The structure and expression of neuron-specific enolase gene

ICU 'Magic Numbers': The Role of Biomarkers in Supporting Clinical Decision-Making

Critical care medicine is a highly complex field where diagnosing diseases and selecting effective therapies pose daily challenges for clinicians. In critically ill patients, biomarkers can play a crucial role in identifying and addressing clinical problems. Selecting the right biomarkers and utilizing them effectively can lead to more informed decisions, ultimately impacting patient outcomes. However, each biomarker has its strengths and limitations, making a thorough understanding essential for accurate diagnosis and treatment management. For instance, neuron-specific enolase (NSE) is commonly used to predict outcomes in out-of-hospital cardiac arrest (OHCA), procalcitonin (PCT) levels strongly correlate with bacterial infections, and NT-proBNP serves as a reliable indicator of cardiac stress. Additionally, serum creatinine (SCr) remains fundamental in renal diagnostics, while prealbumin helps differentiate catabolic and anabolic phases in critically ill patients. This narrative review highlights a carefully selected set of biomarkers known for their clinical utility and reliability in guiding critical care decisions. Further refining the application of biomarkers-especially by integrating them into a multimodal approach-will enhance clinicians' ability to navigate the challenges of critical care, always striving to improve patient outcomes.

Genetic and pharmacologic proteasome augmentation ameliorates Alzheimer's-like pathology in mouse and fly APP overexpression models

The proteasome has key roles in neuronal proteostasis, including the removal of misfolded and oxidized proteins, presynaptic protein turnover, and synaptic efficacy and plasticity. Proteasome dysfunction is a prominent feature of Alzheimer's disease (AD). We show that prevention of proteasome dysfunction by genetic manipulation delays mortality, cell death, and cognitive deficits in fly and cell culture AD models. We developed a transgenic mouse with neuronal-specific proteasome overexpression that, when crossed with an AD mouse model, showed reduced mortality and cognitive deficits. To establish translational relevance, we developed a set of TAT-based proteasome-activating peptidomimetics that stably penetrated the blood-brain barrier and enhanced 20S/26S proteasome activity. These agonists protected against cell death, cognitive decline, and mortality in cell culture, fly, and mouse AD models. The protective effects of proteasome overexpression appear to be driven, at least in part, by the proteasome's increased turnover of the amyloid precursor protein along with the prevention of overall proteostatic dysfunction.

Characterization of neural stem cells modified with hypoxia/neuron-specific VEGF expression system for spinal cord injury

Spinal cord injury (SCI) is an incurable disease causing an ischemic environment and functional defect, thus a new therapeutic approach is needed for SCI treatment. Vascular endothelial growth factor (VEGF) is a potent therapeutic gene to treat SCI via angiogenesis and neuroprotection, and both tissue-specific gene expression and high gene delivery efficiency are important for successful gene therapy. Here we design the hypoxia/neuron dual-specific gene expression system (pEpo-NSE) and efficient gene delivery platform can be achieved by the combination ex vivo gene therapy with erythropoietin (Epo) enhancer, neuron-specific enolase (NSE) promoter and neural stem cells (NSCs). An in vitro model, NSCs transfected with pEpo-NSE were consistently and selectively overexpressing therapeutic genes in response to neural differentiation and hypoxic conditions. Also, in SCI model, ex vivo gene therapy using pEpo-NSE system with NSCs significantly enhanced gene delivery efficiency compared with pEpo-NSE system gene therapy alone. However, microarray analysis reveals that introducing exogenous pEpo-NSE and VEGF triggers biological pathways in NSCs such as glycolysis and signaling pathways such as Ras and mitogen-activated protein kinase, leading to cell proliferation, differentiation and apoptosis. Collectively, it indicates that the pEpo-NSE gene expression system works stably in NSCs and ex vivo gene therapy using pEpo-NSE system with NSCs improves gene expression efficiency. However, exogenously introduced pEpo-NSE system has an influence on gene expression profiles in NSCs. Therefore, when we consider ex vivo gene therapy for SCI, the effects of changes in gene expression profiles in NSCs on safety should be investigated.

Neuron-Specific Enolase as a Biomarker: Biochemical and Clinical Aspects

Neuron-specific enolase (NSE) is known to be a cell specific isoenzyme of the glycolytic enzyme enolase. In vertebrate organisms three isozymes of enolase, expressed by different genes, are present: enolase α is ubiquitous; enolase β is muscle-specific and enolase γ is neuron-specific. The expression of NSE, which occurs as γγ- and αγ-dimer, is a late event in neural differentiation, thus making it a useful index of neural maturation.NSE is a highly specific marker for neurons and peripheral neuroendocrine cells. As a result of the findings of NSE in specific tissues under normal conditions, increased body fluids levels of NSE may occur with malignant proliferation and thus can be of value in diagnosis, staging and treatment of related neuroendocrine tumours (NETs).NSE is currently the most reliable tumour marker in diagnosis, prognosis and follow-up of small cell lung cancer (SCLC), even though increased levels of NSE have been reported also in non-small cell lung cancer (NSCLC). The level of NSE correlates with tumour burden, number of metastatic sites and response to treatment.NSE can be also useful at diagnosis of NETs and gastroenteropancreatic (GEP)-NETs.Raised serum levels of NSE have been found in all stages of neuroblastoma, although the incidence of increased concentration is greater in widespread and metastatic disease. Moreover, NSE determination in cord blood offers an early postnatal possibility of confirming the diagnosis of neuroblastoma in newborns.NSE has been demonstrated to provide quantitative measures of brain damage and/or to improve the diagnosis and the outcome evaluation in ischaemic stroke, intracerebral hemorrhage, seizures, comatose patients after cardiopulmonary resuscitation for cardiac arrest and traumatic brain injury.Increased NSE serum levels have also been found associated with melanoma, seminoma, renal cell carcinoma, Merkel cell tumour, carcinoid tumours, dysgerminomas and immature teratomas, malignant phaechromocytoma, Guillain-Barré syndrome and Creutzfeldt-Jakob disease.

Restricted transgene expression in the brain with cell-type specific neuronal promoters

Tissue-targeted expression is of major interest for studying the contribution of cellular subpopulations to neurodegenerative diseases. However, in vivo methods to investigate this issue are limited. Here, we report an analysis of the cell specificity of expression of fluorescent reporter genes driven by six neuronal promoters, with the ubiquitous phosphoglycerate kinase 1 (PGK) promoter used as a reference. Quantitative analysis of AcGFPnuc expression in the striatum and hippocampus of rodents showed that all lentiviral vectors (LV) exhibited a neuronal tropism; however, there was substantial diversity of transcriptional activity and cell-type specificity of expression. The promoters with the highest activity were those of the 67 kDa glutamic acid decarboxylase (GAD67), homeobox Dlx5/6, glutamate receptor 1 (GluR1), and preprotachykinin 1 (Tac1) genes. Neuron-specific enolase (NSE) and dopaminergic receptor 1 (Drd1a) promoters showed weak activity, but the integration of an amplification system into the LV overcame this limitation. In the striatum, the expression profiles of Tac1 and Drd1a were not limited to the striatonigral pathway, whereas in the hippocampus, Drd1a and Dlx5/6 showed the expected restricted pattern of expression. Regulation of the Dlx5/6 promoter was observed in a disease condition, whereas Tac1 activity was unaffected. These vectors provide safe tools that are more selective than others available, for the administration of therapeutic molecules in the central nervous system (CNS). Nevertheless, additional characterization of regulatory elements in neuronal promoters is still required.

