SEARCH · PubMed Health

Results for “Neuroglobin”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2002

Full-length cDNA cloning of human neuroglobin and tissue expression of rat neuroglobin.

Neuroglobin is a recently discovered respiratory, porphyrin-containing protein that is expressed in the brain of mouse and human. However, the full-length cDNA sequence and genomic organization of human neuroglobin have not been reported. In this paper, the full-length cDNA sequence of human neuroglobin was cloned following bioinformatic analysis and the rapid amplification of cDNA ends (RACE) technique. It was shown that the full-length cDNA sequence (GenBank Accession No. AF422796) of human neuroglobin is 1909 bp in size, and the genomic sequence is 8041 bp in size (GenBank Accession No. AF422797). To further study the characterization of this gene, the coding region of rat neuroglobin (GenBank Accession No. AF333245) was cloned by using degeneracy PCR. The result showed high conservation among human, rat, and mouse neuroglobin. Furthermore, it was demonstrated that NGB was extensively expressed in rat brain by using in situ hybridization and the immunohistochemical technique. Transcription of NGB mRNA was shown to be widely distributed throughout the adult rat brain, including cerebral cortex, hippocampus, thalamus, hypothalamus, olfactory bulb, and cerebellum. NGB protein immunoreactive cells were also widely distributed throughout normal adult rat brain, including cerebral cortex, hippocampus, thalamus, hypothalamus, pons, and cerebellum. It could be seen that the NGB-immunopositive signals were in the cytoplasma and processes of the neuron. These data strongly support the notion that neuroglobin is a highly conserved gene in evolution and is very important in the nervous system, possibly related to the oxygen supply of the neuron.

Aging↗

PubMed2006

Does neuroglobin protect neurons from ischemic insult? A quantitative investigation of neuroglobin expression following transient MCAo in spontaneously hypertensive rats.

Neuroglobin (NGB) is a recently characterized heme globin expressed primarily in retinal nerve cells and at very low levels in endocrine-active regions of vertebrate brains. When artificially over-expressed, NGB reduces the infarct size observed after transient Middle Cerebral Artery occlusion (tMCAo) in rats. This study addresses the post-ischemic NGB expression in vivo. Ten Spontaneously Hypertensive Rats (SHRs) were randomized to tMCAo (n = 6) or sham (n = 4), and euthanized 24 h later. NGB mRNA expression was determined by means of quantitative Reverse Transcription Polymerase Reaction (qRT-PCR). Thirteen animals subjected to either 90 min tMCAo (n = 7) or sham (n = 6) surgery, were euthanized 1 week after surgery. Post-ischemic expression of NGB and the neuronal marker NeuN was studied using free-floating immunohistochemistry. Design-based stereological quantification of NGB- and NeuN-positive cells in the striatum was performed using the optical fractionator. Significantly less NGB mRNA was expressed in the ischemic hemispheres of tMCAo animals after 24 h (P < or = 0.002). At the protein level, we found a significantly lower number of NGB- and NeuN-positive striatal neurons in tMCAo rats (P < or = 0.004). NGB expression was mainly confined to the hypothalamus and amygdala. Less than one out of every two thousand neurons expressed NGB in the striatum. In the ischemic territory we did not observe selective sparing of NGB expressing neurons. No significant change in the NGB/NeuN ratio was observed. Our data indicate that endogenous expressed NGB does not provide protection against ischemic injury induced by tMCAo in SHRs.

Amygdala↗

PubMed2004

Zebrafish reveals different and conserved features of vertebrate neuroglobin gene structure, expression pattern, and ligand binding.

