Psychosis and the genetic spectrum of bipolar disorder: evidence from linkage analysis.
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Bipolar Disorder↗
Biomedical subjects
R Cheng
Publications and source records attributed to R Cheng.
Genome-wide linkage scan in a large bipolar disorder sample from the National Institute of Mental Health genetics initiative suggests putative loci for bipolar disorder, psychosis, suicide, and panic disorder.
We conducted a 9-cM genome scan in a large bipolar pedigree sample from the National Institute of Mental Health genetics initiative (1060 individuals from 154 multiplex families). We performed parametric and nonparametric analyses using both standard diagnostic models and comorbid conditions thought to identify phenotypic subtypes: psychosis, suicidal behavior, and panic disorder. Our strongest linkage signals (genome-wide significance) were observed on chromosomes 10q25, 10p12, 16q24, 16p13, and 16p12 using standard diagnostic models, and on 6q25 (suicidal behavior), 7q21 (panic disorder) and 16p12 (psychosis) using phenotypic subtypes. Several other regions were suggestive of linkage, including 1p13 (psychosis), 1p21 (psychosis), 1q44, 2q24 (suicidal behavior), 2p25 (psychosis), 4p16 (psychosis, suicidal behavior), 5p15, 6p25 (psychosis), 8p22 (psychosis), 8q24, 10q21, 10q25 (suicidal behavior), 10p11 (psychosis), 13q32 and 19p13 (psychosis). Over half the implicated regions were identified using phenotypic subtypes. Several regions - 1p, 1q, 6q, 8p, 13q and 16p - have been previously reported to be linked to bipolar disorder. Our results suggest that dissection of the disease phenotype can enrich the harvest of linkage signals and expedite the search for susceptibility genes. This is the first large-scale linkage scan of bipolar disorder to analyze simultaneously bipolar disorder, psychosis, suicidal behavior, and panic disorder.
Bipolar Disorder↗
Absence of psychosis may influence linkage results for bipolar disorder.
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Bipolar Disorder↗
Linkage analysis of psychosis in bipolar pedigrees suggests novel putative loci for bipolar disorder and shared susceptibility with schizophrenia.
The low-to-moderate resolution of linkage analysis in complex traits has underscored the need to identify disease phenotypes with presumed genetic homogeneity. Bipolar disorder (BP) accompanied by psychosis (psychotic BP) may be one such phenotype. We previously reported a genome-wide screen in a large bipolar pedigree sample. In this follow-up study, we reclassified the disease phenotype based on the presence or absence of psychotic features and subgrouped pedigrees according to familial load of psychosis. Evidence for significant linkage to psychotic BP (genome-wide P<0.05) was obtained on chromosomes 9q31 (lod=3.55) and 8p21 (lod=3.46). Several other sites were supportive of linkage, including 5q33 (lod=1.78), 6q21 (lod=1.81), 8p12 (lod=2.06), 8q24 (lod=2.01), 13q32 (lod=1.96), 15q26 (lod=1.96), 17p12 (lod=2.42), 18q21 (lod=2.4), and 20q13 (lod=1.98). For most loci, the highest lod scores, including those with genome-wide significance (at 9q31 and 8p21), occurred in the subgroup of families with the largest concentration of psychotic individuals (> or =3 in a family). Interestingly, all regions but six--5q33, 6q21, 8p21, 8q24, 13q32 and 18q21--appear to be novel; namely, they did not show notable linkage to BP in other genome scans, which did not employ psychosis for disease classification. Also of interest is possible overlap with schizophrenia, another major psychotic disorder: seven of the regions presumed linked in this study--5q, 6q, 8p, 13q, 15q, 17p, and 18q--are also implicated in schizophrenia, as are 2p13 and 10q26, which showed more modest support for linkage. Our results suggest that BP in conjunction with psychosis is a potentially useful phenotype that may: (1) expedite the detection of susceptibility loci for BP and (2) cast light on the genetic relationship between BP and schizophrenia.
Bipolar Disorder↗
Discovery and mapping of ten novel G protein-coupled receptor genes.
