A Chrnb3-Cre BAC transgenic mouse line for manipulation of gene expression in retinal ganglion cells.

The mechanisms by which retinal ganglion cells (RGCs) make specific connections during development is an intense area of research and have served as a model for understanding the general principles of circuit wiring. As such, genetic tools allowing for specific recombination in RGCs are critical to further our understanding of the cell-specific roles of different genes during these processes. However, many RGC-specific Cre lines have drawbacks, due to their broad expression in other cell types and/or retinorecipient regions or lack of expression in broad swaths of the retina. Here, we characterize a Cre BAC transgenic line driven by elements of the cholinergic receptor nicotinic beta 3 subunit (Chrnb3). We show that Cre expression is restricted to RGCs in the retina and sparsely expressed in the brain, importantly excluding retinorecipient regions. Furthermore, Chrnb3-Cre mice label a wide variety of RGCs distributed throughout the retina and Cre activity is detected embryonically, shortly following RGC differentiation. Finally, we find that Chrnb3-Cre-labeled RGCs innervate multiple retinorecipient areas that serve both image-forming and nonimage forming functions. Thus, this genetic tool will be of broad use to investigators studying the RGC-specific contributions of genes to visual circuit development.

Cholinergic receptor nicotinic beta 3 subunit polymorphisms and smoking in male Chinese patients with schizophrenia.

OBJECTIVE: The aim of this study was to examine if cholinergic receptor nicotinic beta 3 subunit (CHRNB3) was a common genetic basis for both nicotine dependence and schizophrenia. METHODS: Two CHRNB3 promoter single nucleotide polymorphisms (SNPs) were genotyped in 773 patients with schizophrenia and 302 healthy volunteers. Associations between smoking, schizophrenia, smoking+schizophrenia and CHRNB3 were analyzed. The mRNA expression of CHRNB3 in human brains was examined, and the expression correlations between CHRNB3 and dopaminergic and GABAergic receptor genes were evaluated. RESULTS: The association between CHRNB3 and smoking was significant in the total sample, less significant in the smoking with schizophrenia, and suggestive in the smoking without schizophrenia. CHRNB3 had significant mRNA expression that was correlated with dopaminergic or GABAergic receptor expression in human brains. The two CHRNB3 SNPs had significant cis-acting regulatory effects on CHRNB3 mRNA expression. CONCLUSIONS: Risk for smoking behavior was associated with CHRNB3. CHRNB3 mRNA is abundant in human brain and could play important role in the pathogenesis of smoking behavior.

Multiple Small Supernumerary Marker Chromosomes Resulting from Maternal Meiosis I or II Errors.

We present 2 cases with multiple de novo supernumerary marker chromosomes (sSMCs), each derived from a different chromosome. In a prenatal case, we found mosaicism for an sSMC(4), sSMC(6), sSMC(9), sSMC(14) and sSMC(22), while a postnatal case had an sSMC(4), sSMC(8) and an sSMC(11). SNP-marker segregation indicated that the sSMC(4) resulted from a maternal meiosis II error in the prenatal case. Segregation of short tandem repeat markers on the sSMC(8) was consistent with a maternal meiosis I error in the postnatal case. In the latter, a boy with developmental/psychomotor delay, autism, hyperactivity, speech delay, and hypotonia, the sSMC(8) was present at the highest frequency in blood. By comparison to other patients with a corresponding duplication, a minimal region of overlap for the phenotype was identified, with CHRNB3 and CHRNA6 as dosage-sensitive candidate genes. These genes encode subunits of nicotinic acetylcholine receptors (nAChRs). We propose that overproduction of these subunits leads to perturbed component stoichiometries with dominant negative effects on the function of nAChRs, as was shown by others in vitro. With the limitation that in each case only one sSMC could be studied, our findings demonstrate that different meiotic errors lead to multiple sSMCs. We relate our findings to age-related aneuploidy in female meiosis and propose that predivision sister-chromatid separation during meiosis I or II, or both, may generate multiple sSMCs.

Genetic variants of CHRNA5-A3 and CHRNB3-A6 predict survival of patients with advanced non-small cell lung cancer.