Neuroglobin has been identified as a respiratory protein that is primarily expressed in the mammalian nervous system. Here we present the first detailed analysis of neuroglobin from a non-mammalian vertebrate, the zebrafish Danio rerio. The zebrafish neuroglobin gene reveals a mammalian-type exon-intron pattern in the coding region (B12.2, E11.0, and G7.0), plus an additional 5'-non-coding exon. Similar to the mammalian neuroglobin, the zebrafish protein displays a hexacoordinate deoxy-binding scheme. Flash photolysis kinetics show the competitive binding on the millisecond timescale of external ligands and the distal histidine, resulting in an oxygen affinity of 1 torr. Western blotting, immune staining, and mRNA in situ hybridization demonstrate neuroglobin expression in the fish central nervous system and the retina but also in the gills. Neurons containing neuroglobin have a widespread distribution in the brain but are also present in the olfactory system. In the fish retina, neuroglobin is mainly present in the inner segments of the photoreceptor cells. In the gills, the chloride cells were identified to express neuroglobin. Neuroglobin appears to be associated with mitochondria-rich cell types and thus oxygen consumption rates, suggesting a myoglobin-like function of this protein in facilitated oxygen diffusion.

Animals↗

PubMed2002

Expression analysis of neuroglobin mRNA in rodent tissues.

Neuroglobin is a respiratory protein which was reported to be preferentially expressed in the vertebrate brain. Here we present the first detailed analysis of the expression of neuroglobin in mouse and rat tissues. Neuroglobin mRNA was detected in all brain areas studied. Most, but not all, nerve cells were labeled, suggesting differential expression of Ngb. Neuroglobin mRNA was detected in the peripheral nervous system, explaining previous northern hybridization signals in organs other than the brain. Substantial neuroglobin expression was also found in metabolically active endocrine tissues such as the adrenal and pituitary glands. The granule localization of neuroglobin transcripts in various neuronal extensions let us speculate that peripheral translation of neuroglobin protein occurs. This could have important functional consequences for synaptic plasticity, an active metabolic process that needs large amounts of oxygen. The hybridization signals suggest that the local concentration of neuroglobin is sufficient for its putative primary function as an oxygen-supplying protein.

Adrenal Glands↗

PubMed2001

Biochemical characterization and ligand binding properties of neuroglobin, a novel member of the globin family.

Neuroglobin is a recently discovered member of the globin superfamily that is suggested to enhance the O(2) supply of the vertebrate brain. Spectral measurements with human and mouse recombinant neuroglobin provide evidence for a hexacoordinated deoxy ferrous (Fe(2+)) form, indicating a His-Fe(2+)-His binding scheme. O(2) or CO can displace the endogenous protein ligand, which is identified as the distal histidine by mutagenesis. The ferric (Fe(3+)) form of neuroglobin is also hexacoordinated with the protein ligand E7-His and does not exhibit pH dependence. Flash photolysis studies show a high recombination rate (k(on)) and a slow dissociation rate (k(off)) for both O(2) and CO, indicating a high intrinsic affinity for these ligands. However, because the rate-limiting step in ligand combination with the deoxy hexacoordinated form involves the dissociation of the protein ligand, O(2) and CO binding is suggested to be slow in vivo. Because of this competition, the observed O(2) affinity of recombinant human neuroglobin is average (1 torr at 37 degrees C). Neuroglobin has a high autoxidation rate, resulting in an oxidation at 37 degrees C by air within a few minutes. The oxidation/reduction potential of mouse neuroglobin (E'(o) = -129 mV) lies within the physiological range. Under natural conditions, recombinant mouse neuroglobin occurs as a monomer with disulfide-dependent formation of dimers. The biochemical and kinetic characteristics are discussed in view of the possible functions of neuroglobin in the vertebrate brain.

Animals↗

PubMed2006

Neuroglobin in normal retina and retina from eyes with advanced glaucoma.