We report the identification, cloning and tissue distributions of ten novel human genes encoding G protein-coupled receptors (GPCRs) GPR78, GPR80, GPR81, GPR82, GPR93, GPR94, GPR95, GPR101, GPR102, GPR103 and a pseudogene, psi GPR79. Each novel orphan GPCR (oGPCR) gene was discovered using customized searches of the GenBank high-throughput genomic sequences database with previously known GPCR-encoding sequences. The expressed genes can now be used in assays to determine endogenous and pharmacological ligands. GPR78 shared highest identity with the oGPCR gene GPR26 (56% identity in the transmembrane (TM) regions). psi GPR79 shared highest sequence identity with the P2Y(2) gene and contained a frame-shift truncating the encoded receptor in TM5, demonstrating a pseudogene. GPR80 shared highest identity with the P2Y(1) gene (45% in the TM regions), while GPR81, GPR82 and GPR93 shared TM identities with the oGPCR genes HM74 (70%), GPR17 (30%) and P2Y(5) (40%), respectively. Two other novel GPCR genes, GPR94 and GPR95, encoded a subfamily with the genes encoding the UDP-glucose and P2Y(12) receptors (sharing >50% identities in the TM regions). GPR101 demonstrated only distant identities with other GPCR genes and GPR102 shared identities with GPR57, GPR58 and PNR (35-42% in the TM regions). GPR103 shared identities with the neuropeptide FF 2, neuropeptide Y2 and galanin GalR1 receptors (34-38% in the TM regions). Northern analyses revealed GPR78 mRNA expression in the pituitary and placenta and GPR81 expression in the pituitary. A search of the GenBank databases with the GPR82 sequence retrieved an identical sequence in an expressed sequence tag (EST) partially encoding GPR82 from human colonic tissue. The GPR93 sequence retrieved an identical, human EST sequence from human primary tonsil B-cells and an EST partially encoding mouse GPR93 from small intestinal tissue. GPR94 was expressed in the frontal cortex, caudate putamen and thalamus of brain while GPR95 was expressed in the human prostate and rat stomach and fetal tissues. GPR101 revealed mRNA transcripts in caudate putamen and hypothalamus. GPR103 mRNA signals were detected in the cortex, pituitary, thalamus, hypothalamus, basal forebrain, midbrain and pons.
Amino Acid Sequence↗
Similarity of the yellow chromophores isolated from human cataracts with those from ascorbic acid-modified calf lens proteins: evidence for ascorbic acid glycation during cataract formation.
Chromatographic evidence supporting the similarity of the yellow chromophores isolated from aged human and brunescent cataract lenses and calf lens proteins ascorbylated in vitro is presented. The water-insoluble fraction from early stage brunescent cataract lenses was solubilized by sonication (WISS) and digested with a battery of proteolytic enzymes under argon to prevent oxidation. Also, calf lens proteins were incubated with ascorbic acid for 4 weeks in air and submitted to the same digestion. The percent hydrolysis of the proteins to amino acids was approximately 90% in every case. The content of yellow chromophores was 90, 130 and 250 A(330) units/g protein for normal human WISS, cataract WISS and ascorbate-modified bovine lens proteins respectively. Aliquots equivalent to 2.0 g of digested protein were subjected to size-exclusion chromatography on a Bio-Gel P-2 column. Six peaks were obtained for both preparations and pooled. Side by side thin-layer chromatography (TLC) of each peak showed very similar R(f) values for the long wavelength-absorbing fluorophores. Glycation with [U-(14)C]ascorbic acid, followed by digestion and Bio-Gel P-2 chromatography, showed that the incorporated radioactivity co-eluted with the A(330)-absorbing peaks, and that most of the fluorescent bands were labeled after TLC. Peaks 2 and 3 from the P-2 were further fractionated by preparative Prodigy C-18 reversed-phase high-performance liquid chromatography. Two major A(330)-absorbing peaks were seen in peak 2 isolated from human cataract lenses and 5 peaks in fraction 3, all of which eluted at the same retention times as those from ascorbic acid glycated calf lens proteins. HPLC fractionation of P-2 peaks 4, 5 and 6 showed many A(330)-absorbing peaks from the cataract WISS, only some of which were identical to the asorbylated proteins. The major fluorophores, however, were present in both preparations. These data provide new evidence to support the hypothesis that the yellow chromophores in brunescent lenses represent advanced glycation endproducts (AGEs) probably due to ascorbic acid glycation in vivo.
