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.

[The echotomographic assessment of the thyroid bed in thyroidectomized subjects]

This study was aimed at evaluating the US anatomy of the postoperative thyroid bed. Fifteen normal patients (group A), 25 thyroidectomized patients (group B), and 2 patients with thyroid agenesis (group C) were evaluated by means of high-resolution real-time US. The examinations were performed with a 7.5 MHz small-parts linear transducer on the transverse, longitudinal, and oblique planes. Twenty-one patients in group B underwent subtotal thyroidectomy for multinodular goiter, 2 patients underwent an almost total thyroidectomy for Basedow's disease, and 2 patients were submitted to total thyroidectomy for papillary carcinoma. The most typical finding observed in group B was the close apposition of both carotid artery and jugular vein to the trachea. This finding was not observed in the patients in group C. No clear identification of parathyroid glands and of laryngeal nerves was possible in the patients in group B.

[Prenatal diagnosis of hydrolethalus (Salonen-Herva-Norio syndrome) in a woman with unknown risk: presentation of a case with long survival]

A female infant with hydrolethalus (Salonen-Herva-Norio) syndrome, an autosomal recessive disorder, is reported. This condition was suspected at 26 weeks of gestation by fetal ultrasonographic examination. The pregnancy was complicated by polyhydramnios. The newborn showed hydrocephalus, occipital encephalocele, micrognathia, interventricular defect, hallucal duplication. The patient died at age 5 months and 11 days.

Developmental changes of neuron-specific enolase mRNA in primary cultures of rat neurons

1. The level of mRNAs for neuron-specific enolase (NSE) and nonneuronal enolase (NNE) was studied in developing rat brain and in pure neuronal cultures of corresponding ages treated or not treated with triiodothyronine (T3). 2. In brain cortices both messages are already detectable at the earliest age (embryonal day 16; E16). During development the mRNA for NNE remains at a steady level, with a transient decline at postnatal day 5 (P5). 3. On the other hand, NSE mRNA follows a biphasic curve: the signal increases threefold from E-16 to P0 and threefold from P5 to P18, with a plateau between P0 and P5. 4. In neuronal cultures the NNE message is present at a constant level until day 10 and declines sharply thereafter, while in T3-treated cultures it reaches a minimum beforehand. 5. The NSE mRNA, on the other hand, increases continuously throughout the whole culture life span, and a slightly higher level is observed in T3-treated cells during the first ten days.

Differential expression of muscle-specific enolase in embryonic and fetal myogenic cells during mouse development

Three isoforms of the glycolytic enzyme enolase are present in mammals and birds. During development, a switch from the alpha to the beta form takes place in skeletal muscle. In order to investigate the molecular basis of this developmental transition of enolase isoforms, we extracted total RNA from limbs of mouse embryos of different ages, and from cultures of embryonic and fetal myogenic cells. The beta message was detected in limbs from 16-day-old fetuses by Northern-blot analysis and its level was found to increase in newborn and adult muscle; no significant amount of beta mRNA was present in samples from earlier developmental stages, which did however express high levels of the muscle-specific actin mRNA. Analysis of RNA extracted from embryonic and fetal myoblasts differentiated in culture revealed that the level of beta mRNA is about 9-fold higher in fetal myotubes than in embryonic myotubes, although the level of muscle actin is comparable in both types of myotubes. These results were confirmed by S1 nuclease protection experiments. Our data show that the appearance of beta enolase transcripts temporally correlates with the formation of the second generation of muscle fibers and suggest that the developmental transition from alpha to beta enolase is linked to a developmental program which takes place in fetal but not in embryonic muscle.

Structure of the human gene for alpha-enolase

In mammals there are at least three isoforms of the glycolytic enzyme enolase encoded by three similar genes: alpha, beta and gamma. In this report we describe the isolation and characterization of the human alpha-enolase locus. The gene appears to exist as a single copy in the haploid genome and is composed of 12 exons distributed over more than 18,000 bases. The structure of this gene has a high degree of similarity to that of the human and rat gamma-enolase genes, with identical positions for all the intron regions. Primer extension and S1 nuclease protection experiments indicate that transcription is initiated at multiple sites. The putative promoter region, like that of other house-keeping genes, lacks canonical TATA and CAAT boxes, is extremely G + C-rich and contains several potential SP1 binding sites. Furthermore, various sequences similar to known regulatory elements were detected.

The gene for the muscle-specific enolase is on the short arm of human chromosome 17

The human gene encoding the muscle-specific beta-enolase has been isolated. The beta-enolase gene was mapped to chromosome 17 by analysis of a panel of rodent-human somatic cell hybrids. The gene was further localized to the short arm and tentatively to the region 17pter-p11 by analysis of cell hybrids and transfectant cell lines carrying different portions of chromosome 17.

Cloning, expression and sequence homologies of cDNA for human gamma enolase

The nucleotide sequence of the human gamma-enolase mRNA was determined from recombinant cDNA clones. The sequence spans 2273 bp and includes the complete coding region of 1299 bp, a 5'-noncoding region of 74 bp and a 897-bp-long 3'-noncoding region containing a variant polyadenylation signal (ATTAAA). The deduced amino acid (aa) sequence is 433 aa long and shows a 97% similarity with rat gamma-enolase. Both the 5'- and 3'-untranslated regions are similar (82% and 68%, respectively) to the analogous regions of the rat gamma-enolase gene, suggesting that a strong selective pressure operates on noncoding segments of gamma-enolase mRNAs. The size of the gamma-enolase mRNA expressed in human brain is 2.4 kb. A crosshybridizing 1.5-kb message is detected in human skeletal muscle which may be derived from the beta-enolase-coding gene.

Hypothalamus-pituitary-adrenal axis of heroin addicts

The hypothalamus-pituitary-adrenal axis of heroin addicts was investigated by evaluating plasma cortisol levels throughout the day in 37 heroin abusers (HA), 17 of whom showed detectable morphine levels, indicating heroin administration in the previous hours and in 12 controls. All HA showed lower cortisol levels in basal condition (100.7 +/- 61.7 ng/ml, M +/- S.D.) compared to the control group (159.7 +/- 40.6, P less than 0.05). Moreover all HA (65.1 +/- 28.9%), and in particular those taking heroin during the study (39.1 +/- 41.4%), show a reduced cortisol decrease in the evening, which was significantly lower than in controls (85.3 +/- 10.1%; P less than 0.01). As far as the acute effects of opiates are concerned morphine (0.1 mg/kg) significantly reduced plasma cortisol levels within 60 min in a group of 8 healthy subjects. The same pattern was displayed by only 3/8 HA whose morphine levels were higher than 1 ng/ml, i.e. in those reaching the highest plasma morphine concentrations. These data indicate that chronic opiate abuse leads to a hypoadrenalism which could be the result of morphine-induced changes at the hypothalamic level.