The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

The c-Myc target gene network

For more than a decade, numerous studies have suggested that the c-Myc oncogenic protein is likely to broadly influence the composition of the transcriptome. However, the evidence required to support this notion was made available only recently, much to the anticipation of an eagerly awaiting field. In the past 5 years, many high-throughput screens based on microarray gene expression profiling, serial analysis of gene expression (SAGE), chromatin immunoprecipitation (ChIP) followed by genomic array analysis, and Myc-methylase chimeric proteins have generated a wealth of information regarding Myc responsive and target genes. From these studies, the c-Myc target gene network is estimated to comprise about 15% of all genes from flies to humans. Both genomic and functional analyses of c-Myc targets suggest that while c-Myc behaves as a global regulator of transcription, groups of genes involved in cell cycle regulation, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function are over-represented in the c-Myc target gene network. c-Myc also consistently represses genes involved in cell growth arrest and cell adhesion. The overexpression of c-Myc predisposes cells to apoptosis under nutrient or growth factor deprivation conditions, although the critical sets of genes involved remain elusive. Despite tremendous advances, the downstream target genes that distinguish between physiologic and tumorigenic functions of c-Myc remain to be delineated.

DNA damage and mutation in human cells exposed to nitric oxide in vitro

Nitric oxide (NO.) is a physiological messenger formed by several cell types. Reaction with O2 forms oxides that nitrosate amines at pH values near 7. We now report experiments in which NO. was added to intact human cells and to aerobic solutions of DNA, RNA, guanine, or adenine. TK6 human lymphoblastoid cells were mutated 15- to 18-fold above background levels at both the HPRT and TK gene loci. Xanthine and hypoxanthine, from deamination of guanine and adenine, respectively, were formed in all cases. NO. induced dose-responsive DNA strand breakage. Yields of xanthine ranged from nearly equal to about 80-fold higher than those of hypoxanthine. Yields of xanthine and hypoxanthine from nucleic acids were higher than those from free guanine and adenine. This was most pronounced for xanthine; 0.3 nmol/mg was formed from free guanine vs. 550 nmol/mg from calf thymus RNA. Nitric oxide added to TK6 cells produced a 40- to 50-fold increase in hypoxanthine and xanthine in cellular DNA. We believe that these results, plus the expected deaminations of cytosine to uracil and 5-methylcytosine to thymine, account for the mutagenicity of nitric oxide toward bacteria and mammalian cells.

A human gene that shows identity with the gene encoding the angiotensin receptor is located on chromosome 11

We report the cloning of a gene, intronless in its coding region, which we have named APJ. This gene was cloned using the polymerase chain reaction (PCR), with a set of primers designed on the basis of the conservation that members of G protein-coupled receptors (GPCR) have in their transmembrane (TM) regions. The putative receptor protein, APJ, shares closest identity to the angiotensin receptor (AT1) ranging from 40 to 50% in the hydrophobic TM regions of these receptors. The transcripts for this gene were detected in many regions of the brain. PCR analysis of somatic cell lines found APJ-related sequences to be only present on chromosome 11, and high-resolution mapping by fluorescence in situ hybridization (FISH) sublocalized APJ on band q12.

Akt promotes survival of cardiomyocytes in vitro and protects against ischemia-reperfusion injury in mouse heart

BACKGROUND

IGF-1 has been shown to protect myocardium against death in animal models of infarct and ischemia-reperfusion injury. In the present study, we investigated the role of the IGF-1-regulated protein kinase Akt in cardiac myocyte survival in vitro and in vivo.

METHODS AND RESULTS

IGF-1 promoted survival of cultured cardiomyocytes under conditions of serum deprivation in a dose-dependent manner but had no effect on cardiac fibroblast survival. The cytoprotective effect of IGF-1 on cardiomyocytes was abrogated by the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin. Wortmannin had no effect on cardiomyocyte viability in the absence of IGF-1. IGF-1-mediated cytoprotection correlated with the wortmannin-sensitive induction of Akt protein kinase activity. To examine the functional consequences of Akt activation in cardiomyocyte survival, replication-defective adenoviral constructs expressing wild-type, dominant-negative, and constitutively active Akt genes were constructed. Transduction of dominant-negative Akt blocked IGF-1-induced survival but had no effect on cardiomyocyte survival in the absence of IGF-1. In contrast, transduction of wild-type Akt enhanced cardiomyocyte survival at subsaturating levels of IGF-1, whereas constitutively active Akt protected cardiomyocytes from apoptosis in the absence of IGF-1. After transduction into the mouse heart in vivo, constitutively active Akt protected against myocyte apoptosis in response to ischemia-reperfusion injury.