Modeling human neurodegenerative diseases in transgenic systems

Transgenic systems are widely used to study the cellular and molecular basis of human neurodegenerative diseases. A wide variety of model organisms have been utilized, including bacteria (Escherichia coli), plants (Arabidopsis thaliana), nematodes (Caenorhabditis elegans), arthropods (Drosophila melanogaster), fish (zebrafish, Danio rerio), rodents (mouse, Mus musculus and rat, Rattus norvegicus) as well as non-human primates (rhesus monkey, Macaca mulatta). These transgenic systems have enormous value for understanding the pathophysiological basis of these disorders and have, in some cases, been instrumental in the development of therapeutic approaches to treat these conditions. In this review, we discuss the most commonly used model organisms and the methodologies available for the preparation of transgenic organisms. Moreover, we provide selected examples of the use of these technologies for the preparation of transgenic animal models of neurodegenerative diseases, including Alzheimer's disease (AD), frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD) and Parkinson's disease (PD) and discuss the application of these technologies to AD as an example of how transgenic modeling has affected the study of human neurodegenerative diseases.

Transgenic expression of human equilibrative nucleoside transporter 1 in mouse neurons

Transgenic mice that express human equilibrative nucleoside transporter subtype 1 (hENT1) under the control of a neuron-specific enolase promoter have been generated. Southern blot and PCR revealed the presence of the transgene in five founder mice. Mice from each founder line were examined by reverse transcriptase (RT)-PCR and found to express hENT1 in RNA isolated from whole brain, cerebral cortex, striatum, hippocampus, and cerebellum but not liver, kidney, heart, lung or skeletal muscle. Cortical synaptosomes prepared from transgenic mice had significantly increased [(3)H]adenosine uptake and [(3)H]nitrobenzylthioinosine binding, relative to samples from wild-type mice. In behavioral tests, transgenic mice had altered responses to caffeine and ethanol, two drugs that inhibit and enhance, respectively, adenosine receptor activity. Caffeine-induced locomotor stimulation was attenuated whereas the hypnotic effect of ethanol was enhanced in transgenic mice. Caffeine was more potent in inhibiting ethanol-induced motor incoordination in wild-type than in transgenic mice. No differences in expression of mouse genes for adenosine receptors, nucleoside transporters, or purine metabolizing enzymes were detected by RT-PCR analyses. These data indicate that expression of hENT1 in neurons does not trigger adaptive changes in expression of adenosine-related genes. Instead, hENT1 expression affects dynamic changes in endogenous adenosine levels, as revealed by altered behavioral responses to drugs that affect adenosine receptor signalling.

Generation of a transgenic zebrafish model of Tauopathy using a novel promoter element derived from the zebrafish eno2 gene

The aim of this study was to isolate cis-acting regulatory elements for the generation of transgenic zebrafish models of neurodegeneration. Zebrafish enolase-2 (eno2) showed neuronal expression increasing from 24 to 72 h post-fertilization (hpf) and persisting through adulthood. A 12 kb eno2 genomic fragment, extending from 8 kb upstream of exon 1 to exon 2, encompassing intron 1, was sufficient to drive neuronal reporter gene expression in vivo over a similar time course. Five independent lines of stable Tg(eno2 : GFP) zebrafish expressed GFP widely in neurons, including populations with relevance to neurodegeneration, such as cholinergic neurons, dopaminergic neurons and cerebellar Purkinje cells. We replaced the exon 2-GFP fusion gene with a cDNA encoding the 4-repeat isoform of the human microtubule-associated protein Tau. The first intron of eno2 was spliced with high fidelity and efficiency from the chimeric eno2-Tau transcript. Tau was expressed at approximately 8-fold higher levels in Tg(eno2 : Tau) zebrafish brain than normal human brain, and localized to axons, neuropil and ectopic neuronal somatic accumulations resembling neurofibrillary tangles. The 12 kb eno2 promoter drives high-level transgene expression in differentiated neurons throughout the CNS of stable transgenic zebrafish. This regulatory element will be useful for the construction of transgenic zebrafish models of neurodegeneration.

Quantitative profile of five murine core proteomes using label-free functional proteomics

Analysis of primary animal and human tissues is key in biological and biomedical research. Comparative proteomics analysis of primary biological material would benefit from uncomplicated experimental work flows capable of evaluating an unlimited number of samples. In this report we describe the application of label-free proteomics to the quantitative analysis of five mouse core proteomes. We developed a computer program and normalization procedures that allow exploitation of the quantitative data inherent in LC-MS/MS experiments for relative and absolute quantification of proteins in complex mixtures. Important features of this approach include (i) its ability to compare an unlimited number of samples, (ii) its applicability to primary tissues and cultured cells, (iii) its straightforward work flow without chemical reaction steps, and (iv) its usefulness not only for relative quantification but also for estimation of absolute protein abundance. We applied this approach to quantitatively characterize the most abundant proteins in murine brain, heart, kidney, liver, and lung. We matched 8,800 MS/MS peptide spectra to 1,500 proteins and generated 44,000 independent data points to profile the approximately 1,000 most abundant proteins in mouse tissues. This dataset provides a quantitative profile of the fundamental proteome of a mouse, identifies the major similarities and differences between organ-specific proteomes, and serves as a paradigm of how label-free quantitative MS can be used to characterize the phenotype of mammalian primary tissues at the molecular level.

Upregulation of the neuron-specific K+/Cl- cotransporter expression by transcription factor early growth response 4

The expression of the neuron-specific K+/Cl- cotransporter (KCC2) is restricted to the CNS and is strongly upregulated during neuronal maturation, yielding a low intracellular chloride concentration that is required for fast synaptic inhibition in adult neurons. To elucidate the mechanisms of KCC2 gene regulation, we analyzed the KCC2 (alias Slc12a5) promoter and proximal intron-1 regions and revealed 10 candidate transcription factor binding sites that are highly conserved in mammalian KCC2 genes. Here we focus on one of these factors, early growth response 4 (Egr4), which shows a similar developmental upregulation in CNS neurons as KCC2. KCC2 luciferase reporter constructs containing the Egr4 site (Egr4(KCC2)) were strongly induced by Egr4 overexpression in neuro-2a neuroblastoma cells and in cultured neurons. Egr4-mediated induction was decreased significantly by point-mutating the Egr4(KCC2). Insertion of Egr4(KCC2) into the KCC2 basal promoter in the endogenous reverse, but not in the opposite, orientation reestablished Egr4-mediated induction. Electrophoretic mobility shift assay confirmed specific Egr4 binding to Egr4(KCC2). Interference RNA-mediated knock-down of Egr4 and a dominant-negative isoform of Egr4 significantly inhibited KCC2 reporter induction and endogenous KCC2 expression in cultured neurons. Together, the results indicate an important role for Egr4 in the developmental upregulation of KCC2 gene expression.

Tamalin, a PDZ domain-containing protein, links a protein complex formation of group 1 metabotropic glutamate receptors and the guanine nucleotide exchange factor cytohesins

In this investigation, we report identification and characterization of a 95 kDa postsynaptic density protein (PSD-95)/discs-large/ZO-1 (PDZ) domain-containing protein termed tamalin, also recently named GRP1-associated scaffold protein (GRASP), that interacts with group 1 metabotropic glutamate receptors (mGluRs). The yeast two-hybrid system and in vitro pull-down assays indicated that the PDZ domain-containing, amino-terminal half of tamalin directly binds to the class I PDZ-binding motif of group 1 mGluRs. The C-terminal half of tamalin also bound to cytohesins, the members of guanine nucleotide exchange factors (GEFs) specific for the ADP-ribosylation factor (ARF) family of small GTP-binding proteins. Tamalin mRNA is expressed predominantly in the telencephalic region and highly overlaps with the expression of group 1 mGluR mRNAs. Both tamalin and cytohesin-2 were enriched and codistributed with mGluR1a in postsynaptic membrane fractions. Importantly, recombinant and native mGluR1a/tamalin/cytohesin-2 complexes were coimmunoprecipitated from transfected COS-7 cells and rat brain tissue, respectively. Transfection of tamalin and mutant tamalin lacking a cytohesin-binding domain caused an increase and decrease in cell-surface expression of mGluR1a in COS-7 cells, respectively. Furthermore, adenovirus-mediated expression of tamalin and dominant-negative tamalin facilitated and reduced the neuritic distribution of endogenous mGluR5 in cultured hippocampal neurons, respectively. The results indicate that tamalin plays a key role in the association of group 1 mGluRs with the ARF-specific GEF proteins and contributes to intracellular trafficking and the macromolecular organization of group 1 mGluRs at synapses.

