Phylogenetic distribution of neuron-specific enolase

Evolutionary history of the enolase gene family

The enzyme enolase [EC 4.2.1.11] is found in all organisms, with vertebrates exhibiting tissue-specific isozymes encoded by three genes: alpha (alpha), beta (beta), and gamma (gamma) enolase. Limited taxonomic sampling of enolase has obscured the timing of gene duplication events. To help clarify the evolutionary history of the gene family, cDNAs were sequenced from six taxa representing major lineages of vertebrates: Chiloscyllium punctatum (shark), Amia calva (bowfin), Salmo trutta (trout), Latimeria chalumnae (coelacanth), Lepidosiren paradoxa (South American lungfish), and Neoceratodus forsteri (Australian lungfish). Phylogenetic analysis of all enolase and related gene sequences revealed an early gene duplication event prior to the last common ancestor of living organisms. Several distantly related archaebacterial sequences were designated as 'enolase-2', whereas all other enolase sequences were designated 'enolase-1'. Two of the three isozymes of enolase-1, alpha- and beta-enolase, were discovered in actinopterygian, sarcopterygian, and chondrichthian fishes. Phylogenetic analysis of vertebrate enolases revealed that the two gene duplications leading to the three isozymes of enolase-1 occurred subsequent to the divergence of living agnathans, near the Proterozoic/Phanerozoic boundary (approximately 550Mya). Two copies of enolase, designated alpha(1) and alpha(2), were found in the trout and are presumed to be the result of a genome duplication event.

Immunocytochemical expression of protein gene product (PGP) 9.5 in the cat bronchopulmonary neuroendocrine cells and nerves

Variously fixed, wax-embedded lung and gastrointestinal serial tissue sections from newborn to adult cats were stained with hematoxylin-eosin (H&E), Grimelius' silver, and immunohistochemical techniques using antisera to protein gene product (PGP) 9.5, a neuron-specific protein under strong evolutionary constraints. PGP 9.5 is revealed as a pan-neuroendocrine marker useful for tracing the pulmonary diffuse neuroendocrine system (PDNES) and studying the relationships between neuronal and neuroendocrine elements at various stages of life. Its occurrence is also compared in the pulmonary and the gastrointestinal tract. In spite of a close resemblance to already described neuroepithelial bodies (NEB) of other mammals, cat NEB feature typical constitutional and distributional difference, illustrating interspecies differences. The number of PGP 9.5 immunopositive pulmonary neuroendocrine cells declines gradually after 3 weeks and throughout adult life. Immunoreactivity in neuronal elements is lost after 1 week of age. In gastrointestinal tissues, only neuronal elements immunostain, suggesting functional variations or a separate embryological origin for enteroendocrine cells.

A confocal scanning laser microscope study of the peptidergic and serotoninergic components of the nervous system in larval Schistosoma mansoni

The localization and distribution of the serotoninergic and peptidergic elements of the nervous system of larval Schistosoma mansoni have been investigated using an indirect immunofluorescence technique in conjunction with confocal scanning laser microscopy (CSLM). A range of antisera was used, raised to the biogenic amine, 5-hydroxytryptamine (5-HT, or serotonin), the vertebrate peptides pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY) and to the native invertebrate peptide, FMRFamide; all these antisera were shown previously to be immunopositive in the adult worm. No immunoreactivity to 5-HT was detected in any of the larval stages, but both miracidia and cercariae were consistently immunoreactive to all 4 peptides. The peptidergic nervous system of the miracidium is relatively simple, taking the form of a central neural mass with associated paired anterior and posterior nerve tracts. The cercarial peptidergic nervous system comprises a central commissure joining paired anterior ganglia, from which emanate paired dorsal and ventral nerve tracts, which terminate at the body/tail junction. The excretory bladder region of the tail is also immunoreactive for the 4 peptides, and a fine pair of nerve tracts extends the length of the tail shaft. Immunoreactive nerve cell bodies are also evident in the midbody region of the intrasprocystic cercariae, these same structures being immunoreactive for the neuronal marker, neurone-specific enolase (NSE). The organization of the larval peptidergic nervous system is compared to that of the cholinergic nervous system and contrasted with the peptidergic system in the adult worm. The absence of immunoreactivity to 5-HT is discussed in relation to the proposed development of the aminergic nervous system upon establishment in the definitive host.