BACKGROUND: Neuroglobin is a neurone specific respiratory protein that reversibly binds oxygen. Neuroglobin was discovered in 2000, initially in brain and later, at a 100 times greater concentration, in mouse retina. This protein may be involved in oxygen transport, and/or protection against oxidative stress or premature apoptosis. AIM: To examine the expression of neuroglobin in normal human retina and also in retina from eyes with advanced glaucoma, where hypoxia and ischaemia may be pathological factors. METHODS: Immunofluorescence and electron microscopy were used to examine sections of normal human retina and retina from eyes with end-stage glaucoma. RESULTS: Staining for neuroglobin was present in the plexiform layers and the photoreceptor inner segments in human retina, and increased expression was found to occur in these areas, as well as in the nuclear layers in advanced glaucoma. Much less staining for neuroglobin was present in the other retinal layers. CONCLUSION: Neuroglobin is found in those layers of the human retina that are rich in mitochondria and/or synapses, and consume the highest amount of oxygen. Neuroglobin may be involved in oxygen supply to mitochondria, or in protection from oxidative stress or apoptosis. Neuroglobin expression is increased in advanced glaucoma, and it may protect against hypoxic, ischaemic or oxidative stress, which are thought to be pathological factors that affect the retina in glaucoma.

Aged↗

PubMed2006

Gene transcription of neuroglobin is upregulated by hypoxia and anoxia in the brain of the anoxia-tolerant turtle Trachemys scripta.

Neuroglobin is a heme protein expressed in the vertebrate brain in mammals, fishes, and birds. The physiological role of neuroglobin is not completely understood but possibilities include serving as an intracellular oxygen-carrier or oxygen-sensor, as a terminal oxidase to regenerate NAD(+) under anaerobic conditions, or involvement in NO or ROS metabolism. As the vertebrate nervous system is particularly sensitive to hypoxia, an intracellular protein that helps sustain cellular respiration would aid hypoxic survival. However, the regulation of Neuroglobin (Ngb) under conditions of varying oxygen is controversial. This study examines the regulation of Ngb in an anoxia-tolerant vertebrate under conditions of hypoxia and anoxia. The freshwater turtle Trachemys scripta can withstand complete anoxia for days, and adaptations that permit neuronal survival have been extensively examined. Turtle neuroglobin specific primers were employed in RT-PCR for determining the regulation of neuroglobin mRNA expression in turtles placed in normoxia, hypoxia (4 h), anoxia (1 and 4 h), and anoxia-reoxygenation. Whole brain expression of neuroglobin is strongly upregulated by hypoxia and post-anoxic-reoxygenation in T. scripta, with a lesser degree of upregulation at 1 and 4 h anoxia. Our data implicate neuroglobin in mediating brain anoxic survival.

Analysis of Variance↗

PubMed2004

Neuron-specific expression of neuroglobin in mammals.

Neuroglobin, a vertebrate oxygen-binding protein, is expressed in many regions of the adult brain. We examined the cell type-specific expression of neuroglobin in neurons and astroglial cells in primary cultures of fetal hippocampal cells and sections of the adult mouse brain using neuroglobin-specific polyclonal antibodies and cell type-specific markers NeuN and GFAP to differentiate between neurons and glial cells. Neuroglobin is exclusively expressed in neurons, but not in astroglial cells. Accordingly, neuroglobin was detected in two neuroblastoma cell lines (N2a, SH-SY5Y) and the pheochromocytoma cell line PC-12, but not in glioblastoma cell lines (DKMG, GAMG) or other, non-neural cells (HeLa, Vero). Analysis of the neuroglobin genomic sequence from man and mouse identifies sequence motifs with similarity to the neuron-restrictive silencer element, possibly explaining a neuron-specific expression of neuroglobin.

Animals↗

PubMed2003

Localization of neuroglobin protein in the mouse brain.

Neuroglobin is a recently discovered vertebrate oxygen-binding respiratory protein. In situ hybridization data demonstrated that neuroglobin-mRNA is widely expressed in neuronal cells of the central and peripheral nervous systems as well as in endocrine cells. The present study was conducted to investigate the presence of neuroglobin protein in neurons of the mouse brain. A polyclonal antibody directed against a synthetic peptide of neuroglobin was raised in rabbits and affinity-purified. The specificity of the antibody was demonstrated by ELISA and preabsorption tests. We report here for the first time that neuroglobin is expressed on the protein level in many brain sites including cerebral cortical regions, subcortical structures such as thalamus and hypothalamus, nuclei of cranial nerves in the brainstem and cerebellum. Thus, the widespread distribution of neuroglobin protein is in good agreement with its mRNA localization. Regionally differing intensities of immunostaining suggest different levels of neuroglobin protein expression, in line with the idea that brain regions show variation in their tolerance towards hypoxic conditions.

