Functional identification of an osmotic response element (ORE) in the promoter region of the killifish deiodinase 2 gene (FhDio2)
| Autor: | Carlota Garcı́a-G, Carlos Valverde-R, Patricia Kurczyn Villalobos, L López-Bojórquez, Aurea Orozco |
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| Rok vydání: | 2007 |
| Předmět: |
Fish Proteins
Thyroid Hormones Osmotic shock Physiology Deiodinase Electrophoretic Mobility Shift Assay Aquatic Science Response Elements Iodide Peroxidase Gene Expression Regulation Enzymologic Osmotic Pressure Fundulidae Transcriptional regulation Animals Homeostasis Electrophoretic mobility shift assay RNA Messenger Killifish Molecular Biology Conserved Sequence Ecology Evolution Behavior and Systematics Regulation of gene expression Base Sequence NFATC Transcription Factors biology Protein-Tyrosine Kinases biology.organism_classification Molecular biology Cell biology Insect Science Iodothyronine deiodinase Osmoregulation biology.protein Animal Science and Zoology |
| Zdroj: | Journal of Experimental Biology. 210:3126-3132 |
| ISSN: | 1477-9145 0022-0949 |
| Popis: | SUMMARY The physiological role played by thyroid hormones (TH) in hydro-osmotic homeostasis in fish remains a controversial issue. Previous studies have shown that in Fundulus heteroclitus (killifish) hypo-osmotic stress increases liver iodothyronine deiodinase type 2 (D2) mRNA and D2 activity. In this study we identified two conserved osmotic response element (ORE) motifs in the promoter region of the killifish D2 gene (FhDio2) and examined their possible role in the transcriptional regulation of FhDio2during hypo-osmotic stress. As assessed by the electrophoretic mobility shift assay, results from in vivo and in vitro experiments demonstrate that exposure to an abrupt hyposmotic challenge triggers in the liver of killifish a strong nuclear recruitment of a putative osmotic response element binding protein (OREBP). This protein–DNA binding is time-dependent, attains a maximum within 2–8 h after the osmotic stress,and is followed by a significant increase in D2 activity. Furthermore,protein–DNA binding and the subsequent elevation in enzyme activity were blocked by the tyrosine kinase inhibitor genistein. Thus, during hypo-osmotic stress, a putative OREBP kinase-activated pathway stimulates FhDio2transcription and enzymatic activity. These data and the fact that D2 is the major enzyme providing local intracellular T3 suggest that TH plays a direct role in osmoregulation in fish, possibly by participating in hepatic ammonia metabolism. This study provides important insight into the physiological role of TH in hydro-osmotic homeostasis in fish. |
| Databáze: | OpenAIRE |
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