CONCLUSIONS

These data are the first documentation that Akt functions to promote cellular survival in vivo, and they indicate that the activation of this pathway may be useful in promoting myocyte survival in the diseased heart.

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.

Neuroligin 1: a splice site-specific ligand for beta-neurexins

Neurexins are neuronal cell surface proteins with hundreds of isoforms generated by alternative splicing. Here we describe neuroligin 1, a neuronal cell surface protein that is enriched in synaptic plasma membranes and acts as a splice site-specific ligand for beta-neurexins. Neuroligin 1 binds to beta-neurexins only if they lack an insert in the alternatively spliced sequence of the G domain, but not if they contain an insert. The extracellular sequence of neuroligin 1 is composed of a catalytically inactive esterase domain homologous to acetylcholinesterase. In situ hybridization reveals that alternative splicing of neurexins at the site recognized by neuroligin 1 is highly regulated. These findings support a model whereby alternative splicing of neurexins creates a family of cell surface receptors that confers interactive specificity onto their resident neurons.

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.

Primary structure and biological activity of a novel human neurotrophic factor

During development, each tissue receives and maintains a number of specific neuronal projections that are adequate to sustain its function. The mechanism by which this intricate process occurs is not well understood, but it has been proposed that diffusible neurotrophic factors derived from the target tissue may be involved. Here we describe the identification of a novel human protein that is important for the growth, differentiation, and survival of primary sympathetic and placode-derived sensory neurons. This polypeptide, designated neuronotrophin-3, has a broad tissue distribution and is structurally related to both nerve growth factor and brain-derived neurotrophic factor. Its unique range of trophic and differentiation-inducing activities suggests that it is likely to play a wide role in defining the fate and function of nerve cells during development.

Evolution and transmission of stable CTL escape mutations in HIV infection

Increasing evidence indicates that potent anti-HIV-1 activity is mediated by cytotoxic T lymphocytes (CTLs); however, the effects of this immune pressure on viral transmission and evolution have not been determined. Here we investigate mother-child transmission in the setting of human leukocyte antigen (HLA)-B27 expression, selected for analysis because it is associated with prolonged immune containment in adult infection. In adults, mutations in a dominant and highly conserved B27-restricted Gag CTL epitope lead to loss of recognition and disease progression. In mothers expressing HLA-B27 who transmit HIV-1 perinatally, we document transmission of viruses encoding CTL escape variants in this dominant Gag epitope that no longer bind to B27. Their infected infants target an otherwise subdominant B27-restricted epitope and fail to contain HIV replication. These CTL escape variants remain stable without reversion in the absence of the evolutionary pressure that originally selected the mutation. These data suggest that CTL escape mutations in epitopes associated with suppression of viraemia will accumulate as the epidemic progresses, and therefore have important implications for vaccine design.

Cloning of a lymphocyte homing receptor reveals a lectin domain

Lymphocytes express cell surface molecules, termed homing receptors, that mediate their selective attachment to specialized high endothelial venules found within secondary lymphoid organs. Previous work has demonstrated that the adhesive interaction between lymphocytes and the endothelium of peripheral lymph nodes appears to involve a lectin-like activity. Moreover, MEL-14, a monoclonal antibody that blocks lymphocyte-peripheral lymph node binding and presumably recognizes the homing receptor mediating this adhesive interaction, appeared to detect the lectin-like receptor. In this paper we describe the cloning of a murine cDNA that encodes the antigen recognized by the MEL-14 antibody. Characterization of the cDNA encoding the putative mouse peripheral lymph node-specific homing receptor shows that it contains a lectin domain that appears to be involved in the binding of lymphocytes to peripheral lymph node endothelium, thus defining a new type of cellular adhesion molecule. This result supports a novel mechanism for the distribution of lymphocyte populations to various lymphoid organs.