Animals↗
Suppression of platelet-type 12-lipoxygenase activity in human erythroleukemia cells by an RNA-cleaving DNAzyme.
Human platelet-type 12-lipoxygenase (12-LOX) and its metabolites play a crucial role in tumor angiogenesis. A "10-23" deoxyribozyme (DNAzyme) and its phosphorothioate-modified version were designed and synthesized against the 12-LOX mRNA. Both DNAzymes were able to cleave their substrate efficiently in a time- and concentration-dependent manner in vitro. Under a multiple turnover condition, both performed well at 37 degrees C, showing the k(cat) of 1 and 0.26 min(-1), respectively. The phosphorothioate modification of the DNAzyme significantly increased its stability in cells without a substantial loss of kinetic efficiency in vitro. In a cell culture system, transfection of the DNAzymes into HEL cells resulted in a significant down-regulation of the 12-LOX mRNA. Furthermore, the cell extracts from the DNAzyme-transfected cells exhibited a marked reduction in the 12-LOX enzyme activity. The present results indicated the potential use of DNAzyme technology for gene function study and cancer therapy.
Arachidonate 12-Lipoxygenase↗
Transformation of sib-pair values for the Haseman-Elston method.
The squared sib-pair phenotype difference (SQD) has been used as a dependent variable in the Haseman-Elston (H-E) regression quantitative-trait locus (QTL) linkage method, but it has been shown that the SQD does not make full use of linkage information. In this study, we examine the efficiency of SQD in H-E regression compared to other proposed functions of the sib-pair phenotypes. A new function of sib-pair phenotypes, the product of pair values corrected with family mean (PCF), is shown to have desirable properties in many realistic situations. Consistent results were obtained using a combination of large-sample analytic approximations, simulation, and analyses of quantitative-trait data from Genetic Analysis Workshop 10. The advantages of PCF are further improved in the presence of family-specific effects arising from environmental factors or when additional QTLs influence the trait. All of the phenotype functions are incorporated in our new, freely available linkage-mapping program MULTIGENE 1.0 for the PC environment.
Chromosome Mapping↗
Identification of four novel human G protein-coupled receptors expressed in the brain.
We report the discovery and tissue distributions of four novel human genes, GPR61, GPR62, GPR63 and GPR77, all of which encode G protein-coupled receptors (GPCRs). GPR61 was discovered in a search of the patent literature which retrieved a rabbit DNA sequence partially encoding a novel GPCR. This sequence was used to obtain a full-length human cDNA encoding GPR61, a receptor of 417 amino acid length. A search of the GenBank genomic sequence databases revealed three previously unrecognized intronless genes encoding the orphan GPCrs (oGPCRs) GPR62, GPR63 and GPR77, with respective amino acid lengths of 368, 419 and 337. Sequence analysis revealed that GPR61 and GPR62, and a published orphan receptor p47MNR, shared the highest level of identities to each other, ranging from 36 to 45% in the transmembrane (TM) domains. Together, these three oGPCRs appear to comprise a novel subfamily of GPCRs, most closely related to the serotonin 5-HT(6) receptor. Sequence analysis of GPR63 and GPR77 revealed highest sequence identities in the TM regions with the oGPCR PSP24 (58%) and the anaphylatoxin C5a receptor (49%) respectively. Tissue distribution analyses detected the expression of all four novel genes in the human brain. GPR61 mRNA expression was detected in the caudate, putamen and thalamus of human brain, with a more widespread expression pattern in rat brain, with mRNA signals in areas of the cortex, hippocampus, thalamus, hypothalamus and midbrain. GPR62 mRNA expression was detected in the basal forebrain, frontal cortex, caudate, putamen, thalamus and hippocampus. GPR63 mRNA expression was detected in the frontal cortex, with lower levels in the thalamus, caudate, hypothalamus and midbrain. Analysis of GPR77 mRNA expression revealed signals in the frontal cortex, hippocampus and hypothalamus with high transcript levels in the liver.