Enolase isoenzymes in adult and developing Xenopus laevis and characterization of a cloned enolase sequence

As part of a study of glycolysis during early development we have examined the pattern of expression of enolase isoenzymes in Xenopus laevis. In addition, the nucleotide sequence of a cDNA clone coding for the complete amino acid sequence of one enolase gene (ENO1) in X. laevis was determined. X. laevis ENO1 shows highest homology to mammalian non-neuronal enolase. Analysis of enolase isoenzymes in X. laevis by non-denaturing electrophoresis on cellulose acetate strips revealed five isoenzymes. One form was present in all tissues tested, two additional forms were expressed in oocytes, embryos, adult liver and adult brain, and two further forms were restricted to larval and adult muscle. Since enolase is a dimer, three different monomers (gene products) could account for the observed number of isoenzymes. This pattern of enolase isoenzyme expression in X. laevis differs from that of birds and mammals. In birds and mammals the most acidic form is neuron-specific and there is only one major isoenzyme expressed in the liver. RNAase protection experiments showed the presence of ENO1 mRNA in oocytes, liver and muscle, suggesting that it codes for a non-tissue-restricted isoenzyme. ENO1 mRNA concentrations are high in early oocytes, decrease during oogenesis and decrease further after fertilization. Enolase protein, however, is maintained at high concentrations throughout this period.

A comparison of the evolutionary distribution of the two neuroendocrine markers, neurone-specific enolase and protein gene product 9.5

One- and two-dimensional polyacrylamide gel electrophoresis followed by immunoblotting has been used to examine the phylogenetic distribution of the two neuronal and neuroendocrine proteins, neurone-specific enolase and protein gene product 9.5, in animal brains. A new immunoblotting procedure was used in which complex two-dimensional patterns of brain proteins were transferred to nitrocellulose paper simultaneously with the Coomassie Blue stain. This produced a copy of the blue spot pattern against which brown protein spots reacting in a specific antibody-immunoperoxidase procedure could be identified unequivocally. Extracts of human, bovine, sheep, rabbit, rat, guinea-pig, chicken, trout, and frog brains were examined. Proteins cross-reacting with antisera to the human forms of both proteins could be demonstrated in all species examined. This suggests that proteins corresponding to neurone-specific enolase and protein gene product 9.5 could have evolved at least 400 million years ago and have been highly conserved throughout evolution.

PGP 9.5--a new marker for vertebrate neurons and neuroendocrine cells

PGP 9.5 is a new cytoplasmic neuron-specific protein structurally and immunologically distinct from neuron-specific enolase. A specific antiserum has now shown that this protein is widely distributed in vertebrate brains and is also present in cells of the human diffuse neuroendocrine system. PGP 9.5 appears to be older than neuron-specific enolase in evolutionary terms, as an immunologically-related protein can be found in species as remote as the trout.

Neuron-specific and non-neuronal enolase in developing chick brain and primary cultures of chick neurons

Developmental changes of the neuron-specific enolase (NSE) and the non-neuronal enolase (NNE) were determined in pure neuronal, or mixed cultures of neuronal and glial cells, prepared from brains of 8-day-old chick embryos, as a function of cellular development with time in culture. The modifications observed in culture were compared to those measured in brain during the development of the nervous tissue in the embryo and during the post-hatching period. In the whole brain, the total enolase activity increases progressively until the adult level, the NSE appears only 4 days before hatching. The total enolase activity of pure neurons increases until 8 days of culture but the NSE never appears during this period. Mixed cultures of neurons and glial cells present an increase of total activity until 14 days of culture and neuron-specific form of the enzyme can be observed after 6 days of culture. Our results suggest that NSE appears only in the functional brain and is expressed in cultivated neurons only when glial cells are present simultaneously.

Development of neuron-specific enolase immunoreactivity in avian nervous tissue in vivo and in vitro

Neuron-specific enolase (NSE) is a glycolytic isoenzyme that is primarily located in neurons and neuroendocrine cells. The development of NSE immunoreactivity in th avian nervous system at the level of the hind limb has been examined using immunocytochemical methods. NSE immunoreactivity is first detected in ventral horn motor neurons and dorsal root ganglion neurons at embryonic day 9-10. This is at least 2-3 days after some neurons in both these populations are capable of electrical activity. The glycogen body, a non-neuronal structure, also exhibits NSE (+) staining, but the onset of this immunoreactivity is earlier, at 8 days of embryonic development. NSE immunoreactivity was absent from the cell bodies of paravertebral sympathetic ganglia throughout development, but was present in cellular processes and terminals in the adult ganglia. NSE immunoreactivity also develops in tissue cultures containing cells of neural tube and neural crest origin.