Regulation of the antioxidant response element by protein kinase C-mediated phosphorylation of NF-E2-related factor 2

A coordinated cellular response to oxidative stress occurs in part through transcriptional regulation via a cis-acting sequence known as the antioxidant response element (ARE). NF-E2-related factor 2 (Nrf2), a member of the Cap'n'Collar family of basic region-leucine zipper (bZIP) transcription factors, has been implicated as an essential component of an ARE-binding transcriptional complex, but the signaling pathway leading to its activation has remained unclear. Using a reporter gene assay, we found that ARE-directed transcription was activated by phorbol 12-myristate 13-acetate (PMA), but completely suppressed by staurosporine and Ro-32-0432, selective inhibitors of protein kinase C (PKC). Immunocytochemistry and subcellular fractionation revealed that PMA, like tert-butylhydroquinone (tBHQ), promoted the nuclear localization of Nrf2, a process that was blocked by staurosporine or Ro-32-0432. We showed that Nrf2, a previously unidentified kinase target, was phosphorylated in HepG2 cells. PMA transiently activated Nrf2 phosphorylation, whereas the addition of tBHQ or beta-naphthoflavone (betaNF) led to a persistent stimulation, which was abolished by staurosporine, but not by U0126 and SB203580, respective inhibitors of MEK and p38 kinases. Purified Nrf2 was phosphorylated in vitro by the catalytic subunit of PKC, or by PKC immunoprecipitated from cell lysates. Significantly, PKC precipitated from tBHQ- or betaNF-treated cells showed enhanced activity against Nrf2. These findings indicate an important role of the PKC pathway in the ARE-mediated gene expression, and suggest that PKC-directed phosphorylation of Nrf2 may be a critical event for the nuclear translocation of this transcription factor in response to oxidative stress.

RNA interference of influenza virus production by directly targeting mRNA for degradation and indirectly inhibiting all viral RNA transcription

Influenza A virus causes widespread infection in the human respiratory tract, but existing vaccines and drug therapy are of limited value. Here we show that short interfering RNAs (siRNAs) specific for conserved regions of the viral genome can potently inhibit influenza virus production in both cell lines and embryonated chicken eggs. The inhibition depends on the presence of a functional antisense strand in the siRNA duplex, suggesting that viral mRNA is the target of RNA interference. However, siRNA specific for nucleocapsid (NP) or a component of the RNA transcriptase (PA) abolished the accumulation of not only the corresponding mRNA but also virion RNA and its complementary RNA. These siRNAs also broadly inhibited the accumulation of other viral, but not cellular, RNAs. The findings reveal that newly synthesized NP and PA proteins are required for influenza virus transcription and replication and provide a basis for the development of siRNAs as prophylaxis and therapy for influenza infection in humans.

The CD28-related molecule ICOS is required for effective T cell-dependent immune responses

While CD28 is critical for expansion of naive T cells, recent evidence suggests that the activation of effector T cells is largely independent of CD28/B7. We suggest that ICOS, the third member of the CD28/CTLA-4 family, plays an important role in production of IL-2, IL-4, IL-5, and IFNgamma from recently activated T cells and contributes to T cell-dependent B help in vivo. Inhibition of ICOS attenuates lung mucosal inflammation induced by Th2 but not Th1 effector populations. Our data indicate a critical function for the third member of the CD28 family in T cell-dependent immune responses.

Prevention of corticosteroid osteoporosis. A comparison of calcium, calcitriol, and calcitonin

BACKGROUND

Prolonged corticosteroid therapy increases the risk of osteoporosis and fracture. We studied whether corticosteroid-induced osteoporosis could be prevented by treatment with calcium, calcitriol (1,25-dihydroxyvitamin D3), and calcitonin.

METHODS

One hundred three patients starting long-term corticosteroid therapy were randomly assigned to receive 1000 mg of calcium per day orally and either calcitriol (0.5 to 1.0 microgram per day orally) plus salmon calcitonin (400 IU per day intranasally), calcitriol plus a placebo nasal spray, or double placebo for one year. Data on treatment efficacy were available for 92 of these patients. Bone density was measured every four months for two years by photon absorptiometry. There were no significant differences between groups with respect to age, underlying disease, initial bone density, or corticosteroid dose during the first year.

