Molecular cloning of a novel gene involved in serotonin receptor-mediated signal transduction in rat stomach

AbstractIn Xenopus oocytes injected with small size mRNAs (500–700 b), obtained from rat stomach by fractionation, application of 10 μM 5-HT induced a substantial Ca2+-activated Cl− current (ICl-Ca). ICl-Ca was not elicited by 5-HT in native oocytes. Consistent results from this assay in the oocyte expression system motivated cDNA cloning experiments. A novel cDNA (named r at s tomach s erotonin receptor-related cDNA: RSS cDNA) which encodes a small protein involved in specific 5-HT receptor-mediated ICl-Ca activation was identified. The molecular weight of RSS protein in the reticulocyte lysate translation system (∼10 kDa) is identical to that calculated from the amino acid sequence. Computer-aided analysis of the predicted protein does not show any obvious sequence homologies (<18%) to any other proteins including G protein-coupled receptors. Northern analysis revealed that RSS mRNA is ubiquitously expressed at varying levels in a number of different tissues. Furthermore, the binding of [3H]spiperone, a 5-HT2 receptor antagonist, was examined in CHO cells, which highly expressed RSS transcripts (named CHO-RSS). Specific binding of [3H]spiperone was not clearly observed in native CHO but was detected in CHO-RSS. The dissociation constant was 10.3 nM in CHO-RSS. These results suggest that RSS protein may be a factor which facilitates 5-HT receptor expression or, alternatively, an enhancer of the affinity of native 5-HT receptor to 5-HT

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Chemical corrector treatment ameliorates increased seizure susceptibility in a mouse model of familial epilepsy

Epilepsy is one of the most common and intractable brain disorders. Mutations in the human gene LGI1, encoding a neuronal secreted protein, cause autosomal dominant lateral temporal lobe epilepsy (ADLTE). However, the pathogenic mechanisms of LGI1 mutations remain unclear. We classified 22 reported LGI1 missense mutations as either secretion defective or secretion competent, and we generated and analyzed two mouse models of ADLTE encoding mutant proteins representative of the two groups. The secretion-defective LGI1(E383A) protein was recognized by the ER quality-control machinery and prematurely degraded, whereas the secretable LGI1(S473L) protein abnormally dimerized and was selectively defective in binding to one of its receptors, ADAM22. Both mutations caused a loss of function, compromising intracellular trafficking or ligand activity of LGI1 and converging on reduced synaptic LGI1-ADAM22 interaction. A chemical corrector, 4-phenylbutyrate (4PBA), restored LGI1(E383A) folding and binding to ADAM22 and ameliorated the increased seizure susceptibility of the LGI 1(E383A) model mice. This study establishes LGI1-related epilepsy as a conformational disease and suggests new therapeutic options for human epilepsy

The Closely Related RNA helicases, UAP56 and URH49, Preferentially Form Distinct mRNA Export Machineries and Coordinately Regulate Mitotic Progression

UAP56 and URH49, closely related RNA helicases in humans, form different mRNA export machineries, the hTREX complex and the AREX complex, respectively. These helicases regulate different sets of genes, among which are mitotic factors. Consistent with their target genes, each helicase is required for a different step in the mitotic process