Nicotinic acetylcholine receptors (nAChRs) play a key role in carcinogenesis and progression of lung cancer; and polymorphisms in CHRNA5-A3 and CHRNB3-A6, two gene clusters encoding nAChR subunits, have been associated with lung cancer risk. In this study, we investigated whether variants in the two gene clusters were associated with prognosis of advanced non-small cell lung cancer (NSCLC). A total of 165 stage IIIB-IV NSCLC patients were enrolled in this study. Three polymorphisms (rs667282 and rs3743073 in CHRNA5-A3 and rs13280604 in CHRNB3-A6) were genotyped using the TaqMan method. Overall survival (OS) was estimated using the log-rank test and the Cox models. Our results showed that patients with CHRNA5-A3 rs667282 TT or TC genotypes had a significantly shorter OS than those carrying the CC genotype (Log-rank, P = 0.043). Furthermore, multivariate Cox regression analysis showed that rs667282 TT/TC genotypes are significantly associated with increased risk of overall deaths (adjusted hazard ratio, 1.7; 95% CI, 1.1-2.7). However, the similar results were not observed for other two polymorphisms. Furthermore, no evident association was found between these variants and clinicopathologic features of advanced NSCLC. Our present study suggested that rs667282 in CHRNA5-A3 may modify the prognosis of patients with advanced NSCLC.

Nicotinic Receptor Mutation in a Mildly Dysmorphic Girl with Duane Retraction Syndrome.

BACKGROUND: To evaluate possible monogenic and chromosomal anomalies in a patient with unilateral Duane retraction syndrome and modest dysmorphism. MATERIALS AND METHODS: Clinical evaluation, sequencing of candidate genes, and array comparative genomic hybridization (array CGH). RESULTS: The proband had unilateral Duane retraction syndrome (DRS) with low-set ears bilaterally, a high arched palate, and clinodactyly. Motor development and cognitive function were normal. Parents were first cousins, but no other family member was similarly affected. No mutations were detected in the HOXA1. KIF21A. SALL4, TUBB3, and CHN1 genes. Array CGH revealed a 16 Kb de novo deletion at chromosome 8p11.2 that encompassed a portion of only one gene, the Cholinergic Receptor, Nicotinic, Beta-3 (CHRNB3, Neuronal). This gene encodes a protein that is involved in the nicotinic acetylcholine receptor on neurons. It interacts functionally with other genes that code components of the acetylcholine receptor. CONCLUSIONS: This patient's chromosomal abnormality affected only one gene that is highly expressed in the brainstem and brain, involved in neurotransmission, and could be related to her Duane retraction syndrome.

Genetic Association of CHRNB3 and CHRNA6 Gene Polymorphisms with Nicotine Dependence Syndrome Scale in Korean Population.

OBJECTIVE: Cholinergic nicotinic receptor (CHRN) gene family has been known to mediate the highly additive effects of nicotine in the body, and implicated nicotine dependence (ND) and related phenotypes. Previous studies have found that CHRNA6-CHRNB3 cluster polymorphisms were significantly associated with the risk of ND and various tobacco behaviors. The aim of study was to evaluate the genetic association of CHRNB3 and CHRNA6 polymorphisms with the risk of ND based on the Fagerstrom Test for Nicotine Dependence (FTND) score and five subscales of nicotine dependence syndrome scale (NDSS) in Korean population. METHODS: Six SNPs in CHRNA6-CHRNB3 cluster were analyzed in 576 Korean subjects. Association analysis using logistic models and regression analysis with NDSS were performed. RESULTS: There was no association in the case-control analysis, whereas all six SNPs were significantly associated with drive factor among NDSS in subgroup based on the FTND score. CHRNB3 rs4954 and CHRNA6 rs16891604 showed significant associations with NDSSF1 (drive) in dominant models among moderate to severe ND among smokers after correction (p(corr) =0.02 and 0.001, respectively), whereas other four SNPs showed significant associations among mild ND after correction (p(corr) =0.03-0.02 in dominant model). CONCLUSION: This study showed that the genetic influence of CHRNB3-CHRNA6 cluster polymorphisms are found in a ND endophenotype (drive) using NDSS subscales, rather than the risk of ND in Korean population. Our findings might be the first report for the association of CHRNB3-CHRNA6 cluster with ND-related phenotypes in Korean and might offer an approach to elucidating the molecular mechanisms of ND and ND-related phenotypes.

CHRNB3 c.-57A>G functional promoter change affects Parkinson's disease and smoking.

