Interaction between variation in the D2 dopamine receptor (DRD2) and the neuronal calcium sensor-1 (FREQ) genes in predicting response to nicotine replacement therapy for tobacco dependence.

We have previously demonstrated that a functional dopamine D2 receptor promoter variant (DRD2 -141 Ins/Del) predicts response to nicotine replacement therapy (NRT). The present study extends this finding in the same population of 363 NRT-treated subjects, by examining variation in the gene encoding the neuronal calcium sensor-1 protein (FREQ), which functions to regulate D2 receptor desensitization. The results indicate a statistically significant interaction effect of DRD2-141 and FREQ genotypes on abstinence at the end of the NRT treatment phase; 62% of the smokers with at least one copy of the DRD2 -141 Del allele and two copies of the FREQ rs1054879 A allele were abstinent from smoking, compared to 29-38% abstinence rates for other smokers in the trial. This result suggests that the interaction between variation in the DRD2 and FREQ genes, which both encode components of the D2 dopamine receptor signal transduction pathway, impacts the efficacy of NRT.

Confirmation of association between the Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) gene and bipolar I disorder.

Recent studies have indicated that the brain-derived neurotrophic factor (BDNF) gene is involved in the etiology of bipolar disorder (BPD). Two family-based association studies showed that the Val allele of the functional polymorphism Val66Met in the BDNF gene is associated with BPD; however, others could not confirm the results. Here we performed a replication study in an independent sample and tested the hypothesis that the Val66 allele in the BDNF gene confers susceptibility to bipolar I disorder (BPI). Six hundred twenty-one patients with BPI and 998 control subjects were genotyped for the Val66Met polymorphism. All cases and controls were of European descent. All BPI patients had a positive family history of affective disorder. The frequency of the Val allele was significantly increased in BPI patient when compared to controls (chi2 = 4.8; df = 1; P = 0.028; two-sided; OR = 1.22; 95% CI: 1.02-1.47). Results confirm previous findings and suggest that the Val allele increases risk for BPI in patients of European descent. Further studies are necessary to elucidate the involvement of the BDNF gene in the pathophysiology of BPD.

In- and outbound spreading of a free-particle s-wave.

We show that a free quantum particle in two dimensions with zero angular momentum (s wave) in the form of a ring-shaped wave packet feels an attraction towards the center of the ring, leading first to a contraction followed by an expansion. An experiment to demonstrate this effect is also outlined.

Participation of Na,K-ATPase in FGF-2 secretion: rescue of ouabain-inhibitable FGF-2 secretion by ouabain-resistant Na,K-ATPase alpha subunits.

We have examined the relationship between Na,K-ATPase and FGF-2 secretion in transfected primate cells. FGF-2 lacks a classic hydrophobic export signal, and the mechanisms mediating its secretion are unknown. To monitor secretion, a FLAG epitope tag was inserted into the carboxyl terminus of the 18 kDa form of human FGF-2, and the construct was transfected into either human HEK 293 or monkey CV-1 cells. Exported FGF-2 was detected in the culture medium using the FLAG-specific monoclonal antibody M2. FGF-2 secretion from HEK 293 or CV-1 cells was linear over time and sensitive to inhibition by the cardiac glycoside ouabain, a specific inhibitor of the Na,K-ATPase. In contrast, the secretion of FGF-8 (an FGF family member that contains a hydrophobic secretory signal) was not inhibited by treatment of HEK 293 or CV-1 cells with ouabain. FGF-2 secretion was also assayed in CV-1 cells expressing the naturally ouabain-resistant rodent Na,K-ATPase alpha1 subunit. In cells expressing the rodent alpha1 subunit, FGF-2 secretion was unaffected by high levels of ouabain, indicating that the rodent alpha1 subunit was capable of rescuing ouabain-inhibitable FGF-2 export. Expression of ouabain-resistant mutants of the rodent alpha2 and alpha3 subunits, or the naturally ouabain-resistant rodent alpha4 subunit, also supported FGF-2 secretion in ouabain-treated cells. Taken together, our studies are consistent with the idea that the Na,K-ATPase plays a prominent role in regulating FGF-2 secretion, although none of the alpha subunit isoforms exhibited specificity with regard to FGF-2 export.

The Na,K-ATPase alpha4 gene (Atp1a4) encodes a ouabain-resistant alpha subunit and is tightly linked to the alpha2 gene (Atp1a2) on mouse chromosome 1.

We have isolated and characterized cDNA clones encoding the murine homologue of a putative fourth Na,K-ATPase alpha subunit isoform (alpha4). The predicted polypeptide is 1032 amino acids in length and exhibits 75% amino acid sequence identity to the rat alpha1, alpha2, and alpha3 subunits. Within the first extracellular loop, the alpha4 subunit is highly divergent from other Na,K-ATPase alpha subunits. Because this region of Na,K-ATPase is a major determinant of ouabain sensitivity, we tested the ability of the rodent alpha4 subunit to transfer ouabain resistance in a transfection protocol. We find that a cDNA containing the complete rodent alpha4 ORF is capable of conferring low levels of ouabain resistance upon HEK 293 cells, an indication that the alpha4 subunit can substitute for the endogenous ouabain-sensitive alpha subunit of human cells. Nucleotide sequences specific for the murine alpha4 subunit were used to identify the chromosomal position of the alpha4 subunit gene. By hybridizing an alpha4 probe with a series of BACs, we localized the alpha4 subunit gene (Atp1a4) to the distal portion of mouse chromosome 1, in very close proximity to the murine Na,K-ATPase alpha2 subunit gene. In adult mouse tissues, we detected expression of the alpha4 subunit gene almost exclusively in testis, with low levels of expression in epididymis. The close similarities in the organization and expression pattern of the murine and human alpha4 subunit genes suggest that these two genes are orthologous. Together, our studies indicate that the alpha4 subunit represents a functional Na,K-ATPase alpha subunit isoform.