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M Brüss

Publications and source records attributed to M Brüss.

45 records · Page 3Linked to original sources
PubMed1996

Systematic search for variation in the human norepinephrine transporter gene: identification of five naturally occurring missense mutations and study of association with major psychiatric disorders.

The complete coding region of the norepinephrine transporter (NET) gene was systematically screened for genetic variants in 137 unrelated individuals (including 46 probands with bipolar affective disorder and 45 schizophrenic probands, as well as 46 blood donors) using single-strand conformation analysis. We identified 13 DNA sequence variants, among them five missense substitutions. The missense substitutions Val69Ile, Thr99Ile, Val245Ile, Val449Ile, and Gly478Ser are located at putative transmembrane domains (TMD) 1, 2, 4, 9, and 10, respectively. The Thr99Ile substitution is at the 5th position of the putative leucine-zipper in TMD2. In a case-control study distribution of missense substitutions was found to be similar in 103 patients with bipolar affective disorder, in 228 schizophrenia patients and in 187 controls, indicating that presence of these variants is not causally related to major psychiatric diseases. The detection of a highly polymorphic silent 1287G/A polymorphism was utilized to demonstrate biallelic expression of the NET in adult human brain.

Adult↗
PubMed1996

Expression of the extraneuronal monoamine transporter (uptake2) in human glioma cells.

Tritiated methylphenylpyridinium ([3H]MPP+), a substrate of the neuronal and extraneuronal noradrenaline transporter (uptake1 and uptake2, respectively) and of the organic cation transporter (OCT1), was used to characterize the amine transport system of the established human glioma cell line SK-MG-1. Uptake of [3H]MPP+ (25 nM) into SK-MG-1 cells increased linearly with time for up to 15 min. Selective uptake1 inhibitors (e.g. (+)oxaprotiline) or omission of Na+ or Cl-ions did not affect [3H]MPP+ uptake, whereas uptake2 inhibitors such as O-methyl-isoprenaline (OMI) or corticosterone as well as depolarizing concentrations of K+ or Ba2+ strongly reduced [3H]MPP+ uptake. Initial rates of OMI(100 microM)-sensitive [3H]MPP+ uptake were saturable, with a K(m) of about 17 microM and a maximal rate of about 50 pmol/(min x mg protein). IC50 (or Ki) values for inhibition of [3H]MPP+ uptake by substrates and inhibitors of uptake2 or OCT1 were highly significantly correlated with published IC50 values for inhibition of uptake2 but not with corresponding values for inhibition of OCT1. The results presented here clearly demonstrate that human glioma cells express an uptake2 transporter. Thus, glial cells in the human central nervous system endowed with this transporter are likely to contribute to the inactivation of neuronally released noradrenaline.

1-Methyl-4-phenylpyridinium↗
PubMed1995

Molecular cloning and organization of the coding region of the human norepinephrine transporter gene.

A lambda phage genomic library was screened with the digoxygenin labeled cDNA of the human norepinephrine transporter (hNET). Six overlapping lambda clones were analysed by restriction enzyme analysis and sequencing of the exon-intron boundaries. The coding region of the hNET gene was found to be encoded by 14 exons, spanning 45 kb from the start to the stop codon, disrupted by 13 introns. The organization of the gene is highly homologous to other known neurotransmitter transporter genes. However, the hNET gene differs from the other genes in that it has an additional exon encoding the C-terminus of the protein. The gene structure shows two large introns in the 5'-region and a cluster of 11 exons in the 3'-region. All exon-intron junctions contain the gt/ag consensus splice site. Knowledge of the gene structure of the antidepressant-sensitive hNET should facilitate investigation of its potential role in psychiatric disorders.

Alternative Splicing↗
PubMed1995

Antipeptide antibodies confirm the topology of the human norepinephrine transporter.