Production of transgenic miniature pigs by pronuclear microinjection

Miniature pig is an attractive animal for a wide range of research fields, such as medicine and pharmacology, because of its small size, the possibility of breeding it under minimum environmental controls and the physiology that is potentially similar to that of human. Although transgenic technology is useful for the analysis of gene function and for the development of model animals for various diseases, there have not yet been any reports on producing transgenic miniature pig. This study is the first successful report concerning the production of transgenic miniature pig by pronuclear microinjection. The huntingtin gene cloned from miniature pig, which is a homologue of candidate gene for Huntington's disease, connected with rat neuron-specific enolase promoter region, was injected into a pronucleus of fertilized eggs with micromanipulator. The eggs were transferred into the oviduct of recipient miniature pigs, whose estrus cycles were previously synchronized with a progesterone analogue. A total of 402 injected eggs from 171 donors were transferred to 23 synchronized recipients. Sixteen of them maintained pregnancy and delivered 65 young, and one resulted in abortion. Five of the 68 offspring (three of which were aborted) were determined to have transgene by PCR and Southern analysis. The overall rate of transgenic production was 1.24% (transgenic/injected eggs). This study provides the first success and useful information regarding production of transgenic miniature pig for biomedical research.

The Na-G ion channel is transcribed from a single promoter controlled by distinct neuron- and Schwann cell-specific DNA elements

Na-G is a putative sodium (or cationic) channel expressed in neurons and glia of the PNS, in restricted neuronal subpopulations of the brain, and in several tissues outside the nervous system, like lung and adrenal medulla. To analyze the mechanisms underlying tissue-specific expression of this channel, we isolated the 5' region of the corresponding gene and show that Na-G mRNA transcription proceeds from a single promoter with multiple initiation sites. By transgenic mice studies, we demonstrate that 600 bp containing the Na-G proximal promoter region and the first exon are sufficient to drive the expression of a beta-galactosidase reporter gene in neurons of both CNS and PNS, whereas expression in Schwann cells depends on more remote DNA elements lying in the region between -6,500 and -1,050 bp upstream of the main transcription initiation sites. Crucial elements for lung-specific expression seem to be located in the region between -1,050 and -375 bp upstream of the promoter. Using in vivo footprint experiments, we demonstrate that several sites of the Na-G proximal promoter region are bound specifically by nuclear proteins in dorsal root ganglion neurons, as compared with nonexpressing hepatoma cells.

Efficient gene transfer and long-term expression in neurons using a recombinant adenovirus with a neuron-specific promoter

Adenoviruses are highly efficient vectors for gene transfer into brain cells. Restricting transgene expression to specific cell types and maintaining long-term expression are major goals for gene therapy in the central nervous system. We targeted gene expression to neurons by constructing an adenoviral vector that expressed the E. coli LacZ reporter gene under the control of the rat neuron-specific enolase promoter (Ad-NSE). Expression from Ad-NSE was compared with that from an adenoviral vector encoding the same reporter gene under the control of the Rous sarcoma virus LTR promoter (Ad-RSV). Both recombinant adenoviruses were injected stereotactically into rat hippocampus, cerebellum and striatum. Anatomical and immunohistochemical analyses of the Ad-NSE-stained cells showed that neurons were preferentially transduced. More neurons were stained in the hippocampus following infection with Ad-NSE than with Ad-RSV. Cytotoxicity from Ad-NSE was lower than from Ad-RSV. beta-Galactosidase gene expression after Ad-NSE infection remained stable for 3(1/2) months, and was detectable for 6 months. Thus, the NSE-adenoviral vector can be used to transfer potentially therapeutic genes into neuronal cells. The use of a cell-specific promoter also resulted in high in vivo efficiency and long-term transgene expression.

Purification and properties of gammagamma-enolase from pig brain

Isoelectric focusing revealed three enolase isoforms in pig brain, which were designated as alphaalpha-(pI = 6.5), alphagamma- (pI = 5.6), and gammagamma-enolase (pI = 5.2). The pI of purified gammagamma-enolase was also 5.2. The gammagamma-enolase isoform of enolase was purified from pig brain by a purification protocol involving heating to 55 degrees C for 3 min, acetone precipitation, ammonium sulfate precipitation (40%-80%), DEAE Sephadex ion-exchange chromatography (pH 6.2), and Sephadex G200 gel filtration. The final specific activity was 82 units/mg protein. As with other vertebrate enolases, gammagamma-enolase from pig proved to be a dimer with a native mass of 85 kDa and a subunit mass of 45 kDa. The pH optimum for the reaction in the glycolytic direction is 7.2. The Km values for 2-PGA, PEP, and Mg2+ were determined to be 0.05, 0.25, and 0.50 mM, respectively, similar to Km values of other vertebrate enolases. The amino acid composition of pig gammagamma-enolase, as determined by amino acid analysis, shows strong similarity to the compositions of gammagamma-enolases from rat, human, and mouse, as determined from their amino acid sequences. Despite the differences seen with some residues, and considering the ways that the compositions were obtained, it is assumed that pig gammagamma-enolase is more similar than the composition data would indicate. Moreover, it is likely that the sequences of pig gammagamma-enolase and the other gammagamma-enolases are almost identical. Li+ proved to be a noncompetitive inhibitor with either 2-PGA or Mg2+ as the variable substrate. This enolase crystallized in the monoclinic space group P2, or P2(1). An Rsymm <5% was obtained for data between 50 and 3.65 A, but was a disappointing 30% for data between 3.65 and 3.10 A, indicating crystal disorder.

Sequences in the proximal 5' flanking region of the rat neuron-specific enolase (NSE) gene are sufficient for cell type-specific reporter gene expression

We investigated the regulation of the rat neuron-specific enolase gene using a transient transfection approach. Recent transgenic mouse studies have shown that a 1.8-kb segment of the rat NSE gene 5' flanking region, including the first (noncoding) exon but not the first intron, is able to drive expression of a reporter gene in parallel with endogenous NSE. These data suggest that cis-acting elements responsible for the spatial and temporal pattern of NSE gene expression are located within the proximal 1.8 kb of the 5' flanking sequence. To further investigate this region, we joined the 1.8-kb regulatory cassette to the cat reporter gene and generated a number of constructs in which the flanking sequence was progressively deleted from the 5' end. These constructs were tested by transient transfection into neuronal and nonneuronal cells, followed by an assay for CAT activity. We found that as little as 255 bp of 5' flanking sequence was able to confer cell type-specificity on the reporter gene. Further truncation to 120 bp of 5' sequence resulted in a sharp downregulation of reporter activity in PC12 cells but a significant rise in both Neuro-2A neuroblastoma cells and nonneuronal Ltk- cells, indicating that cis-acting elements controlling the regulation of NSE in Ltk-, Neuro-2A, and PC12 cells may lie within the 135 bp region covered by this deletion. This region contains an AP-2 site and an element similar in sequence and position to a motif identified in the proximal promoter region of the neuron-specific peripherin gene. Reduction to 95 bp of 5' sequence resulted in a slight downregulation of CAT activity in all cell lines tested, and further truncation to 65 bp of 5' sequence caused a universal reduction to background levels of CAT activity, concomitant with the disruption of the basal NSE promoter. Our results show that the 5' flanking region of the NSE gene is capable of conferring cell type-specificity on a heterologous gene in transfected cells and that elements responsible for this are located within the proximal 255 bp.

