had hypermobility at one level, and one had hypermobility at two levels. We found that the more numerous the occipito-C1 abnormalities, the more significant the neurologic risk. In contrast, this risk was not related to the number of "mobile blocks" or to age. Various mechanisms of neural complications have been studied in the literature: medullary abnormality, spinal instability, narrowing of the cervical canal, and vascular dysfunction. Surgery is usually thought to be required in cases with neurologic complications. The indication for surgery is, however, less clear in cases of pure instability without neurologic involvement because surgery is likely to increase the future risks at mobile disks either above or below the fuse level. Careful clinical and radiologic observation is necessary in such patients. Magnetic resonance imaging (MRI) with lateral views in flexion and extension seem to be the best method for detecting impingement of the spine on the cord.     

Isolation and characterization of a trisulfide variant of recombinant human growth hormone formed during expression in Escherichia coli

A new variant of human growth hormone was recently found [Pavlu, B. & Gellerfors, P. (1993) Bioseparation 3, 257-265]. We report here the identification and the structural determination of this variant. The variant, which is formed during the expression of human growth hormone in Escherichia coli, was found to be more hydrophobic than rhGH as judged by its prolonged elution time by hydrophobic interaction chromatography. The rhGH hydrophobic variant (rhGH-HV) was isolated and subjected to trypsin digestion and RP-HPLC analysis, resulting in an altered retention time of one single tryptic peptide as compared to the corresponding fragment of rhGH. This tryptic peptide constitutes the C-terminus (aa 179-191) of hGH and contains one of the two disulfide bridges in hGH, viz. Cys182-Cys189. Amino acid sequences and composition analyses of the tryptic peptide from rhGH-HV (Tv18-19) and the corresponding tryptic peptide from rhGH (T18+19) were identical. Electrospray mass spectrometry (ES MS) of Tv18+19 isolated from rhGH-HV revealed a monoisotopic mass increase of 32.7, as compared to T18+19 from rhGH. A synthetic Tv18+19 peptide having a trisulfide bridge between Cys182 and Cys189 showed identical fragment in ES/MS compared to Tv18+19 isolated from rhGH-HV, i.e. m/z 617.7 and 682.9. These fragments are formed through a unique cleavage in the trisulfide (Cys182-SSS-Cys189) bridge not found in the corresponding T18+19 disulfide peptide. Furthermore, the synthetic Tv18+19 co-eluted in RP-HPLC with Tv18+19 isolated from rhGH-HV. Two-dimensional NMR spectroscopy of the synthetic T18+19 and Tv18+19 peptides were performed. Using these data all protons were assigned. The major chemical shift changes (delta delta > 0.05 ppm) observed were for the beta-protons of Cys182 and Cys189 in Tv18+19 as compared to T18+19. CD spectroscopy data were also in agreement with the above results. Based on these physico-chemical data rhGH-HV has been structurally defined as a trisulfide variant of rhGH. The receptor binding properties of rhGH-HV was studied by a biosensor device, BIAcore. The binding capacity of rhGH-HV was similar to rhGH with a binding stoichiometry to the rhGHBP of 1:1.6 and 1:1.5, respectively, indicating that the trisulfide modification did not affect its receptor binding properties.     

A gene which causes severe ocular alterations and occipital encephalocele (Knobloch syndrome) is mapped to 21q22.3

Knobloch syndrome (KS), characterized by high myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities and occipital encephalocele, was recently confirmed as autosomal recessive. Here we report the assignment of the gene for this syndrome to 21q22.3 with the marker D21S171 through homozygosity mapping in a highly inbred Brazilian family with 11 affected individuals. A total of nine markers spanning a region of 15.2 cM of the chromosome 21q22.3 were tested and the candidate region was restricted to an interval of 4.3 cM.     