We have raised polyclonal antibodies (N6-28, L211-226, L371-384, and C590-607) against peptides corresponding to hydrophilic sequences of the human norepinephrine transporter (hNET). The antisera immunoprecipitated the [35S]Met-labeled hNET. Antiserum L211-226, directed against a sequence of the putative second (large) extracellular loop of hNET, also immunoprecipitated the human dopamine transporter. Antisera N6-28 and C590-607, raised against a hNET peptide region of the N and the C termini, respectively, recognized a 58-kDa protein from transfected COS-7 cells expressing the hNET. This 58-kDa species represents a functional, glycosylated form of the hNET and not a degradation product. Tunicamycin treatment of transfected COS-7 cells as well as peptide-N-glycosidase F digestion of the transporter converted the 58-kDa species to a 50-kDa form, indicating that the latter represents the hNET core protein. In indirect immunofluorescence studies, our antisera confirmed the originally proposed topology of hNET. Antisera N6-28 and C590-607 detected hNET only in permeabilized cells. In contrast, antisera L211-226 and L371-384 directed against peptide sequences of the second and fourth putative extracellular loop displayed fluorescence signals with the intact cells.

Amino Acid Sequence↗
PubMed1995

Binding properties of the naturally occurring human 5-HT1A receptor variant with the Ile28Val substitution in the extracellular domain.

The cDNA from a schizophrenic patient heterozygous for a mutation of the 5-HT1A receptor gene was used to clone the variant and wild-type DNA into a eukaryotic expression vector. The mutation was characterized by a base pair substitution (A --> G) at the first position of codon 28, leading to an Ile --> Val amino acid exchange. COS-7 cells were transfected with the cDNA of either the wild type or the variant 5-HT1A receptor. The potencies of the 5-HT1A receptor agonists 8-hydroxy-2-(di-n-propylamino) tetraline (8-OH-DPAT), 5-HT and roxindole, and of the antagonists methiothepin and spiperone in inhibiting specific binding of [3H]8-OH-DPAT of the mutant and wild-type 5-HT1A receptor ligands concentration-dependently inhibited specific [3H]8-OH-DPAT binding to both the wild-type and the variant 5-HT1A receptor. The rank order of potency of the ligands in inhibiting [3H]8-OH-DPAT binding was identical at both receptors and was roxindole > 8-OH-DPAT > 5-HT> methiothepin > spiperone. This rank order is characteristic for 5-HT1A receptors. The negative logarithms of the concentrations required for 50% inhibition (pIC50 values) of the ligands at the mutant 5-HT receptor correlated highly significantly with those at the wildtype receptor (r = 0.995). It is concluded that the pharmacological profile of the mutant 5-HT1A receptor does not differ from that of the wild-type 5-HT1A receptor.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Cloning and expression of the bovine sodium- and chloride-dependent noradrenaline transporter.

A cDNA encoding a functional bovine, tricyclic antidepressant-sensitive noradrenaline transporter has been identified by screening a lambda gt11 cDNA library of the bovine adrenal medulla using the cDNA of the human noradrenaline transporter [1991, Nature 350, 350-354]. The sequence predicts a protein of 615 amino acids (M(r) 68,900). The bovine transporter shares 93% amino acid identity with the human sequence, but displays two more consensus sites for phosphorylation by protein kinase C. Transient expression of the transporter in COS-7 cells resulted in a sodium- and chloride-dependent uptake of noradrenaline with a pharmacology typical for a neuronal noradrenaline transporter.

Amino Acid Sequence↗
PubMed1993

Chromosomal mapping of the human gene for the tricyclic antidepressant-sensitive noradrenaline transporter.

The neuronal Na(+)- and Cl(-)-dependent transporter for the neurotransmitter noradrenaline (NA) is the primary target for the tricyclic antidepressant desipramine. The NA-transporter belongs to a new gene family of structurally related Na(+)- and Cl(-)-dependent neurotransmitter transporters. In this study, the chromosomal localization for the gene encoding the human NA-transporter (h-NAT) was determined. By hybridization of a panel of somatic cell hybrids and by fluorescent in situ hybridization to metaphase chromosomes, the hNAT gene was localized on chromosome 16q12.2. In addition, evidence is presented for an intron-exon structure of the gene.

Animals↗