Expression of APP in transgenic mice: a comparison of neuron-specific promoters

The beta-amyloid precursor protein (APP) carries mutations in codons 717 or 670/671, which cosegregate with familial forms of Alzheimer's disease (AD). As an initial step to study the related pathogenetic mechanisms in vivo we have generated transgenic mice expressing APP with these mutations. Several neuron-specific promoters were used to drive expression of human APP cDNAs. Only the Thy-1 promoter yielded transgene expression levels comparable to or above the endogenous mouse levels. Deletion of a 121 bp sequence from the 3' untranslated region of APP appeared to increase mRNA levels. Transgene mRNA was found throughout the brain with highest levels in hippocampus and cerebral cortex. Accordingly, human APP was detected in these regions by Western blotting. Protein levels paralleled mRNA levels reaching or exceeding the amount of endogenous APP. Variable reactivity of human APP in cell bodies was shown by immunocytochemistry. Although our initial histological examinations did not reveal any alterations characteristic of AD, further studied will be required.

Gene structure and chromosomal localization of the mouse NMDA receptor channel subunits

Multiple espilon subunits are major determinants of the diversity of the N-methyl-D-aspartate (NMDA) receptor channel. The four epsilon subunit mRNAs exhibit distinct expression patterns in the brain. In an attempt to elucidate the molecular basis of selective and characteristic expression of the NMDA receptor channel subunits, we have isolated the gene encoding the mouse NMDA receptor epsilon 3 subunit and have determined its structural organization. The epsilon 3 subunit gene spans 17.5 kb and consists of 14 exons. The major transcription start site is 439 bp upstream of the ATG initiation codon as determined by primer extension and S1 nucleas protection analyses. Two polyadenylation sites are 397 (or 398) and 402 bp downstream of the termination codon. The 5'-flanking region of the epsilon 3 subunit gene contains GC-rich segments including consensus sequences for binding of the transcription factors Spl and EGR-1. The murine chromosomal locations of the five NMDA receptor channel subunits, the epsilon 1 (Grin2a), epsilon 2 (Grin2b), epsilon 3 (Grin2c), epsilon 4 (Grin2d) and zeta 1 (Grinl) subunits, were determined using an interspecific backcross mapping panel derived from crosses of [(C57BL/6JxM. spretus) F1xC57BL/6J] mice. Each of these genes mapped to a single chromosome location. The mapping results assigned the five loci to five different mouse autosomes, indicating that they have become well dispersed among mouse chromosomes.

Cloning, expression, and chromosomal localization of the rat mitochondrial capsule selenoprotein gene (MCS): the reading frame does not contain potential UGA selenocysteine codons

The mitochondrial capsule selenoprotein (MCS) is a selenium-containing polypeptide. It is one of three proteins that are important for the maintenance and stabilization of the crescent structure of the sperm mitochondria. In this paper, we report the isolation and characterization of the rat MCS cDNA and gene. The cDNA contains a reading frame for a 145-amino-acid protein and it lacks the UGA codons, which have been found in the reading frame of the mouse MCS cDNA and have been presumed to encode the selenocysteine in the amino terminal of the deduced mouse amino acid sequence. The deduced amino acid sequence of the rat and mouse MCS shows a high level of homology (79%). The rat MCS gene contains two exons; the intron sequence interrupts the 5' untranslated sequence at the same position as in the mouse MCS gene. The transcription start site is located 184 bp upstream of the translation start site. Alignment of the 5'-flanking regions of the mouse and rat genes reveals that the first 400 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 73%. This conserved region contains no TATA or CAAT box motifs. Northern blot analysis indicates that the MCS mRNA is detectable only in the testis after day 30 of postnatal development. Moreover, in situ hybridization revealed that the rat MCS gene is mainly expressed in round spermatids. From the analysis of mouse-rat cell hybrids that segregate rat chromosomes, the MCS gene was assigned to rat chromosome 2.

Multiple neuron-specific enhancers in the gene coding for the human neurofilament light chain

To define DNA regions involved in the neuron-specific expression of the neurofilament light (NF-L) gene, we generated transgenic mice bearing different NF-L constructs. A 4.9-kilobase human NF-L fragment including -292 base pairs of 5'-flanking sequences contained sufficient elements for nervous system expression in transgenic mice. Deletion of introns 1 and 2 from this 4.9-kilobase DNA fragment resulted in reduced levels of transgene expression in the cortex, while deletion of intron 3 had little effect. Both introns 1 and 2 could act independently as enhancers to confer neuronal expression of the basal heat shock promoter (hsp68) fused to lacZ in transgenic mice. The hNF-L basal promoter (-292 base pairs) was found to contain elements for directing neuronal expression of either the lacZ reporter gene or an intronless hNF-L construct. Sequence comparison revealed that intron 1, intron 2, and the basal human NF-L promoter all contain an ETS-like motif, CAGGA, present in a variety of genes expressed in the nervous system.

Consequences of cytotoxic T lymphocyte interaction with major histocompatibility complex class I-expressing neurons in vivo

Neurons have evolved strategies to evade immune surveillance that include an inability to synthesize the heavy chain of the class I major histocompatibility complex (MHC), proteins that are necessary for cytotoxic T lymphocyte (CTL) recognition of target cells. Multiple viruses have taken advantage of the lack of CTL-mediated recognition and killing of neurons by establishing persistent neuronal infections and thereby escaping attack by antiviral CTL. We have expressed a class I MHC molecule (Db) in neurons of transgenic mice using the neuron-specific enolase (NSE) promoter to determine the pathogenic consequences of CTL recognition of virally infected, MHC-expressing central nervous system (CNS) neurons. The NSE-Db transgene was expressed in H-2b founder mice, and transgene-derived messenger RNA was detected by reverse transcriptase-polymerase chain reaction in transgenic brains from several lines. Purified primary neurons from transgenic but not from nontransgenic mice adhered to coverslips coated with a conformation-dependent monoclonal antibody directed against the Dv molecule and presented viral peptide to CTL in an MHC-restricted manner, indicating that the Db molecule was expressed on transgenic neurons in a functional form. Transgenic mice infected with the neurotropic lymphocytic choriomeningitis virus (LCMV) and given anti-LCMV, MHC-restricted CTL displayed a high morbidity and mortality when compared with controls receiving MHC-mismatched CTL or expressing alternative transgenes. After CTL transfer, transgenic brains showed an increased number of CD8+ cells compared with nontransgenic controls as well as an increased rate of clearance of infectious virus from the CNS. Additionally, an increase in blood-brain barrier permeability was detected during viral clearance in NSE-Db transgenic mice and lasted several months after clearance of virus from neurons. In contrast, LCMV-infected, nontransgenic littermates and mice expressing other gene products from the NSE promoter showed no CNS disease, no increased intraparenchymal CTL, and no blood-brain barrier damage after the adoptive transfer of antiviral CTL. Our study indicates that viral infections and CTL-CNS interactions may induce blood-brain barrier disruptions and neurologic disease by a "hit-and-run" mechanism, triggering a cascade of pathogenic events that proceeds in the absence of continual viral stimulation.