Animals↗

PubMed2004

Interspecies comparison of neuroglobin, cytoglobin and myoglobin: sequence evolution and candidate regulatory elements.

Neuroglobin and cytoglobin are two novel members of the vertebrate globin family. Their physiological role is poorly understood, although both proteins bind oxygen reversibly and may be involved in cellular oxygen homeostasis. Here we investigate the selective constraints on coding and non-coding sequences of the neuroglobin and cytoglobin genes in human, mouse, rat and fish. Neuroglobin and cytoglobin are highly conserved, displaying very low levels of non-synonymous nucleotide substitutions. An oxygen supply function predicts distinct modes of gene regulation, involving hypoxia-responsive transcription factors. To detect conserved candidate regulatory elements, we compared the neuroglobin and cytoglobin genes in mammals and fish. The myoglobin gene was included to test if it also contains hypoxia-responsive regulatory elements. Long conserved non-coding sequences, indicative of gene-regulatory elements, were found in the cytoglobin and myoglobin, but not in the neuroglobin gene. Sequence comparison and experimental data allowed us to delimit upstream regions of the neuroglobin and cytoglobin genes that contain the putative promoters, defining candidate regulatory regions for functional tests. The neuroglobin and the myoglobin genes both lack conserved hypoxia-responsive elements (HREs) for transcriptional activation, but contain conserved hypoxia-inducible mRNA stabilization signals in their 3' untranslated regions. The cytoglobin gene, in contrast, harbors both conserved HREs and mRNA stabilization sites, strongly suggestive of an oxygen-dependent regulation.

Animals↗

PubMed2002

Hemin induces neuroglobin expression in neural cells.

Neuroglobin is a newly identified vertebrate globin that binds O(2) and is expressed in cerebral neurons. We found recently that neuronal expression of neuroglobin is stimulated by hypoxia and ischemia and protects neurons from hypoxic injury. Here we report that, like hemoglobin and myoglobin, neuroglobin expression can also be induced by hemin. Induction was concentration dependent and time dependent, with maximal (about 4-fold) increases in neuroglobin mRNA and protein levels occurring with 50 microM hemin and at 8 to 24 hours. The inductive effect of hemin was attenuated by the protein kinase G inhibitor KT5823 and the soluble guanylate cyclase inhibitor LY83583, was mimicked by treatment with 8-bromo-cyclic guanosine 3',5'-monophosphate, and was accompanied by a greater than 10-fold increase in cGMP levels, suggesting that it is mediated through protein kinase G and soluble guanylate cyclase. In contrast, hypoxic induction of neuroglobin was blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor PD98059, indicating that hemin and hypoxia regulate neuroglobin expression by different mechanisms. These results provide evidence for regulation of neuroglobin expression by at least 2 signal transduction pathways.

Base Sequence↗

PubMed2001

Neuroglobins from the zebrafish Danio rerio and the pufferfish Tetraodon nigroviridis.

Neuroglobin is a recently discovered respiratory, porphyrin-containing protein that is expressed in the brain of mouse and man. Here we show that neuroglobin is also present in the teleost fish. Complete cDNA sequences are reported from the pufferfish Tetraodon nigroviridis and the zebrafish Danio rerio. In addition, the neuroglobin gene of T. nigroviridis was sequenced, demonstrating the conservation of the B12.2, E11.0 and G7.0 introns plus the presence of an additional intron in the 5' noncoding region. The fish neuroglobins each comprise 159 amino acids and are 84.3% identical. Phylogenetic analyses show a basal position of the neuroglobins within the metazoan globin tree. An enhanced amino acid substitution rate was estimated for the fish neuroglobins ( approximately 0.93 x 10(-9) amino acid substitutions per site and year) compared with their mammalian proteins ( approximately 0.39 x 10(-9) replacements per site and year).