Isolation and characterization of PDE9A, a novel human cGMP-specific phosphodiesterase

We have cloned and characterized the first human isozyme in a new family of cyclic nucleotide phosphodiesterases, PDE9A. By sequence homology in the catalytic domain, PDE9A is almost equidistant from all eight known mammalian PDE families but is most similar to PDE8A (34% amino acid identity) and least like PDE5A (28% amino acid identity). We report the cloning of human cDNA encoding a full-length protein of 593 amino acids, including a 261-amino acid region located near the C terminus that is homologous to the approximately 270-amino acid catalytic domain of other PDEs. PDE9A is expressed in all eight tissues examined as a approximately 2. 0-kilobase mRNA, with highest levels in spleen, small intestine, and brain. The full-length PDE9A was expressed in baculovirus fused to an N-terminal 9-amino acid FLAG tag. Kinetic analysis of the baculovirus-expressed enzyme shows it to be a very high affinity cGMP-specific PDE with a Km of 170 nM for cGMP and 230 microM for cAMP. The Km for cGMP makes PDE9A one of the highest affinity PDEs known. The Vmax for cGMP (4.9 nmol/min/microg recombinant enzyme) is about twice as fast as that of PDE4 for cAMP. The enzyme is about twice as active in vitro in 1-10 mM Mn2+ than in the same concentration of Mg2+ or Ca2+. PDE9A is insensitive (up to 100 microM) to a variety of PDE inhibitors including rolipram, vinpocetine, SKF-94120, dipyridamole, and 3-isobutyl-1-methyl-xanthine but is inhibited (IC50 = 35 microM) by zaprinast, a PDE5 inhibitor. PDE9A lacks a region homologous to the allosteric cGMP-binding regulatory regions found in the cGMP-binding PDEs: PDE2, PDE5, and PDE6.     

Isolation and characterization of a novel, human neuronal nitric oxide synthase cDNA

The G protein beta subunit G beta 5 deviates significantly from the four other members of the G beta family in amino acid sequence, unique expression pattern (only in the CNS), and cytosolic localization. To identify the members of the G beta 5-mediated signaling pathway, we purified the native protein complex containing G beta 5 from the cytosolic fraction of bovine retina. Analysis of the isolated complex revealed that G beta 5 is tightly associated with RGS7, a member of the superfamily of negative regulators of G protein signaling. This finding, for the first time, demonstrates an interaction between a G beta subunit and an RGS protein. G beta 5 was not detected in the outer segments of photoreceptor cells, suggesting that the cytosolic G beta 5-RGS7 complex is not directly involved in phototransduction.     

Isolation and characterization of a novel connexin gene, Cx-60, in porcine ovarian follicles

Sequences present at the genomic termini of herpesviruses become linked during lytic-phase replication and provide the substrate for cleavage and packaging of unit length viral genomes. We have previously shown that homologs of the consensus herpesvirus cleavage-packaging signals, pac1 and pac2, are located at the left and right genomic termini of human herpesvirus 6 (HHV-6), respectively. Immediately adjacent to these elements are two distinct arrays of human telomeric repeat sequences (TRS). We now show that the unique sequence element formed at the junction of HHV-6B genome concatemers (pac2-pac1) is necessary and sufficient for virally mediated cleavage of plasmid DNAs containing the HHV-6B lytic-phase origin of DNA replication (oriLyt). The concatemeric junction sequence also allowed for the packaging of these plasmid molecules into intracellular nucleocapsids as well as mature, infectious viral particles. In addition, this element significantly enhanced the replication efficiency of oriLyt-containing plasmids in virally infected cells. Experiments revealed that the concatemeric junction sequence possesses an unusual, S1 nuclease-sensitive conformation (anisomorphic DNA), which might play a role in this apparent enhancement of DNA replication--although additional studies will be required to test this hypothesis. Finally, we also analyzed whether the presence of flanking viral TRS had any effect on the functional activity of the minimal concatemeric junction (pac2-pac1). These experiments revealed that the TRS motifs, either alone or in combination, had no effect on the efficiency of virally mediated DNA replication or DNA cleavage. Taken together, these data show that the cleavage and packaging of HHV-6 DNA are mediated by cis-acting consensus sequences similar to those found in other herpesviruses, and that these sequences also influence the efficiency of HHV-6 DNA replication. Since the adjacent TRS do not influence either viral cleavage and packaging or viral DNA replication, their function remains uncertain.     