The human synapsin II gene promoter. Possible role for the transcription factor zif268/egr-1, polyoma enhancer activator 3, and AP2

Synapsin II is a neuron-specific phosphoprotein that selectively binds to small synaptic vesicles in the presynaptic nerve terminal. Here we report the cloning and sequencing of the 5'-flanking region of the human synapsin II gene. This sequence is very GC-rich and lacks a TATA or CAAT box. Two major transcriptional start sites were mapped. A hybrid gene consisting of the Escherichia coli chloramphenicol acetyltransferase gene under the control of 837 base pairs of the synapsin II 5'-upstream region was transfected into neuronal and nonneuronal cells. While reporter gene expression was low in neuroblastoma and non-neuronal cells, high chloramphenicol acetyltransferase activities were monitored in PC12 pheochromocytoma cells. However, there was no correlation between reporter gene expression in the transfected cells and endogenous synapsin II immunoreactivity. Using DNA-protein binding assays we showed that the transcription factors zif268/egr-1, polyoma enhancer activator 3 (PEA3), and AP2 specifically contact the synapsin II promoter DNA in vitro. Moreover, the zif268/egr-1 protein as well as PEA3 were shown to stimulate transcription of a reporter gene containing synapsin II promoter sequences. In the nervous system, zif268/egr-1 functions as a "third messenger" with a potential role in synaptic plasticity. PEA3 is expressed in the brain and its activity is regulated by proteins encoded from non-nuclear oncogenes. We postulate that zif268/egr-1 and PEA3 couple extracellular signals to long-term responses by regulating synapsin II gene expression.

Functional dissection of the brain-specific rat aldolase C gene promoter in transgenic mice. Essential role of two GC-rich boxes and an HNF3 binding site

The aldolase C gene product is a glycolytic isoenzyme specifically detected in brain. We have previously defined a short 115-base pair promoter fragment able to confer on a reporter chloramphenicol acetyltransferase (CAT) gene a specific expression in brain of transgenic mice. In this promoter fragment, two GC-rich regions (A/A' and B boxes) were detected by in vitro DNase1 footprinting experiments with brain, fibroblast, or liver nuclear extracts. Both A/A' and B boxes, sharing structural homology, are able to interact with Sp1, Krox20/Krox24 factors and with other proteins (Thomas, M., Makeh, I., Briand, P., Kahn, A., and Skala, H. (1993) Eur. J. Biochem. 218, 143-151). In this paper, we describe a new ubiquitous factor termed Ub able to bind the A/A' box. We also delimit a third element (box C) binding a hepatocyte-enriched protein displaced by a hepatocyte nuclear factor 3-specific oligonucleotide. The functional involvement of each binding site in brain-specific transcription of the aldolase C gene has been tested in transgenic mice carrying different mutant promoters cloned in front of the CAT gene. A promoter containing only box C was totally inactive, suggesting an essential role of the region containing A/A' and B boxes. However, mutations or deletions of either the A/A' or the B box have no significant effect on the CAT gene expression. We therefore hypothesize that the A/A' and B sites may be functionally redundant. Indeed, constructs harboring only one of these two boxes (A/A' or B) linked to the C box displayed a brain-specific CAT activity similar to that obtained with the wild-type promoter. Furthermore, a transgene with disruption of the C box, keeping intact the A/A' and B boxes, was totally inactive, suggesting a crucial role of the hepatocyte nuclear factor 3 binding site in activation of the aldolase C gene.

Structure and regulation of the gene encoding the neuron-specific protein kinase C substrate neurogranin (RC3 protein)

A 13-kilobase pair genomic DNA encoding a 78-amino acid brain-specific calmodulin-binding protein kinase C (PKC) substrate, neurogranin (Ng/RC3; also known as RC3 or p17), has been sequenced. The Ng/RC3 gene is composed of four exons and three introns, with the protein-coding region located in the first and second exons. This gene was found to have multiple transcriptional start sites clustered within 20 base pairs (bp); it lacks the TATA, GC, and CCAAT boxes in the proximal upstream region of the start sites. The promoter activity was characterized by transfection of 293 cells with nested deletion mutants of the 5'-flanking region fused to the luciferase reporter gene. A minimal construct containing bp +11 to +256 was nearly as active as that covering bp -1508 to +256, whereas a shorter one covering bp +40 to +256 had a greatly reduced activity. Between bp +11 and +40 lies a 12-nucleotide sequence (CCCCGCCCACCC) containing overlapping binding sites for AP2 (CCGCCCACCC) and SP1 (CCCGCC); this region may be important for conferring the basal transcriptional activity of the Ng/RC3 gene. The expression of a Ng/RC3-luciferase fusion construct (-1508/+256) in transfected 293 cells was stimulated by phorbol 12-myristate 13-acetate (PMA), but not by cAMP, arachidonic acid, vitamin D, retinoic acid, or thyroxines T3 and T4. PMA caused a 2-4-fold stimulation of all the reporter gene constructs ranging from +11/+256 to -1508/+256. The stimulatory effects of PMA could be magnified by cotransfection with both Ca(2+)-dependent and -independent phorbol ester-binding PKC-alpha, -beta I, -beta II, -gamma, -delta, and -epsilon cDNAs, but not by non-phorbol ester-binding PKC-zeta cDNA. The Ng/RC3 and PKC-gamma genes have a similar expression pattern in the brain during development. These two genes share at least four conserved sequence segments 1.5 kilobase pair upstream from their transcriptional start sites and a gross similarity in that they possess several AT-rich segments within bp -550 to -950. A near homogeneous 20-kDa DNA-binding protein purified from rat brain was able to bind to these AT-rich regions of both Ng/RC3 and PKC-gamma genes with footprints containing ATTA, ATAA, and AATA sequences.

Upstream and intron regulatory regions for expression of the rat neuron-specific enolase gene

Neuron-specific enolase (NSE) occurs in mature neurons and paraneurons. We have isolated the genomic clone coding for rat NSE and clarified its gene structure. In order to analyze the regulatory sequence in the 5'-upstream region and introns, we carried out transient expression experiments of NSE genomic DNA fragments fused to chloramphenicol acetyltransferase (CAT) gene which were transfected into several cultured cells. The used cells were primary cultured rat neurons, PC12, neuroblastoma 35, neuroblastoma 103, C6, primary cultured rat glial cells and HeLa cells. The promoter sequence (190 bp) upstream to the transcription initiation site was important in the expression of CAT gene in these cells. From the experiments with external and internal deletion mutants of the fusion gene, the cis-acting regulatory region responsible for the enhanced expression of the CAT activity in the primary cultured neuron and PC12 cells was found to be localized at upstream 500 bp sequence of the intron 1 and 1.5 kbp upstream sequence of the transcription initiation site. In the upstream important sequences, there were the nearest sequences for AP-1 binding motif, AP-2 binding element, SP-1 binding sequence, cAMP response element, half site of glucocorticoid receptor (GRE) binding sequence, half site of thyroid hormor receptor (TR) or retinoic acid receptor (RAR) binding sequence and MTF-1 binding sequence. Furthermore, Octamer-6 binding motifs also were found. In the intron 1, 5' end upstream 50 bp and downstream 100 bp were the most important sequences. We found the nearest sequences for cAMP response element, E2F binding sequence, early growth response (EGR)-1 binding motif, half site of TCF-1 binding sequence and a neuron-specific element-like sequence in the intron 1.

