Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the expression of myosin heavy chain (MHC) isoenzymes in embryonic rat ventricles cultured in the anterior eye chamber of an adult rat. In oculo, these grafts beat and mature in an environment where the hormonal milieu can be manipulated. S1 nuclease protection assays were performed on pooled samples of ventricle grafts and compared to normally growing ventricles. At the time of grafting (embryonic day 12, E-12), 23 +/- 4% of the MHC mRNA was of the alpha isoform. While the proportion of ventricular alpha-MHC mRNA did not increase in utero, embryonic ventricles cultured in oculo showed a rapid increase in the relative amount of alpha-MHC mRNA expression (to 84 +/- 10% by 3 days and 86 +/- 5% by 8 days in oculo). alpha-MHC mRNA expression predominated through 8 weeks of culture in oculo, being 76% at 8 weeks in oculo. Additional experiments were performed to determine whether the rapid conversion to alpha-MHC expression resulted from exposure to adult levels of testosterone or thyroid hormone. Reduction of testosterone exposure to nondetectable levels by host orchiectomy did not affect the rapid conversion to alpha-MHC mRNA expression. Exposure to a hypothyroid milieu (i.e., PTU-treated hosts) decreased but did not prevent the conversion from beta- to alpha-MHC mRNA expression at 8 days in oculo; with 83% of the MHC mRNA being of the alpha isoform in hypothyroid hosts compared to 95% in euthyroid hosts. After 8 weeks of culture in hypothyroid hosts, however, alpha-MHC mRNA expression was undetectable in grafted ventricles. These data suggest that E-12 myocardial grafts respond to the hormonal milieu of an adult rat with rapid conversion from beta- to alpha-MHC mRNA expression and that alpha-MHC expression in early developing heart may show reduced sensitivity to downward modulation by a hypothyroid hormonal milieu.
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PMID:Rapid conversion from beta-MHC to alpha-MHC mRNA expression in embryonic rat ventricle cultured in oculo is not dependent on thyroid hormone or testosterone. 747 87

In oviparous species, in addition to a full-length estrogen receptor alpha (ER alpha), another ER alpha isoform lacking the A domain and exhibiting a ligand-independent transactivation function has been consistently reported. Although both isoforms are expressed in the liver, their respective sites of expression in other potential target tissues are unknown. In contrast to the situation in Xenopus and chicken, the two isoforms of rainbow trout (Oncorhynchus mykiss) are generated from two classes of transcripts with different 5' untranslated sequences issued from the same gene by alternative splicing and promoter usage. The aim of this study was to take advantage of the unique organization of the rainbow trout ER alpha gene to investigate the tissue distribution of these two messenger species along the reproductive axis of female trout. The S1 nuclease assay and in situ hybridization were used, with probes specific for each of the transcripts. Reverse transcription polymerase chain reaction (RT-PCR) with primers specific for each of the isoforms also was performed. The data indicated that the full-length ER alpha is expressed in liver, brain, pituitary, and ovary, whereas expression of the isoform with the truncated A domain is restricted to the liver, demonstrating a tissue-specific expression of these two ER alpha isoforms. The presence of a short liver-specific isoform in oviparous species suggests its role in the development and/or maintenance of the unique function of the liver in the vitellogenesis process.
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PMID:Tissue-specific expression of two structurally different estrogen receptor alpha isoforms along the female reproductive axis of an oviparous species, the rainbow trout. 1167 74