ABSTRACT
In an initial study, we compared quantitative transcriptome data across mouse brain territories using the serial analysis of gene expression method. Among the novel regional markers that we discovered, we focused on a striatum-enriched transcript with no available experimental cDNA sequence. Here, we report its cloning, gene structure, and detailed distribution in mouse brain. Quantitative RT-PCR and in situ hybridization demonstrated predominant expression in dorsolateral striatum. We therefore named it capucin for caudate-and putamen-enriched sequence. Mouse capucin is a 237-amino-acid protein, without any registered ortholog in mammalian species. It contains no recognizable motif other than two predicted carboxy-terminal transmembrane domains. When expressed in fusion with a fluorescent protein, it localized to the Golgi apparatus in two mammalian cell lines. Interestingly, we observed a significant down-regulation of capucin mRNA levels in two rodent models of Huntington disease, indicating a possible contribution to the pathogenesis of this disorder.
Subject(s)
Corpus Striatum/metabolism , Disease Models, Animal , Down-Regulation , Huntington Disease/genetics , Membrane Proteins/genetics , Amino Acid Sequence , Animals , Biomarkers , Cloning, Molecular , DNA, Complementary , Humans , In Situ Hybridization , Male , Membrane Proteins/chemistry , Mice , Mice, Inbred C57BL , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Amino Acid , Subcellular Fractions/metabolismABSTRACT
Catechol-O-methyltransferase is a candidate in the predisposition to schizophrenia both because of its function and the position of its gene. A multipoint non-parametric linkage analysis and a transmission disequilibrium test were performed on 42 multiplex families genotyped for Pml I and Bcl I polymorphisms using two definitions of the affected phenotype. Neither linkage nor preferential transmission of any allele or haplotype was detected, failing to replicate previous positive findings.
Subject(s)
Catechol O-Methyltransferase/genetics , Catechol O-Methyltransferase/metabolism , Linkage Disequilibrium/genetics , Schizophrenia , Alleles , Female , France/epidemiology , Gene Expression , Genetic Predisposition to Disease , Haplotypes/genetics , Humans , Male , Polymorphism, Genetic/genetics , Schizophrenia/enzymology , Schizophrenia/epidemiology , Schizophrenia/geneticsABSTRACT
Postsynaptic clustering of the glycine receptor requires the cytoplasmic protein gephyrin, which interacts with the receptor beta subunit. Several variants of gephyrin are generated by alternative splicing and differ by the presence of short amino acid sequences (cassettes) in the N-terminal half of the molecule. In this work, seven isoforms of gephyrin were cloned from adult rat spinal cord, some of then containing new cassettes. The relationships between gephyrin structure and recognition of glycine receptor beta subunit were analyzed. This was carried out by GST-pulldown assays using the beta subunit cytoplasmic loop and cotransfection experiments of GFP-tagged gephyrins with an alpha1 subunit bearing the gephyrin-binding site of the beta subunit. Data demonstrated that not all gephyrin molecules can bind to the beta subunit. Identified cassettes modulate this interaction. It is thus concluded that the function of gephyrin in synapse formation can rely on a structure acquired through cassette combinations.
Subject(s)
Carrier Proteins , Genetic Heterogeneity , Membrane Proteins , Synapses/metabolism , Alternative Splicing/physiology , Amino Acid Sequence , Animals , Base Sequence , Binding Sites/physiology , COS Cells , Carrier Proteins/chemistry , Carrier Proteins/genetics , Carrier Proteins/metabolism , Gene Expression/physiology , Genes, Reporter , Green Fluorescent Proteins , Indicators and Reagents/metabolism , Isomerism , Luminescent Proteins/genetics , Membrane Proteins/chemistry , Membrane Proteins/genetics , Membrane Proteins/metabolism , Molecular Sequence Data , Mutagenesis, Insertional/physiology , Neural Inhibition/physiology , Protein Structure, Tertiary , Rats , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Spinal Cord/chemistry , Structure-Activity Relationship , Synapses/chemistry , TransfectionABSTRACT
Catechol-O-methyltransferase (COMT) catalyzes the degradation of catecholamines and could therefore play a role in the etiology of schizophrenia. Moreover, microdeletions including the COMT locus have been found in schizophrenics presenting typical features of the velo-cardio-facial syndrome. In the present work, five single-strand conformation polymorphisms were detected in exons of the COMT gene. The linkage disequilibria between the polymorphisms were estimated, and the genotypic frequencies were calculated on a sample of 126 to 137 schizophrenics and 136 to 140 controls, depending on the marker. Patients and controls were matched for ethnicity and geographical origin. A trend toward association was found between schizophrenia and (i) genotype 11 of the Pml I polymorphism (p = 0.034; OR = 1.82); (ii) haplotype 1-2 for the Pml I and Bcl I polymorphisms (p = 0.022; OR = 1.75). The Pml I polymorphism is in complete linkage disequilibrium with the common Met-->Val(158) substitution, which affects the activity of the enzyme. This finding suggests a possible minor effect of COMT in a multifactorial threshold model of vulnerability to schizophrenia.