Cigarette smoking is protective in Parkinson's disease (PD), possibly because of nicotine action on brain nicotinic-acetylcholine receptors. The ß3 nicotinic-acetylcholine receptor subunit (encoded by CHRNB3) is depleted in the striatum of PD patients and associated with nicotine dependence. Herein, the CHRNB3 gene was sequenced, and the c.-57G allele frequency was 0.31 and 0.26 among patients (n = 596) and controls (n = 369), respectively (p = 0.02, odds ratio = 1.33, 95% confidence interval = 1.03-1.73). The c.-57G allele was strongly associated with smoking in patients, as 48.4% of c.-57G carriers compared with 32.6% of noncarriers reported smoking history (p < 0.0001). The transcription factor Oct-1 binding was almost eliminated in lymphoblasts with the c.-57G/G genotype, to only 6.5% percent, and the CHRNB3 promoter activity was reduced in cells with the c.-57G/G genotype by 96%-70%. These findings suggest that the CHRNB3 c.-57A>G alteration affects the promoter activity and is associated with PD and smoking in PD patients. It is therefore possible that nicotine may be valuable for patients who carry this alteration and beneficial in PD only for patients with specific genotypes.

Combined effect between CHRNB3-CHRNA6 region gene variant (rs6474412) and smoking in psoriasis vulgaris severity.

BACKGROUND: Many factors associated with causing psoriasis have been reported, such as the genetic and environmental factors. Smoking is one of the well-established environmental risk factors for psoriasis and also associated with the disease severity. In addition, several studies of psoriasis and psoriatic arthritis have documented gene-environment interactions involving smoking behavior. Although gene polymorphisms on nicotinic acetylcholine receptor subunits CHRNB3-CHRNA6 region gene have been found to correlate with smoking behavior and lung cancer susceptibility in Chinese Han population, the combined effect between the smoking-related genetic variants and smoking behavior on psoriasis vulgaris (PV) has been unreported. OBJECTIVE: To evaluate the combined effect of the smoking-related (rs6474412-C/T) polymorphism on CHRNB3-CHRNA6 region gene and smoking behavior on PV risk and clinic traits in Chinese Han population. METHODS: A hospital-based case-control study including 672 subjects (355 PV cases and 317 controls) was conducted. The variant of rs6474412 was typed by SNaPshot Multiplex Kit (Applied Biosystems Co., USA). RESULTS: The higher body mass index (BMI≥25), smoking behavior and alcohol consumption were risk factors for PV, and the estimated ORs were 1.55 (95% CI, 1.09-2.29), 1.74 (95% CI, 1.22-2.49) and 1.81 (95% CI, 1.25-2.62) respectively. The smoking patients had more severe conditions than non-smokers (OR=1.71, 95% CI, 1.08-2.70, P=0.020). The alleles and genotypes of rs6474412 were not associated with risk of PV, but the combined effect of rs6474412 genotype (TT) and smoking behavior increased severity of PV (OR=5.95; 95% CI, 1.39-25.31; P<0.05; adjusted OR=2.20; 95% CI, 1.55-3.14; P<0.001). CONCLUSIONS: Our results demonstrate that the combined effect of rs6474412-C/T polymorphism in smoking-related CHRNB3-CHRNA6 region gene and smoking behavior may not confer risk to PV, but may have impact on PV severity in Chinese Han population.

Genetic Association of CHRNB3 and CHRNA6 Gene Polymorphisms with Nicotine Dependence Syndrome Scale in Korean Population

OBJECTIVE: Cholinergic nicotinic receptor (CHRN) gene family has been known to mediate the highly additive effects of nicotine in the body, and implicated nicotine dependence (ND) and related phenotypes. Previous studies have found that CHRNA6-CHRNB3 cluster polymorphisms were significantly associated with the risk of ND and various tobacco behaviors. The aim of study was to evaluate the genetic association of CHRNB3 and CHRNA6 polymorphisms with the risk of ND based on the Fagerstrom Test for Nicotine Dependence (FTND) score and five subscales of nicotine dependence syndrome scale (NDSS) in Korean population. METHODS: Six SNPs in CHRNA6-CHRNB3 cluster were analyzed in 576 Korean subjects. Association analysis using logistic models and regression analysis with NDSS were performed. RESULTS: There was no association in the case-control analysis, whereas all six SNPs were significantly associated with drive factor among NDSS in subgroup based on the FTND score. CHRNB3 rs4954 and CHRNA6 rs16891604 showed significant associations with NDSSF1 (drive) in dominant models among moderate to severe ND among smokers after correction (p(corr)=0.02 and 0.001, respectively), whereas other four SNPs showed significant associations among mild ND after correction (p(corr)=0.03-0.02 in dominant model). CONCLUSION: This study showed that the genetic influence of CHRNB3-CHRNA6 cluster polymorphisms are found in a ND endophenotype (drive) using NDSS subscales, rather than the risk of ND in Korean population. Our findings might be the first report for the association of CHRNB3-CHRNA6 cluster with ND-related phenotypes in Korean and might offer an approach to elucidating the molecular mechanisms of ND and ND-related phenotypes.