Amino Acid Sequence↗

PubMed2005

Neuroglobin and cytoglobin in search of their role in the vertebrate globin family.

Neuroglobin and cytoglobin are two recent additions to the family of heme-containing respiratory proteins of man and other vertebrates. Here, we review the present state of knowledge of the structures, ligand binding kinetics, evolution and expression patterns of these two proteins. These data provide a first glimpse into the possible physiological roles of these globins in the animal's metabolism. Both, neuroglobin and cytoglobin are structurally similar to myoglobin, although they contain distinct cavities that may be instrumental in ligand binding. Kinetic and structural studies show that neuroglobin and cytoglobin belong to the class of hexa-coordinated globins with a biphasic ligand-binding kinetics. Nevertheless, their oxygen affinities resemble that of myoglobin. While neuroglobin is evolutionarily related to the invertebrate nerve-globins, cytoglobin shares a more recent common ancestry with myoglobin. Neuroglobin expression is confined mainly to brain and a few other tissues, with the highest expression observed in the retina. Present evidence points to an important role of neuroglobin in neuronal oxygen homeostasis and hypoxia protection, though other functions are still conceivable. Cytoglobin is predominantly expressed in fibroblasts and related cell types, but also in distinct nerve cell populations. Much less is known about its function, although in fibroblasts it might be involved in collagen synthesis.

Amino Acid Sequence↗

PubMed2002

How does the eye breathe? Evidence for neuroglobin-mediated oxygen supply in the mammalian retina.

Visual performance of the vertebrate eye requires large amounts of oxygen, and thus the retina is one of the highest oxygen-consuming tissues of the body. Here we show that neuroglobin, a neuron-specific respiratory protein distantly related to hemoglobin and myoglobin, is present at high amounts in the mouse retina (approximately 100 microm). The estimated concentration of neuroglobin in the retina is thus about 100-fold higher than in the brain and is in the same range as that of myoglobin in the muscle. Neuroglobin is expressed in all neurons of the retina but not in the retinal pigment epithelium. Neuroglobin mRNA was detected in the perikarya of the nuclear and ganglion layers of the neuronal retina, whereas the protein was present mainly in the plexiform layers and in the ellipsoid region of photoreceptor inner segment. The distribution of neuroglobin correlates with the subcellular localization of mitochondria and with the relative oxygen demands, as the plexiform layers and the inner segment consume most of the retinal oxygen. These findings suggest that neuroglobin supplies oxygen to the retina, similar to myoglobin in the myocardium and the skeletal muscle.

Animals↗

PubMed2002

Nitric oxide binding properties of neuroglobin. A characterization by EPR and flash photolysis.

Neuroglobin is a recently discovered member of the globin superfamily. Combined electron paramagnetic resonance and optical measurements show that, in Escherichia coli cell cultures with low O(2) concentration overexpressing wild-type mouse recombinant neuroglobin, the heme protein is mainly in a hexacoordinated deoxy ferrous form (F8His-Fe(2+)-E7His), whereby for a small fraction of the protein the endogenous protein ligand is replaced by NO. Analogous studies for mutated neuroglobin (mutation of E7-His to Leu, Val, or Gln) reveal the predominant presence of the nitrosyl ferrous form. After sonication of the cells wild-type neuroglobin oxidizes rapidly to the hexacoordinated ferric form, whereas NO ligation initially protects the mutants from oxidation. Flash photolysis studies of wild-type neuroglobin and its E7 mutants show high recombination rates (k(on)) and low dissociation rates (k(off)) for NO, indicating a high intrinsic affinity for this ligand similar to that of other hemoglobins. Since the rate-limiting step in ligand combination with the deoxy-hexacoordinated wild-type form involves the dissociation of the protein ligand, NO binding is slower than for the related mutants. Structural and kinetic characteristics of neuroglobin and its mutants are analyzed. NO production in rapidly growing E. coli cell cultures is discussed.