Animals↗
Comparison of marker intervals and number of sib pairs used for linkage analysis on simulated nuclear family data.
Using a two-stage global scan design, we analyzed general population replicates 1 and 42 of the Genetic Analysis Workshop (GAW) 12 simulated data set using three methods: revisited Haseman-Elston (HER), maximum likelihood variance estimation (ML), and variance components (VC). Three marker densities, 5-, 10-, and 15-cM intervals, were examined in the first-stage scan. We found that the 10-cM interval appears to be the most cost-effective approach in genotyping without sacrificing power when using a first stage significance level of 0.01. Subsequently, we performed the second-stage scan at 1-cM intervals for those putative positive regions identified in the first-stage scan at a significance level of 0.01. We also compared the power to detect linkage using different numbers of sib pairs for a genome-wide scan at a 10-cM interval and found that power decreases nonlinearly as the number of sib pairs decreases.
Analysis of Variance↗
Genetic crossover interference in the human genome.
Positive crossover interference refers to the phenomenon that the occurrence of a crossover reduces the probability of another crossover in its vicinity. There have been studies reporting the presence of positive interference in humans. Some studies have also found evidence suggesting within and between chromosomal interference heterogeneity on some of the chromosomes. However, there has been no systematic study of interference and interference heterogeneity in the whole human genome, using pedigree data without first inferring crossovers. In this paper, we studied the Chi-square interference model and other models extensively to compare the relative performance of each of these models for accounting for interference and measuring strength of interference. Our results showed that the Chi-square model consistently fitted the data well and provided easily interpretable estimates of interference strength. The Chi-square model was then used to study interference and interference heterogeneity within and between chromosomes. We found strong evidence of positive interference in the whole human genome. Our results also indicated that the level of interference was fairly constant in most parts of the genome, but there was some evidence suggesting that the levels of interference for two of the chromosomes were different from the rest. We also found evidence of within chromosomal interference heterogeneity for several of the chromosomes.
Chromosomes↗
Discovery of a novel member of the histamine receptor family.
We report the discovery, tissue distribution and pharmacological characterization of a novel receptor, which we have named H4. Like the three histamine receptors reported previously (H1, H2, and H3), the H4 receptor is a G protein-coupled receptor and is most closely related to the H3 receptor, sharing 58% identity in the transmembrane regions. The gene encoding the H4 receptor was discovered initially in a search of the GenBank databases as sequence fragments retrieved in a partially sequenced human genomic contig mapped to chromosome 18. These sequences were used to retrieve a partial cDNA clone and, in combination with genomic fragments, were used to determine the full-length open reading frame of 390 amino acids. Northern analysis revealed a 3.0-kb transcript in rat testis and intestine. Radioligand binding studies indicated that the H4 receptor has a unique pharmacology and binds [(3)H]histamine (K(d) = 44 nM) and [(3)H]pyrilamine (K(d) = 32 nM) and several psychoactive compounds (amitriptyline, chlorpromazine, cyproheptadine, mianserin) with moderate affinity (K(i) range of 33-750 nM). Additionally, histamine induced a rapid internalization of HA-tagged H4 receptors in transfected human embryonic kidney 293 cells.
Amino Acid Sequence↗
The pathogenesis of ataxia-telangiectasia. Learning from a Rosetta Stone.
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Ataxia Telangiectasia↗
[Effect of hepatitis C virus nonstructural protein NS3 on telomerase activity].