RESULTS

Calcitriol (mean dose, 0.6 microgram per day), with or without calcitonin, prevented more bone loss from the lumbar spine (mean rates of change, -0.2 and -1.3 percent per year, respectively) than calcium alone (-4.3 percent per year, P = 0.0035). Bone loss at the femoral neck and distal radius was not significantly affected by any treatment. In the second year, lumbar bone loss did not occur in the group previously treated with calcitonin plus calcitriol (+0.7 percent per year), but it did occur in the group given calcium alone (-2.3 percent per year). The calcitriol group also lost lumbar bone (-3.6 percent per year) but received more corticosteroid in the second year than the other two groups.

CONCLUSIONS

Calcitriol and calcium, used prophylactically with or without calcitonin, prevent corticosteroid-induced bone loss in the lumbar spine.

Prediction of osteoporotic fractures by postural instability and bone density

OBJECTIVE

To investigate the utility of risk factors such as bone mineral density, lifestyle, and postural stability in the prediction of osteoporotic fractures.

DESIGN

Longitudinal, epidemiological, and population based survey.

SETTING

City of Dubbo, New South Wales.

SUBJECTS

All residents of Dubbo aged > or = 60 on 1 January 1989.

MAIN OUTCOME MEASURE

Incidence of fracture for individual subjects.

RESULTS

The overall incidence of atraumatic fractures in men and women was 1.9% and 3.1% per annum respectively. The predominant sites of fracture were hip (18.9%), distal radius (18.5%), ribs and humerus (11.9% in each case), and ankle and foot (9.1% and 6.6% respectively). Major predictors of fractures in men and women were femoral neck bone mineral density, body sway, and quadriceps strength. Age, years since menopause, height, weight, and lifestyle factors were also correlated with bone mineral density and body sway and hence were indirect risk factors for fracture. Discriminant function analysis correctly identified 96% and 93% (sensitivities 88% and 81%) of men and women, respectively, who subsequently developed atraumatic fractures. Predictions based on this model indicated that a woman with a bone mineral density in the lowest quartile in the hip together with high body sway had a 8.4% probability of fracture per annum. This represented an almost 14-fold increase in risk of fracture compared with a woman in the highest bone mineral density quartile with low postural sway. An individual with all three predictors in the "highest risk" quartile had a 13.1% risk of fracture per annum.

CONCLUSIONS

Bone mineral density, body sway, and muscle strength are independent and powerful synergistic predictors of fracture incidence.

Symptomatic fracture incidence in elderly men and women: the Dubbo Osteoporosis Epidemiology Study (DOES)

This longitudinal population-based study documents the incidence of all symptomatic fractures from 1989 to 1992 in an elderly, predominantly Caucasian population of males and females (> or = 60 years as at 1 January 1989) living in the geographically isolated region of the city of Dubbo, NSW, Australia. Fractures were ascertained by reviewing reports from all radiology services in the region. There were 306 fractures in 271 patients during the study period representing 11,401 person-years of observation. In the 60-80 year age group only 10% of fractures involved the hip, while in the over-80 age group this proportion rose to 41%. Incidence of distal forearm, hip and total fractures increased exponentially in both sexes with increasing age. Rib fractures were relatively common, with incidence rates for rib fractures similar to those for humeral fractures. Overall fracture incidence was 2685 per 100,000 person-years (males 1940 per 100,000 and females 3250 per 100,000). Residual lifetime fracture risk in a person aged 60 years with average life expectancy was 29% for males and 56% for females. Symptomatic fracture rates with the improved methodology in this study were higher than previously reported in both elderly males and females, with a marked preponderance of non-hip fractures in the 60-80 year age group. These symptomatic fractures have previously been underestimated, if not largely ignored, in public health approaches including cost-benefit analyses of osteoporosis prevention and treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Discovery of a receptor related to the galanin receptors