Recombinant human phenylethanolamine N-methyltransferase: overproduction in Escherichia coli, purification, and characterization

We studied major malformations in 5,581 infants with Down syndrome (DS) from three registers of congenital malformations. THe prevalence at birth of 23 different malformations was compared with the program-specific rates for each malformation in non-DS infants. An about 300 times risk increase was seen for annular pancreas, cataracts and duodenal atresia and an about 100 times risk increase for megacolon and small choanal atresia. Esophageal, anal and small bowel atresia, preaxial polydactyly, and omphalocele all showed risk increases between 10 and 30 times. Statistically significantly elevated risk ratios around 3-5 were seen for cleft palate, cleft lip/palate, and limb deficiencies. No increased risk was seen for neural tube defects, hydrocephaly, microtia, renal agenesis or severe dysgenesis, hypospadias or polydactyly other than preaxial. Oral clefts were more often present in DS in the Swedish material than in the other two materials. Cardiac defects were registered in 26% of all cases (varying between programs) but 28% of the cardiac defects were unspecified. DS infants born to women younger than 25 years had a significantly increased risk for megacolon and there was a trend increasing risk for esophageal or anal atresia with maternal age. A decreased risk for cardiac defect in DS infants born to teenage mothers was found, quite pronounced for endocardial cushion defects and ventricular septum defects. There were no statistically significant differences in the sex distribution of specific malformations in infants with DS and in non-DS infants.     

Isolation, characterization, molecular gene cloning, and sequencing of a novel phytase from Bacillus subtilis

The Bacillus subtilis strain VTT E-68013 was chosen for purification and characterization of its excreted phytase. Purified enzyme had maximal phytase activity at pH 7 and 55 degrees C. Isolated enzyme required calcium for its activity and/or stability and was readily inhibited by EDTA. The enzyme proved to be highly specific since, of the substrates tested, only phytate, ADP, and ATP were hydrolyzed (100, 75, and 50% of the relative activity, respectively). The phytase gene (phyC) was cloned from the B. subtilis VTT E-68013 genomic library. The deduced amino acid sequence (383 residues) showed no homology to the sequences of other phytases nor to those of any known phosphatases. PhyC did not have the conserved RHGXRXP sequence found in the active site of known phytases, and therefore PhyC appears not to be a member of the phytase subfamily of histidine acid phosphatases but a novel enzyme having phytase activity. Due to its pH profile and optimum, it could be an interesting candidate for feed applications.     

Isolation and characterization of the human X-arrestin gene

In previous publications we have discussed the stabilization mechanism of hydration forces as applied to the development of latex agglutination tests. We describe here how we have obtained stable and reactive IgG-latex conjugates in a high-ionic-strength reaction buffer. To this end we have made agglutination tests with polystyrene beads sensitized with IgG, measuring the immunoaggregation reaction with human C-reactive protein in a stopped-flow nephelometer. The results are compared to those obtained with a F(ab')2-latex conjugate with similar antibody molecule coverage. Adsorption isotherms of F(ab')2 and IgG on latex at pH 7.2 were obtained to study the affinity of these antibodies for the surface. The results of the electrokinetic characterization of the antibody-latex conjugates agree satisfactorily with those obtained from stability studies. This research throws light upon the use of hydration forces as a new approach to stabilizing immunoassay reagents that are colloidally unstable in physiological reaction buffers.     

Identification and characterization of a novel human aldose reductase-like gene

We have identified a novel human protein that is highly homologous to aldose reductase (AR). This protein, which we called ARL-1, consists of 316 amino acids, the same size as AR, and its amino acid sequence is 71% identical to that of AR. It is more closely related to the AR-like proteins such as mouse vas deferens protein, fibroblast growth factor-regulated protein, and Chinese hamster ovary reductase, with 81, 82, and 83%, respectively, of its amino acid sequence identical to the amino acid sequence of these proteins. The cDNA of ARL-1 was expressed in Escherichia coli to obtain recombinant protein for characterization of its enzymatic activities. For comparison, the cDNA of human AR was also expressed in E. coli and analyzed in parallel. These two enzymes differ in their pH optima and salt requirement, but they act on a similar spectrum of substrates. Similar to AR, ARL-1 can efficiently reduce aliphatic and aromatic aldehydes, and it is less active on hexoses. While AR mRNA is found in most tissues studied, ARL-1 is primarily expressed in the small intestines and in the colon, with a low level of its mRNA in the liver. The ability of ARL-1 to reduce various aldehydes and the locations of expression of this gene suggest that it may be responsible for detoxification of reactive aldehydes in the digested food before the nutrients are passed on to other organs. Interestingly, ARL-1 and AR are overexpressed in some liver cancers, but it is not clear if they contribute to the pathogenesis of this disease.