OBJECTIVE: To study the effect of hepatitis C virus nonstructural protein NS3 (HCV NS3) on telomerase activity and its carcinogenesis, and to observe the practical use of in situ telomerase activity labeling. METHODS: NIH3T3 cells were transfected with plasmid pRcHCNS3-5prime prime or minute (expressing HCV NS3 C-terminal deleted protein), pRcHCNS3-3prime prime or minute (expressing HCV NS3 N-terminal deleted protein) and blank plasmid pRcCMV. Positive clones, 11 with plasmid pRcHCNS3-5prime prime or minute, 11 with pRcHCNS3-3prime prime or minute and 8 with plasmid pRcCMV were harvested respectively. Streptavidin-peroxidase conjugated method (SP) was used to detect the expression of HCV NS3 protein in NIH3T3 cells transfected with plasmid pRcHCNS3-5prime prime or minute and pRcHCNS3-3prime prime or minute. Telomerase activity was detected by in situ telomerase activity labeling method and telomerase PCR ELISA technique in the transfected and non-transfected NIH3T3 cells. RESULTS: HCV NS3 protein was expressed in the cells transfected with plasmid pRcHCNS3-5prime prime or minute or plasmid pRcHCNS3-3prime prime or minute. The positive signals of HCV NS3 protein were localized in the cytoplasm of transfected NIH3T3 cells, and the signal intensity of the former was stronger (chi(2) = 6.667 P < 0.05). There was significant difference on telomerase activity between each group (F = 134.083 P < 0.01). Telomerase activity in all 11 clones with plasmid pRcHCNS3-5prime prime or minute was stronger than cells with plasmid pRcHCNS3-3prime prime or minute (P < 0.01), whereas telomerase activity in NIH3T3 cells transfected with the plasmid pRcCMV or non-transfected NIH3T3 cells were weaker than the cells with the plasmid pRcHCNS3-3prime prime or minute. The expression level of HCV NS3 protein were correlated significantly with the strength of telomerase activity (rs = 0.8084 P < 0.01). The results obtained with in situ telomerase activity labeling corresponded to those with telomerase PCR ELISA technique (rs = 0.50196 P < 0.01). CONCLUSIONS: (1) HCV NS3 protein may activate telomerase through endogenous mechanism to induce host cells transformation. (2) The effect of HCV NS3 C-terminal deleted protein on telomerase activity in host cells may be more intense than that of HCV NS3 N-terminal deleted protein. (3) In situ telomerase activity labeling is a reliable technique for studying pathological morphology and telomerase activity in tissues and cells.
3T3 Cells↗
Characterization of the human cysteinyl leukotriene 2 receptor.
The contractile and inflammatory actions of the cysteinyl leukotrienes (CysLTs), LTC(4), LTD(4), and LTE(4), are thought to be mediated through at least two distinct but related CysLT G protein-coupled receptors. The human CysLT(1) receptor has been recently cloned and characterized. We describe here the cloning and characterization of the second cysteinyl leukotriene receptor, CysLT(2), a 346-amino acid protein with 38% amino acid identity to the CysLT(1) receptor. The recombinant human CysLT(2) receptor was expressed in Xenopus oocytes and HEK293T cells and shown to couple to elevation of intracellular calcium when activated by LTC(4), LTD(4), or LTE(4). Analyses of radiolabeled LTD(4) binding to the recombinant CysLT(2) receptor demonstrated high affinity binding and a rank order of potency for competition of LTC(4) = LTD(4) LTE(4). In contrast to the dual CysLT(1)/CysLT(2) antagonist, BAY u9773, the CysLT(1) receptor-selective antagonists MK-571, montelukast (Singulair(TM)), zafirlukast (Accolate(TM)), and pranlukast (Onon(TM)) exhibited low potency in competition for LTD(4) binding and as antagonists of CysLT(2) receptor signaling. CysLT(2) receptor mRNA was detected in lung macrophages and airway smooth muscle, cardiac Purkinje cells, adrenal medulla cells, peripheral blood leukocytes, and brain, and the receptor gene was mapped to chromosome 13q14, a region linked to atopic asthma.
Adrenal Medulla↗
Cloning and characterization of additional members of the G protein-coupled receptor family.