Synaptotrophic effects of human amyloid beta protein precursors in the cortex of transgenic mice

The amyloid precursor protein (APP) is involved in Alzheimer's disease (AD) because its degradation products accumulate abnormally in AD brains and APP mutations are associated with early onset AD. However, its role in health and disease appears to be complex, with different APP derivatives showing either neurotoxic or neurotrophic effects in vitro. To elucidate the effects APP has on the brain in vivo, cDNAs encoding different forms of human APP (hAPP) were placed downstream of the neuron-specific enolase (NSE) promoter. In multiple lines of NSE-hAPP transgenic mice neuronal overexpression of hAPP was accompanied by an increase in the number of synaptophysin immunoreactive (SYN-IR) presynaptic terminals and in the expression of the growth-associated marker GAP-43. In lines expressing moderate levels of hAPP751 or hAPP695, this effect was more prominent in homozygous than in heterozygous transgenic mice. In contrast, a line with several-fold higher levels of hAPP695 expression showed less increase in SYN-IR presynaptic terminals per amount of hAPP expressed than the lower expressor lines and a decrease in synaptotrophic effects in homozygous compared with heterozygous offspring. Transgenic mice (2-24 months of age) showed no evidence for amyloid deposits or neurodegeneration. These findings suggest that APP may be important for the formation/maintenance of synapses in vivo and that its synaptotrophic effects may be critically dependent on the expression levels of different APP isoforms. Alterations in APP expression, processing or function could contribute to the synaptic pathology seen in AD.

Repeated electroconvulsive shock selectively increases the expression of the neuron specific enolase in piriform cortex

The effect of repeated electroconvulsive shock (ECS) on the activities of the three enolase isoenzymes present in rat brain: neuron specific enolase (NSE), non-neuronal enolase (NNE) and the hybrid enolase was investigated in piriform cortex. The activities were estimated on isoenzymes separated by agarose gel electrophoresis. Whereas the specific activities of NNE and hybrid enolase were unchanged in piriform cortex or ECS-treated rats the specific activity of NSE was increased by 16.3 percent (P < 0.02). The brain enolase isoenzymes are dimers of alpha- and gamma-enolase subunits. The calculated ratio between the gamma-subunit present in both NSE and hybrid enolase and the alpha-subunits present in both NNE and hybrid enolase was increased by 11.7 percent in piriform cortex of ECS-treated rats (P < 0.05). Previously, it has been shown that the gamma-subunit is only expressed in neurons whereas the alpha-subunit is expressed in both neurons and glial cells. The selectively increased expression of the enolase gamma-subunit in ECS-treated rats might either reflect an increased transcription of a whole group of neuronal genes or rather the trophic role of NSE in ECS-enhanced synaptic remodelling of the rat brain.

Methylation patterns in the human muscle-specific enolase gene (ENO3)

The methylation status in the human-muscle enolase gene (ENO3) was assayed. Previous sequence data and MspI cleavage sites indicate the presence of a 5' CpG-rich island of at least 4 kb: none of 22 characterized MspI CCGG sites is methylated in any of muscle, sperm or brain DNA. However a complex pattern of complete and partial methylation of MspI sites that is different between tissues is observed within the ENO3 gene: events at one site may be specific to muscle DNA. The absence of methylation in the promoter region of the ENO3 gene makes it unlikely that methylation plays a causal role either in transcriptional events or in the divergence of enolase-isogene regulation. The role of tissue-specific methylation events within ENO3 remains to be determined.

Structural features of the human gene for muscle-specific enolase. Differential splicing in the 5'-untranslated sequence generates two forms of mRNA

We report here the isolation and characterization of the human gene for the beta or muscle-specific isoform of the glycolytic enzyme enolase. The nucleotide sequence analysis revealed structural features, such as organization as 11 coding exons, the first exon consisting of an untranslated sequence and hence resembling sequences of the other two members of the gene family, the alpha and gamma enolase genes. The beta enolase locus spans about 6 kbp genomic DNA. Sequences matching the consensus sequence for muscle-specific regulatory factors are present in the 5'-flanking region and within the first intron. A combination of primer extension, S1 nuclease protection and RNA-sequencing experiments indicates that the gene has a unique transcriptional start site, 26 bp downstream of a TATA-like box; the differential usage of two donor sites within the untranslated exon I generates two alternatively spliced transcripts. The existence of the two mRNA, differing from one another in the presence or absence of a 42-nucleotide fragment in the leader sequence, was confirmed by cloning the corresponding cDNA using the rapid amplification of cDNA ends strategy. Secondary-structure predictions indicated that the leader sequences of the spliced forms could form hairpin structures with different free energies of formation, suggesting translational control.

Molecular cloning of cDNA and analysis of protein secondary structure of Candida albicans enolase, an abundant, immunodominant glycolytic enzyme

We isolated and sequenced a clone for Candida albicans enolase from a C. albicans cDNA library by using molecular genetic techniques. The 1.4-kbp cDNA encoded one long open reading frame of 440 amino acids which was 87 and 75% similar to predicted enolases of Saccharomyces cerevisiae and enolases from other organisms, respectively. The cDNA included the entire coding region and predicted a protein of molecular weight 47,178. The codon usage was highly biased and similar to that found for the highly expressed EF-1 alpha proteins of C. albicans. Northern (RNA) blot analysis showed that the enolase cDNA hybridized to an abundant C. albicans mRNA of 1.5 kb present in both yeast and hyphal growth forms. The polypeptide product of the cloned cDNA, which was purified as a recombinant protein fused to glutathione S-transferase, had enolase enzymatic activity and inhibited radioimmunoprecipitation of a single C. albicans protein of molecular weight 47,000. Analysis of the predicted C. albicans enolase showed strong conservation in regions of alpha helices, beta sheets, and beta turns, as determined by comparison with the crystal structure of apo-enolase A of S. cerevisiae. The lack of cysteine residues and a two-amino-acid insertion in the main domain differentiated C. albicans enolase from S. cerevisiae enolase. Immunofluorescence of whole C. albicans cells by using a mouse antiserum generated against the purified fusion protein showed that enolase is not located on the surface of C. albicans. Recombinant C. albicans enolase will be useful in understanding the pathogenesis and host immune response in disseminated candidiasis, since enolase is an immunodominant antigen which circulates during disseminated infections.

Intragenic regulatory elements contribute to transcriptional control of the neurofilament light gene

To date, no DNA regions involved in the neuron-specific expression of the neurofilament light gene (NF-L) have been defined using transfection assays in cultured cells. To identify those regulatory regions in the human NF-L gene, we generated transgenic mice with a construct containing the basal NF-L promoter (-292 to +15) fused to the cat gene and with three DNA fragments of 21.5, 7.6 and 4.9 kb each, including NF-L with different lengths of either 5'- or 3'-flanking sequences. We show that the proximal NF-L 5' region (0.3 kb) constitutes a weak promoter and that it lacks information to confer neural specificity. However, appropriate expression in the nervous system occurred when this minimal promoter was combined with either 7.3 or 4.6 kb of NF-L sequences downstream from the transcription start point. We conclude that the intragenic NF-L region contains cis-acting elements conferring cell-type-specific regulation on the basal activity of the NF-L promoter. Interestingly, AP-2 motifs were found within homologously placed introns of all three NF genes, as well as in the promoter regulatory regions of many neuronal genes. We propose that the acquisition of introns by an ancestral intronless IF gene may have contributed to the emergence of a lineage of IF genes expressed in the nervous system.

