Single nucleotide polymorphisms in NOS2A and NOS3 genes are not associated with treatment response of non-small cell lung cancer patients following the definitive radiochemotherapy.

Nitric oxide (NO), is endogenously synthesized from L-arginine by nitric oxide synthase (NOS), exhibits a dual role in sensitivity to radiotherapy and chemotherapy of cancer cells. The aim of this study was to evaluate the influence of polymorphisms in NOS genes on treatment response of non-small-cell lung cancer (NSCLC) patients after radiochemotherapy. A cohort of 198 NSCLC patients treated with radiochemotherapy between 2009 and 2011 were included in this study. Genotyping analyses of 35 SNPs ( NOS2A, 21 and NOS3, 14) in each sample were conducted by using the Sequenom MassArray system. Unconditional logistic regression was performed to assess the association between treatment response and each genotype while adjusting or not for other covariates. Of 198 patients, 87 (43.9%) had objective responses, and 111(56.1%) did not respond. We observed no significant associations between treatment response and each genotype. While adjusting for other covariates, the associations were also not significant. Our results suggest that genetic variations within the NOS2A and NOS3 genes may not influence the treatment response in NSCLC patients with radiochemotherapy. Future studies in this problem are required to confirm our findings.

Identification of two novel splice mutations of the ADAR1 gene in two Chinese families with dyschromatosis symmetrica hereditaria.

Dyschromatosis symmetrica hereditaria (DSH) is a rare, autosomal dominant dermatosis, characterized by a mixture of hyperpigmented and hypopigmented macules on the dorsa of the hands and feet. The DSH locus has been mapped to chromosome 1q21, and in 2003, pathogenic mutations were identified in the ADAR1 (adenosine deaminase acting on RNA1) gene. In this study, we performed mutation detection of the ADAR1 gene in two Chinese families with DSH. PCR and direct sequencing of the ADAR1 gene were used to identify and confirm the mutations in the two families. Furthermore, we analysed the RNA transcripts by reverse transcriptase (RT)-PCR. Two aberrant splice products were confirmed with RT-PCR and DNA direct sequence analysis. These novel findings further extend our understanding of the role of ADAR1 in DSH.

Mapping of an NH2-terminal ligand binding site of the insulin receptor by alanine scanning mutagenesis.

Affinity labeling studies and mutational analyses have implicated the involvement of a predicted domain of the insulin receptor (L1, amino acids 1-119) in ligand binding. In order to obtain a higher resolution localization of this ligand binding site, we have performed alanine scanning mutagenesis of this domain. Alanine mutant cDNAs encoding a secreted recombinant insulin receptor extracellular domain were expressed transiently in adenovirus transformed human embryonic kidney cells and the affinity of the expressed receptor for insulin was determined. Mutation of 14 amino acids located in four discontinuous peptide segments to alanine was disruptive of insulin binding: Segment 1, amino acids 12-15; Segment 2, amino acids 34-44; Segment 3, amino acids 64-67; and Segment 4, amino acids 89-91. The quantitative contribution of the four segments to the free energy of insulin binding was 1 > 3 > 2 > 4. Of the 14 amino acids whose mutation compromised insulin binding, 3 are charged, 3 hydrophobic, 5 aromatic, and 3 are amides.

Genetic evidence for modulation of the activator by two regulatory proteins involved in the exogenous induction of phosphoglycerate transport in Salmonella typhimurium.

Previous work from this laboratory has identified in a fragment of DNA, cloned from Salmonella typhimurium, two genes involved in the exogenous induction of phosphoglycerate transport. These two genes, the transporter gene, pgtP, and the activator gene, pgtA, are closely linked physically; they are only 3.4 kilobases apart. In the accompanying paper, we describe the determination of the nucleotide sequence of this 3.4-kilobase DNA segment and show that this segment contains two genes, pgtB and pgtC, encoding two polypeptides of 593 and 397 amino acid residues, respectively. This paper presents an analysis of the effects of insertions and deletions in pgtBC on the expression of pgtP gene and on the expression of lacZ fused to the pgtP gene. The results indicate that both pgtBC genes are necessary for expression of the pgtP gene. Strikingly, deletion of both genes resulted in a constitutive phenotype, suggesting that PgtB and PgtC polypeptides modulate PgtA activity. The expression of the pgtP gene appears to be regulated by the pgtA gene product, which acts as an activator. A model of induction is proposed in which the central feature is the interaction of the three regulatory proteins in the membrane such that the activity of the activator (PgtA) is subject to modulation by the binding of an inducer.

Nucleotide sequence and transcription start point of the phosphoglycerate transporter gene of Salmonella typhimurium.

We identified the phosphoglycerate transporter gene of Salmonella typhimurium and its polypeptide product and determined the nucleotide sequence of the gene. The predicted translation product was a protein of 406 amino acid residues and was extremely hydrophobic, a feature that is consistent with its role in membrane transport. Hydropathy analysis suggested that there are eight transmembrane segments of at least 20 amino acid residues for the protein. The transcription start point was mapped to lie at position -44 relative to the putative translational initiation start point. Comparison of PgtP with UhpT and GlpT, the membrane-bound proteins involved in the transport of hexose-6-phosphate and glycerol-3-phosphate, respectively, revealed a very high degree of amino acid sequence similarity among them, reflecting not only similar structures and functions among these polypeptides but also a common evolutionary origin for them.

Identification and nucleotide sequence of the activator gene of the externally induced phosphoglycerate transport system of Salmonella typhimurium.

A recent study from this laboratory (G-q. Yu, D. Goldrick, H.R. Kaback and J-s. Hong, in preparation) indicates that the externally induced phosphoglycerate transport system (pgt) of Salmonella typhimurium is positively regulated by the activator gene, pgtA, and that the pgtA is localized in the SalI-PstI restriction fragment 3.0 kb from the permease gene, pgtP. In this paper, we describe the identification of the activator gene and its gene product and the determination of the complete nucleotide (nt) sequence of the activator gene as well as of a downstream gene not required for pgtP expression. The amino acid sequence of the activator based on the nt sequence shows an N-terminal signal-like sequence which is apparently not cleaved and three potential transmembrane sequences in the C-terminal half of the protein based on the hydropathy analysis.