We report the isolation of a cDNA clone named GPR54, which encodes a novel G protein-coupled receptor (GPCR). A PCR search of rat brain cDNA retrieved a clone partially encoding a GPCR. In a library screening this clone was used to isolate a cDNA with an open reading frame (ORF) encoding a receptor of 396 amino acids long which shared significant identities in the transmembrane regions with rat galanin receptors GalR1 (45%), GalR3 (45%) and GalR2 (44%). Northern blot and in situ hybridization analyses revealed that GPR54 is expressed in brain regions (pons, midbrain, thalamus, hypothalamus, hippocampus, amygdala, cortex, frontal cortex, and striatum) as well as peripheral regions (liver and intestine). In COS cell expression of GPR54 no specific binding was observed for 125I-galanin. A recent BLAST search with the rat GPR54 ORF nucleotide sequence recovered the human orthologue of GPR54 in a 3.5 Mb contig localized to chromosome 19p13.3.

Structures, alternative splicing, and neurexin binding of multiple neuroligins

Neuroligin 1 is a neuronal cell surface protein that binds to a subset of neurexins, polymorphic cell surface proteins that are also localized on neurons (Ichtchenko, K., Hata, Y., Nguyen, T., Ullrich, B., Missler, M., Moomaw, C., and Südhof, T. C. (1995) Cell 81, 435-443). We now describe two novel neuroligins called neuroligins 2 and 3 that are similar in structure and sequence to neuroligin 1. All neuroligins contain an N-terminal hydrophobic sequence with the characteristics of a cleaved signal peptide followed by a large esterase homology domain, a highly conserved single transmembrane region, and a short cytoplasmic domain. The three neuroligins are alternatively spliced at the same position and are expressed at high levels only in brain. Binding studies demonstrate that all three neuroligins bind to beta-neurexins both as native brain proteins and as recombinant proteins. Tight binding of the three neuroligins to beta-neurexins is observed only for beta-neurexins lacking an insert in splice site 4. Thus, neuroligins constitute a multigene family of brain-specific proteins with distinct isoforms that may have overlapping functions in mediating recognition processes between neurons.

Inhibition of influenza virus production in virus-infected mice by RNA interference

Influenza A virus infection is a major source of morbidity and mortality worldwide. Because the effectiveness of existing vaccines and antiviral drugs is limited, development of new treatment modalities is needed. Here, we show that short interfering RNAs (siRNAs) specific for conserved regions of influenza virus genes can prevent and treat influenza virus infection in mice. Virus production in lungs of infected mice is reduced by siRNAs given either before or after initiating virus infection, by using slow i.v. administration of small volumes containing siRNAs in complexes with a polycation carrier. Similar effects also are observed when mice are given DNA vectors i.v. or intranasally, from which siRNA precursors can be transcribed. Development of delivery systems that may be compatible with human use demonstrates the potential utility of siRNAs for prophylaxis and therapy of influenza virus infections in humans.

Ligand-, cell-, and estrogen receptor subtype (alpha/beta)-dependent activation at GC-rich (Sp1) promoter elements

17beta-Estradiol (E2) induces expression of several genes via estrogen receptor (ER)-Sp1 protein interactions with GC-rich promoter elements in which Sp1 but not ER binds DNA. This study reports the ligand- and cell context-dependent ER(alpha)/Sp1 and ER(beta)/Sp1 action using an E2-responsive construct (pSp1) containing a GC-rich promoter. Both ER(alpha) and ER(beta) proteins physically interact with Sp1 (coimmunoprecipitation) and preferentially bind to the C-terminal region of this protein in pull-down assays. E2- and antiestrogen-dependent transcriptional activation of ER(alpha)/Sp1 was observed in MCF-7, MDA-MB-231, and LnCaP cells, but not in HeLa cells. E2 did not affect or significantly decrease ER(beta)/Sp1 action, and antiestrogens had minimal effects in the same 4 cell lines. Exchange of activation function-1 (AF-1) domains of ER subtypes gave chimeric ER(alpha/beta) (AF-1alpha/AF-2beta) and ER(beta/alpha) (AF-1beta/AF-2alpha) proteins that resembled wild-type ER (alpha or beta) in terms of physical association with Sp1 protein. Transcriptional activation studies with chimeric ER(beta/alpha) and ER(alpha/beta) showed that only ER(alpha/beta) can activate transcription from an Sp1 element, not ER(beta/alpha). This indicates that the AF-1 domain from ER(alpha) is responsible for activation at an Sp1 element, independent of ER subtype context. In order to further characterize this observation, deletion constructs in the AF-1 domain of both ER(alpha) and ER(alpha/beta) were made, and transactivation studies indicated that the region between amino acids 79 and 117 of this domain is important for activation at an Sp1 element.