A search of the expressed sequence tag (EST) database retrieved a human cDNA sequence which partially encoded a novel G protein-coupled receptor (GPCR) GPR26. A human genomic DNA fragment encoding a partial open reading frame (ORF) and a rat cDNA encoding the full length ORF of GPR26 were obtained by library screening. The rat GPR26 cDNA encoded a protein of 317 amino acids, most similar (albeit distantly related) to the serotonin 5-HT(5A) and gastrin releasing hormone BB2 receptors. GPR26 mRNA expression analysis revealed signals in the striatum, pons, cerebellum and cortex. HEK293 and Rh7777 cells transfected with GPR26 cDNA displayed high basal cAMP levels, slow growth rate of clonal populations and derangements of normal cell shape. We also used a sequence reported only in the patent literature encoding GPR57 (a.k.a. HNHCI32) to PCR amplify a DNA fragment which was used to screen a human genomic library. This resulted in the cloning of a genomic fragment containing a pseudogene, psiGPR57, with a 99.6% nucleotide identity to GPR57. Based on shared sequence identities, the receptor encoded by GPR57 was predicted to belong to a novel subfamily of GPCRs together with GPR58 (a.k.a. phBL5, reported only in the patent literature), putative neurotransmitter receptor (PNR) and a 5-HT(4) pseudogene. Analysis of this subfamily revealed greatest identities (approximately 56%) between the receptors encoded by GPR57 and GPR58, each with shared identities of approximately 40% with PNR. Furthermore, psiGPR57, GPR58, PNR and the 5-HT(4) pseudogene were mapped in a cluster localized to chromosome 6q22-24. PNR and GPR58 were expressed in COS cells, however no specific binding was observed for various serotonin receptor-specific ligands.
1-Methyl-3-isobutylxanthine↗
Characterization of apelin, the ligand for the APJ receptor.
The apelin peptide was recently discovered and demonstrated to be the endogenous ligand for the G protein-coupled receptor, APJ. A search of the GenBank databases retrieved a rat expressed sequence tag partially encoding the preproapelin sequence. The GenBank search also revealed a human sequence on chromosome Xq25-26.1, containing the gene encoding preproapelin. We have used the rat sequence to screen a rat brain cDNA library to obtain a cDNA encoding the full-length open reading frame of rat preproapelin. This cDNA encoded a protein of 77 amino acids, sharing an identity of 82% with human preproapelin. Northern and in situ hybridization analyses revealed both human and rat apelin and APJ to be expressed in the brain and periphery. Both sequence and mRNA expression distribution analyses revealed similarities between apelin and angiotensin II, suggesting they that share related physiological roles. A synthetic apelin peptide was injected intravenously into male Wistar rats, resulting in immediate lowering of both systolic and diastolic blood pressure, which persisted for several minutes. Intraperitoneal apelin injections induced an increase in drinking behavior within the first 30 min after injection, with a return to baseline within 1 h.
Amino Acid Sequence↗
TRH-R2 exhibits similar binding and acute signaling but distinct regulation and anatomic distribution compared with TRH-R1.
TRH (thyroliberin) is a tripeptide (pGlu-His-ProNH2) that signals via G protein-coupled receptors. Until recently, only a single receptor for TRH was known (TRH-R1), but two groups identified a second receptor, TRH-R2. We independently discovered TRH-R2. Using an extensive set of TRH analogs, we found no differences in TRH-R1 and TRH-R2 binding or in acute stimulation of signaling. TRH-R2 was more rapidly internalized upon binding TRH and exhibited a greater level of TRH-induced down-regulation than TRH-R1. During prolonged exposure to TRH, cells expressing TRH-R2 exhibited a lower level of gene induction than cells expressing TRH-R1. TRH-R2 receptor mRNA was present in very discrete nuclei and regions of rat brain. A major mRNA transcript for TRH-R2 was seen in the cerebral cortex, pons, thalamus, hypothalamus, and midbrain with faint bands found in the striatum and pituitary. The extensive distribution of TRH-R2 in the brain suggests that it mediates many of the known functions of TRH that are not transduced by TRH-R1. The variations in agonist-induced internalization and down-regulation/desensitization, and anatomic distribution of TRH-R2 compared with TRH-R1, suggest important functional differences between the two receptors.
Amino Acid Sequence↗