Animals↗

PubMed2005

Divergent distribution in vascular and avascular mammalian retinae links neuroglobin to cellular respiration.

The visual function of the vertebrate retina relies on sufficient supply with oxygen. Neuroglobin is a respiratory protein thought to play an essential role in oxygen homeostasis of neuronal cells. For further understanding of its function, we compared the distribution of neuroglobin and mitochondria in both vascular and avascular mammalian retinae. In the vascular retinae of mouse and rat, oxygen is supplied by the outer choroidal, deep retinal, and inner capillaries. We show that in this type of retina, mitochondria are concentrated in the inner segments of photoreceptor cells, the outer and the inner plexiform layers, and the ganglion cell layer. These are the same regions in which oxygen consumption takes place and in which neuroglobin is present at high levels. In the avascular retina of guinea pig the deep retinal and inner capillaries are absent. Therefore, only the inner segments of the photoreceptors adjacent to choroidal capillaries display an oxidative metabolism. We demonstrate that in the retina of guinea pigs both neuroglobin and mitochondria are restricted to this layer. Our results clearly demonstrate an association of neuroglobin and mitochondria, thus supporting the hypothesis that neuroglobin is a respiratory protein that supplies oxygen to the respiratory chain.

Amino Acid Sequence↗

PubMedDate not supplied

Functional properties of neuroglobin and cytoglobin. Insights into the ancestral physiological roles of globins.

Neuroglobin and cytoglobin are two recently discovered vertebrate globins, which are expressed at low levels in neuronal tissues and in all tissues investigated so far, respectively. Based on their amino acid sequences, these globins appear to be phylogenetically ancient and to have mutated less during evolution in comparison to the other vertebrate globins, myoglobin and hemoglobin. As with some plant and bacterial globins, neuroglobin and cytoglobin hemes are hexacoordinate in the absence of external ligands, in that the heme iron atom coordinates both a proximal and a distal His residue. While the physiological role of hexacoordinate globins is still largely unclear, neuroglobin appears to participate in the cellular defence against hypoxia. We present the current knowledge on the functional properties of neuroglobin and cytoglobin, and describe a mathematical model to evaluate the role of mammalian retinal neuroglobin in supplying O2 supply to the mitochondria. As shown, the model argues against a significant such role for neuroglobin, that more likely plays a role to scavenge reactive oxygen and nitrogen species that are generated following brain hypoxia. The O2 binding properties of cytoglobin, which is upregulated upon hypoxia, are consistent with a role for this protein in O2-requiring reactions, such as those catalysed by hydroxylases.

Animals↗

PubMed2002

Neuroglobin, a novel member of the globin family, is expressed in focal regions of the brain.

Hemoproteins are widely distributed among unicellular eukaryotes, plants, and animals. In addition to myoglobin and hemoglobin, a third hemoprotein, neuroglobin, has recently been isolated from vertebrate brain. Although the functional role of this novel member of the globin family remains unclear, neuroglobin contains a heme-binding domain and may participate in diverse processes such as oxygen transport, oxygen storage, nitric oxide detoxification, or modulation of terminal oxidase activity. In this study we utilized in situ hybridization (ISH) and RT-PCR analyses to examine the expression of neuroglobin in the normoxic and hypoxic murine brain. In the normoxic adult mouse, neuroglobin expression was observed in focal regions of the brain, including the lateral tegmental nuclei, the preoptic nucleus, amygdala, locus coeruleus, and nucleus of the solitary tract. Using ISH and RT-PCR techniques, no significant changes in neuroglobin expression in the adult murine brain was observed in response to chronic 10% oxygen. These results support the hypothesis that neuroglobin is a hemoprotein that is expressed in the brain and may have diverse functional roles.

Animals↗