Gene expression in cells of the central nervous system

This review summarized a part of our studies over a long period of time, relating them to the literature on the same topics. We aimed our research toward an understanding of the genetic origin of brain specific proteins, identified by B. W. Moore and of the high complexity of the nucleotide sequence of brain mRNA, originally investigated by W. E. Hahn, but have not completely achieved the projected goal. According to our studies, the reason for the high complexity in the RNA of brain nuclei might be the high complexity in neuronal nuclear RNA as described in the Introduction. Although one possible explanation is that it results from the summation of RNA complexities of several neuronal types, our saturation hybridization study with RNA from the isolated nuclei of granule cells showed an equally high sequence complexity as that of brain. It is likely that this type of neuron also contains numerous rare proteins and peptides, perhaps as many as 20,000 species which were not detectable even by two-dimensional PAGE. I was possible to gain insight into the reasons for the high sequence complexity of brain RNA by cloning the cDNA and genomic DNA of the brain-specific proteins as described in the previous sections. These data provided evidence for the long 3'-noncoding regions in the cDNA of the brain-specific proteins which caused the mRNA of brain to be larger than that from other tissues. During isolation of such large mRNAs, a molecule might be split into a 3'-poly(A)+RNA and 5'-poly(A)-RNA. In the studies on genomic DNA, genes with multiple transcription initiation sites were found in brain, such as CCK, CNP and MAG, in addition to NSE which was a housekeeping gene, and this may contribute to the high sequence complexity of brain RNA. Our studies also indicated the presence of genes with alternative splicing in brain, such as those for CNP, MAG and NGF, suggesting a further basis for greater RNA nucleotide sequence complexity. It is noteworthy that alternative splicing of the genes for MBP and PLP also produced multiple mRNAs. Such a mechanism may be a general characteristic of the genes for the myelin-specific proteins produced by oligodendrocytes. In considering the high nucleotide sequence complexity, it is interesting that MAG and S-100 beta genes etc. possess two additional sites for poly(A).(ABSTRACT TRUNCATED AT 400 WORDS)

Structure and expression of the duck alpha-enolase/tau-crystallin-encoding gene

In the duck, the glycolytic enzyme, alpha-enolase (alpha ENO) and the lens structural protein, tau-crystallin (tau CRY), are products of the same gene, an example of protein multi-functionality. We report that duck alpha ENO/tau CRY mRNA levels are developmentally regulated: alpha ENO/tau CRY mRNA levels in the lens increase over those in the liver by embryonic day 14 and, within the lens, are higher in the lens epithelium than in fiber cells. We determined the structure of the duck alpha ENO/tau CRY-encoding gene (alpha ENO/tau CRY), sequenced 1 kb of 5'-flanking region, and demonstrated that this region contains a functional promoter. The gene is 13 kb in size and is composed of twelve exons; the exon organization is identical to that of mammalian enolase-encoding genes. A fragment of 5'-flanking region (-803/+3) containing three CCAAT boxes and a TATA box was able to activate transcription of a heterologous reporter gene when transfected into cultured lens cells. However, in spite of greater quantities of alpha ENO/tau CRY mRNA and protein in the lens, the promoter was equally active in primary cultures of embryonic lens, liver and fibroblast cells. Since the cultured cells unexpectedly lost the restricted pattern of alpha ENO/tau CRY mRNA levels observed in vivo, evaluation of the promoter's tissue specificity was precluded.

Formation of beta-amyloid protein deposits in brains of transgenic mice

Deposits of beta-amyloid are one of the main pathological characteristics of Alzheimer's disease. The beta-amyloid peptide constituent (relative molecular mass 4,200) of the deposits is derived from the beta-amyloid precursor protein (beta-APP) which is expressed in several different isoforms. The two most prevalent beta-APP isoforms are distinguished by either the presence (beta-APP751) or absence (beta-APP695) of a Kunitz serine protease inhibitor domain. Changes in the abundance of different beta-APP messenger RNAs in brains of Alzheimer's disease victims have been widely reported. Although these results have been controversial, most evidence favours an increase in the mRNAs encoding protease inhibitor-containing isoforms of beta-APP and it is proposed that this change contributes to beta-amyloid formation. We have now produced an imbalance in the normal neuronal ratio of beta-APP isoforms by preparing transgenic mice expressing additional beta-APP751 under the control of a neural-specific promoter. The cortical and hippocampal brain regions of the transgenic mice display extracellular beta-amyloid immunoreactive deposits varying in size (less than 5-50 microns) and abundance. These results suggest that one mechanism of beta-amyloid formation may involve a disruption of the normal ratio of neuronal beta-APP isoform expression and support a direct relationship between increased expression of Kunitz inhibitor-bearing beta-APP isoforms and beta-amyloid deposition.

Purkinje cell protein-2 regulatory regions and transgene expression in cerebellar compartments

The Purkinje cell protein 2 (Pcp-2) is expressed in cerebellar Purkinje cells and retinal bipolar neurons. To illuminate how Pcp-2 expression is restricted to only two neuronal types and to derive tools to express heterologous genes in these neuronal subpopulations, genomic sequences of the mouse Pcp-2 gene have been cloned and flanking sequences have been evaluated as a source of neuron-specific regulatory elements. An upstream region with homology to other genes expressed in neurons was identified and a hybrid gene containing this sequence was constructed by ligating 0.4 kb of upstream and 0.3 kb of downstream Pcp-2-flanking DNA to lacZ. Transgenic mice bearing this construct exhibited beta-galactosidase in a wide array of neuron types, suggesting that this sequence may play an important role in specifying neuronal expression. Addition of a further 3.1 kb of Pcp-2 upstream sequences restricted expression of beta-galactosidase to a small number of neuron types and most notably to Purkinje cells within parasagitally oriented cerebellar compartments. The presence of elements lying within the 3.1-kb upstream region and acting to specifically restrict Pcp-2 expression is therefore suggested. Moreover, as beta-galactosidase was not expressed in the bipolar cells of these transgenic mice, retinal expression of the endogenous Pcp-2 gene must involve elements in addition to those conferring expression within Purkinje cells.

Structure of the gene encoding VGF, a nervous system-specific mRNA that is rapidly and selectively induced by nerve growth factor in PC12 cells

Nerve growth factor (NGF) plays a critical role in the development and survival of neurons in the peripheral nervous system. Following treatment with NGF but not epidermal growth factor, rat pheochromocytoma (PC12) cells undergo neural differentiation. We have cloned a nervous system-specific mRNA, NGF33.1, that is rapidly and relatively selectively induced by treatment of PC12 cells with NGF and basic fibroblast growth factor in comparison with epidermal growth factor. Analysis of the nucleic acid and predicted amino acid sequences of the NGF33.1 cDNA clone suggested that this clone corresponded to the NGF-inducible mRNA called VGF (A. Levi, J. D. Eldridge, and B. M. Paterson, Science 229:393-395, 1985; R. Possenti, J. D. Eldridge, B. M. Paterson, A. Grasso, and A. Levi, EMBO J. 8:2217-2223, 1989). We have used the NGF33.1 cDNA clone to isolate and characterize the VGF gene, and in this paper we report the complete sequence of the VGF gene, including 853 bases of 5' flank revealed TATAA and CCAAT elements, several GC boxes, and a consensus cyclic AMP response element-binding protein binding site. The VGF promoter contains sequences homologous to other NGF-inducible, neuronal promoters. We further show that VGF mRNA is induced in PC12 cells to a greater extent by depolarization and by phorbol-12-myristate-13-acetate treatment than by 8-bromo-cyclic AMP treatment. By Northern (RNA) and RNase protection analysis, VGF mRNA is detectable in embryonic and postnatal central and peripheral nervous tissues but not in a number of nonneural tissues. In the cascade of events which ultimately leads to the neural differentiation of NGF-treated PC12 cells, the VGF gene encodes the most rapidly and selectively regulated, nervous-system specific mRNA yet identified.