Crucial role of the interleukin 1 receptor family member T1/ST2 in T helper cell type 2-mediated lung mucosal immune responses

T1/ST2 is an orphan receptor of unknown function that is expressed on the surface of murine T helper cell type 2 (Th2), but not Th1 effector cells. In vitro blockade of T1/ST2 signaling with an immunoglobulin (Ig) fusion protein suppresses both differentiation to and activation of Th2, but not Th1 effector populations. In a nascent Th2-dominated response, anti-T1/ST2 monoclonal antibody (mAb) inhibited eosinophil infiltration, interleukin 5 secretion, and IgE production. To determine if these effects were mediated by a direct effect on Th2 cells, we next used a murine adoptive transfer model of Th1- and Th2-mediated lung mucosal immune responses. Administration of either T1/ST2 mAb or T1/ST2-Ig abrogated Th2 cytokine production in vivo and the induction of an eosinophilic inflammatory response, but failed to modify Th1-mediated inflammation. Taken together, our data demonstrate an important role of T1/ST2 in Th2-mediated inflammatory responses and suggest that T1/ST2 may prove to be a novel target for the selective suppression of Th2 immune responses.

Comparison of improved precipitation methods for quantification of high-density lipoprotein cholesterol

We compared the standard Lipid Research Clinics heparin-Mn2+ (46 mmol/L) method and five improved precipitation methods for quantification of high-density lipoprotein (HDL) cholesterol. Three of these methods--a dextran sulfate-Mg2+ procedure, reported as a Selected Method, a modified heparin-Mn2+ (92 mmol/L) method, and a modified phosphotungstate-Mg2+ procedure--all gave similar results. Three other methods--the standard heparin-Mn2+ (46 mmol/L) method and two polyethylene glycol methods (75 g/L or pH 10 reagent at 100 g/L final concentrations)--gave slightly higher values for HDL cholesterol. Addition of NaCl or glucose to specimens did not significantly change protein precipitation. In terms of sedimentation effectiveness with hypertriglyceridemic specimens, the methods were ranked in the following order: polyethylene glycol (pH 10, 100 g/L) greater than dextran sulfate-Mg2+ greater than heparin-Mn2+ (92 mmol/L) = polyethylene glycol (75 g/L) greater than phosphotungstate-Mg2+ greater than heparin-Mn2+ (46 mmol/L).

Transcriptional regulation of the antioxidant response element. Activation by Nrf2 and repression by MafK

The antioxidant response element (ARE) mediates the transcriptional activation of many genes encoding phase II drug-metabolizing enzymes in response to oxidative stress. Recent studies using knockout mice suggest that NF-E2-related factor 2 (Nrf2), along with small Maf proteins, binds and activates the ARE. In this study, using in vitro binding assays, Nrf2/MafK heterodimers were found to interact with high affinity to the ARE. However, distinct differences were observed when this interaction was compared with that formed with nuclear proteins from H4II EC3 or HepG2 cells. Overexpression of Nrf2 activated ARE-mediated transcription in HepG2 cells, and this activation was further increased by tert-butylhydroquinone. In HeLa cells, overexpression of Nrf2 resulted in activation of the ARE, but this activation was no longer induced by tert-butylhydroquinone. Using ARE constructs with point mutations in the core sequence, we found that only mutations at the T or G nucleotides within the core (TGAC) render the ARE unresponsive to Nrf2. Overexpression of MafK led to dose-dependent repression of ARE activity. Activation of the ARE by Nrf2 was similarly antagonized by MafK. These data suggest that Nrf2 plays an important role mediating basal activity of the ARE but that small Maf proteins are repressors and not activators of ARE-mediated transcription.