Complete structure of the human gene encoding neuron-specific enolase

At least three genes encode the different isoforms of the glycolytic enzyme enolase. We have isolated the gene for the human gamma- or neuron-specific enolase and determined the nucleotide sequence from upstream to the 5' end to beyond the polyadenylation site. The gene contains 12 exons distributed over 9213 nucleotides. Introns occur at positions identical to those reported for the homologous rat gene, as well as for the human alpha- or nonneuronal enolase gene, supporting the existence of a single ancestor for the members of this gene family. Primer extension analysis indicates that the gene has multiple start sites. The putative promoter region lacks canonical TATA and CAAT boxes, is very G + C-rich, and contains several potential regulatory sequences. Furthermore, an inverted Alu sequence is present approximately 572 nucleotides upstream of the major start site. A comparison of the 5'-flanking region of the human gamma-enolase gene with the same region of the rat gene revealed a high degree of sequence conservation.

Structure of the gene encoding VGF, a nervous system-specific mRNA that is rapidly and selectively induced by nerve growth factor in PC12 cells

Nerve growth factor (NGF) plays a critical role in the development and survival of neurons in the peripheral nervous system. Following treatment with NGF but not epidermal growth factor, rat pheochromocytoma (PC12) cells undergo neural differentiation. We have cloned a nervous system-specific mRNA, NGF33.1, that is rapidly and relatively selectively induced by treatment of PC12 cells with NGF and basic fibroblast growth factor in comparison with epidermal growth factor. Analysis of the nucleic acid and predicted amino acid sequences of the NGF33.1 cDNA clone suggested that this clone corresponded to the NGF-inducible mRNA called VGF (A. Levi, J. D. Eldridge, and B. M. Paterson, Science 229:393-395, 1985; R. Possenti, J. D. Eldridge, B. M. Paterson, A. Grasso, and A. Levi, EMBO J. 8:2217-2223, 1989). We have used the NGF33.1 cDNA clone to isolate and characterize the VGF gene, and in this paper we report the complete sequence of the VGF gene, including 853 bases of 5' flank revealed TATAA and CCAAT elements, several GC boxes, and a consensus cyclic AMP response element-binding protein binding site. The VGF promoter contains sequences homologous to other NGF-inducible, neuronal promoters. We further show that VGF mRNA is induced in PC12 cells to a greater extent by depolarization and by phorbol-12-myristate-13-acetate treatment than by 8-bromo-cyclic AMP treatment. By Northern (RNA) and RNase protection analysis, VGF mRNA is detectable in embryonic and postnatal central and peripheral nervous tissues but not in a number of nonneural tissues. In the cascade of events which ultimately leads to the neural differentiation of NGF-treated PC12 cells, the VGF gene encodes the most rapidly and selectively regulated, nervous-system specific mRNA yet identified.

Molecular structure of the human muscle-specific enolase gene (ENO3)

The single human gene for muscle-specific enolase was isolated and its structure was characterized, from which the mature mRNA transcript and encoded protein were also deduced. The gene contains 12 exons, spans approx. 6 kb and encodes a protein of 433 residues. The gene structure is similar to that found for the rat neuron-specific enolase gene, and the deduced protein aligns precisely with other enolase sequences, including the sequence of the only published crystallized enolase, yeast eno-1. The 5' boundary of the gene includes a 5' non-coding exon and is characterized by an upstream TATA-like box and CpG-rich region. This region contains potential recognition motifs for general transcriptional regulation involving Sp1, activator protein 1 and 2, CCAAT box transcription factor/nuclear factor I and cyclic AMP, and for muscle-specific transcriptional regulation involving a CC(A + T-rich)6GG box, M-CAT-box CAATCCT and two myocyte-specific enhancer-binding factor 1 boxes.

The synaptophysin-encoding gene in rat and man is specifically transcribed in neuroendocrine cells

Synaptophysin (SY) is an integral membrane protein of presynaptic small (30-80-nm) translucent vesicles also present in dispersed neuroendocrine cells. As the occurrence of this type of vesicle is specific for two major pathways of differentiation, the neuronal and neuroendocrine-epithelial information on the regulation of SY synthesis should contribute to an understanding of regulatory principles common to both pathways. Isolation and comparison of the complete rat and human single-copy genes showed that despite the difference in size (16 kb in rat vs. 13 kb in man) intron/exon boundaries are precisely conserved. Surprisingly, intron VI is located in the 3'-noncoding region in both species. The major transcriptional start point, as determined by primer extension and S1-nuclease protection analyses in rat pheochromocytoma-derived PC12 cells and rat brain, mapped to a site 27 nt 5' of the first methionine codon. Unexpectedly, the 5' upstream region is devoid of any TATA or CAAT boxes, but shows instead typical features of 'housekeeping' genes, i.e., G + C-rich islands and four Sp1-binding motifs. Using 'nuclear run-on' assays, we have identified examples in which SY synthesis is regulated at the transcriptional level. Reporter gene constructs showed that approx. 1.2 kb of the immediate upstream region contains promoter enhancer elements that were, however, insufficient to confer cell-type specific expression, whereas sequences farther upstream were able to suppress thymidine kinase promoter activity in a cell-type-dependent fashion.

Structure and expression of rat muscle-specific enolase gene

The structure of rat muscle-specific enolase (beta beta enolase) gene was determined. It comprises 12 exons of various lengths (59-223 bp) spanning about 6 kbp and its exon-intron organization is similar to that of neuron-specific enolase (gamma gamma enolase) gene. A transcriptional start site was identified by a combination of S1 nuclease mapping and primer extension analyses. In the 5'-flanking region we found a TATA-box-like sequence and several MyoD-binding motifs. The in vitro cell free transcription of the truncated genomic DNA fragment using HeLa cell extract showed that the transcription start site has been correctly identified and the promoter sequences work well.

Expression of DNA sequences containing neuron specific enolase gene in Escherichia coli

There is evidence that the gene for gamma-gamma enolase (neuron specific enolase, NSE) is regulated during cell differentiation and development, conserved in a variety of organisms and contains mRNA destabilizing sequences. In order to investigate further the mechanisms of these processes and to obtain large quantity of this protein, the NSE gene was isolated from neuroblastoma cells and cloned in E. coli using standard molecular biology techniques. The NSE gene expression was studied and the expressed protein (recombinant NSE) was characterized extensively. The recombinant NSE behaves like parental NSE in antisera specificity, resistance for chaotropic agents like urea, thermal stability at higher temperatures etc. The physical parameters like secondary structure, hydrophilicity, antigenic index and flexibility of the expressed protein were studied. The results of the present investigation collectively form the basis for initial investigations of how the expression of NSE gene is regulated. This is the first report where the recombinant NSE gene has been characterized so extensively.

Characterization of the transcription-initiation site and of the promoter region within the 5' flanking region of the human aldolase C gene

Several aldolase C clones from a human genomic library have been identified using a mouse aldolase C cDNA as a hybridization probe. The most complete fragment of the clones identified is 14 kb long and contains the complete aldolase C gene. The nucleotide sequence analysis of more than 5 kb includes the intron/exon organization structure of the gene and the 3' and 5' flanking regions. Although no human cDNA is yet available, a canonical polyadenylation signal at the 3' end of the gene indicates the proximity of the poly(A) addition site. We have analyzed the 5' noncoding region by S1 mapping and primer-extension experiments. The transcription-initiation sites for the human aldolase C gene in brain tissue was located about 1300 bp upstream from the methionine initiation codon. Preliminary functional assays of the promoter by transfection into rat glioma cells have indicated that promoter elements lie between positions -161 and -416 from the start point of transcription.

Alternative splicing of mouse brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase mRNA

A second cDNA for mouse brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase (cDNAII) encoding 420 amino acids was isolated. The only difference from the cDNA obtained previously (cDNAI), which encodes 400 amino acids, was the 5'-end 53 bp. Comparison of the sequence of the mouse gene with the sequence of cDNAII indicates alternative splicing within exon 1. The 5'-end sequence of cDNAII was found in a region of the gene upstream of exon 1 and a second transcription initiation site was identified.